| 摘要 |
<p>1,190,399. Preparing hydroxy-alkylidene diphosphonic acids. MONSANTO CO. 19 Dec., 1967 [19 Dec., 1966], No. 57597/67. Heading C2C. 1-Hydroxy, alkylidene- 1,1-diphosphonic acids are prepared by reacting together a condensed phosphorous acid and an aliphatic monocarboxylic acid to form a normally solid anhydrous reaction product. Preferred aliphatic acids are those containing from 2 to 5 carbon atoms, and it is possible to use an aliphatic monocarboxylic acid containing some of the corresponding anhydride. The preferred temperature range is from 100‹ to 260‹ C., and the carboxylic acid reactant is preferably used in excess. The desired phosphonic acid product is preferably recovered by steaming. The reaction may be carried out continuously or batchwise. Specification 978,297 is referred to. Reference has been directed by the Comptroller to Specification 978,297.</p> |
