Question

6.28 Rank the three carbocations shown in terms of increasing stability: (a)

Answer 1

Order of stability of carbocation is:

primary < secondary < tertiary

Primary carbocation: Positive charge Carbon to which only one other carbon is directly bonded

Secondary carbocation: Positive charge Carbon to which two other carbons is directly bonded

tertiary carbocation: Positive charge Carbon to which three other carbons is directly bonded

a)

Left one: tertiary carbocation

Middle one: Secondary carbocation

Right one: Primary carbocation

SO, stability ordre is:

Right < middle < left

b)

Left one: Secondary carbocation (but stabilised by resonance from ring)

Middle one: Secondary carbocation

Right one: Primary carbocation

SO, stability ordre is:

Right < middle < left