1-hydroxy organic 1,1-diphosphonic acids - prepn from phosphorus trihalide and aliphatic carboxylic acid separating org halide

摘要

Title cpds. (I) are prepd. by (a) reacting a lower aliphatic carboxylic acid with PCl3 or PBr3 at 10 degrees - 80 degrees C in mole ratio of 2:1 to form a liquid reaction product, (b) heating to 90 degrees-180 degrees C and volatilising out the organic halide by-product and storing it, (c) cooling to ca 60 degrees C (near the gel point of the liquid), (d) adding a further 70% wt. carboxylic acid, (e) adding to this mixt. up to 70% wt. PCl3 or PBr3, (f) heating this mixt. until it forms two phases i.e. a phosphorous acid phase and an organic halide by-product phase, (h) sepg. the phases and heating the phosphorous acid phase to 90 degrees - 180 degrees C and putting back a certain quantity of the organic halide and (j) recovering I from the anhydrous solid reaction product. Increased prodn. of (I) per unit time is achieved, and (I) is used as a sequestering agent for (heavy) metal cations in aq. systems.