REACTIONS OF CHROMIUM(6) WITH PHOSPHORUS(3) AND PHOSPHORUS(I) .I. DIHYDROGEN PHOSPHITE PHOSPHOROUS ACID AND HYPOPHOSPHOROUS ACID

Dihydrogen phosphite ion, H2PO3-, is not oxidized by HCrO4- at pH 4 but does form an anhydride, HO2POCrO32-. At pH 0, H3PO3 is slowly oxidized by HCrO4-, yielding H3PO4 and Cr(III).3 Kinetic studies indicate that the oxidation involves anhydride formation (H2PCrO6- or H3PCrO6) and general acid catalysis [formula omitted] wherein the attacking proton can come from any acid in the system. In our system B may be H20 or H2PO3-. The presence and strength of the H-P bond inhibits oxidation of P(III). Deuterated phosphorous acid DP(=O)-(OH)2 is oxidized more slowly than the protonated form by a factor of 4. Chloride ion inhibits the oxidation in 1 M H+ by forming CrO3Cl- which is less reactive than HCrO4-. Dihydrogen hypophosphite ion, H2PO2-, forms no anhydride with HCrO4- at pH 4 nor is it oxidized by HCrO4-. Hypophosphorous acid, H3PO2, is oxidized like H3PO3 at pH 0 with similar kinetic patterns. © 1968, American Chemical Society. All rights reserved.