Richard M. Flynn

Preparation, stability and acidity of difluoromethylene bis phosphonic acid

Abstract Hydrolysis of difluoromethylene phosphonate esters quantitatively yields difluoromethylene bis phosphonic acid as a dihydrate. In vacuo drying leads to either the monohydrate or the anhydrous acid. Titration of either the free acid or its disodium salt and computer fit of the data gives all four pKas. The disodium salt and the free acid are thermally stable, and the disodium salt is extremely stable even to strong base.

Difluoromethylene exchange in the preparation of fluorinated bis-phosphonates

Abstract The application of the Michaelis-Becker variation to the preparation of unsymmetrical F -methylene bis -phosphonates gives a mixture of both symmetrical and unsymmetrical bis -phosphonates. The reaction is best explained by dissociation of the intermediate F -methylene phosphonate ylide and carbene scrambling among the potential dialkyl phosphite anions.

Phospine and phosphite mediated difluorocarbene exchange reactions of brom-F-methyl phosphonium salts

Abstract Bromo- F -methyl phosphonium salts undergo facile exchange of the bromo- F -methyl group when treated with tertiary phosphines or trialkyl phosphites. The mechanism of this exchange process, the influence of R′ on the ease of exchange, and comparison of this salt system to other halomethyl phosphonium salts will be discussed.