COMEDK · Chemistry · 14. Hydrocarbons

When 2-bromopentane is heated with alcoholic solution of potassium hydroxide, the major product obtained is

A pent-l-ene
B pent-2-ene
C pent-l-yne
D pent-2-yne

Verified Solution

Answer & Solution

Correct Answer

(B) pent-2-ene

Step-by-step Solution

Detailed explanation

According to Saytzeff rule, in dehydrohalogenation reactions, the preferred product is that alkene which has the greater number of alkyl groups attached to the doubly bonded carbon atoms. Thus, 2 -bromopentane gives pent-2-ene as the major product.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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