Fumaric acid

Fumaric acid

Names
Preferred IUPAC name (2E)-But-2-enedioic acid
Other names Fumaric acid trans-1,2-Ethylenedicarboxylic acid 2-Butenedioic acid trans-butenedioic acid Allomaleic acid Boletic acid Donitic acid Lichenic acid
Identifiers
CAS Number	110-17-8 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:18012 Y
ChEMBL	ChEMBL503160 Y
ChemSpider	10197150 Y
DrugBank	DB04299 Y
ECHA InfoCard	100.003.404
EC Number	203-743-0
E number	E297 (preservatives)
KEGG	C00122 Y
UNII	88XHZ13131 Y
InChI InChI=1S/C4H4O4/c5-3(6)1-2-4(7)8/h1-2H,(H,5,6)(H,7,8)/b2-1+ Y Key: VZCYOOQTPOCHFL-OWOJBTEDSA-N Y InChI=1/C4H4O4/c5-3(6)1-2-4(7)8/h1-2H,(H,5,6)(H,7,8)/b2-1+ Key: VZCYOOQTPOCHFL-OWOJBTEDBF
SMILES C(=C/C(=O)O)\C(=O)O
Properties
Chemical formula	C4H4O4
Molar mass	116.07 g·mol−1
Appearance	White solid
Density	1.635 g/cm3
Melting point	287 °C (549 °F; 560 K) (decomp)
Solubility in water	4.9 g/L at 20°C
Acidity (pKa)	pka1 = 3.03, pka2 = 4.44
Magnetic susceptibility (χ)	-49.11·10−6 cm3/mol
Pharmacology
ATC code	D05AX01 (WHO)
Hazards
EU classification (DSD)	Irritant (Xi)
R-phrases	R36
S-phrases	(S2)-S26
NFPA 704	1 2 0
Related compounds
Related carboxylic acids	maleic acid succinic acid crotonic acid
Related compounds	fumaryl chloride fumaronitrile dimethyl fumarate iron(II) fumarate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Fumaric acid or trans-butenedioic acid is the chemical compound with the formula HO₂CCH=CHCO₂H. This white crystalline compound is one of two isomeric unsaturated dicarboxylic acids, the other being maleic acid. In fumaric acid the carboxylic acid groups are trans (E) and in maleic acid they are cis (Z). Fumaric acid has a fruit-like taste.

The salts and esters are known as fumarates. Fumarate can also refer to the C₄H₂O₄⁻⁻ ion (in solution).

Fumaric acid was first prepared from succinic acid. A traditional synthesis involves oxidation of furfural (from the processing of maize) using chlorate in the presence of a vanadium-based catalyst. Currently, industrial synthesis of fumaric acid is mostly based on catalytic isomerisation of maleic acid in aqueous solutions at low pH. Maleic acid is accessible in large volumes as a hydrolysis product of maleic anhydride, produced by catalytic oxidation of benzene or butane.

The chemical properties of fumaric acid can be anticipated from its component functional groups. This weak acid forms a diester, it undergoes additions across the double bond, and it is an excellent dienophile.

Fumaric acid does not combust in a bomb calorimeter under conditions where maleic acid deflagrates smoothly. For teaching experiments designed to measure the difference in energy between the cis- and trans- isomers, a measured quantity of carbon can be ground with the subject compound and the enthalpy of combustion computed by difference.