Formic acid

Formic acid

Names
Preferred IUPAC name Formic acid[1]
Systematic IUPAC name Methanoic acid[1]
Other names Carbonous acid; Formylic acid; Hydrogen carboxylic acid; Hydroxy(oxo)methane; Metacarbonoic acid; Oxocarbinic acid; Oxomethanol
Identifiers
CAS Number	64-18-6 Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30751 Y
ChEMBL	ChEMBL116736 Y
ChemSpider	278 Y
DrugBank	DB01942 Y
ECHA InfoCard	100.000.527
EC Number	200-579-1
E number	E236 (preservatives)
KEGG	C00058 Y
PubChem CID	284
RTECS number	LQ4900000
UNII	0YIW783RG1 Y
CompTox Dashboard (EPA)	DTXSID2024115
SMILES O=CO
Properties
Chemical formula	CH2O2
Molar mass	46.03 g·mol−1
Appearance	Colorless fuming liquid
Odor	Pungent, penetrating
Density	1.220 g/mL
Melting point	8.4 °C (47.1 °F; 281.5 K)
Boiling point	100.8 °C (213.4 °F; 373.9 K)
Solubility in water	Miscible
Solubility	Miscible with ether, acetone, ethyl acetate, glycerol, methanol, ethanol Partially soluble in benzene, toluene, xylenes
log P	−0.54
Vapor pressure	35 mmHg (20 °C)[2]
Acidity (pKa)	3.77[3]
Conjugate base	Formate
Magnetic susceptibility (χ)	-19.90·10−6 cm3/mol
Refractive index (nD)	1.3714 (20 °C)
Viscosity	1.57 cP at 268 °C
Structure
Molecular shape	Planar
Dipole moment	1.41 D (gas)
Thermochemistry
Std enthalpy of formation ΔfHo298	−425.0 kJ/mol
Std enthalpy of combustion ΔcHo298	−254.6 kJ/mol
Standard molar entropy So298	131.8 J/mol K
Pharmacology
ATCvet code	QP53AG01 (WHO)
Hazards
Main hazards	Corrosive; irritant; sensitizer
NFPA 704	2 3 1
R-phrases	Template:R10 R35
S-phrases	(S1/2) S23 S26 S45
Explosive limits	14–34%[source?] 18%–57% (90% solution)[2]
U.S. Permissible exposure limit (PEL)	TWA 5 ppm (9 mg/m3)[2]
Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Formic acid, or methanoic acid, is the simplist carboxylic acid and has the chemical formula HCO
₂H. Many animals use for defence. The word "formic" comes from the Latin word for ant, formica, referring to its early isolation by the distillation of ant bodies, and the trivial name in some languages means "ant-acid", such as Dutch mierenzuur, Danish myresyre, Faroese meyrusýra, Français acide formique and German Ameisensäure. Esters, salts, and the anions derived from formic acid are called formates.

In the 15th century, many alchemists reported that ants use an acidid fluid for defense. English naturalist John Ray was the first to get formic acid, by distilling ants, in 1671.

In nature, it is found in most ants.^[4] The wood ants from the genus Formica can spray formic acid on their preys or to defend the nest. It is also known from the trichomes of stinging nettle (Urtica dioica). Formic acid is a naturally occurring component of the atmosphere due primarily to forest emissions.^[5]

1. ↑ ^{1.0 1.1} Favre, Henri A.; Powell, Warren H. (2014). Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. p. 745. doi:10.1039/9781849733069. ISBN 978-0-85404-182-4.
2. ↑ ^{2.0 2.1 2.2} NIOSH Pocket Guide to Chemical Hazards. "#0296". National Institute for Occupational Safety and Health (NIOSH).
3. ↑ Brown, H. C. et al., in Braude, E. A. and Nachod, F. C., Determination of Organic Structures by Physical Methods, Academic Press, New York, 1955.
4. ↑ Hoffman, Donald R. "Ant venoms" Current Opinion in Allergy and Clinical Immunology 2010, vol. 10, pages 342–346. doi:10.1097/ACI.0b013e328339f325
5. ↑ "Emission of formic and acetic acids from tropical savanna soils". Geophysical Research Letters. 18 (9): 1707–1710. 1991. Bibcode:1991GeoRL..18.1707S. doi:10.1029/91GL01565. {{cite journal}}: Unknown parameter |authors= ignored (help)