Inhibiting polymerisation of unsaturated - esters

摘要

Process comprises incorporating in aqs. solutions of unsatd. carboxylic acid esters, e.g. ester of (meth) acrylic acid, a polymerisation inhibitor (I) together with condensed phosphoric acid salt(s) and/or silicic acid salts. (I) is, e.g. hydroquinone or its monomethyl ether, pyrogallol, resorcinol and/or methylene blue, and sodium or potassium silicates and pyrophosphates, tripolyphosphate and/or hexametaphosphates are suitable salts. Pref. solutions contain 0.001-1.0% by wt. (based on wt. of system) of salt and 0.001-0.5% by wt. (I). Provides an aid for prep. and purification of the esters without polymerisation taking place.