Question

The correct order of increasing stabilities for the following carbocations is
(1) allyl carbocation
(2) neopentyl carbocation
(3) benzyl carbocation
(4) isobutyl carbocation

• A. $(1)<(4)<(2)<(3)$
• B. $(4)<(1)<(2)<(3)$
• C. $(2)<(4)<(1)<(3)$
• D. $(2)<(4)<(3)<(1)$

Answer 1

Answer: (C)

Allyl carbocation (stabilised by resonance)

Neopentyl carbocation :

Benzyl carbocation (stabilised by resonance)

Isobutyl carbocation :

Benzyl and allyl carbocations are much more stable due to resonance
Hence, the stability order is
Neopentyl carbocation $<$ isobutyl carbocation $<$ allyl carbocation $<$ benzyl carbocation