Predict the major product of acid catalysed dehydration of (i) 1-methylcyclohexanol and (ii) butan-1-ol
The acid catalysed dehydration of 1-methylcyclohexanol results in the formation of 1-Methylcyclohexene as the major product. This process effectively removes a molecule of water to generate the alkene.
In the case of butan-1-ol, the reaction produces a mixture of but-1-ene and but-2-ene. The major product identified is but-2-ene. This selectivity is explained by a rearrangement mechanism that leads to the formation of a secondary carbocation, making but-2-ene the predominant product over but-1-ene.
Explanation
The answer is derived directly from the textbook solution provided in the context for question 7.7. Part (i) corresponds to the direct elimination product. Part (ii) highlights the rearrangement aspect mentioned in the text, where butan-1-ol (a primary alcohol) typically requires rearrangement to form a more stable secondary carbocation intermediate, leading to the major product but-2-ene.