Chapter 11, Problem 11.16P

Interpretation Introduction

Interpretation:

The major 1, 2-addition and 1, 4-addition product of the given reaction are to be drawn.

Concept introduction:

The electrophilic addition reaction in a case of conjugated diene system leads to the formation of a mixture of the isomeric products that are 1, 2-addition and 1, 4-addition products. The major products in 1, 2-addition and 1, 4-addition depend on the stability of the carbocation formed as the reaction intermediate. The most stable carbocation gives the major 1, 2-addition and 1, 4-addition products. The stability order for carbocation is Secondary benzylic > Tertiary > Primary benzylic, allylic > Secondary > Primary > Methyl etc. The 1, 2-addition occurs according to the Markovnikov rule, where the electrophile and a nucleophile get attached to C1 and C2 carbon atoms of an alkene (double bonded carbon atoms). In the 1, 4-addition, an electrophile and a nucleophile get added to C1 and C4 carbon atoms in the alkene. 1, 4-addition results when the carbocation intermediate is resonance stabilized.