Organische Phosphorverbindungen XXXVII. Darstellung und Eigenschaften von Bis‐(dialkoxyphosphonyl‐methyl)‐, Bis‐(alkoxyphosphinyl‐methyl)‐und Bis‐(oxophosphoranyl‐methyl)‐phosphinsäureestern sowie der entsprechenden Säuren [1]

Bis‐chloromethyl‐alkyl‐and ‐ aryl‐phosphine oxides, (CICH2)2P(O)R, which are obtained by reaction of (CICH2)2P(O)Cl with GRIGNARD reagents, undergo a MICHAELIS‐ARBUSOV reaction when heated for several hours with trivalent phosphorus esters (phosphites, phosphonites, or phosphinites) at 170–180°C. The reaction affords bis‐(dialkyloxyphosphonyl‐methyl)‐, bis (alkyloxyphosphinyl‐methyl)‐, and bis‐(oxophosphoranyl‐methyl)‐, ‐alkyl‐ or ‐aryl‐phosphine oxides, R(O)P[CH2P(O)R′R″]2 R = CH3, C2H5, n‐C8H17, n‐C12H25, C6H5; R′ and R″ = C2H5O, C4H9O, C6H5, CH3 in good yields. Conversion of the compounds containing alkyloxy groups to the free acids is achieved by refluxing with conc. HCl. Bis‐(dihydroxyphosphonyl‐methyl)‐dodecylphosphine oxide, n‐C12H25(O)P[CH2P(O) (OH)2]2, obtained by hydrolysis of the all‐ethyl ester, titrates in aqueous solution as a tetrabasic acid with breaks at pH = 4 (two equivalents), pH = 6,9 (one equivalent) and pH = 9,6 (one equivalent). This acid, its disodium salt (m. p. 405–410°) and its tetrasodium salt (m.p. > 460°) are surface active and are excellent chelating agents. The 1H‐ and 31P‐NMR. spectra of all the compounds prepared are discussed.