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Ketonic decarboxylation (also known as decarboxylative ketonization) is a type of organic reaction and a decarboxylation converting two equivalents of a carboxylic acid (R−C(=O)OH) to a symmetric ketone (R 2 C=O) by the application of heat.
It can also be prepared by combining ethylene, CO, and H 2. [4] When the reaction is catalyzed by dicobalt octacarbonyl, water can be used as a source of hydrogen.A proposed intermediate is the ethylene-propionyl species [CH 3 C(O)Co(CO) 3 (ethylene)] which undergoes a migratory insertion to form [CH 3 COCH 2 CH 2 Co(CO) 3].
Decarboxylation is one of the oldest known organic reactions. It is one of the processes assumed to accompany pyrolysis and destructive distillation. Overall, decarboxylation depends upon stability of the carbanion synthon R −, [1] [2] although the anion may not be a true chemical intermediate.
This was a result of the fact that any halide anion generated in the reaction inhibited the Cu-catalyzed decarboxylation process. [15] Further optimization of the system and catalyst conditions has made decarboxylative cross-coupling using bimetallic Pd–Cu systems applicable to organic synthesis, most predominantly in the formation of biaryls ...
In contrast to the relatively facile decarboxylation of β-keto acids, the decarboxylation of α-keto acids presents a mechanistic challenge. Thiamine pyrophosphate (TPP) provides the biochemical and enzymological answer. TPP is the key catalytic cofactor used by enzymes catalyzing non-oxidative and oxidative decarboxylation of α-keto acids.
Dibenzyl ketone is prepared by ketonic decarboxylation of phenylacetic acid. One method is where phenylacetic acid is reacted with acetic anhydride and anhydrous potassium acetate and refluxed for two hours at 140−150 °C. The mixture is distilled slowly so that the distillate is mostly acetic acid. Carbon dioxide is released in this reaction ...
By decarboxylation of carboxylic anhydride. Ketones can be prepared from haloketones in reductive dehalogenation of halo ketones. In ketonic decarboxylation symmetrical ketones are prepared from carboxylic acids. [10] [17] Hydrolysis of unsaturated secondary amides, [18] β-Keto acid esters, [10] or β-diketones (the acetoacetic ester synthesis).
The Kochi reaction is an organic reaction for the decarboxylation of carboxylic acids to alkyl halides with lead(IV) acetate and a lithium halide. [ 1 ] The reaction is a variation of the Hunsdiecker reaction .