JEE Chemistry 2023 Question with Solution

Step-by-step solution

Standard Method

Given: The substrate is a phenyl-substituted hydroxy aldehyde treated with $\mathrm{Zn(Hg)/HCl}$ and heat.

Find: The major product among the given structures.

The solution states that the major product corresponds to B only, and the marked correct option on the page is D because option D says B only.

Under strongly acidic Clemmensen conditions, the aldehyde function is reduced, and the benzylic alcohol-containing substrate undergoes dehydration to give the more stable alkene. The product shown in the solution is structure B.

Therefore, the correct option is D.

Common mistakes

• Mistake: Choosing option C by placing the double bond at the wrong position. Why it is wrong: the product shown in the solution has the alkene corresponding to structure B, not the rearranged alternative. What to do instead: follow the exact product connectivity after reduction and dehydration under acidic conditions.

• Mistake: Interpreting the answer as option B directly from the structure label. Why it is wrong: the MCQ options are statements like C only, A only, B only, D only. What to do instead: first identify the product structure as B, then map it to the listed choice, which is option D.