(Carbomethoxymethyl)triphenylphosphonium bromide is much closer to a molecular construction tool. Its specialty is one of organic chemistry's classic transformations: the Wittig reaction. Imagine starting with an aldehyde containing a C=O bond.
A chemist wants something very different at exactly that location: C=C The Wittig reaction can make that change. First, this phosphonium salt is treated with a base to generate a phosphorus ylide—a carbon atom with unusual reactivity.
Global Chemical Database