Abstract: A process for dehydrogenating 1,4-butanediol to .gamma.-butyrolactone in the gas phase in the presence of a copper-containing catalyst, wherein the catalyst contains 4-40% by weight of copper and 0-5% by weight of Na.sub.2 O, based on the total weight of the catalyst, on a carrier consisting of 80-100% by weight of SiO.sub.2 and 0-20% by weight of CaO.

Abstract: N-Substituted cyclic amines are prepared by reacting diols with primary amines over a copper-containing catalyst which is obtainable by impregnation of an inert support with an aqueous solution of an ammine complex of a readily thermally decomposable copper compound and subsequent drying and calcination and contains from 5 to 50% by weight of copper, calculated as CuO.

Abstract: Impurities are separated from aqueous solutions of 1,6-hexanediol or 1,6-hexanediol precursors, such as adipic and 6-hydroxycaproic acid, by a process which comprises adding at least one carboxylic acid to a solution (a) of 1,6-hexanediol and subjecting this solution (a) or a solution (b) containing carboxylic acid(s) as precursor(s) of 1,6-hexanediol to a heat treatment at temperatures above room temperature in the absence of hydrogen.

Abstract: Polytetrahydrofuran or polytetrahydrofuran monoesters of C.sub.1 -C.sub.20 -monocarboxylic acids or polytetrahydrofuran monoethers of monohydric C.sub.1 -C.sub.20 -alcohols, having an average molecular weight of from 250 to 10,000 Dalton and liquid at room temperature, are prepared by the cationic polymerization of tetrahydrofuran in the presence of a telogen by a process in which tetrahydrofuran is polymerized in the presence of water, 1,4-butanediol and/or polytetrahydrofuran having an average molecular weight of from 200 to 700 Dalton and/or of a C.sub.1 -C.sub.20 -monocarboxylic acid and/or of a monohydric C.sub.1 -C.sub.20 -alcohol with the aid of a catalytic amount of a zeolite catalyst which has an SiO.sub.2 /Al.sub.2 O.sub.3 molar ratio of from 4:1 to 100:1 and in which the population ratio P of the acid centers on the external surface of the zeolite to the total number of acid centers of the zeolite is 0.03/l or more.

Abstract: A process for the preparation of cyclohexene by partial hydrogenation of benzene with hydrogen in the presence of water and ruthenium catalysts modified with nickel, at elevated temperature in the liquid phase, wherein alloys of ruthenium with nickel are used as catalysts.

Abstract: A process for the continuous production of cyclohexene from a cyclohexyl ester of a carboxylic acid having 1 or 2 carbon atoms, which comprises the following steps:a) heating a cyclohexyl ester of a carboxylic acid having 1 or 2 carbon atoms in the presence of an acid catalyst with the formation of cyclohexene and a carboxylic acid having 1 or 2 carbon atoms;b) removing, by distillation, cyclohexene and carboxylic acid having 1 or 2 carbon atoms from the reaction mixture from stage a) at the same rate as they are formed;c) adding a cyclohexyl ester of a carboxylic acid having 1 or 2 carbon atoms to stage a) at the rate cyclohexene and carboxylic acid are distilled off; andd) separating the mixture comprising cyclohexene and carboxylic acid having 1 or 2 carbon atoms coming from stage b).