Question

Among the given cations, .................. is most stable. (sec-butyl carbonium ion, tert - butyl carbonium ion, n-butyl carbonium ion and iso-butyl carbonium ion)

• A. t - Butyl carbonium ion
• B. sec-butyl carbonium ion
• C. n-butyl carbonium ion
• D. iso-butyl carbonium ion

Answer 1

Answer: (A)

t - Butyl carbonium ion

Among the given cations, (sec-butyl carbonium ion, tert - butyl carbonium ion, n-butyl carbonium ion) t - Butyl carbonium ion is most stable.
This is because, methyl group has + I effect and stabilizes the positive charge.
In tert butyl carbonium ion, three methyl groups are attached to C atom bearing positive charge which results in maximum stability.