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The structure of the functionalized trans-diphosphiranes 1a-e, obtained by reaction of halogenocarbenes with the trans-diphosphene is confirmed by X-ray diffraction. The photolysis of 1a-e lead to the functionalized cis- and trans-1,3-diphosphapropenes 2a-e as major products, via the diphosphiranyl and the diphosphapropenyl radical intermediates. The latter are characterized by ESR spectroscopy using the spin-trap method. The trans configuration of 2a is also confirmed by X-ray diffraction. The mechanism of the ring-opening, involving P-P bond rupture, is discussed

Direct synthesis of free (alpha-hydroxyalkyl)phosphinic acid amphiphiles 1 can be readily realized by sonication of the heterogeneous mixture of 50% aqueous hypophosphorous acid and long-chain aldehydes in the presence of catalytic amounts of hydrochloric acid. Oxidation of these phosphinic acids by DMSO in the presence of catalytic amounts of iodine quantitatively leads to the corresponding phosphonic acids 3. IR spectra of the phosphinic acids 1 in the condensed phase and in solution reveal the presence of intra- and intermolecular associations. Dissociation constants of the phosphorus acids 1 and 3 determined by potentiometric and (31)P NMR titrations show a good correlation between the two methods. The phosphinic acid amphiphiles 1 are slightly stronger than the corresponding phosphonic acids 3. (alpha-Hydroxyalkyl)phosphonium chlorides are prepared in good yields from the phosphine PH(3) and long-chain aldehydes in acidic media.