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Decarboxylation is a chemical reaction that removes a carboxyl group and releases carbon dioxide (CO 2). Usually, decarboxylation refers to a reaction of carboxylic acids , removing a carbon atom from a carbon chain.
The major sources of benzene exposure are tobacco smoke, automobile service stations, exhaust from motor vehicles, and industrial emissions; however, ingestion and dermal absorption of benzene can also occur through contact with contaminated water. Benzene is hepatically metabolized and excreted in the urine.
Here decarbonylation accompanies the preparation of cyclopentadienyliron dicarbonyl dimer: 2 Fe(CO) 5 + C 10 H 12 → (η 5 −C 5 H 5) 2 Fe 2 (CO) 4 + 6 CO + H 2. Decarbonylation can be induced photochemically as well as using reagents such as trimethylamine N-oxide: Me 3 NO + L + Fe(CO) 5 → Me 3 N + CO 2 + LFe(CO) 4
Another example is the synthesis of 2,7-dimethyl-2,7-dinitrooctane from 4-methyl-4-nitrovaleric acid: [3] The Kolbe reaction has also been occasionally used in cross-coupling reactions . In 2022, it was discovered that the Kolbe electrolysis is enhanced if an alternating square wave current is used instead of a direct current .
Water and carbon dioxide are byproducts: [1] 2 RCO 2 H → R 2 CO + CO 2 + H 2 O. Bases promote this reaction. The reaction mechanism is proposed to involve nucleophilic attack of the alpha-carbon of one acid group on the other carboxylic acid group, possibly as a concerted reaction with the decarboxylation. [1]
Then, decarboxylation occurs to produce a carbanion intermediate. The intermediate picks up a hydrogen from water to form the products. [2] The suggested reaction mechanism of α,α-disubstituted esters in the Krapcho decarboxylation reaction. R 1, R 2, and R 3 are any carbon containing substituents.
Studies of decarboxylation over nickel and palladium-based catalysts were first reported by Wilhelm Maier et al., in 1982, [6] when they achieved the deoxygenation of several carboxylic acids via decarboxylation under a hydrogen atmosphere. This included the conversion of aliphatic acids (such as heptanoic and octanoic acids) to alkanes (namely ...
The above mechanism is consistent with all available experimental evidence. [3] The equilibrium between species 1 and 2 is supported by 18 O Isotopic labeling experiments. In deuterated water , carbonyl oxygen exchange occurs much faster than the rearrangement, indicating that the first equilibrium is not the rate-determining step.