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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 Buchner ring expansion reaction was first used in 1885 by Eduard Buchner and Theodor Curtius [1] [2] who prepared a carbene from ethyl diazoacetate for addition to benzene using both thermal and photochemical pathways in the synthesis of cycloheptatriene derivatives. The resulting product was a mixture of four isomeric carboxylic acids ...
As benzene is ubiquitous in gasoline and hydrocarbon fuels that are in use everywhere, human exposure to benzene is a global health problem. Benzene targets the liver, kidney, lung, heart and brain and can cause DNA strand breaks and chromosomal damage, hence is teratogenic and mutagenic. Benzene causes cancer in animals including humans.
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 .
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.
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
In commercial applications, the alkylating agents are generally alkenes, some of the largest scale reactions practiced in industry.Such alkylations are of major industrial importance, e.g. for the production of ethylbenzene, the precursor to polystyrene, from benzene and ethylene and for the production of cumene from benzene and propene in cumene process:
Reaction mechanism for the amine formation from a carboxylic acid via Schmidt reaction. In the reaction mechanism for the Schmidt reaction of ketones, the carbonyl group is activated by protonation for nucleophilic addition by the azide, forming azidohydrin 3, which loses water in an elimination reaction to diazoiminium 5.