E1 mechanism readily occur in 3∘ carbocation. Presence of higher alkyl groups in alkyl halide also favours E1 mechanism. The neopentyl halide in ethanol yields alkenes by E1 mechanism due to steric factor which prevents E2 mechanism. In E1 mechanism, Heterolytic dissociation of alkyl halide followed by abstraction of proton by base from a C adjacent to the positively charged C atom (β−C atom ), takes place as follows: