Question

Why is ch3_ch_ch3 more stable than ch3_ch2_ch2

Answer 1

In this case CH3-CH2+ is more stable than CH2=CH+. First I'll explain about CH3-CH2+ carbocation. The positive charge on the CH2 is stabilised by the inductive effect from the neighbouring carbon atom.

Coming to CH2=CH+. The two carbon atoms involved are sp2 hybridised. An sp2 hybridised atom is averse to a positive charge and this aversion increases as the s-character of a hybridised carbon atom increases. Also the inductive effect decreases by the neighbouring carbon atom because that is also sp2 hybridised.