Abstract: A mixture of two or more gases is contacted with a surface of a gas separation membrane and a gas having a different composition is removed from the vicinity of an opposite surface of the membrane, where the membrane is formed from a sulphonated polyarylsulphone or polyarylketone. The membrane may be a dense film or may be an asymmetric membrane. The process is particularly suitable for the separation of hydrogen from a hydrogen/nitrogen mixture when separation factors considerably in excess of 100 may be achieved together with an acceptable permeability. The membrane is preferably formed from a sulphonated polyarylethersulphone, for example one having repeat units of the formula ##STR1## where Ph.sup.1 is a phenylene residue and at least some of the groups Ph.sup.1 are sulphonated and n is 1 or 2 and the value can differ along the polymer chain. Divalent metal salts give membranes of high permeability which have a good separation factor.

Abstract: Amorphous aromatic etherketone/sulphone copolymers, normally of reduced viscosity.gtoreq.0.

Abstract: Production of a dihydroxy arylophenone by reacting a diaryl carbonate in the presence of a fluoroalkane sulphonic acid. The diaryl carbonate is preferably diphenyl carbonate, the product so formed being 4,4'-dihydroxy-benzophenone. The sulphonic acid is preferably trifluoromethane sulphonic acid.

Abstract: Aromatic polyethers containing --SO.sub.2 -- and/or --CO-- groups are made by reacting (i) an equimolar mixture of a bisphenol and an aromatic dihalo compound or (ii) a halophenol, in which dihalo compound or halophenol the halogen atoms are activated by ortho or para --SO.sub.2 -- or --CO-- groups, with sodium carbonate or bicarbonate in admixture with a second alkali metal carbonate or bicarbonate the alkali metal of the second carbonate or bicarbonate being of higher atomic number than that of sodium. The amount of the second alkali metal carbonate or bicarbonate is such that there is 0.001 to 0.2 gram atom of the second alkali metal per gram atom of sodium.