Elimination Reactions

Generally, an alkyl derivative, under appropriate conditions, will eliminate HX, where X is commonly a halide, ester, or -onium function, provided that there is a hydrogen located on the carbon adjacent to that bearing the X function:

An important feature of many elimination reactions is that they occur with the same combination of reagents that cause nucleophilic substitution. In fact, elimination and substitution often are competitive reactions. Therefore it should be no surprise that substitution and elimination have closely related mechanisms.