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Succinic acid
IUPAC name Butanedioic acid
other names ethane-1,2-dicarboxylic acid
Identifiers
CAS number	110-15-6 Y
ChemSpider	1078
SMILES	OC(CCC(O)=O)=O
Properties
Molecular formula	C4H6O4
Molar mass	118.09 g/mol
Density	1.56 g/cm³
Melting point	185–187 °C
Boiling point	235 °C, 508 K, 455 °F
Solubility in 2-propanol, ethanol	2-propanol 0.32 M, ethanol 0.4 M [1]
Acidity (pKa)	pKa1=4.2 pKa2=5.6
Related compounds
Other anions	succinate
Related carboxylic acids	propionic acid malonic acid butyric acid crotonic acid malic acid tartaric acid fumaric acid diglycolic acid pentanoic acid glutaric acid
Related compounds	butanol butyraldehyde crotonaldehyde sodium succinate
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Succinic acid ( pronunciation: [sək-ˈsi-nik ˈa-səd]; IUPAC systematic name: butanedioic acid; historically known as spirit of amber) is a dicarboxylic acid. Succinate plays a biochemical role in the citric acid cycle. The name derives from Latin succinum, meaning amber, from which the acid may be obtained.

The carboxylate anion is called succinate and esters of succinic acid are called alkyl succinates.

Physical properties

At room temperature, pure succinic acid is a solid that forms colorless, odorless crystals. It has a melting point of 185 °C and a boiling point of 235 °C. It is a diprotic acid.

Biochemical role

Succinate is a component of the citric acid cycle and is capable of donating electrons to the electron transport chain by the reaction:

succinate + FAD → fumarate + FADH₂.

This is catalysed by the enzyme succinate dehydrogenase (or complex II of the mitochondrial ETC). The complex is a 4 subunit membrane-bound lipoprotein which couples the oxidation of succinate to the reduction of ubiquinone. Intermediate electron carriers are FAD and three Fe₂S₂ clusters part of subunit B.

History

Spirit of amber was procured from amber by pulverising and distilling it using a sand bath. It was chiefly used externally for rheumatic aches and pains, and internally in inveterate gleets.

Safety

The acid is combustible and corrosive, capable of causing burns.

In nutraceutical form as a food additive and dietary supplement, is safe and approved by the U.S. Food and Drug Administration.^[2] As an excipient in pharmaceutical products it is used to control acidity^[3] and, more rarely, in effervescent tablets.^[4]

Reactions

Succinic acid can be converted to fumaric acid by oxidation. The diethyl ester is a substrate in the Stobbe condensation.

Fermentation

Succinic acid is created as a byproduct of the fermentation of sugar. It lends to fermented beverages such as wine and beer a common taste that is a combination of saltiness, bitterness and acidity.^[5]

References

1. ^ Solubility of succinic acid in non-aqueous solvents
2. ^ http://www.accessdata.fda.gov/scripts/cder/iig/index.cfm
3. ^ http://drugtopics.modernmedicine.com/drugtopics/Drugtopics.com+Exclusives/Overview-of-pharmaceutical-excipients-used-in-tabl/ArticleStandard/Article/detail/561047
4. ^ Lachman, Leon; Joseph B. Schwartz (1990). Pharmaceutical Dosage Forms--tablets. p. 288. ISBN 0824780442, 9780824780449. 
5. ^ Peynaud, Emile (1984) Knowing and Making Wine.

• This article incorporates content from the 1728 Cyclopaedia, a publication in the public domain.

See also

• Oil of amber, procured by heating succinic acid

External links

• MSDS Data
• FDA
• Succinic Acid
• Calculator: Water and solute activities in aqueous succinic acid

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