Question

The major product of the following reaction is:

• A. 2-Phenylhepta-2,4-diene
• B. 6-Phenylhepta-3,5-diene
• C. 6-Phenylhepta-2,4-diene
• D. 2-Phenylhepta-2,5-diene

Hint:

In elimination reactions with excess base, the most stable conjugated diene product is favored due to its resonance stability.

Answer 1

The Correct Option is C

The given reaction involves a dehydrohalogenation process, where a halogen (Br) is eliminated in the presence of an excess base, KOH in ethanol. This reaction typically leads to the formation of alkenes by the elimination of H and Br atoms. Since the reagent is in excess, it leads to a conjugated diene product.
The elimination occurs in such a way that the resulting product has two double bonds conjugated with the phenyl group. The correct product formed in this reaction is 6-Phenylhepta-2,4-diene, as it has the conjugation in positions 2 and 4.