Question

which ones are major and minor?

In the given reaction, predict the major and minor products. CH,CH, OH major and minor products

Answer 1

(3) is the major product because it follows SN¹ pathway and as bromide ion leaves a secondary carbocation is formed. Hydrogen present at back position in the adjacent carbon can migrate to form a more stable tertiary carbication where the nucleophile , which is ethoxide ion, attacks to form the major product. As methyl group is at front, ethoxide ion attacks from back. This is why (1) is not a major product. For (2) , whenever there is a possibility of formation of more stable carbocation, it readily forms via migration. (4) can be a minor product as the nucleophile attacks from opposite side of the leaving group, leading to inversion of configuration. This follows a SN₂pathway. If HBr is removed, (5) and (7) are minor products. (6) is not possible as the position of methyl group is changed.