E1 vs. E2 elimination reactions

S. No.

E1 elimination Reaction

E2 elimination Reaction

1. Unimolecular (Rate of reaction depends on one molecule that is alkyl halide) Bimolecular (Rate of reaction depends on two molecules that is alkyl halide and base)
2. First order of reaction Second order of reaction
3. Two step reaction One step reaction
4. Involves weak base like n-BuOH Involves strong base like C2H5O
5. Rearrangement of intermediate carbocation possible Rearrangement of carbocation is not possible (Single step reaction)
6. Order of alkyl halide reactivity 3o>2o>1o Order of alkyl halide reactivity 3o>2o>1o7
7. Specific stereochemistry not required Leaving group must be anti to hydrogen removed