| 摘要 |
1,159,066. Oxalic acid. RHONE-POULENC S.A. 25 May, 1967 [25 May, 1966], No. 24443/67. Heading C2C. Oxalic acid is prepared by oxidizing propylene, or an intermediate product (for example lactic acid or α-nitratolactic acid) containing two or three carbon atoms which can be formed by nitric acid and/or nitrogen peroxide oxidation of propylene, with nitric acid in the presence of, as catalyst, a compound of iron, aluminium, chromium, tin, bismuth, iodine, which is soluble in the reaction medium. The catalyst, which may be present in an amount from 0À01 to 10% and preferably from 0À1 to 2% by weight (expressed as metal or as iodine) based on the weight of the reaction mixture, is preferably a sulphate, nitrate, chloride or phosphate of iron, aluminium, chromium, tin or bismuth; ferrous oxide, ferric oxide, or chromium trioxide; an iodate; a chromate; or chromic acid. The catalysts may be used in processes wherein gaseous propylene is passed into an aqueous medium containing at least 50% by weight of nitric acid at 40-80‹ C. or by introducing the propylene into nitric acid and then heating the solution obtained and wherein the catalyst may be introduced at the beginning of the reaction or at the beginning of the conversion of the oxidation products, for example lactic acid or α-nitratolactic acid, preferably by dissolving the catalyst in the oxidizing agent. Oxalic acid is prepared by treating propylene with nitric acid containing chromium nitrate and subsequently passing oxygen through the reaction mixture and heating; by treating propylene with aqueous nitric acid containing nitrogen peroxide and subsequently heating with chromium nitrate, ferric nitrate, stannous chloride, aluminium nitrate, bismuth nitrate or potassium iodate; by treating α-nitratolactic acid with nitric acid containing chromic acid; and by reacting lactic acid with nitric acid containing chromic acid. Suitable apparatus for the reaction is described by reference to drawings (not shown). α-Nitrato-lactic acid is obtained by treating a mixture of oxygen and propylene with nitrogen peroxide at 0‹ C. |
