Arrange the following carbocations in decreasing order of stability: (I) C6H5-CH2+, (II) (CH3)2CH+, (III) CH3-CH2+, (IV) CH3+.

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Arrange the following carbocations in decreasing order of stability: (I) $C X_{6} H X_{5} - CH X_{2} X^{+}$ , (II) $(CH X_{3}) X_{2} CH X^{+}$ , (III) $CH X_{3} - CH X_{2} X^{+}$ , (IV) $CH X_{3} X^{+}$ .

A $II > I > III > IV$
B $I > III > II > IV$
C $IV > III > II > I$
D $I > II > III > IV$

Answer: D

Benzyl (I) is stabilised by resonance into the ring and is the most stable. Among the alkyl cations, stability follows the number of alkyl groups (hyperconjugation and +I): secondary (II) > primary (III) > methyl (IV). The order is I > II > III > IV.

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Arrange the following carbocations in decreasing order of stability: (I) CX6​HX5​−CHX2​X+, (II) (CHX3​)X2​CHX+, (III) CHX3​−CHX2​X+, (IV) CHX3​X+.

Answer: D

More questions on Stability of resonating structures and conjugated species

Arrange the following carbocations in decreasing order of stability: (I) $C X_{6} H X_{5} - CH X_{2} X^{+}$ , (II) $(CH X_{3}) X_{2} CH X^{+}$ , (III) $CH X_{3} - CH X_{2} X^{+}$ , (IV) $CH X_{3} X^{+}$ .