Please help me rank these compounds in order of decreasing reactivity toward SN1 & SN2 reaction:?

Question

1) chlorocyclopentane
2) chloromethane
3) 1-chloro-1-pentane
4) 3-chloro-1-pentane
5) chloromethylbenzene
6) 2-chloro-2-methylbutane
7) 1-chloropentane

Answer 1

towards SN1:
chloromethylbenzene > 3-chloro-1-pentene > 2-chloro-2-methylbutane > chlorocyclopentane > 1-chloropentane > chloromethane > 1-chloro-1-pentene

towards SN2:
chloromethane > 1-chloropentane > chlorocyclopentane > chloromethylbenzene > 3-chloro-1-pentene > 2-chloro-2-methylbutane > 1-chloro-1-pentene

Answer 2

In SN2 reactions, chloromethane > 1-chloropentane > chlorocyclopentane because of increasing crowding of groups around the carbon atom. 1-Chloro-1-pentene would be unreactive toward SN1 or SN2 reaction, because it is a vinyl-type derivative. 3-Chloro-1-pentene would go SN1 rather than SN2, because it goes through an very stable allylic carbonium ion. Chloromethylbenzene likewise, because the carbonium ion is benzylic. 2-Chloro-2-methylbutane likewise, because the carbonium ion is tertiary. Chlorocyclopentane could go SN1 or SN2 depending on solvent polarity, because the carbonium ion would be a less stable secondary.