The<unk>  is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide (often called a<unk>  reagent) to give an alkene and triphenylphosphine oxide.
The<unk>  was discovered in 1954 by Georg<unk> , for which he was awarded the Nobel Prize in Chemistry in 1979.  It is widely used in organic synthesis for the preparation of alkenes. It should not be confused with the<unk>  rearrangement.<unk> s are most commonly used to couple aldehydes and ketones to singly substituted phosphine ylides.  With simple ylides this results in almost exclusively the Z-alkene product.  In order to obtain the E-alkene, the Schlosser modification of the<unk>  can be performed.
Wittig reaction
Achmatowicz reaction
Chichibabin reaction
Sabatier reaction
Aldol reaction
Doebner modification
Ethanol fermentation
Wolffenstein-Böters reaction