Title: Formaldehyde
CAS Registry Number: 50-00-0
Additional Names: Methanal; oxomethane; oxymethylene; methylene oxide; formic aldehyde; methyl aldehyde
Molecular Formula: CH2O
Molecular Weight: 30.03
Percent Composition: C 40.00%, H 6.71%, O 53.28%
Line Formula: HCHO
Literature References: Formed by incomplete combustion of many organic substances. Present in coal and wood smoke, esp in smoke as produced for smoking ham and fish. Found in the atm, esp over large cities. Prepd commercially by catalytic vapor phase oxidation of methanol using air as the oxidizing agent and heated silver, copper, alumina, or coke as catalysts. Process using molybdenum iron oxide catalyst: Allyn et al., US 2812309 (1957) and US 2849492 (1958 to Reichhold Chem.). Prepn of stable formaldehyde by heating low molecular polyoxymethylenes with P2O5: DE 1070611 (1959 to BASF). Mfg processes: Faith, Keyes & Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Interscience, New York, 4th ed., 1975) pp 422-429. Prepn of semicarbazone: M. Pomerantz et al., J. Org. Chem. 47, 2217 (1982). Toxicity data: H. F. Smyth et al., J. Ind. Hyg. Toxicol. 23, 259 (1941). Carcinogenicity study: J. A. Swenberg et al., Cancer Res. 40, 3398 (1980). Assessment, regulation and evaluation of carcinogenicity: F. Perera, C. Petito, Science 216, 1285 (1982). Review: H. R. Gerberich et al., in Kirk-Othmer Encyclopedia of Chemical Technology vol. 11 (John Wiley & Sons, New York, 4th ed., 1994) pp 929-951. Review of toxicology: H. d'A. Heck et al., Crit. Rev. Toxicol. 20, 397-426 (1990); of oral toxicity: P. Restani, C. L. Galli, ibid. 21, 315-328 (1991).
Properties: Flammable colorless gas at ordinary temp. Pungent suffocating odor. d 1.067 (air = 1.000). d4-20 0.815. mp -92°. bp760 -19.5°; bp400 -33.0°; bp200 -46.0°; bp100 -57.3°; bp60 -65.0°; bp40 -70.6°; bp20 -79.6°; bp10 -88.0°. Ignition temp about 300° (572°F). Very sol in water, up to 55%; sol in alcohol, ether. Very reactive, combines readily with many substances, and polymerizes easily. See also Paraformaldehyde.
Melting point: mp -92°
Boiling point: bp760 -19.5°; bp400 -33.0°; bp200 -46.0°; bp100 -57.3°; bp60 -65.0°; bp40 -70.6°; bp20 -79.6°; bp10 -88.0°
Density: d 1.067 (air = 1.000); d4-20 0.815
Derivative Type: Formaldehyde solution
Trademarks: Formalin; Formol; Morbicid; Veracur (Typharm)
Properties: A soln of about 37% by wt of formaldehyde gas in water, usually with 10-15% methanol added to prevent polymerization. This soln is the full strength and also known as Formalin 100% or Formalin 40 which signifies that it contains 40 grams of formaldehyde within 100 ml of the soln. Colorless liq; pungent odor. On standing, esp in the cold, may become cloudy and on exposure to very low temp a ppt of trioxymethylene is formed. When evaporated, some formaldehyde escapes, but most of it is changed to trioxymethylene. It is a powerful reducing agent especially in presence of alkali. In the air it slowly oxidizes to formic acid. d2525 1.081-1.085. One gallon weighs 9.1 lbs. bp760 96°. nD20 1.3746. Flash pt 60°C (140°F). pH 2.8-4.0. Misc with water, alcohol, acetone. Keep well closed in a moderately warm place. LD50 orally in rats: 0.80 g/kg (Smyth).
Boiling point: bp760 96°
Flash point: Flash pt 60°C (140°F)
Index of refraction: nD20 1.3746
Density: d2525 1.081-1.085
Toxicity data: LD50 orally in rats: 0.80 g/kg (Smyth)
Derivative Type: Formaldehyde semicarbazone
Molecular Formula: C2H5N3O
Molecular Weight: 87.08
Percent Composition: C 27.59%, H 5.79%, N 48.25%, O 18.37%
Properties: Crystals from ethanol, mp 120-121°. uv max (CH3CN): 227 nm (log e 3.73).
Melting point: mp 120-121°
Absorption maximum: uv max (CH3CN): 227 nm (log e 3.73)
CAUTION: Potential symptoms of overexposure to formaldehyde are irritation of eyes, nose, throat and respiratory system; lacrimation; coughing; bronchial spasm. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 148. May act as a primary irritant on skin causing erythmatous or eczematous dermatitis. Sensitization can result. See Patty's Industrial Hygiene and Toxicology vol. 2A, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 3rd ed., 1981) pp 2637-2646. Ingestion may cause immediate intense pain in mouth, pharynx and stomach; nausea, vomiting, hematemesis, abdominal pain, diarrhea; pale, clammy skin and other signs of shock; difficult urination, hematuria, anuria; vertigo, convulsions, stupor, coma; death due to respiratory failure. See Clinical Toxicology of Commercial Products, R. E. Gosselin et al., Eds. (Williams & Wilkins, New York, 5th ed., 1984) Section III, pp 196-197. Formaldehyde gas is reasonably anticipated to be a human carcinogen: Report on Carcinogens, Eleventh Edition (PB2005-104914, 2004) p III-125.
Use: In the prodn of amino, phenolic, and polyacetal resins, wood products, plastics, fertilizers and foam insulation. As a textile finish, preservative, stabilizer, disinfectant and antibacterial food additive.
Therap-Cat: Solution as disinfectant.
Therap-Cat-Vet: Solution as antiseptic; fumigant; has been used in tympany, diarrhea, mastitis, pneumonia, internal bleeding.
Formaldehyde Sodium Bisulfite Formamide Formanilide Formestane Formic Acid

Skeletal fomula of formaldehyde with explicit hydrogens added Spacefill model of formaldehyde
Ball and stick model of formaldehyde
CAS number 50-00-0 YesY
PubChem 712
ChemSpider 692 YesY
UNII 1HG84L3525 YesY
EC number 200-001-8
UN number 2209
DrugBank DB03843
KEGG D00017 YesY
MeSH Formaldehyde
ChEBI CHEBI:16842 YesY
RTECS number LP8925000
ATCvet code QP53AX19
Beilstein Reference 1209228
Gmelin Reference 445
3DMet B00018
Jmol-3D images Image 1
Molecular formula CH2O
Molar mass 30.03 g mol−1
Appearance Colorless gas
Density 0.8153 g/cm³ (−20 °C)[1]
Melting point −92 °C; −134 °F; 181 K
Boiling point −19 °C; −2 °F; 254 K ([1])
Solubility in water 400 g dm−3
log P 0.350
Acidity (pKa) 13.3
Basicity (pKb) 0.7
Dipole moment 2.33 D
Molecular shape Trigonal planar
EU Index 605-001-00-5
EU classification Toxic (T)
Corrosive (C)
Carc. Cat. 1
R-phrases R23/24/25 R34 R43 R45
S-phrases (S1/2) S26 S36/37/39 S45 S51 S53 S60
NFPA 704
NFPA 704.svg
Flash point 64 °C; 147 °F; 337 K
Autoignition temperature 430 °C; 806 °F; 703 K
Explosive limits 7–73%
LD50 100 mg/kg (oral, rat)
Related compounds
Related aldehydes Acetaldehyde


Related compounds methanol
formic acid
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Formaldehyde is an organic compound with the formula CH2O or HCHO. It is the simplest aldehyde, and is also called by its systematic name methanal. The common name of the substance comes from its similarity and relation to formic acid.

A gas at room temperature, formaldehyde is colorless and has a characteristic pungent, irritating odor. It is an important precursor to many other materials and chemical compounds. In 1996, the installed capacity for the production of formaldehyde was estimated to be 8.7 million tonnes per year.[3] Commercial solutions of formaldehyde in water, commonly called formol, were formerly used as disinfectants and for preservation of biological specimens.

In view of its widespread use, toxicity and volatility, exposure to formaldehyde is a significant consideration for human health.[4] In 2011, the US National Toxicology Program described formaldehyde as "known to be a human carcinogen".[5][6][7]