Abstract: The invention relates to a bismaleimide compound of the formula (I) substantially free of oligomeric, amidic and uncyclized impurities: ##STR1## wherein Ar is an optionally substituted aromatic residue; andAr' is an optionally substituted aromatic residue which provides either good conjugation between the nitrogen-containing groups shown in formula (I) or steric or other restrictions capable of moderating the reactivity of an unreacted amine moiety attached to said residue, methods for their preparation and curable compositions containing them. The curable compositions may also be used in impregnated fibre reinforced materials and advanced composite materials.

Abstract: Macrocyclic epoxy resins comprising at least one compound of the formula (I) ##STR1## wherein n is an integer from 3 to 10.R.sup.1 and R.sup.3 are either the same or different and are selected from hydrogen, hydroxyl, alkoxy, allyloxy and epoxypropyloxy (glycidyloxy);R.sup.2 is selected from hydrogen, arylakalkyl optionally substituted with halogen, alkyl optionally substituted with halogen, and aryl optionally substituted with halogen;R.sup.4 is selected from hydrogen, alkyl optionally substituted with halogen, arylalkyl optionally substituted with alkyl or halogen, and aryl optionally substituted with halogen;R.sup.5 is selected from hydrogen, aryl and alkyl; with the proviso that the resin contains on average at least one epoxy group per molecule.

Abstract: Gold is selectively extracted from an aqueous solution by contacting the gold-containing solution, which may contain other metals, with a resin which is a diallylamine homopolymer or copolymer, and then separating the resin from the solution.

Abstract: Ferric ions may be removed very selectively from aqueous solutions by means of a metal-chelating resin consisting of the acid-quaternized form of a cross-linked polymer produced by the condensation of a phenolic component comprising one or more phenols, formaldehyde, and a diamino component comprising one or more di-(secondary amino) compounds under neutral conditions. The resin is prepared by treating the cross-linked polymer with an aqueous solution of a strong mineral acid.

Abstract: Mercury and copper ions may be removed very selectively from aqueous solutions by means of a metal-chelating resin consisting of a polymer produced by the condensation of a phenolic component comprising one or more phenols, formaldehyde, and a diamino component comprising one or more di-(secondary amino) compounds under neutral conditions. The resin is prepared by condensing approximately equimolar quantities of a phenolic component comprising one or more phenols, and a diamino component comprising one or more di-(secondary amino) compounds with approximately twice the molar quantity of formaldehyde under Mannich reaction conditions.