Alkene synthesis refers to the various chemical methods used to create alkenes, which are hydrocarbons containing at least one carbon-carbon double bond. Common techniques include elimination reactions, where a small molecule, like water or hydrogen halide, is removed from a saturated compound, resulting in the formation of an alkene. Another method involves the dehydrohalogenation of alkyl halides, where a base removes a hydrogen atom and a halogen atom from adjacent carbon atoms. Additionally, alkyne hydrogenation can also yield alkenes, as can the Wittig reaction, which allows for the formation of alkenes from carbonyl compounds.