Properties of Onium Salts of Phosphorus and Nitrogen

Abstract

Ammonium and phosphonium halides when heated with excess dimethyl or diethyl phosphite can undergo anion exchange as a result of alkylation of halide ions with dialkyl phosphites. Experimental data were obtained, that cast some doubt in the commonly accepted opinion that reactions of tertiary amines and phosphines with dihalides in apolar media result in exclusive formation of monosalts.

Phosphine-Catalyzed Vinylation at Low Acetylene Pressure

“…The quantum-chemical investigations of the reaction mechanism were further supported by subsequent experimental results. Applying acetylene to a solution of Brønsted acid–base adduct tributylphosphonium tetrafluoroborate ( 4 ) and heating the resulting mixture to 140 °C led to the formation of the dicationic trialkyl ethylene bisphosphonium species , 5 , which could be characterized by NMR spectroscopy, mass spectrometry, and X-ray (Scheme A). As already suggested by the quantum-chemical calculations, the observation of 5 proves the preferred nucleophilic reactivity of the phosphine with acetylene as a key activation step, instead of a phosphine base-catalyzed deprotonation of the amide substrate and subsequent direct amide vinylation.…”