Other decarboxylation reactions from the citric acid cycle include:
Chemical decarboxylations reactions often require extensive heating in high-boiling solvents. Copper salts are often added as catalysts. Heating a carboxylic acid strongly with soda lime is also able to effect decarboxylation. Heating the product of the malonic ester synthesis with hydrochloric acid also affords decarboxylation. 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.
Kolbe electrolysis — the electrolysis of salts of carboxylic acids give the decarboxylated dimer products:
This reaction occurs via a radical mechanism as well.