I came across a question where the following compound except with two methyls, ortho and meta to the nitro group, is dissolved in methylene chloridde, and then treated with trifluoroacetic acid.
It is given that $\ce{CO2}$ gas is given off in a decarboxylation reaction. I cannot find any sources about this. The solution explains that:
Treatment of a carboxylic acid with acid results in decarboxylation, and the evolution of $\ce{CO2}$, especially if the resulting compound contains a benzylic or allylic carbon, as is the case here.
First of all, what mechanism would allow for acid catalyzed decarboxylation? I know how decarboxylation of carboxylic acids with beta-carbonyls with heat works, and that acid can help that but that doesn't seem to have relevance here.
Secondly, why does having a benzylic or allylic carbon confer any special stability to promote the reaction?