JEE MainChemistryGeneral Organic Chemistry
Consider the following isomeric carbocations that can theoretically form as intermediates during the electrophilic addition of H^+ to 1-methoxybuta-1,3-diene. Which of these carbocations is the most thermodynamically stable?
Options
- ACH₃-O- + C H-CH₂-CH=CH₂
- BCH₃-O-CH₂- + C H-CH=CH₂
- CCH₃-O-CH=CH- + C H-CH₃
- DCH₃-O-CH=CH-CH₂- + C H₂
Correct answer
C. CH₃-O-CH=CH- + C H-CH₃
Step-by-step solution
The stability of a carbocation is determined by the extent of delocalization of the positive charge and the ability of substituents to donate electron density. Let us analyze the given carbocations: - CH₃-O-CH=CH- + C H-CH₃ : This is an allylic carbocation. The positive charge can delocalize via resonance to the carbon adjacent to the oxygen atom ( CH₃-O- + C H-CH=CH-CH₃ ). The oxygen atom then donates its lone pair through a strong +M effect, creating a resonance structure where all atoms have complete octets. Thi