Sciencemadness Discussion Board

Decarboxylation with H2SO4?

Filemon - 16-4-2008 at 16:26

Is it may decarboxylate an organic acid with H2SO4 concentrate?

Nicodem - 17-4-2008 at 05:34

You should explain what you mean. What type of decarboxylation and what type of substrate and so on?

One example of an apparent "decarboxylation" with sulfuric acid is that of citric acid (an alpha-hydroxy carboxylic acid) is the synthesis of acetonedicarboxylic acid:
However that is not a true decarboxylation (elimination of CO2) but the fragmentation of the intermediate carbocation (R-CO<sup>+</sup>;) by the elimination of carbon monoxide (CO). (The carbocations of the type R-CO<sup>+</sup> readily form trough the interaction of crboxylic acids with strong acids like H2SO4 or AlCl3. For example, mixing formic acid with sulfuric acid results in the formation of CO and H2O since the HCO<sup>+</sup> intermediate is unstable.)