Question

S. Some diacids can lose a molecule of water when the two carboxyl groups react to form a cyclic anhydride. Phthalic acid is a diacid that reacts as follows Co,H heat Co2H Phthalic Acid Phthalic Anhydride Maleic acid can also lose a molecule of water and form maleic anhydride in a similar manner, but fumaric acid cannot. Explain why. Does this seem consistent with your assignment of maleic acid to being the cis or the trons isomer?

Answer 1

maleic acid on heating results in the formation of anhydride due to the cis orientation of the two carboxyl group. On the contrary, the fumaric acid the orientati6n of two carboxyl group is trans to one another, thus removal of water to produce anhydride doesn't occur