Decarboxylation

Decarboxylation is any chemical reaction in which a carboxyl group (-COOH) is split off from a compound as carbon dioxide (CO2).

In biochemistry
Common biosynthetic decarboxylations of amino acids to amines are:
 * tryptophan to tryptamine
 * phenylalanine to phenylethylamine
 * tyrosine to tyramine
 * histidine to histamine
 * serine to ethanolamine
 * glutamic acid to GABA
 * lysine to cadaverine
 * arginine to agmatine
 * ornithine to putrescine
 * 5-HTP to serotonin
 * L-DOPA to dopamine

Other decarboxylation reactions from the citric acid cycle include:
 * pyruvate to acetyl-CoA
 * oxalosuccinate to α-ketoglutarate
 * α-ketoglutarate to succinyl-CoA.

Enzymes that catalyze decarboxylations are called decarboxylases or, more formally, carboxy-lyases (EC number 4.1.1).

In organic chemistry
Chemical decarboxylations reactions often require extensive heating in high-boiling solvents. Copper salts are often added as catalysts. Also the addition of catalytic amounts of cyclohexen-2-one has been reported to catalyze the decarboxylation of amino acids. Decarboxylations are especially easy for beta-keto acids due to the formation of a cyclic transition state for instance in Knoevenagel condensations. The Barton decarboxylation and Hunsdiecker reaction are radical reactions.