Aldehydes Ketones And Carboxylic Acids

P and Q are isomers of dicarboxylic acid C₄H₄O₄. Both decolorise Br₂/H₂O. On heating, P forms the cyclic anhydride. Upon treatment with dilute alkaline KMnO₄, P as well as Q could produce one or more than one from S, T and U.

In the following reaction sequences V and W are, respectively,