| 摘要 |
<p>1,182,483. Preparing 1-hydroxy, aliphatic-1,1- diphosphonic acids. MONSANTO CO. 5 May, 1967 [5 May, 1966 (3); 13 Sept., 1966 (3)], No. 21050/67. Heading C2C. 1-Hydroxy aliphatic- 1,1 diphosphonic acids are prepared by reacting a C 2-7 aliphatic monocarboxylic acid with phosphorus tribromide or phosphorus trichloride in a reaction zone, separating aliphatic carboxylic acid halide byproduct, returning at least part of the separated by-product to the reaction zone and recovering the desired product. The by-product acid halide can be removed from the reaction mixture as a gas or as a liquid and the desired phosphonic acid is normally obtained in a solid anhydrous reaction product from which it is separated, e.g. by steaming. The reaction is usually carried out employing a molar ratio of carboxylic acid to phosphorus trihalide of at least 2:1 and a temperature of 90‹ to 180‹ C. or 60‹ to 150‹ C. Several specific embodiments are disclosed.</p> |
