GB975365A - Cation exchange resin - Google Patents

Abstract

A cation exchange resin contains a cross-linked vinyl aryl polymer to aryl groups of which are attached groups of formula <FORM:0975365/C3/1> where <FORM:0975365/C3/2> is an aliphatic, aromatic or cycloaliphatic hydro-PO3= and M is a cation, e.g. H, a metal, carbon groups, n is 1 or 2,Z is -CO2, -SO3-2 or NH4 and/or substituted NH4, equivalent to the bond sites on Z. The polymer may be a copolymer of styrene and, e.g. 0.2-20%, divinylbenzene. The resins may be made by reacting a cross-linked polymer vinylaryl sulphonium salt with a stoichiometric amount of a water-soluble nucleophillic mercaptide of formula <FORM:0975365/C3/3> where M1 is an alkali metal and the other symbols are as before, e.g. di-sodium thiosalicylate, tri-sodium 1-thio-cyclo-hexane-1, 2-dicarboxylate or trisodium mercaptomethane phosphonate.. The reaction may be carried out at 50-100 DEG C. in the presence of a swelling agent for the polymeric sulphonium salt and an excess of mercaptide. The salt may be formed in situ by reaction of a cross-linked polymeric vinylbenzyl halide, e.g. the reaction product of styrene, vinyltoluene, vinylxylene, chlorostyrene, dichlorostyrene, or vinylnaphthalene, containing 0.25-1.5 halomethyl groups/aromatic nucleus, and a mixture of a sulphide which contains one or two C1- 4 alkyl groups and/or correspondingly one or two C2- 4 hydroxyalkyl groups and the nucleophillic mercaptide. In an example a chloromethylated styrene-divinylbenzene copolymer was refluxed with dimethylsulphide, methylene dichloride, methanol and water to produce beads of the resin.