Provide an example of the E1 and E2 elimination.

E1 and E2 eliminations are two types of reactions that involve the removal of a leaving group from a molecule to form a double bond. E1 elimination is a two-step process that involves the formation of a carbocation intermediate, while E2 elimination is a one-step process that occurs with the simultaneous departure of the leaving group and the formation of the double bond.

In E1 elimination, the leaving group departs first to form a carbocation intermediate, which is then deprotonated by a base to form the double bond. This reaction is favoured by the presence of a weak base and a polar solvent, as they stabilise the carbocation intermediate. E1 elimination is also stereospecific, meaning that the stereochemistry of the starting material determines the stereochemistry of the product.

In E2 elimination, the leaving group and a proton on the adjacent carbon are removed simultaneously by a strong base to form the double bond. This reaction is favoured by the presence of a strong base and a non-polar solvent, as they promote the concerted elimination of the leaving group and the proton. E2 elimination is also stereospecific, as it occurs with the anti-periplanar arrangement of the leaving group and the proton.

Overall, E1 and E2 eliminations are important reactions in organic chemistry, as they allow the synthesis of alkenes from a wide range of starting materials. Understanding their mechanisms and conditions is crucial for predicting and controlling their outcomes in chemical reactions.