JEE Main levelSingle correct optionDifficulty 2 of 3o2191
Assertion: Oxymercuration-demercuration of 3,3-dimethylbut-1-ene gives 3,3-dimethylbutan-2-ol without any methyl shift.
Reason: The intermediate is a bridged mercurinium ion in which the positive charge is delocalised over mercury, so no free carbocation is formed.
ABoth Assertion and Reason are true and the Reason is the correct explanation of the Assertion
BBoth Assertion and Reason are true but the Reason is not the correct explanation of the Assertion
CAssertion is true but Reason is false
DAssertion is false but Reason is true
Answer: A
A methyl shift needs a free carbocation next to the quaternary carbon. The bridged mercurinium ion is opened by water without such an ion forming, so the skeleton is retained. Both statements are true and the reason explains the assertion.