Succinic acid (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.

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

Biochemical role

Succinate is a component of the citric acid cycle and is capable of donating electrons to the electron transfer chain via the following 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. "Harmful by inhalation, ingestion and through skin absorption. Wash after handling. Eye contact may cause serious damage."

In nutraceutical form as a food additive and dietary supplement, is safe and approved by the FDA.

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.

References

See also

• Oil of amber, procured by heating succinic acid

External links

• MSDS Data
• FDA
• Succinic Acid