Monothio-phosphonic/-phosphinic acids

III. INTERCONVERSIONS OF THE MONOTHIO(OR SELENO) -PHOSPHONIC AND -PHOSPHINIC ACIDS AND THEIR... 

In this section, consideration is given to some further, mutually related replacement reactions of monothio- and monoseleno-phosphonic and -phosphinic acids and their simple derivatives and, where appropriate, the stereochemical changes accompanying those reactions, most of which are also of preparative value. 

The almost exclusive O-acylation (as opposed to S -alkylation) of salts of monothio- or monoseleno-phosphonic or -phosphinic acids by acetyl chloride or bromide or benzoyl bromide proceeds, as might be expected, with retention of configuration at phosphorus. The formation of monothiodiphosphonates as by-products has been reported, but the use of ketene for acetylation purposes allows a cleaner reaction without anhydride formation . ... 

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