GB327707A - Improvements in the oxidation of organic compounds of high molecular weight - Google Patents

Abstract

327,707. Johnson, J. Y., (I. G. Farbenindustrie Akt.-Ges.). Jan. 5, 1929. Fatty acids; esters.-In the oxidation of hydrocarbons of high molecular weight, such as paraffin wax, by means of gaseous oxidizing agents, the formation of hydroxy-carboxylic acids is largely prevented by making the working conditions gradually milder as the reaction proceeds, for example, as regards the temperature, concentration, pressure, or velocity of the said gaseous agents. Suitable oxidizing agents are the higher oxides of nitrogen, or mixtures containing them, such as is obtained by the oxidation of ammonia, or air may be used. A catalyst such as zinc or aluminium stearate, metal enolate, or metal phosphate may be present if desired. In the examples, a crude paraffin wax is oxidized in three stages by means of a mixture of nitrogen oxides, the temperatures at these successive stages being 110, 90, and 60‹ C. respectively; the product contains less than 10 per cent of hydroxy-carboxylic acids and only 8 per cent of unsaponifiable substance. In a second example for the oxidation of paraffin wax with nitrogen oxides, the reaction is carried out while gradually reducing the velocty of flow of the oxidizing gas, the product in this case containing about 6 per cent hydroxy-carboxylic acids. An example is given of the oxidation of paraffin wax in a cyclic manner, the oxidation being carried out in a series of autoclaves; the first autoclave, which contains the starting material is subjected to the highest temperature and pressure and is fed with nitrogen dioxide. The gas leaving this autoclave contains a proportion of monoxide, and is passed into the second autoclave which is at a slightly lower temperature and pressure, and contains partially oxidized wax from the first autoclave. This is repeated for any number of stages, fresh material being continuously pumped into the first autoclave, and the partially oxidized material being continuously passed to the next lower autoclave, in which the oxidation is continued under slightly milder conditions. Under these conditions, the product contains only 3 per cent of hydroxy-carboxylic acids. Other examples are given of the oxidation of American fuel oil by a mixture of air and nitrogen oxides, and of paraffin wax by means of air; the conditions of oxidation are made gradually milder in the first case by reducing the rate of flow of the oxidizing gas, and in the second by lowering the temperature.