Exams › JEE Advanced › Chemistry
An epoxide of the type CH3-C(CH3)(O-bridge)-CH2 (2-methyl-1,2-epoxypropane, i.e. isobutylene oxide) undergoes hydrolysis with H2¹⁸O (labeled water) under basic conditions. The major final product is:
- CH3-C(OH)(CH3)-CH2-¹⁸OH
- CH3-¹⁸OH-C(CH3)-CH2OH
- CH3-C(OH)(CH3)-CH2OH
- CH3-¹⁸OH-C(CH3)-CH2-¹⁸OH
Correct answer: CH3-C(OH)(CH3)-CH2-¹⁸OH
Solution
Base-catalyzed epoxide opening proceeds via SN2 at the less sterically hindered primary carbon (CH2). The ¹⁸OH- (from H2¹⁸O) attacks the primary carbon, giving CH3-C(OH)(CH3)-CH2-¹⁸OH. The tertiary carbon gets a regular OH from proton transfer.
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