An Efficient Separation Method for Enol Phosphate and Corresponding β-Ketophosphonate from Their Mixtures Under Aqueous Conditions

Abstract

Separation of a mixture β-ketophosphonate 3 and their corresponding enol phosphate 4 is efficiently carried out in aqueous alkaline solutions. Enol phosphate 4 is first extracted with hexanes:dichloromethane (19:1). Acidification of the aqueous layer followed by extraction of the β-ketophosphonate 3 with dichloromethane completes the separation. Thus, when 1-bromo-2,4-pentadione 1a reacted with triethyl phosphite to give diethyl (2,4-dioxopentyl)phosphonate 3a (Arbuzov-product) and the corresponding enol phosphate 4a (Perkow-product), separation of the two compounds was carried out using this method.

Acknowledgments

The expertise of Mr. Marshall Hughes and Dr. Noel Davies (University of Tasmania) for mass spectral analyses is gratefully acknowledged. A preliminary investigation into the separation of the vinylenolphosphate 4f and β-ketophosphonate 3f was carried out at the University of Stellenbosch.