Given below are two statements : In the light of the above statements, choose the correct answer from the options given below :
- Both Statement I and Statement II are correct
- Both Statement I and Statement II are incorrect
- Statement I is correct but Statement II is incorrect
- Statement I is incorrect but Statement II is correct
Answer
(3) Statement I is correct but Statement II is incorrect
Solution
Statement I: Alkyl groups are electron releasing (+I). They increase the negative charge density on the carbanion carbon and destabilise it. More alkyl groups ⇒ less stable:
CH3- > CH3-CH2- > (CH3)2CH- > (CH3)3C- – correct.
Statement II: In allyl and benzyl carbanions the negative charge is delocalised over the π system ( CH2=CH- CH2 CH2-CH=CH2), so they are stabilised mainly by resonance – incorrect.
Answer: (3)