Which of the following mechanisms feature carbocation intermediates: SN1 only, SN2 only, E1 only, E2 only or both SN1 and E1?

1 Answer
May 20, 2015

Both #"S"_"N"1# and #"E1"# reactions feature carbocation intermediates.

The first step in both reactions is the same: departure of the leaving group to form an intermediate carbocation.

This is the rate determining step. It is a unimolecular reaction, and that accounts for the "#1#" in the names #"S"_"N"1# and #"E1"#.

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#"S"_"N"1 "# Reaction

If the nucleophile attacks and bonds to the cationic carbon atom, we have a nucleophilic substitution (#"S"_"N"#) reaction.

#"E"1#Reaction

If, instead, a base attacks the β hydrogen to form an alkene, we have an elimination (#"E1"#) reaction.