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PARAFORMALDEHİT (PARAFORMALDEHYDE)

PARAFORMALDEHYDE

SYNONYMS: paraformaldehyde; para formaldehyde; para form aldehyde; peraformaldehyde; pera form aldehyde; pera formaldehyde; paraformaldehit; para formaldehit; para form aldehit; Paraformaldehyde; Para Formaldehyde; Para Form Aldehyde; Peraformaldehyde; Pera Form Aldehyde; Pera Formaldehyde; Paraformaldehit; Para formaldehit; Para Form Aldehit; PARAFORMALDEHIT; PARA FORMALDEHYDE; PARA FORM ALDEHYDE; PARAFORMALDEHYDE; PERA FORM ALDEHYDE; PERA FORMALDEHYDE; PARAFORMALDEHYDE; PARA FORMALDEHIT; PARA FORM ALDEHIT; formalin; methanal; formol; methylene oxide; paraformaldehyde; oxomethane; paraform; formic aldehyde; oxymethylene; methyl aldehyde; Polyoxymethylene; Polyoxymethylene; metaformaldehyde; paraform; formagene; paraffinize; paraffinoid; paraffinoma; parafoil; parafollicular cell; paraformaldehyde; paraganglioma; paraganglion; paragenesis; parageusia; paraglide; paraflutizide; parafoil; parafoils; parafollicular; paraformaldehyde; paraformer; paraformers; parafoveal; parafransoletite; paraganglia; formaldehyde; formalin; methanal; formol; Paraformaldehyde; Formaldehyde; Formalin; Formol; Methanal; Oxomethane; formaldehyde; formalin; methanal; formol; Paraformaldehyde; 50-00-0; Methylene oxide; Oxomethane; Paraform; Formic aldehyde; Oxymethylene; Methyl aldehyde; Fannoform; Formalith; Formaldehyde solution; Methaldehyde; Superlysoform; Formalina; Lysoform; Morbicid; Karsan; Formaldehyd; Formaline; Oxomethylene; Polyoxymethylene; Aldehyde formique; FYDE; Formaldehyde, gas; Formalin 40; Aldeide formica; 30525-89-4; Oplossingen; Dormol; Polyformaldehyde; Formalin-loesungen; Paraformic aldehyde; Rcra waste number U122; Aldacide; Aldehyd mravenci; Paraformaldehydum; Oilstop, Halowax; Flo-Mor; CH2O; UN 2209 (formalin); Formaldehyde (gas); Formaldehyde polymer; Formaline [German]; NCI-C02799; Formalina [Italian]; Oplossingen [Dutch]; HCHO; Caswell No. 465; Caswell No. 633; FORMYL GROUP; Polyoxymethylene glycol; Polymerised formaldehyde, Fordor; UN 1198; Aldehyd mravenci [Czech]; POLY(OXYMETHYLENE); Aldeide formica [Italian]; Aldehyde formique [French]; Formalin-loesungen [German]; Formaldehyd [Czech, Polish]; CCRIS 315; NSC 298885; Formaldehyde [USP]; HSDB 164; Aldehyde formique [ISO-French]; BFV; Formaldehyde, solution; UNII-1HG84L3525; CHEBI:16842; AI3-26806; HSDB 4070; Paraformaldehyde, polymer; UN1198; UN2209; UN2213; RCRA waste no. U122; EPA Pesticide Chemical Code 043001; EPA Pesticide Chemical Code 043002; Formalin Solution; UGFAIRIUMAVXCW-UHFFFAOYSA-N; WSFSSNUMVMOOMR-UHFFFAOYSA-N; Formaldehyde, Para; Formaldehyde (USP); MFCD00003274; 1HG84L3525; Formaldehyde, solution (37% to 50%); Formalde-Fresh Solution; DSSTox_CID_637; Formalin, Buffered, 10%; DSSTox_RID_82549; DSSTox_GSID_47796; CAS-NOCAS_47796; Formaldehyde, 37% by Weight; Formaldehyde, 40% by Volume; Paraformaldehyde, 90%, pure; Formaldehyd (CZECH, POLISH); Formalde-Fresh Solution, Buffered; Formalaz; Formaldehyde, solutions, flammable [UN1198] [Flammable liquid]; MFCD00133991; Formaldehyde, solutions with not <25% formaldehyde [UN2209] [Corrosive];; Buffer Solution, pH 4.00, Color-Coded Red; Formic aldehyde; Paraformaldehyde [JAN]; formaidehyde; formaldeyde; formaldhyde; methanon; paraformaldehyd; paraformaldehye; Paraformaldehyde [USP:JAN]; UNII-Y19UC83H8E; Formadehyde; Formaldehye; Veracur; Durine; paraformaidehyde; Formaldehyde, 37 wt% sol. in water, stab. with 5-15% methanol; Formaldehyde, ACS reagent, 37 wt% sol., stab. 10-15% methanol; para formaldehyde; paraform-aldehyde; Para-formaldehyde; Formalin solution, neutral buffered, 10%, histological tissue fixative; F-gen; Hyperband (TN); Formalin [JAN]; EINECS 200-001-8; Methan 21; CARBONMONOXIDE; HCOH; Floguard 1015; Formalin (JP17); CARBON-MONOXIDE; Hercules 37M6-8; RFPDT@; FORMALDEHYDE, ACS; H2CO; WLN: VHH; Formaldehyde [BSI:ISO]; Paraformaldehyde (JP17); ACMC-1AVX8; FORMALDEHYDE 37%; bmse000256; Epitope ID:116196; Melamine-Formaldehyde Resin; EC 200-001-8; Formaldehyde, 4% in PBS; Formaldehyde, methanol-free; AC1L19UQ; C3H8O; CHEMBL1255; Formaldehyde solution, 10%; BIDD:ER0493; GTPL4196; Y19UC83H8E; DTXSID7020637; CTK1G9461; Formaldehyde, solution, flammable; Formaldehyde, as formalin solution; Formaldehyde, solutions, flammable; KS-000010JW; Tox21_111160; Tox21_302438; ANW-44009; FM 282; LS-134; NSC298885; AKOS008967440; BufferPacTM Color-Coded Solutions; DB03843; Formaldehyde, 37% in aqueous solution; MCULE-1476806907; NA 9202; NSC-298885; RL03829; RTR-017915; UN 1016; UN 2209; Formaldehyde solution 37 wt. % in H2O; NCGC00255116-01; AN-24361; BP-21234; E240; SC-46956;Formaldehyde solution, 37 wt. % in H2O; AB1002009; LS-101266; TR-017915; F0622; FT-0626522; FT-0689115; P0018; Y1318; Formaldehyde solution ACS 37 wt. % in H2O; Paraformaldehyde [UN2213] [Flammable solid]; C00067; D00017; D01494; Formaldehyde, solutions (Formalin) (corrosive); Paraformaldehyde [UN2213] [Flammable solid]; A827922; Formaldehyde solution, tested according to Ph.Eur.; SR-01000944454; Formaldehyde, solutions with not <25% formaldehyde; SR-01000944454-1; I14-19020; I14-94270; I14-114193; Formaldehyde Solution, 10% w/w in 84.8 - 94.2% H2O; Paraformaldehyde, 16% w/v aqueous solution, methanol freeFormaldehyde neutral buffer solution, 3.7% formaldehyde in H2O; Formaldehyde neutral buffer solution, 7.5% formaldehyde in H2O; Formaldehyde solution, puriss. p.a., ACS reagent, >=36.5%; Formaldehyde solution, for molecular biology, 36.5-38% in H2O; Formaldehyde solution, meets analytical specification of USP, >=34.5 wt. %; Formaldehyde solution, puriss., 37.0%, contains 6.0-9.0% Methanol; Formaldehyde solution, AR, contains 5-8% methanol as stabilizer, 37-41 % (w/v); Formaldehyde solution, contains 10-15% methanol as stabilizer, 37 wt. % in H2O; Formaldehyde solution, for molecular biology, BioReagent, >=36.0% in H2O (T); Formaldehyde solution, JIS special grade, 36.0-38.0%, contains methanol as stabilizer; Formaldehyde solution, LR, contains 5-8% methanol as stabilizer, 37-41 % (w/v); Formaldehyde solution, SAJ first grade, >=35.0%, contains methanol as stabilizer; Formalin solution, neutral buffered, 10%, case of 24 x 60 mL, histological tissue fixative; Formalin solution, neutral buffered, 10%, case of 48 x 15 mL, histological tissue fixative; Formaldehyde solution, ACS reagent, 37 wt. % in H2O, contains 10-15% Methanol as stabilizer (to prevent polymerization); Formaldehyde solution, meets analytical specification of Ph.??Eur., BP, 35 wt. %, contains 10% methanol as stabilizer; Formaldehyde solution, meets USP testing specifications, contains 9.0-15% methanol as stabilizer; Formaldehyde solution, stabilized with methanol, ~37 wt. % in H2O, certified reference material; Formalin solution, neutral buffered, 10%, case of 24 x 120 mL, histological tissue fixative

 

Paraformaldehyde (PFA) is the smallest polyoxymethylene, the polymerization product of formaldehyde with a typical degree of polymerization of 8-100 units. Paraformaldehyde commonly has a slight odor of formaldehyde due to decomposition. Paraformaldehyde is a poly-acetal. Contents Synthesis Reactions Uses Toxicity See also References Synthesis Paraformaldehyde forms slowly in aqueous formaldehyde solutions as a white precipitate, especially if stored in the cold. Formalin actually contains very little monomeric formaldehyde; most of it forms short chains of polyformaldehyde. A small amount of methanol is often added as a stabilizer to limit the extent of polymerization. Reactions Paraformaldehyde can be depolymerized to formaldehyde gas by dry heating[1] and to formaldehyde solution by water in the presence of a base or heat. The high purity formaldehyde solutions obtained in this way are used as a fixative for microscopy and histology. The resulting formaldehyde gas from dry heating paraformaldehyde is flammable.
Uses
Paraformaldehyde Paraformaldehyde is the informal name of polyoxymethylene, a polymer of formaldehyde (also known by many other and confusing names, such as ‘paraform`, ‘formagene`, ‘para`, ‘polyoxymethane`). From: Materials Science for Dentistry (Tenth Edition), 2018 Related terms: TissuesAntibodyProteinGlutaraldehydeTriton X 100Fixative View all Topics Download as PDF Set alert About this page Learn more about Paraformaldehyde Gene Probes Joseph T. McCabe, Donald W. Pfaff, in Methods in Neurosciences, 1989
4% Paraformaldehyde in PBS Paraformaldehyde powder is dangerous to mucous membranes. When handling, avoid contact with eyes, wear gloves and a mask. To prepare paraformaldehyde fixative, warm PBS up to 65°C. Only then, with vigorous stirring, slowly add paraformaldehyde. Add 160 g paraformaldehyde/4 liters PBS, 40 g paraformaldehyde/1000 ml PBS, or 32 g/800 ml PBS. Gradually add a few drops of 6 M NaOH as a final clearing step, then filter with fluted filter paper. Do not allow the temperature of the paraformaldehyde solution to exceed 68°C and do not prepare paraformaldehyde too long before use (longer than 1 month) since it will polymerize. An alternative procedure is to prepare 2× paraformaldehyde in water. This paraformaldehyde will not polymerize as quickly, and can be used by diluting with 2× PBS.

 

 

1 Fixatives a "Karlsson-Schultz": 2.5% Glutaraldehyde/4% Formaldehyde in Phosphate Buffer pH 7.3 According to Karlsson and Schultz (1965) Paraformaldehyde (16%) stock solution: Mix 80 g paraformaldehyde with 450 ml H2O. Stir at 60°C for 15-20 min. Add droplets of 1 M NaOH until solution turns clear. Add H2O to a final volume of 500 ml. Filter with a NalgeneTM filter unit and freeze aliquots for storage (-20°C). Thaw aliquots at 60°C for use, the solution should be clear. Fixative working solution (200 ml): 0.36 g NaH2PO4∙H2O.
The amount of glutaraldehyde in this fixing solution can be reduced to 0.2% when samples should be processed for immunoelectron microscopy. In case of sensitive antigens, glutaraldehyde can also be omitted, but this will result in a less-preserved ultrastructure. An excellent and detailed protocol for cryosectioning according to Tokuyasu (1973) and immunolabeling of thawed cryosections is provided by Peters and Pierson (2008) and therefore not explained further here. b "Perfixol": 5% Glutaraldehyde/4% Formaldehyde in Cacodylate Buffer pH 7.2 According to Griffiths et al. (1981 Buffer (0.08 M Na-cacodylate, pH 7.2): Dissolve 8.56 g Na-cacodylate in 450 ml H2O. Adjust pH to 7.2 with 1 M HCl. Add H2O to a final volume of 500 ml. Fixative working solution (500 ml): 150 ml 0.08 M cacodylate buffer 250 ml 8% paraformaldehyde in H2O (final: 4%) 100 ml glutaraldehyde 25% in H2O, EM-grade (final: 5%) 0.33 g CaCl2∙2H2O Filter with a NalgeneTM filter, adjust pH to 7.2 if necessary. Embryo dishes (preferably black, if used for small, quasi-transparent samples) or crystallization dishes (e.g., from Agar, Stansted, U.K.); -0.2 M cacodylate buffer (contains arsenic compounds!), optionally supplemented with 2 mM sucrose; 0.05-0.1 M phosphate buffer, optionally supplemented with 2 mM sucrose and/or 0.02 mM magnesium sulfate; 0.001 M Tris-HCl, 1 mM CaCl2, 0.1 mM MgCl2, 0.1 mM KCl, 1 mM NaH2CO3, pH 7.8 (Hydra culture medium); Urethane was from Sigma-Aldrich, Inc (St Louis, U.S.A.); Paraformaldehyde (Sigma-Aldrich), glutaraldehyde, OsO4 crystals, epoxy resins (Epon, Spurr`s) were from Sigma-Aldrich (St Louis, MO), Agar-Scientific (Stansted, England), EMS (Hatfield, PA), Polysciences (Warrington, PE), or Ted Pella (Redding, CA). B Chemical Fixation 1 Chemicals (be aware that most of the reagents are more or less toxic and/or hazardous to health; for their safe use and disposal consult the relevant Material Safety Data Sheets) 0.05-0.2 M cacodylate buffer (contains arsenic compounds!), optionally supplemented with varying concentrations of sucrose. 0.05-0.1 M phosphate buffer, optionally supplemented with varying concentrations of sucrose and/or magnesium sulfate. Hydra culture medium: 0.001 M Tris-HCl, 1 mM CaCl2, 0.1 mM MgCl2, 0.1 mM KCl, 1 mM NaH2CO3; pH 7.8 (all Sigma-Aldrich or Merck). Urethane and 1-phenoxy-2-propanol (Sigma-Aldrich). Paraformaldehyde, potassium dichromate, as well as glutaraldehyde, OsO4 crystals, epoxy resins (Epon, Spurr`s) from Sigma-Aldrich, Agar (Stansted, U.K.), EMS (Hatfield, PA, U.S.A.), Polysciences (Warrington, PE, U.S.A.), or Ted Pella (Redding, CA, U.S.A.), LR-White acrylic resin from Sigma-Aldrich or London Resin Co (Woking, Surrey, U.K.). 2 Tools For specimen handling, embryo dishes (preferably black, if used for small, quasi-transparent species) or crystallization dishes (e.g., from Agar) and fine glass or small plastic pipettes were used.

 

 

D Preparation of Skin Tissue for In Situ Hybridization Paraformaldehyde is yet another method of fixation that allows for morphological and histological analyses, including in situ hybridization. Samples harvested for these types of experiments should be fixed immediately for optimal results. It is essential that tissues be handled quickly with RNAse-free instruments to protect against RNA degradation.
Samples should be immediately fixed in 4% paraformaldehyde that was freshly prepared in DEPC-treated H2O. Fix tissues for 16-24 hours at 4 °C and rinse thoroughly with DEPC-treated PBS. For whole-mount or large tissue samples only, permeabilize with 50% methanol in DEPC-treated PBS briefly and then 100% methanol at -20 °C. Permeabilization time can range from 30 minutes to several months, depending on the size of tissue. Rehydrate by washing with 50% methanol in PBST-DEPC for 5 minutes on a rocker. Repeat with 30% methanol in PBST-DEPC with two final washes in PBST-DEPC for 5 minutes each. Transfer samples to 20% DEPC-treated sucrose, and incubate at 4 °C until tissues sink to the bottom. This time can range from 2 hours to overnight. Transfer samples to OCT compound and embed as described previously. If possible, cut sections per slide at 5-10 μm. The steps involved in the preparation of probes, and their application for the detection of specific keratin mRNAs in skin tissue sections, have been described elsewhere (Tong and Coulombe, 2004; Wang et al., 2003).

 

Sörensen`s buffer: Make two stock solutions, 67 mM KH2PO4·H2O and 67 mM Na2HPO4 in Milli-Q water; to make a buffer solution of pH 7.2, mix 19.6 ml of 67 mM KH2PO4 and 80.4 ml of 67 mM Na2HPO4. Phosphate buffer (0.1 M): Make two stock solutions, 0.2 M NaH2 PO4·H2O and 0.2 M Na2HPO4; for 1 liter of pH 7.2, mix 95 ml of 0.2 M NaH2PO4·H2O, 405 ml of 0.2 M Na2HPO4, and 500 ml Milli-Q water. Tris buffer: 8.5 mM Na2HPO4, 3.5 mM KH2PO4, 120 mM NaCl, 41 mM tris(hydroxmethyl)aminomethane; adjust the pH to 7.6. Streptavidin diluent: 0.7% λ-carrageenan (Sigma, Type IV), 0.4% Triton X-100 in Tris buffer. Antibody diluent: 0.7% λ-carrageenan (Type IV), 0.4% Triton X-100, and 3% bovine serum albumin in Tris buffer. Poly-l-lysine (0.1%) for coating slides: 0.1% poly-l-lysine (MW > 300,000; Sigma) in Milli-Q water; aliquot in 1-ml vials; can be stored at -20°C for 3-4 months.

 

•3.1 Formaldehyde
Paraformaldehyde is the informal name of polyoxymethylene, a polymer of formaldehyde (also known by many other and confusing names, such as ‘paraform`, ‘formagene`, ‘para`, ‘polyoxymethane`). It is slowly formed as a white precipitate by condensation from the predominant species methanediol (formaldehyde hydrate) in solutions of formaldehyde (which may also be called ‘formalin`, ‘formal`, or ‘formalose`) on standing, in an equilibrium (Fig. 3.1). The solution is predominantly of oligomers, but when n becomes large enough the material becomes sufficiently insoluble as to precipitate, when the condensation may still continue. The resulting solid may have n range from ~ 8 to 100, or more. The reaction is driven to the left, to release formaldehyde, by a low concentration of formaldehyde, and accelerated by acidic or alkaline conditions. Solid paraformaldehyde smells plainly of the monomer (b.p. - 21 °C), so it is essentially a convenient means of delivering formaldehyde slowly.
Formaldehyde reacts (as the hydrate) with proteins, cross-linking them, by condensing with secondary amines at the peptide linkage (Fig. 27§3.5), and with the primary amines at the N-terminal or the side chains of arginine, histidine and lysine residues to create irreversible methylene bridges (Fig. 3.2).[48][49] Similar reactions also occur with the -SH group of cysteine residues, and the amines of DNA and RNA. Whilst such reactions are useful when tissue needs to be fixed for histological work, or simply museum specimens (or cadavers for dissection), clearly they are problematic in living systems. Indeed, formaldehyde is now known variously to be allergenic, generally toxic, extremely cytotoxic, mutagenic and carcinogenic, and so is increasingly under strict control in many contexts. Inhalation of the vapour must be avoided (the vapour pressure is high[50]). It is implicated as an asthma-inducer or exacerbator, and is a major component of house-fire smoke and photochemical smog. The use of paraformaldehyde, therefore, as an ingredient of endodontic cements[51] - to achieve so-called "mummification" (i.e. fixed tissue) - is now considered inappropriate (although not without controversy[52]). The inclusion of alkaline ingredients only serves to accelerate the hydrolysis and depolymerization. Sterilization would, of course, occur anyway. Formaldehyde itself is also used.[53] The acid hydrolysis of hexamethylene tetramine[54] (Fig. 3.3) (solubility in water ~ 850 g/L, 20 °C), an ingredient of one known endodontic product,[55] also yields formaldehyde.

 

Formaldehyde was formerly used as a dentine desensitizing agent, and has even been included in toothpastes (with a pungent taste!) for the same supposed effect, although unsuccessfully.[56][57]

Formaldehyde is also formed as a by-product of free-radical polymerization of methacrylates (as in filled resins) in the presence of oxygen (6§6),[58] and in this context may be a contributory factor to adverse reactions,[59] being released slowly over a long period, presumably as the peroxides break down. This might also occur with acrylic denture bases as an irritant for denture stomatitis or ‘sore mouth` in addition to residual MMA (5§2.7).[60] Since the precursor peroxides are not thermally stable, in heat-cured materials these will be decomposed and the resulting formaldehyde may escape, if allowed sufficient time. In cold-cure materials (5§3), this decomposition will not occur, and the available concentration will therefore be higher. Similar effects will occur in any chemically-similar system, such as so-called "resin-modified" GI cement (9§8.9).[61][62] This underlines the value of removing the oxygen-inhibited layer wherever possible.

Degradation of cyanoacrylates may proceed through depolymerization by hydrolysis (10§6.2), by the simple hydrolysis of the ester first, but another reaction occurs that also generates formaldehyde (Fig. 3.4).[63] Again, this may lead to the irritation of living tissue.

There is much concern over human exposure to formaldehyde because of the possibility of adverse reactions, despite the fact that it is present (at a low concentration, generally) in the environment from a number of natural sources as well as being a normal and essential physiological metabolite in man at very low concentrations, where it is not toxic.[64]

Paraformaldehyde: To 1 liter doubly distilled H2O, add 40 g paraformaldehyde and 12.5 g Na2HPO4 Chromic sulfuric acid: Combine 1800 ml sulfuric acid and 5 ml Chromerge (chromic sulfuric acid cleaning solution, J. T. Baker Chemical Co., Phillipsburg, NJ). Reuse until solution turns green Subbing solution [1% (w/v) gelatin, 0.1% (w/v) chrome alum]: To 1 liter doubly distilled H2O, add 10 g gelatin (heated to dissolve). Then add 1 g chromium potassium sulfate (chrome alum) Mounting solution: Combine 1 ml subbing solution with 9 ml doubly distilled H2O Concentrated (0.25 M) sodium phosphate buffer stock solution: Combine 30 g Na2HPO4 and 5.35 g NaH2PO4 · H2O and bring to 1000 ml with doubly distilled H2O. Store refrigerated up to 3 months Sodium phosphate-buffered saline (0.01 M, working solution): Combine 40 ml concentrated sodium phosphate buffer stock, 8.5 g NaCl, and 960 ml doubly distilled H2O. Bring to pH 7.4 with HNO3 or NaOH Boric acid/sodium tetraborate buffer (0.2 M): Bring 0.2 M boric acid (0.62 g in 50 ml doubly distilled H2O) to pH 8.5 with 0.05 M sodium tetraborate (0.95 g sodium tetraborate in 50 ml doubly distilled H2O). Store at room temperature 1-3 months 11.4 mg allantoin 3 ml boric acid/sodium tetraborate buffer, pH 7.5 20.2 mg cupric nitrate 1.2 g silver nitrate 6.4 ml pure pyridine Pour into washed container, wrap in aluminum foil, and place in 40°C water bath for 20-30 min before adding slides

 

Ammoniacal silver: Dissolve 18 g silver nitrate completely in 97.65 ml doubly distilled H2O; add
47.7 ml 0.4% (w/v) sodium hydroxide (NaOH)
4.5 ml acetone

 

Note: Add just enough ammonia to clear the solution. Ammonia may lose its potency over time, so the precise amount required may vary. This is a critical step since it determines the degree of silver impregnation. Too much ammonia prevents silver impregnation and too little can cause impregnation of normal tissue 7 ml 1% (w/v) citric acid 100 ml 100% (v/v) ethanol 881 ml neutralized doubly distilled H2O Sodium thiosulfate: 250 ml of a 1.0% (w/v) solution Potassium ferricyanide: 250 ml of a 0.5% (w/v) solution Sodium hydroxide: 250 ml of a 0.4% (w/v) solution Citric acid: 250 ml of a 1.0% (w/v) solution Formalin (10%, v/v): Add 2 ml 37% commercial formaldehyde solution to 18 ml doubly distilled H2O

 

2.1 Reagents
Paraformaldehyde (PFA) (Sigma, P6148) 5 M NaCl (Sigma, S5150-1L) SDS (Sigma) 1 M Tris-Cl, pH 6.5 at 25°C (KD Medical) 1 M Tris-Cl, pH 8.0 at 25°C (KD Medical) KOH (Sigma) Triton X-100 (Sigma) 0.5 M EDTA (Sigma) 0.1 M EGTA (Sigma) Proteinase Inhibitor cocktail (Roche, 11 836 153 001) DNase/RNase-Free Distilled Water (Invitrogen, 10977-023) PBS (KD Medical) TE (KD Medical) 8 M LiCl (Sigma, L7026) IGEPAL-CA630 (Sigma, 18896) Sodium deoxycholate monohydrate (Sigma, D5670) NaHCO3 (Sigma, S5761) Dynabeads Protein G (Invitrogen, Cat no: 10004D) Proteinase K, 20 mg/mL (Thermo Fisher Scientific # 25530049) Anti-DMC1 antibody (Abcam, Ab 11054) MinElute PCR Cleanup Kit (Qiagen, 28004) TruSeq Nano DNA LT Library Preparation Kit (Illumina) T4 DNA polymerase (3 U/μL, New England Biolabs, M0203) DNA Polymerase I Large (Klenow) Fragment (5 U/μL, New England Biolabs, M0210) T4 Polynucleotide Kinase (PNK) (10 U/μL, New England Biolabs, M0201) Klenow fragment (3′ → 5′ exo-) (5 U/μL with 10 × NEBuffer 2, New England Biolabs, M0212) Quick ligation kit (New England Biolabs, M2200) T4 DNA Ligase Reaction Buffer (New England Biolabs, B0202) dATP and dNTPs (New England Biolabs) Qubit dsDNA HS Assay Kit (Thermo Fisher Scientific # Q32851) or Quant-iT PicoGreen dsDNA Assay Kit (Thermo Fisher Scientific, P7589) AMPureXP beads (Beckman Coulter) Solutions for Perfusion and Postfixation Depolymerized paraformaldehyde (4%) for perfusion: Combine 40 g of paraformaldehyde powder, 22.6 g of NaH2PO4, and 25.2 g of NaOH; adjust final volume to 1000 ml with distilled H2O, and adjust pH to 7.3; heat solution to 65°C and add drops of 10 N NaOH until solution clears. Let solution cool before use Phosphate-buffered saline (PBS) (10 ×): Combine 90 g of NaCl, 1.22 g of KH2PO4, and 8.15 g of Na2PO4; adjust final volume to 1000 ml with distilled H2O, and adjust pH to 7.4. (To make 1 × PBS, dilute 100 ml of 10 × PBS in 900 ml of distilled H2O)
Sucrose medium: Combine the following: Turkey / TurkishHızlı Satın AlmaFavorilerBize Ulaşın Tümü ürün, CAS, Anahtar kelime, ... arama Arama GirişKayıt Ol 0 Sepet Home Ürünler Hizmetler Dokümanlar Sorumluluk Destek Hakkımızda About Our Brands Home>Reagents, Chemicals and Labware>Organic Synthesis>Organic Synthesis Product Groups>Aldehydes>Aliphatic and Araliphatic Aldehydes>Paraformaldehyde 818715 Sigma-Aldrich Paraformaldehyde Download Zoom

Paraformaldehyde for synthesis. CAS 30525-89-4, chemical formula (CH₂O)n. Paraformaldehyde: Malzeme Güvenlik Bilgi Formu (MSDS) veya SDS, Analiz Sertifikası (COA) ve Kalite Uygunluk Sertifikası (COQ), dosyalar, broşürler ve diğer dokümanlar. SDSCoA Hill Formula: (CH₂O)n CAS #: 30525-89-4 Chemical Formula: (CH₂O)n 818715 View Pricing & Availability Download Product Safety Card OverviewSupporting DocumentationRelated Products & Applications Overview Replacement Information Description Product Information Applications Physicochemical Information Toxicological Information Safety Information according to GHS Safety Information Storage and Shipping Information Transport Information Specifications Key Spec Table Pricing & Availability Replacement Information Replacement Information In North America 818715.1000 is identical to PX0055-3 but in a different pack size In North America 818715.0100 is identical to PX0055-3 but in a different pack size Key Spec Table CAS # Hill Formula Chemical Formula 30525-89-4 (CH₂O)n (CH₂O)n Pricing & Availability Number Availability Packaging Qty/Pack Price Quantity 8187150100 Contact Customer Service Plastic bottle 100 g Upon Order Completion More Information - Add To Favorites 8187151000 Contact Customer Service Plastic bottle 1 kg Upon Order Completion More Information Add To Favorites Add To Cart Description Catalogue Number 818715 Replaces PX0055-3 Product Information CAS number 30525-89-4 Hill Formula (CH₂O)n Chemical formula (CH₂O)n HS Code 2912 60 00 Structure formula Image Structure formula Image Applications Application Paraformaldehyde for synthesis. CAS 30525-89-4, chemical formula (CH₂O)n. Physicochemical Information Density 1.4 g/cm3 (20 °C) Explosion limit 7 - 73 %(V) Ignition temperature 300 °C Melting Point 100 - 130 °C pH value 5.5 (H₂O, 20 °C) (saturated solution) Vapor pressure 1.93 hPa (25 °C) Toxicological Information LD 50 oral LD50 Rat 592 mg/kg Safety Information according to GHS Hazard Pictogram(s) Hazard Pictogram(s) Hazard Pictogram(s) Hazard Pictogram(s) Hazard Statement(s) H350: May cause cancer. H302 + H332: Harmful if swallowed or if inhaled. H315: Causes skin irritation. H317: May cause an allergic skin reaction. H318: Causes serious eye damage. H335: May cause respiratory irritation. H341: Suspected of causing genetic defects. Precautionary Statement(s) P201: Obtain special instructions before use. : Wear protective gloves. P280: Wear eye protection. P302 + P352: IF ON SKIN: Wash with plenty of soap and water. P305 + P351 + P338: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
Signal Word Danger
RTECS RV0540000
Storage class 4.1B Flammable solid hazardous materials
WGK WGK 2 obviously hazardous to water
Disposal 3
Relatively unreactive organic reagents should be collected in container A. If halogenated, they should be collected in container B. For solid residues use container C.
Safety Information
Hazard Symbols Hazard SymbolsToxic
Categories of danger harmful, irritant, carcinogenic, sensitizing
R Phrase R 45-20/22-37/38-68-41-43
May cause cancer.Also harmful by inhalation and if swallowed.Irritating to respiratory system and skin.Possible risk of irreversible effects.Risk of serious damage to eyes.May cause sensitisation by skin contact.
S Phrase S 22-26-36/37-45-53
Do not breathe dust.In case of contact with eyes, rinse immediately with plenty of water and seek medical advice.Wear suitable protective clothing and gloves.In case of accident or if you feel unwell, seek medical advice immediately (show the label where possible).Avoid exposure - obtain special instructions before use.
Storage and Shipping Information
Storage Store at <= 20°C.
Transport Information
Declaration (railroad and road) ADR, RID UN 2213 , 4.1, III
Declaration (transport by air) IATA-DGR UN 2213 , 4.1, III
Declaration (transport by sea) IMDG-Code UN 2213 , 4.1, III
Specifications
Assay (acidimetric) ≥ 95.0 %
Identity (IR) passes test
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818715 Sigma-Aldrich
Paraformaldehyde
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104005
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Paraformaldehyde
Paraformaldehyde, 100 g sc-253236A 100 g RMB226.00 
Paraformaldehyde, 500 g sc-253236B 500 g RMB271.00 
Paraformaldehyde has documented uses as a disinfectant, fungicide, fixation reagent and in the preparation of formaldehyde. In fluorescence studies, paraformaldehyde has been used as as a formalin fixative to fix cells and tissues. To use the chemical as a fixative, it must be converted to the monomer formaldehyde by heating as formaldehyde is the active chemical in fixation.
Protocol for Making a 4% Formaldehyde Solution in PBS
The vast majority of IHC/ICC procedures employ fixation of tissues and cells using formaldehyde-based fixatives. The protocol below describes the technique for generating a 4% formaldehyde solution in PBS. The most effective fixative must be determined experimentally. Caution: Formaldehyde is toxic. Please read the MSDS before working with this chemical. Gloves and safety glasses should be worn and solutions made inside a fume hood. Please read the protocol in its entirety before starting.
Paraformaldehyde powder
1X PBS: 0.145 M NaCl, 0.0027 M KCl, 0.0081 M Na2HPO4, 0.0015 M KH2PO4, pH 7.4 Materials Filter units Glassware and stir bar (dedicated for formaldehyde solution) Gloves and eye protection Hot plate with magnetic stirrer Thermometer Ventilated hood Procedure For 1 L of 4% Formaldehyde, add 800 mL of 1X PBS to a glass beaker on a stir plate in a ventilated hood. Heat while stirring to approximately 60 °C. Take care that the solution does not boil. Add 40 g of paraformaldehyde powder to the heated PBS solution. The powder will not immediately dissolve into solution. Slowly raise the pH by adding 1 N NaOH dropwise from a pipette until the solution clears. Once the paraformaldehyde is dissolved, the solution should be cooled and filtered. Adjust the volume of the solution to 1 L with 1X PBS.
Recheck the pH, and adjust it with small amounts of dilute HCl to approximately 6.9. The solution can be aliquoted and frozen or stored at 2-8 °C for up to one month.
The difference between paraformaldehyde, formaldehyde, and formalin Paraformaldehyde (chemical name is polyoxymethylene) is a powder of polymerized formaldehyde that by itself cannot fix tissues. To be usable as a tissue fixative, paraformaldehyde has to be dissolved in hot water to become a formaldehyde solution. Formalin is a saturated formaldehyde solution in water (37% by weight, 40% by volume) containing 10-15% methanol. Methanol is added to slow down the polymerization to formaldehyde, which reduces the fixing power of formalin. Formalin can also be made in an alcohol-free form from powdered paraformaldehyde.
ICC/IHC Protocols
Paraformaldehyde (Paraform)
Abbreviation PFA
Plant Niigata
Main Applications Coating compounds, adhesive agent, textile-processing resins, phenol resins
Existing Chemical Substance No. (9)-1941
Properties
86%PFA 92%PFA
Chemical Formula HO(CH2O)nH
Molecular Weight n=2~100 (Melecular weight differs with number of `n`)
Appearance or other feature White, granular solid, pungent odor
Specific Gravity (true specific gravity) 1.25~1.35 1.30~1.40
Boiling Point (℃ 30mmHg) No data
Freezing Point (℃) 80~160 120~170
Flash Point (℃) Approx. 63 Approx. 93
Ignition Temperature (℃) Approx. 300
Dust Explosion: Lower Explosive Limit 40g/m3
Minimum Ignition Energy 20mJ
Solubility Hardly soluble in water, readily soluble in hot water
Stability&
Reactivity Highly reactive substance; mainly produces methylol and methylene compounds.
Applicable Laws
86%PFA 92%PFA
Industrial Safety and Health Law Hazard indication required, specified type 3 chemical (as formalin)
High Pressure Gas None
Fire Service Law Specified combustible
Poisonous and Deleterious Substances Control Law Deleterious substance (when containing formaldehyde)
Law on the Prevention of Marine Pollution and Maritime Disaster -
Ship Safety Law Hazardous material, Flammable materials
Civil Aeronautics Law Explosives, Flammable materials
Other Major Applicable Laws Air Pollution Control Law: specified toxic substance (as formalin)
Pharmaceutical Affairs Law: dangerous drug (designated drug)
(MGC does not directly market this chemical.)
Classification of Hazard
86%PFA 92%PFA
Classification Release corrosive and flammable formaldehyde.
Hazardous Explosive and hazardous mixture can be formed when flammable solid or dust is dispersed into the air.
Depolymerize with temperature increase and will release flammable formaldehyde which is toxic and corrosive.
Harmful Acute toxicity of medium grade and irritates the skin and the eye. Generated formaldehyde is classified into 2A of IARC, which means it is a probable carcinogen to man, and designated R43 (skin contact may cause sensitization) according to the EEC convention.
Product Standard
86%PFA 92%PFA
Appearance White solid
Formaldehyde Content (%) 86.0±1.0 92.0±1.0
Free Acid (% as formic acid) 0.02 or less
Ignition Residue (%) 0.01 or less
Chloride (Cl) (%) 0.002 or less
Heavy Metal (Pb) (%) 0.002 or less
Iron (Fe) (%) 0.001 or less
Inquiries Concerning Products
Natural Gas Chemicals Company
Organic Chemicals Division
Sales & Marketing Department II
TEL:+81-3-3283-4791 / FAX:+81-3-3214-0930
GUIDELINES FOR THE SAFE USE OF FORMALDEHYDE AND PARAFORMALDEHYDE
Exposure to formaldehyde can be irritating to the eyes, nose, and upper respiratory tract. In certain
individuals, repeated skin exposure to formaldehyde can cause sensitization that may result in allergic
dermatitis. Formaldehyde is a known human carcinogen1
and a suspected reproductive hazard.
The aqueous solution formalin is 37-40 percent formaldehyde in water or methanol. Paraformaldehyde is
the crystallized polymer of formaldehyde (97%) that is weighed out and dissolved in solution for
experimentation or for cell and tissue fixation. Typically 3-10% formalin or paraformaldehyde solutions
are used to perfuse or fix tissues.
OSHA has adopted a permissible exposure limit (PEL) of 0.75 ppm (parts per million) for airborne
formaldehyde averaged over an 8-hour work shift (TWA). Formaldehyde can be smelled at less than 0.5
ppm. A short-term exposure limit (STEL) of 2 ppm for 15 minutes has also been established. For an
assessment of airborne formaldehyde in the work area or lab, contact EH&S at 412-624-9505 via your
supervisor or PI.
1. Formaldehyde training is required for anyone exposed above 0.1 ppm for an 8-hour period.
2. All work with concentrated formalin solutions must be done in a chemical fume hood. If work
tasks cannot be done in a fume hood or other engineering control , EH&S must be contacted to
assure that hazardous exposures to faculty, staff and students are prevented. Recommendations
for protocol modification or protective equipment will be made based on air sampling results.
3. Formaldehyde exposures can occur while dissecting or working with tissue specimens perfused
with or fixed in formaldehyde. Chemical exposures can be minimized by working in a ventilated
device. Eliminating puddles of formaldehyde in the specimen by rinsing or blotting the excess
with paper towels can also reduce evaporation and exposure.
4. Gloves must be worn whenever tissues preserved in or fixed with formaldehyde are handled.
While latex gloves provide some protection against formaldehyde, butyl or nitrile gloves are
recommended and should be used when contact is anticipated.
5. Formaldehyde splashed in the eye can cause irreversible damage to the cornea. Safety glasses
with side shields, face shields or splash goggles must always be worn when working with
formaldehyde.
6. Labeling and Signage Requirements
6.1 All forms of formaldehyde or paraformaldehyde containing 0.1 % formaldehyde or greater
must be labeled in a manner to include the word "formaldehyde" and the concentration.
6.2 Signs warning of flammability hazards should be posted on the doors to any area where more
than 10 gallons of formaldehyde are stored. 
University of Pittsburgh
Safety Manual EH&S Guideline Number: 04-007
Subject:
FORMALDEHYDE AND
PARAFORMALDEHYDE
Effective Date
07/30/14 Page 2 of 3
7. Special Safety Precautions
7.1 If formaldehyde contacts the skin, flush with water for at least 15 minutes and report to Concentra
Medical Center, 120 Lytton Ave, Suite 275 or UPMC Emergency Department.
7.2 All solutions of formaldehyde and tissues preserved in formalin must be stored in tightly sealed,
properly labeled, containers to prevent leakage, spills and evaporation.
7.3 Do not pour formaldehyde or formalin waste into sinks or drains. Formalin waste solutions must
be placed in tightly sealed, labeled containers and segregated for disposal via the EH&S
Chemical Waste Program.
7.4 All spills of formalin solutions must be cleaned up immediately.
7.4.1 Wear nitrile or butyl gloves and eye protection.
7.4.2 Cover spill with paper towel or other suitable absorbent material. Do not mop
up a spill with reusable mops. If dry absorbents are used, scoop the absorbed
formaldehyde solution with a dustpan into a plastic bag.
7.4.3 Double bag, seal, and label the material. Call EH&S at 624-9505 for
assistance.
7.4.4 Dispose of all formalin containing material via the EH&S Chemical Waste
Program.
7.5 If the spilled formaldehyde causes severe eye, nose, or throat irritation, immediately evacuate the
area. Close all doors to contain vapors. Call Environmental Health and Safety at 412-624-9505.
8. Several common protocols involving formaldehyde have already been evaluated by EH&S, and based
on the air monitoring results, formaldehyde exposure has been demonstrated to be sufficiently low
enough to be excluded from annual training requirements. These activities include:
a. Animal perfusion done inside a chemical fume hood
b. Small animal perfusion involving 10cc or less formaldehyde
c. Paraformaldehyde weighing and solution preparation done inside a certified chemical fume
hood
d. Northern blot assays done inside a certified chemical fume hood
e. Cell fixing done inside a certified chemical fume hood or biosafety cabinet
f. Tissue immersion into formaldehyde in screw cap vials
g. Microscopic evaluation of fixed tissue or cells

 

 

9. Paraformaldehyde
9.1 Open containers of paraformaldehyde crystals or powder dissolved in solution give off
formaldehyde vapors. Users should minimize exposures to paraformaldehyde and avoid the
weighing and dissolving steps by purchasing "ready to use" buffered formalin solutions in
concentrations ranging from 2 to 10 percent and using these solutions in chemical fume hoods. 
University of Pittsburgh
Safety Manual EH&S Guideline Number: 04-007
Subject:
FORMALDEHYDE AND
PARAFORMALDEHYDE
Effective Date
07/30/14 Page 3 of 3
9.2 Paraformaldehyde is moderately toxic by skin contact. It has recently been designated as a
probable human carcinogen. Skin contact with paraformaldehyde may cause itching and rash that
may lead to skin allergy upon repeated exposure. It has also been reported to cause reproductive
and mutagenic problems in humans exposed long term.
9.3 Breathing paraformaldehyde powders or vapors will irritate the nose and throat after prolonged
exposure causing a cough, shortness of breath and possible lung damage including pulmonary
edema. Chronic inhalation exposures may lead to an asthmatic or allergic condition with
wheezing and chest tightness. Acute exposure may cause irritation to the eyes and respiratory
tract.
9.4 All weighing and handling of paraformaldehyde should be done with adequate ventilation using
chemicals fume hoods, vented balance enclosures or other local exhaust ventilation. Pre-weighed
packets or purchase of prepared formalin solutions should be substituted if possible to minimize
potential exposures.
10. Respiratory protection from formaldehyde vapors should not be necessary if other control measures
are utilized. If ventilation measures are inadequate or not available, use of respiratory protection may
be warranted. Consult EH&S. All users of respiratory protection must be enrolled in the University
Respiratory Protection Program. Particulate filtering respirators (dust masks) provide no protection
against formaldehyde vapors.
11. Paraformaldehyde or concentrated formalin solutions may react violently with strong oxidizing
agents, ammonia, strong alkalis, isocyanates, peracids, anhydrides and inorganic acids. Contact and
storage with these reactive chemicals should be avoided. 
12. Paraformaldehyde and formalin solutions should be stored in a cool, well ventilated area away from
heat, sunlight and moisture. Vapors emitting from paraformaldehyde and formalin solutions are
flammable, and the Guidelines for the Storage and use of Flammable Liquids found in this manual
apply. 
Paraformaldehyde possesses the common characteristics with a wide range of applications. Paraformaldehyde is the smallest solid form of liquid formaldehyde, formed by the polymerization of formaldehyde with a typical degree of polymerization of 8-100 units. As paraformaldehyde is basically a condensed form of formaldehyde, it possesses the common characteristics with a wide range of applications. Advantages of paraformaldehyde in resin production as compared to aqueous formaldehyde Paraformaldehyde does not need to be dissolved in water in order to take part in a chemical reaction. Higher productivity from existing equipment and less water to be removed from the resin product. Paraformaldehyde made with very low acid content in a chemical resistant environment can prevent the formation of acidic by-products.
We offer a prilled form, which is stable and very easy to store. Paraformaldehyde storage is less expensive than the storage of formaldehyde solution, which requires expensive tanks and which may need stabilization or be kept warm. It eliminates the risk of transporting liquid formalin, which is notoriously dangerous. Perfect for small uses straight from the bag. Use of paraformaldehyde is convenient and safe. It avoids pollution arising from the disposal of the distillate obtained in the thermosetting resin production which is contaminated with organic matter. Typical Properties Color White Number 30525-89-4 Appearance Free Flowing Prilled Molecular Formula OH-(CH2O)n-H where n=8 to 100 units Paraformaldehyde Content 92% ± 1% / 96% ± 1% Water Content 8% ± 1% / 4% ± 1% Reactivity 2 - 8 min Mean Particle Size 250 - 350 µm Ash 0.01 - 0.05% Bulk Density 650 - 850 kg/m3 Melting Point 120 - 175 C Ph 4 - 7 Flammability combustible, with flash point (tag open cup) of about 93 C Vapour Pressure varies with air humidity, being between 23 and 26 mmHg at 25 CApplications  Resins Industry The most important use of paraformaldehyde is as a source of formaldehyde groups in the production of many thermosetting resins, together with phenol, urea, melamine, resorcinol and other similar reagents. These resins are used as moulding powders; in the wood industry as glues for chipboard, plywood and furniture; as bonding resins for brakes, abrasives and foundry dyes; as finishing resins for paper and textiles; as driers and glossing agents for paints; as insulating varnishes for electrical parts.
Disinfectant
Paraformaldehyde generates formaldehyde gas when it is depolymerized by heating. The depolymerized material reacts with the moisture in the air to form formaldehyde gas. This process is used for the decontamination of large spaced and laminar-flow biological safety cabinets when maintenance work or filter changes require access to the sealed portion of the cabinet. It is used in the poultry industry as a disinfectant in the hatcheries, and cattle and sheep industry for sanitizing the bedding in the sheds. It releases formaldehyde gas when the temperatures increase. It reduces contamination levels caused by moulds, viruses and bacteria. Agriculture and Pesticides Most paraformaldehyde consumed by the agrochemicals industry is for the herbicides such as bismerthiazol, butachlor, acetochlor, glyphosate, and machete. Paraformaldehyde, Formadehyde and Formalin Confused? Formaldehyde is CH2O, the simplest aldehyde. Formalin is the name for saturated (37%) formaldehyde solution. Thus, a protocol calling for 10% formalin is roughly equivalent to 4% formaldehyde. Beware though, that some solutions have methanol in them to stop polymerization but this could have a negative effect on your sample. Paraformaldehyde (PFA) is actually polymerized formaldehyde. "Pure", methanol-free formaldehyde can be made by heating the solid PFA. This might be called paraformaldehyde, but it actually isn`t because it`s not the polymer form. You can buy EM grade formaldehyde or you can make your own . . .
Making Paraformaldehyde Solution 4% paraformaldehyde is usually made in PBS or TBS at 70 °C with several drops of 5N NaOH to help clarify the solution. Prepare 4% paraformaldehyde solution in a chemical hood if you don`t want to be slightly fixed yourself.
Often PFA stocks have insoluble impurities and it`s best that these be removed via a quick spin in a table-top centrifuge or by passing the prepared solution through a filter syringe. It is also important to realize that the efficacy and impurity content of powdered PFA can vary greatly from lot number to lot number of reagent. Don`t be surprised if your fixation concentrations & conditions may need to be tweeked when you open a new bottle of PFA. You can store the solution but all solutions go bad with time so using freshly prepared solutions that are colorless is often best. (Storing aliquotes at -20 °C and using them over a couple of months is typical). SDS Paraformaldehyde, 96%, ACROS OrganicsTM Available on GSA/VA Contract for Federal Government customers only. 25g, Plastic bottle Quantity: 25g 500g 1kg 3kg 10kg Packaging: Plastic bottle Plastic drum CAS 30525-89-4 Molecular Formula CH2O Molecular Weight (g/mol) 30.026 InChI Key WSFSSNUMVMOOMR-UHFFFAOYSA-N Synonym formalin,methanal,formol,methylene oxide,paraformaldehyde,oxomethane,paraform,formic aldehyde,oxymethylene,methyl aldehydeShow More PubChem CID 712 ChEBI CHEBI:16842 IUPAC Name formaldehyde SMILES C=O Catalog No.AC416780250 Mfr: Acros Organics416780250 $15.65 / Each Request bulk or custom formats Qty Check Availability Add to cart Description This product(s) resides on a Fisher Scientific GSA or VA contract. If you are viewing this page as a nonregistered user, the price(s) displayed is List Price. To view your GSA or VA contract pricing, log in using your account number, or become a registered user by contacting one of our Customer Service teams. You can also view your contract price by searching for this item(s) on GSA Advantage. To place an order, contact Fisher Scientific Customer Service.

 

Specifications Packaging Plastic bottle Melting Point 120.0°C to 170.0°C Flash Point 71°C Quantity 25g Ash 0.02% max. pH 4.0 to 5.5 (10% suspension) Additional Information Vapor Pressure: 1.2mmHg at 25°C Free Acid 0.03% max. Decomposition Information 260°C Infrared Spectrum Authentic Show More Certificates Certificate of Analysis (30)

 

Lot Number B0148337Lot Number A0409947Lot Number A0408957Lot Number B0147499Lot Number B0146924Lot Number B0146924ALot Number A0404674Lot Number A0401853Lot Number B0146648Lot Number A0400640Lot Number B0145208Lot Number B0145986
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0% Paraformaldehyde (Formaldehyde) Aqueous Solution, EM Grade, different packing units

Paraformaldehyde - Methanol free solution. A more efficient and rapid penetrant fixative used in combination with Glutaraldehyde and Acrolein fixatives. Easy to break, prescored, 10 ml ampoules sealed under inert gas, or 100 ml bottles.
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20% Paraformaldehyde (Formaldehyde) Aqueous Solution, EM Grade, 10x 10ml
20% Paraformaldehyde (Formaldehyde) Aqueous Solution, EM Grade, 100ml
E15713-S
Paraformaldehyde (Formaldehyde) Aqueous Solution, EM Grade, different packing units
from €43.10 from €51.29 Incl. Tax plus shipping
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Specification Datasheet Related Products & Accessories 
Type Formaldehyde
Symbol GHS 
S08
Signal word Warning
Hazard statements H302_H312, Harmful if swallowed, in contact with skin or if inhaledH315, Causes skin irritation.H317, May cause an allergic skin reaction.H319, Causes serious eye irritation.H335, May cause respiratory irritation.H351Suspected of causing cancer .
Precautionary statements P261, Avoid breathing dust/fume/gas/mist/vapours/sprayP280, Wear protective gloves/protective clothing/eye protection/face protectionP281, Use personal protective equipment as requiredP305_351, IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do - continue rinsingP405Store locked up
Mandatory sign 
Protective gloves
Tightly sealed goggles
Condition fluid
Delution 20%
Shipping Class Hazardous Good LQ
Storage Temperature RT
Application EM
Datasheet SDS english
Description
United States Patent 1O 5 Application september 25, 1953, Serial No. 382,450 s 9Claims. (Cl. 260-615) V p This invention relates principally to a new and novel process for the 1 production of paraformaldehyde. More particularly, this invention relates to a new and novel `process for the production of paraformaldehyde in a formexhibiting a greater reactivity and a greater solubility than paraformaldehyde prepared by presently known commercial procedures. As is well known, formaldehyde is an extremely important chemical raw material. This aldehyde is produc`d in enormous quantities, either by the partial oxidation of natural gas or by the partial oxidation of methanol. Formaldehyde is a gas (B. P. -2l C. which l ven at the boiling point slowly changes to the cyclic jtrimer, trioxymethylene, the rate of this polymerization reaction increasing rapidly with increasing temperature. lAccordingly, the large scale preparation,-transportation an`dfstor age of formaldehyde for subsequent use in chemical syntheses is not practical.
Fortunately, formaldehyde is very soluble in water and an aqueous solution containing 37% formaldehyde by weight (formalin) is the form in which this aldehydemost frequently appears in commerce. However, for: malin leaves muchto be desired as a chemical raw material. The solution is corrosive and is not too stable in storage, especially at temperatures `above and below ordinary roomtemperatures. In addition,`due to the low concentration of formaldehyde in formalin the rates of reaction in syntheses employing formalin are frequently quite low and thesize of .a batch that can be processed in a given piece of equipment is small. Since formalin contains over 60% by weight of water it is necessary to transport, handle and store this large amount of solvent.

 

To offset the corrosivenature of formalin, this material is usually shipped in insulated resin lined tank cars or in resin lined drums. At the point of consumption, handling of the solution should be through chemical rubber hose or corrosion resistant pipe to storage fa:

T cilities constructed of stainless steel (type 304 or, preferably, types 316 or 317), aluminum (types 25, 38, 528

or 61S-T) or mild steel coated with a suitable resin. Obviously, these requirements add greatly to the cost of transporting, handling and storing formalin. It should be noted that these requirements with respect to materials of construction are necessary not only to prevent corrosion of equipment but also to avoid contamination of the formalin with the products of corrosion. Traces of many metal salts, for example, iron salts, greatly reduce the stability of formalin.

Formalin is quite unstable. To enhance the stability l of the solution it is common practice to incorporate methanol therein as an inhibitor. For tank car shipments about 7% methanol is commonly employed while drum shipments commonly contain 1214% methanol. Methanol is a valuable chemical and chemical raw materialand is, in fact, one of the major raw materials for the production of formaldehyde. The use of such large amounts of-methanol as an inhibitor is a distinct eco nomic waste and represents an appreciable item in the a 1,"? MN -n M...

cost of the so inhibited formalin. The stability of. inhibited formalin still leaves much to be desired. When exposed to cold weather paraformaldehyde separates from the solution. After relatively short exposure to but moderately low temperatures the separated paraformaldehyde may be dissolved by heating the solution but if the formalin is in resin lined containers care must be taken not to heat the solution above 60C. lest the resin lining be injured. Prolonged exposure to very low temperatures results in the separation of large quantities of paraformaldehyde in a formthat is impossible to dissolve. High temperature storage is equally undesirable.` At high temperatures the acidity of the solution increases, due probably to the enhanced rate of oxidation of formaldehyde to formic acid. The increased acidity accelerates many decomposition reactions of formaldehyde. For example, the union of formaldehyde with methanol to form methylal is accelerated by acids, especially in the presence of, traces of metal salts. Also, under acidic conditions and at elevated temperatures the Cannizzaro reaction may occur resulting in the formation of formic acid (which stillfurther increases acidity) and methanol (which may react to form additional methylal). For all these reasons it is generally recommended that even inhibited formalin be stored for as short a period as possible atatemperature above 15 C. and below 40 C. This generally requires that storage containers be provided withheating coils and some means for cooling.

The `high water content (63% by weight) of formalin is obviously highly disadvantageous. Most natural gas fields are located `at great distances frommajor formaldehyde consuming centers and if formalin is prepared at or near thesefields it is necessary to` ship ahnost two pounds of water to the distant major consuming centers in order to deliver one pound of formaldehyde thereto. The transportation cost of this large quantity of water accounts for a very appreciable part of the delivered cost of the formalin. For this reason, in some instances natural `gas is employed to produce methanol at or near the gas field and this methanol is shipped to formaldehyde consuming centers where it is converted into formalin for use in the immediate vicinity. The consumer of formalin must not only pay the transportation cost of the`large quantity ofwate`r; contained therein but also, in most instances, must goto the trouble and expense of removingthis water at some stage of the process in which formalin is employed as a reactant since most chemical products synthesized by use of formalin are marketed in water freeform.

Also, because of the low concentration of formaldehyde in formalin, the volumetric yield from a reaction vesselinwhich formalin`is one of the reactants is low. In addition, the low concentration offormaldehyde in formalin frequently results in a low reaction rate in synthetic processes employing this material as a reactant. Finally, most formaldehyde reactions of commercial importance are condensations involving the elimination of water. Obviously, the addition of large quantities of water to reactions of this type is contrary to the teachings of chemical kinetics and, in fact, many condensations that can be achieved when formaldehyde is employed do not occur when formalin is used as the source of formaldehyde.

Because of the above mentioned and many other disadvantages of formalin, many attempts have been made to produce formaldehyde in. a form more amenable to transportation, handling, storage and use. Formaldehyde series of linear formaldehyde polymers which may conj tain from two to a large number of oxymethylene units.

While gaseous formaldehyde is an extxremely reactive aldehyde formalin does not show this high degree of reactivity. Many theories have been put forward to explain-the relative non-reactivity of formalin. 1 According to one such theory, a molecule of formaldehyde immediately unites with a molecule of water to form the hypothetical formaldehyde hydrate or the hypothetical methylene diol, either of which would be expected to be less reactive than form-aldehyde itself. Although the gemdicl configuration is very rare in organic chemistry, the additive power of the carbonyl group of formaldehyde is so great that the formation of a formaldehyde hydrate or even a methylene diol would not be too surprising. As such-a formalin solution ages, hydrated formaldehyde polymers of-low molecular weight form very rapidly. These may be either hydrates of low molecular weight true polymers or a polyoxymethyl-ene alpha omega diol of low molecular weight. These compounds, regardless oftheir true structure, would be expected to be considerably less reactive than formaldehyde itself. It is to be noted that, on the basis of this theory, paraformaldehyde is not a truepolymer but rather a compound that may be represented by the empirical formula (CH20).1:`H2O. In accordance with the long established practice of the art, in this specification and in the appended claims, paraformaldehyde`will be referred to as a polymer.

Commercial forms of paraformaldehyde are produced by evaporation of an aqueous solution of formaldehyde. This evaporation is carried out under reduced pressure in order .to avoid excessive loss of formaldehyde in the evolved vapors. When an aqueous solution of formaldehyde is heated to its boiling point under atmospheric pressure a large portion of the formaldehyde is lost with the vapors and comparatively little paraformaldehyde is obtained from the still bottoms. As explained previously, an aqueous formaldehyde solution probably consists of an aqueous solution of low molecular weight polymers (t-rimers, tetramers, pentamers, et cetera) which exist in complicated equilibrium with each other and the water present. This equilibrium may be indicated as follows on the basis of the hydrated polymer structure:

(CHzOh-HzO (CHzO),,-H2O (I) (CH2O):|-,,-HzO H20 ll ll 101120 11 01120 H2O where x is a small whole numberand y is-a sm-allwhole number the same as or different than x.

Or, on the basis of the alpha omega diol configuration: (I porno 1120 (1 memo H20 ll li where x is zero or a small whole num-berand y is zero or a small whole number which number maybe the same as or different than x. At elevated temperatures, for example, the temperature at which an aqueous solution of formaldehyde boils at atmospheric pressure, the polymers tend to depolymerize, forming monomeric formaldehyde and water. This accounts for the large loss of formaldehyde when an aqueous solution of formaldehyde is boiled at atmospheric pressure and also for the greater chemical instability of formalin at elevated storage temperatures (e. g. greater tendency to oxidize to for-micacid,`greater tenden oy to undergo the Cannizzaro reaction under-acidic conditions, et cetera). I

Also, `as the above equations show, the low molecular weight polymers can condense with each-other toLform polymers of higher molecular-weight witnelimination-of water. This reaction is favored by low temperatures and accounts for the separation of paraformaldehyde-from tortnalin solutions when stored at low temperatures for extended periods.

1n the commercial preparation of paraform-aldehyde by evaporation of aqueous formaldehyde solutions at reduced pressures the evaporation temperature is low. Because of the low temperatures employed, depolymerization of the low molecular weight polymers present to monomeric formaldehyde and` loss of the monomer in the vapors is very considerably reduced (in comparison with evaporation at atmospheric pressure) and the conditions necessary for the productionof polymers ofhigher molecular weight obtain.

-It might be thought that the production of paraformaldehyde by the evaporation of`aqueous formaldehyde solutions at reduced pressuresrepresents`a simple solution of all the difliculties entailed in the transportation, handling, storage and use of formalin. That this is not true is shown by the fact that practically all formaldehyde is produced, sold and used in the form of formalin. The production of paraformaldehyde involves so many difficulties that the price of flake paraformaldehyde delivered to major consuming centers issomeWha-t greater than that offormalin on the basis of equal weights of formaldehyde. Also, commercially available flake paraformaldehyde leaves much-to be desiredwith respect to solubility and reactivity. These last named disadvantages are only very partially overcome by-useof powdered paraformaldehyde but`this product commands a premium of some 3.5 cents per pound over the flake material.

During the concentration of an aqueous solution of formaldehyde `at reduced pressures a point is reachedpq usually at a form-aldehyde content of 5060%, atwhicho separation of insoluble polymers causes the`solution`tof gel. As additional wateris removed,"the still contents become a tough, viscous, plastic mass`which fina-lly`solidifies. On the commercial scale, after the reaction`mass has reached the gel stage, it is-impossible to achieve a high rate of heat input throughout the still contents in the absence of stirring and since the mass soon`b`ecomes tough and plastic and then-gradually solidifies an extremely powerful stirrer is required. Commercially it is usual practice to conduct the evaporation in a specially designed kneader which is expensive to construct and operate-and has a low capacity. The final`product from such a-processing procedure is an insoluble and relatively unreactive paraformaldehyde far different in physical and chemical properties from the soluble and relatively`reactive polymers contained in formalin solutions.

I have discovered a new andnovel process forthe preparationof paraformaldehyde whichcanbe conducted in standard equipment and gives-rise to a soluble`an`d reactive paraformaldehyde in high yields.

One object of my inventionis to provide a new and novel process for the production of paraformaldehyde.

Another object of my invention is`to`provide a new through standard procedures.

A further object of my invention is to provide anew and novel process for the production of a paraformaldehyde that is-morereadily soluble than varieties of paraformaldehyde hitherto available.

An additionalobject of my invention is to provide a new and novel`process` for the`production`o`f` paraformaldehyde exhibiting a higher `degree`of chemical reactivity than hitherto available `varieties` of paraformal`dehyde.

Other objects of my inventionwill become apparent as the description`thereof proceeds.

Broadlyand briefly, in my irnprovedprocessfor the production of paraformaldehyde, an aqueous solution of formaldehyde is heated at a temperature just below .the boiling point thereof for a time sufiicient to achieve essentiallycomplete depolymerization of the low molecular weight polymers contained therein following which water is-evaporated from the -depolymerizedxsolutioniat reduced pressure. Removal of uncombined water :by evaporation of the depolymerized aqueous solution of pin the aqueous formaldehyde solution.

tf combined water is evaporated under reduced pressure formaldehyde at reduced pressure produces a liquid still bottoms which is clear or only very slightly turbid and is readily discharged from the still to suitable con tainers in which the bottoms rapidly solidify to form readily soluble and highly reactive paraformaldehyde.

. It is evident that my new and novel process forthe production of paraformaldehyde differs materially in methods and means employed and in results obtained from the prior art process. In the prior art process, an aqueous solution of formaldehyde, in which the greater part of the formaldehyde is present as low molecular weight polymers, is evaporated at reduced pressure. The polymers immediately begin to react with each other to form polymers of higher molecular weight and when only a comparatively small proportion of the uncombined water has been removed this reaction has proceeded to such an extent that the concentration of relatively insoluble, high molecular Weight polymers is suflicient to gel the mixture and make it unmanageable unless highly specialized and expensive equipment is used. Continuationof water removal in suchspecialized .squipment results in further increase in the molecular weight and decrease in the reactivity and solubility of the polymer. When all uncombined water has been removed, an insoluble and relatively unreactive paraformaldehyde is obtained.

":Incontrast, in my new and novel process, the first step involves depolymerization of the polymers present Then the unflfrom a solution which initially consists of monomeric "formaldehyde which, as previously explained, is probably present largely in the form of formaldehyde hydrate or methylene dioL- All free water may be removed before polymerization of the monomeric formaldehyde has proceeded to such an extent as to form insoluble polymers. Accordingly, after uncombined water has been removed, the still contents are in the form of a clear or, at worst, slightly turbid liquid consisting of moderately low molecular weight formaldehyde polymers. These still bottoms are discharged to a convenient container, for example a pan, wherein cooling "and some additional .polymerizationsoon results in solidification of the mass. The resulting solid, which is free from paraformalde hyde molecules of extremely high molecular weight, is readily soluble and highly reactive. i

Forthe better understanding of my invention the following illustrative but non-limiting example thereof is Example t "T Four hundred parts by weight of a 37% (by weight) aqueous`solutionof formaldehyde uninhibited with-methanol was maintained at a temperature just below the x boiling point (9095 C.) for a period of one hour.

, Yield: 148 parts After this depolymerizing step, vacuum was gradually 1:

duced to mm. of mercury. Uncombined water was applied to the solution, the pressure finally being reremoved from the solution at this reduced pressure, the evaporation being continued until `the temperature of the liquid in the still reached75-85"; C. Vacuum was then released and the clear to very slightly turbid still contents were discharged to a shallow pan and were allowed to solidify.

by weight; formaldehyde assay,`9l%. Recovery of formaldehyde as solid polymer, 91%.

The polymer product was readily soluble in warm water, phenol and butanol, giving clear solutions within fifteen minutes or less. A commercialsample of paraformaldehyde could not be dissolved in any of these solvents over a period of more than two hours.

The time required for the depolymerization step depends upon the age of the formaldehyde solution being proc`essed. In actual practice, my new and novel process fwould usually be employed in connection with aqueous `solutions of formaldehyde soon after they have been produced. Such fresh solutions may be depolymerized by holding at 90-100 C. for a half hour to an hour.

Depolymerization time also depends upon the temperature employed in the depolymerization step. A temperature of 90-95 C. is preferably used for at this temperature loss of formaldehyde from the solution is not appreciable while the depolymerization reactionproceeds rapidly. If desired, the rate of depolymerization may be somewhat accelerated by boiling the solution under reflux. In such an operation it is preferable to pass evolved vapors through a packed column and thence to a total condenser. Liquid from the total condenser discharges into the upper part of the packed column and on passing downward therethrough serves to scrub formaldehyde from the ascending vapors and return it to the depolymerizer. Also, if desired, the depolymerization may be accomplished with extreme rapidity by heating aqueous formaldehyde solutions under pressure to a temperature above the atmospheric pressure boiling point of the solutions. Depolymerization also occurs at temperatures below 90 C. but, as would be expected, the time required for depolymerization increases as the depolymerization temperature is decreased.

The adequacy of a given depolymerization treatment may be readily determined by taking an aliquot of the so treated liquid, for example, about one pint, and subjecting it to distillation at a pressure of say 20 mm. of mercury, the rate of heat input to the still being so regulated that at least two hours are required for the temperature of the still contents to reach 75-85 C. If at or prior to this point the still contents contain appreciable solid material the depolymerization treatment was inadequate. If, on the other hand, on reaching a temperature of 75- 85 C. the still contents are clear or, at worst, slightly turbid, they are poured onto a glass tray and allowed to cool and solidify. One part by weight of the resulting solid is added to two parts by weight water at -100 C. If complete solubility is attained within fifteen minutes the depolymerization conditions were adequate. If desired, phenol or butanol may be substituted for water in this test.

The pressure at which the free water is evaporated from the depolymerized solution is not too critical but is subject to certain limitations. If the pressure is too high this will result in a high evaporation temperature which reduces the rate of polymer formation and results in considerable loss of formaldehyde in the vapors. I have found that pressures below about 01 atmosphere are suitable for removal of free water from depolymerized formaldehyde solutions. The evaporation temperature corresponding to this pressure is suflicient to permit rapid polymerization of formaldehyde. Preferably, I employ a pressure in the approximate range 10 to 30 mm. of mercury as such a pressure is eminently suited for the purposes of the present invention and is readily attained by any one of a number of simple devices such as a steam jet ejector.

Paraformaldehyde prepared in accordance with my in vention can be shipped and stored in standard multi-wall.

paper bags or fiber drums. It can be stored at ordinary temperatures for any desired period in such packages without adversely affecting solubility or reactivity.

Paraformaldehyde prepared in accordance with my invention may be employed in all applications where formalin is customarily employed. If an aqueous solution of formaldehyde is necessary (for example, in the preparation of pentaerythritol) such a solution is readily and quickly prepared from the paraformaldehyde of my invention. Such aqueous solutions may be employed, if desired, in the preparation of phenolic resins (for example) by standard procedures or, due to the ready solubility of the .paraformaldehyde of my invention in phenols, these resins may be prepared in the essential absence of water thereby achieving a higher productive capacity from a given resin producing installation.

Formalin is not`suitable for use in certain formaldehyde condensation reactions, fol-example, the formolit reaction involving`the condensationofformaldehyde and aromatichydrocarbons. Paraformaldehyde prepared in accordance with my invention is an eminently suitable source of formaldehyde for use in condensations of this type. 7

Be it remembered, that While this invention has been described in connection With specific`details and a specific example thereof, these are illustrative only and are not to be considered limitations on the spirit or scope of said invention except in so far as-these may be incorporated in the appended claims.

I claim:

l. The process of producing paraformaldehyde comprising heating to a temperature within the approximate range 90-100 C. an aqueous solution containing hydrated formaldehyde and formaldehyde polymers, maintaining said solution at`said temperature for a period .of about one half to one hour, removing water from the resulting depolymerized solution by evaporation at reduced pressure at such a rate that the still`bottoms reach a temperature in the range 75.85 C. before the still bottoms exhibitmore than a slight turbidity and cooling the still bottoms to produce solidparaformaldehyde.

2. The process of producing paraformaldehyde comprising heating to the atmospheric pressure boiling point thereof an aqueous: solution containing hydrated formaldehyde and formaldehyde polymers, maintaining said solution at its atmosphericpressureboiling point for a period of about one half to one hour,.removing Water from the resulting depolymerized solution by evaporation at reducel pressure at such a ratethat the still hot toms reach a temperature. in the range 7585 C. before the still bottoms exhibit more than a slight turbidity and cooling the still bottoms.to produce`solid paraformalde `hyde.

3. The process of producing paraformaldehyde comprising heating to a temperature Within the approximate range 90-95 C. an aqueous`solution containing hydrated formaldehyde and formaldehyde polymers, maintaining said solution at said`temperature for a period of about one half to one hour, removing Water from the resulting depolymerized solution by evaporation at reduced pressure atsucha rate thatthe-still bottoms`reach a tempera ture in the range 75`85 C. before the still bottoms exhibit more than a slight turbidity and cooling the: still bottoms toproduce solid paraformaldehyde.

4. The process ofaproducing paraformaldehyde comprising heating to a temperature within the approximate range 90-100" C. an aqueous solution containing hydrated`formaldehy`de and formaldehyde polymers,. maintaining said solution at saidternperature fora period of about one half; to one hour, removing Water from the resulting depolymerized solution by evaporation at a pressure below 0.1..atmosphereat such a rate that the still bottoms reach a temperature in the range 75-85 `C. before the still bottoms-exhibit more than a slight turbidity and cooling the still bottoms to produce solid paraformaldehyde.

`5. The process of producing `paraformaldehyde comprising heating" to attemperature within the approximate range 90-l00 C..an.aqueous solution containing hydrated formaldehyde 2 and .formaldehydepolymers, maintaming said solution at said temperature for a period of about one half to one hour, removing Water from the resulting depolymerized solution by evaporation at a pressure in the approximate range 10 to 30 mm. of mercury at such a rate that the still bottoms reach a temperature in the range -85 C. before the still bottoms exhibit more than a slight turbidity and cooling the still bottoms to produce solid paraformaldehyde.

6. The process of producing paraformaldehyde comprising heating to the atmospheric boilingpoint thereof an aqueous solution containing hydrated formaldehyde and formaldehyde polymers, maintaining said solution at its atmospheric pressure boiling point for a period of about one half to one hour, removing water from the resulting deploymerized solution by evaporation at a pressure below 0.1 atmosphere at such a rate that the still bottoms reach a temperature in the range 75-85 C. before the still bottoms. exhibit more than a slight turbidity and cooling the still bottoms toproduce solid paraformaldehyde.

7. The process of producing paraformaldehyde comprising heating to the atmospheric pressure boiling point thereof an aqueous solution containing hydrated formaldehyde and formaldehyde polymers, maintaining said solution at its atmospheric pressure boiling point for a period of about one half to one hour, removing water from the resulting depolymerized solution by evaporation ata pressure in the approximate range 10 to `30 mm. mercury at such arate that the still bottoms reach a tem-q perature in the range 75-85 C. before the still bottomsi exhibit more thana slight turbidity and cooling the stillf` bottoms to produce solid paraformaldehyde. i

8. The process of producing,paraformaldehyde comprising heating to a temperature Within the approximate range 95 .C. anaqueous solution containing hydrated-formaldehyde and formaldehyde polymers, maintaining said solution at; said temperature fora period of about one "half `to one hour, removing water from the resulting depolymerized solution by evaporation at a pressure :below 0;1 atmosphere`at such a rate that the still bottoms reachea temperature in the range 7585 C. before the still bottoms exhibit`more than a slight turbidity and cooling the still bottoms`to produce solid paraformaldehyde.

9. The process of producing paraformaldehyde comprisingheating to a temperature within the approximate range 9095 C. an aqueoussolution containing hydrated formaldehyde and formaldehyde polymers, maintaining said solution at said temperature for a period of about one half to one hour, removing Water from the resulting depolymerized solution by evaporation at a pressure in the approximate range .10 to 30 mm. of mercury at such arate that the still bottoms reach a temperature in the range 75-85" C. before the bottomsexhibit more than a slight turbidityand cooling the still bottoms`to produce solid, paraformaldehyde.

I References Cited in the file of this patent UNITED STATES PATENTS P 1,871,019 Walker Aug. 9, 1932 2,568,016 Walker Sept. 18, 1951 2,675,346 MacLean Apr. 13, 1954 FOREIGN PATENTS 420,993 Great Britain Dec. 12, 1934

 

 

Claims (1)
Hide Dependent 
1. THE PROCESS OF PRODUCING PARAFORMALDEHYDE COMPRISING HEATING TO A TEMPERATURE WITHIN THE APPROXIMATE RANGE 90-100* C. AN AQUEOUS SOLUTION CONTAINING HYDRATED FORMALDEHYDE AND FORMALDEHYDE POLYMERS, MAINTAINING SAID SOLUTION AT SAID TEMPERATURE FOR A PERIOD OF ABOUT ONE HALF TO ONE HOUR, REMOVING WATER FROM THE RESULTING DEPOLYMERIZED SOLUTION BY EVAPORATION AT REDUCED PRESSURE AT SUCH A RATE THAT THE STILL BOTTOMS REACH A TEMPERATURE IN THE RANGE 75-85* C. BEFORE THE STILL BOTTOMS EXHIBIT MORE THAN A SLIGHT TURBIDITY AND COOLING THE STILL BOTTOMS TO PRODUCE SOLID PARAFORMALDEHYDE.
Patent Citations (4)
Publication number Priority date Publication date Assignee Title
US1871019A * 1930-03-26 1932-08-09 Roessler & Hasslacher Chemical Process for concentrating formaldehyde solutions
GB420993A * 1932-07-15 1934-12-12 Leonhard Nasch Method of manufacturing formaldehyde in a solid state
US2568016A * 1949-03-12 1951-09-18 Celanese Corp Formaldehyde conversion
US2675346A * 1949-11-04 1954-04-13 Celanese Corp Concentration of formaldehyde by distillation and fractional condensation
Family To Family Citations 
* Cited by examiner, † Cited by third party
Cited By (2)
Publication number Priority date Publication date Assignee Title
US3342779A * 1963-07-03 1967-09-19 Toyo Koatsu Ind Inc Process for producing alphapolyoxymethylene
CN106832160A * 2017-02-27 2017-06-13 安徽泗县新科农林开发有限公司 Productionmethod of alpha-polyoxymethylene
Family To Family Citations 
* Cited by examiner, † Cited by third party, ‡ Family to family citation
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Once paraformaldehyde is depolymerized, the resulting formaldehyde may be used as a fumigant, disinfectant, fungicide, and fixative. Longer chain-length (high molecular weight) polyoxymethylenes are used as a thermoplastic and are known as polyoxymethylene plastic (POM, Delrin). It was used in the past in the discredited Sargenti method of root canal treatment.[2]

Paraformaldehyde is not a fixative; it must be depolymerized to formaldehyde in solution. In cell culture, a typical formaldehyde fixing procedure would involve using a 4% formaldehyde solution in phosphate buffered saline (PBS) on ice for 10 minutes.

Paraformaldehyde is also used to crosslink proteins to DNA, as used in ChIP (chromatin immunoprecipitation) which is a technique to determine which part of DNA certain proteins are binding to.

Paraformaldehyde can be used as a substitute of aqueous formaldehyde to produce the resinous binding material, which is commonly used together with melamine, phenol or other reactive agents in the manufacturing of particle board, medium density fiberboard and plywood.[3]

 

 

Toxicity
As a formaldehyde releasing agent, paraformaldehyde is a potential carcinogen.[4] Its acute oral median lethal dose in rats is 592 mg/kg.[5]
Paraformaldehyde
powder, 95%
Synonym: Polyoxymethylene

 

 

 

CAS Number 30525-89-4 Linear Formula HO(CH2O)nH Molecular Weight 30.03 (as monomer) MDL number MFCD00133991 PubChem Substance ID 24849719
Paraformaldehyde powder, 95%
SDSSimilar Products
SKU-Pack Size Availability Pack Size Price (EUR) 
158127-5G
Description
General description
Paraformaldehyde is also referred as polyoxymethylene. It participates as an external CO source in the synthesis of aromatic aldehydes and esters.[4]
Paraformaldehyde is an ideal fixative used in histology.[7] It is generally preferred over other fixative as the others result in more silver grains on the tissues. Paraformaldehyde, appropriately combined with DMSO (dimethyl sulfoxide) ensures its uniform distribution over the tissue section.[7] Paraformaldehyde is also used in recognizing and stabilizing the expression of intracellular antigen.[6]

 

 

Application
Paraformaldehyde has been used as a fixative[8][10][11] in histological analysis.[9] It has also been used in mitotic catastrophe assay.[5]
Packaging

 

 

25, 100, 500 g in poly bottle 3 kg in poly drum 5 g in glass bottle
Safety Information
Symbol GHS02GHS05GHS07GHS08 GHS02, GHS05, GHS07, GHS08Signal word DangerHazard statements H228-H302 + H332-H315-H317-H318-H335-H351Precautionary statements P210-P261-P280-P301 + P312 + P330-P305 + P351 + P338 + P310-P370 + P378Personal Protective Equipment Eyeshields, Faceshields, full-face particle respirator type N100 (US), Gloves, respirator cartridge type N100 (US), type P1 (EN143) respirator filter, type P3 (EN 143) respirator cartridgesRIDADR UN 2213 4.1 / PGIIIWGK Germany 2RTECS RV0540000Flash Point(F) 158 °FFlash Point(C) 70 °C

 

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