Martin Sicken

Formation of Methylphosphonous Acid by Alkylation of Yellow Phosphorus

Methylphosphonous acid is a key intermediate in the synthesis of phosphinic acid salts, a new class of halogen-free flame retardants. This paper describes a novel and simple synthesis of this synthon: By alkylation of elemental yellow phosphorus with methyl chloride under phase-transfer conditions, methylphosphonous acid alkali salt is formed as the main product. Most of the by-products were identified. The mechanism of the reaction is discussed.