Answer to Question #86706 in Organic Chemistry for rajeev kumar

Question

Reaction of 1,3- butadiene to maleic acid gives cis product while fumaric acid
gives trans product

Answer 1

First of all, for my opinion it isn`t correct question.

From 1,3- butadiene by oxidation we can formate maleic anhydride. In industry, maleic acid is derived by hydrolysis of maleic anhydride. Meanwhile Maleic acid is the cis isomer of butenedioic acid, whereas fumaric acid is the trans isomer.

The major industrial use of maleic acid is its conversion to fumaric acid. This conversion, an isomerization, is catalysed by a variety of reagents, such as mineral acids and thiourea. Again, the large difference in water solubility makes fumaric acid purification easy.

The isomerization is a popular topic in schools. Maleic acid and fumaric acid do not spontaneously interconvert because rotation around a carbon carbon double bond is not energetically favourable. However, conversion of the cis isomer into the trans isomer is possible by photolysis in the presence of a small amount of bromine. Light converts elemental bromine into a bromine radical, which attacks the alkene in a radical addition reaction to a bromo-alkane radical; and now single bond rotation is possible. The bromine radicals recombine and fumaric acid is formed. In another method (used as a classroom demonstration), maleic acid is transformed into fumaric acid through the process of heating the maleic acid in hydrochloric acidsolution. Reversible addition (of H⁺) leads to free rotation about the central C-C bond and formation of the more stable and less soluble fumaric acid.