MHT CET · Chemistry · Alcohols Phenols and Ethers

The alcohol that produces turbidity immediately with \(\mathrm{ZnCl}_{2} /\) conc. HCl at room temperature

A 1-hydroxy butane
B 2-hydroxy butane
C 2-hydroxy-2-methyl propane
D 1-hydroxy-2-methyl propane

Verified Solution

Answer & Solution

Correct Answer

(C) 2-hydroxy-2-methyl propane

Step-by-step Solution

Detailed explanation

Mixture of anhydrous \(\mathrm{ZnCl}_{2}\) and conc. HCl is known as Lucas reagent. Lucas test is used for the distinction between primary, secondary and tertiary alcohols. The tertiary alcohol reacts immediately with Lucas reagent producing turbidity. The secondary alcohol gives turbidity within 5-10 min and primary alcohol do not give turbidity at all at room temperature. In the given alternates, 2 -hydroxy-2-methyl propane is \(3^{\circ}\) alcohol, so it is more reactive.

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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