Synthesis in high vacuum and synthesis in the absence of solvent: Two new options for obtaining β-styryl phosphonic acid

Abstract

Terminal olefins allow the addition of phosphorus pentachloride to give substances that can be considered as phosphonic acid chlorides. Hydrolysis transforms the addition products in phosphonic acids, usually with simultaneous dehydrochlorination. The initial addition reaction takes place under mild conditions, in an inert solvent, and in 40 to 50% yields of á,â-unsaturated phosphonic acid. Search for alternative ways of preparing (1) led to establish the best reaction conditions for four different procedures: (a) microwave irradiation; (b) sonication; (c) solvent-free synthesis; (d) synthesis in high vacuum. Results were compared with those obtained by the conventional method. Of the four procedures, the solvent-free synthesis and synthesis in high seem to be the most suitable for obtaining this type of á,â-unsaturated phosphonic acids.