Réaction de quelques amides substitués de l'acide benzénephosphosphoneux avec les α‐halogénococétones

Bis‐dimethylaminophenylphosphine reacts with α‐halogeno esters and ketones to give hygroscopic quaternary phosphonium salts, leading to ill‐defined betaines which readily undergo the W ITTIG reaction with benzaldehyde. In alcohol solution, the reaction with phenacyl chloride gives the corresponding ketone, dialkyl phenyl‐phosphonate and amine hydrochloride. A mixture of trimethylammonium and tetra‐methylammonium chloride has been obtained from methanol, but dimethylammonium chloride only from ethanol. These observations are interpreted by a bimolecular (S N 2) de‐alkylation of a trimethoxyphosphonium intermediate in methanol, and a unimolecular (S N 1) de‐alkylation of the corresponding triethoxyphosphonium intermediate in ethanol.