Conversion of organophosphonic acids into their salts using intense shear

摘要

Process for the conversion of an organophosphonic acid of the formula <IMAGE> (I) in which n=3-5 and R=H or C1-C3 alkyl, into an alkali metal or ammonium salt comprising reacting the moist filter cake which accumulates during the production of organophosphonic acids by known processes (water content 10 to 40% by weight) with anhydrous or concentrated aqueous alkali metal hydroxide or ammonia and exposing the paste formed, which has a water content of from 20 to 80% by weight, to intense shear forces in mixing, dispersing, or kneading units, water being removed from the paste under reduced pressure and with application of heat until the paste changes into a free-flowing powder.