Q 27P - Organic Chemistry (Mcmurry)

Question

A chemist requires a large amount of 1-bromo-2-pentene as starting material for synthesis and decides to carry out an NBS allylic bromination reaction. What is wrong with the following synthesis plan? What side products would form in addition to the desired product?

Step-by-Step Solution

Answer

                                                            Formation of 3 possible products

S tep-by-Step Solution Step 1: Unsymmetrical alkene

An unsymmetrical alkene is an alkene in whose molecule the pair of ligands or alkane attached on either side of a double bond are different from one another.

Step 2: Given reaction

The given alkene is an unsymmetrical alkene that forms a mixture of products. Of which the products are 1-Bromo pent-2-ene, 3-Bromo pent-1-ene, and 2-Bromo pent-3ene respectively. The major product formed is 1-Bromo pent-2-ene. The reaction is represented as:

                                                               Formation of 3 possible products