CS Knowledge Base

In organic chemistry, an epoxide is a molecule that has a ring-shaped structure with three atoms: two carbon and one oxygen. These atoms make the corners of a triangle, with chemical bonds as its sides. The epoxide ring's shape gives the molecule ring strain, making it very reactive.

Epoxides can be made by oxidation of alkenes. There are many ways to do this. Usually, a peroxide is used. Some ways can even make only one enantiomer of the epoxide.

The oxygen atom pulls electrons away from the carbon-carbon bond, making that bond an electrophile that can react with many different nucleophiles.

Normally, epoxides react like an S_N2 reaction. The nucleophile's lone pair bonds to one of the carbon atoms, which breaks its bond with the oxygen atom. The oxygen atom then has a negative charge, which attracts a hydrogen ion or other electrophile to make the compound.

The reaction changes in a strong acid: the acid will give hydrogen to the oxygen atom first, breaking a bond to a carbon atom and making a carbocation intermediate that will attract and react with a nucleophile from the solution. Using an acid as a catalyst allows epoxides to react with even weak nucleophiles like water.^[1]

The end product of a reaction depends on the nucleophile. Once you have made an epoxide, you can make alcohols, ethers, and halohydrins, among other things.