Fumaric acid
IUPAC name (E)-Butenedioic acid
Other names 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
ChemSpider	10197150 Y
UNII	88XHZ13131 Y
EC number	203-743-0
DrugBank	DB04299
KEGG	C00122 Y
ChEBI	CHEBI:18012 Y
ChEMBL	CHEMBL503160 Y
ATC code	D05AX01
Jmol-3D images	Image 1
SMILES C(=C/C(=O)O)\C(=O)O
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
Properties
Molecular formula	C4H4O4
Molar mass	116.07 g/mol
Appearance	White solid
Density	1.635 g/cm³, solid
Melting point	287 °C
Solubility in water	0.63 g/100 mL
Acidity (pKa)	pka1 = 3.03, pka2 = 4.44
Hazards
EU classification	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
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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.

  Biology

Fumaric acid is found in fumitory (Fumaria officinalis), bolete mushrooms (specifically Boletus fomentarius var. pseudo-igniarius), lichen, and Iceland moss.

Fumarate is an intermediate in the citric acid cycle used by cells to produce energy in the form of adenosine triphosphate (ATP) from food. It is formed by the oxidation of succinate by the enzyme succinate dehydrogenase. Fumarate is then converted by the enzyme fumarase to malate. Human skin naturally produces fumaric acid when exposed to sunlight.^{[citation needed]}

Fumarate is also a product of the urea cycle.

  Medicine

A fumaric acid ester is currently under investigation for treatment of multiple sclerosis.^[1]

  Food

As a food additive, it is used as an acidity regulator and is denoted by the E number E297. Fumaric acid is a food acidulent used since 1946. It is non-toxic. It is generally used in beverages and baking powders for which requirements are placed on purity. It is generally used as a substitute for tartaric acid and occasionally in place of citric acid, at a rate of 1.36 g of citric acid to every 0.91 grams of fumaric acid to add sourness, similar to the way malic acid is used. It is also used as a coagulant in stovetop pudding mixes.

It is approved for use as a food additive in the EU^[2], USA^[3] and Australia and New Zealand^[4] (where it is listed by its INS number 297).

  Chemistry

Fumaric acid was first prepared from succinic acid.^[5] A traditional synthesis involves oxidation of furfural (from the processing of maize) using chlorate in the presence of a vanadium-based catalyst.^[6] 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.^[7]

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.

  Other uses

Fumaric acid is used in the manufacture of polyester resins and polyhydric alcohols and as a mordant for dyes.

  Safety

Fumaric acid converts to the irritant maleic anhydride, upon partial combustion.

  Interactive pathway map

Click on genes, proteins and metabolites below to link to respective articles. ^[8]

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  Citric_acid_cycle edit

  See also

• Dermatology
• Photosynthesis
• Maleic acid, the cis-isomer of fumaric acid

  References

1. ^ Moharregh-Khiabani, D.; Linker, R.; Gold, R.; Stangel, M. (2009). "Fumaric Acid and its esters: an emerging treatment for multiple sclerosis". Current neuropharmacology 7 (1): 60–64. DOI:10.2174/157015909787602788. PMC 2724664. PMID 19721818. //www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2724664.  edit
2. ^ UK Food Standards Agency: "Current EU approved additives and their E Numbers". http://www.food.gov.uk/safereating/chemsafe/additivesbranch/enumberlist. Retrieved 2011-10-27. 
3. ^ US Food and Drug Administration: "Listing of Food Additives Status Part II". http://www.fda.gov/Food/FoodIngredientsPackaging/FoodAdditives/ucm191033.htm#ftnT. Retrieved 2011-10-27. 
4. ^ Australia New Zealand Food Standards Code"Standard 1.2.4 - Labelling of ingredients". http://www.comlaw.gov.au/Details/F2011C00827. Retrieved 2011-10-27. 
5. ^ Volhard, J. "Darstellung von Maleïnsäureanhydrid" Justus Liebig's Annalen der Chemie 1892, volume 268, page 255-6. doi:10.1002/jlac.18922680108
6. ^ Milas, N. A. "Fumaric Acid" Organic Synthesis 1943, Collective Volume 2, page 302. Online version
7. ^ British Patent No. 775,912, publicated on the May 29, 1957, by Monsanto Chemical Company.
8. ^ The interactive pathway map can be edited at WikiPathways: "TCA_Cycle_WP78". http://www.wikipathways.org/index.php/Pathway:WP78. 

  External links

• International Chemical Safety Card 1173

Citric Acid Cycle Metabolic Pathway
			Oxaloacetate			Malate			Fumarate			Succinate			Succinyl-CoA
Acetyl-CoA				NADH + H+	NAD+			H2O		FADH2	FAD		CoA + ATP(GTP)	Pi + ADP(GDP)
	+	H2O														NADH + H+ + CO2
		CoA														NAD+
					H2O		H2O			NAD(P)+	NAD(P)H + H+			CO2
			Citrate			cis-Aconitate			Isocitrate			Oxalosuccinate			α-Ketoglutarate
M: MET mt, k, c/g/r/p/y/i, f/h/s/l/o/e, a/u, n, m k, cgrp/y/i, f/h/s/l/o/e, au, n, m, epon m(A16/C10),i(k, c/g/r/p/y/i, f/h/s/o/e, a/u, n, m)

Urea cycle Metabolic Pathway
L-citrulline Carbamoyl phosphate L-ornithine Pi L-aspartate Urea + ATP PPi + AMP H2O L-argininosuccinate Fumarate L-arginine
M: MET mt, k, c/g/r/p/y/i, f/h/s/l/o/e, a/u, n, m k, cgrp/y/i, f/h/s/l/o/e, au, n, m, epon m(A16/C10),i(k, c/g/r/p/y/i, f/h/s/o/e, a/u, n, m)