Abstract: A process is disclosed for the selective hydrogenation of butynediol to 2-butene-1,4-diol using a palladium catalyst to which either copper and zinc, or silver and zinc, or copper, silver and zinc are added as doping agents. In the preferred embodiment, it has been possible, by optimizing the composition of the catalyst, to improve the activity and selectivity of the catalysts in question while also eliminating the need to handle toxic substances during the catalyst manufacturing process.

Abstract: Aqueous glyoxylic acid solutions, essentially free of other acids, are recovered from aqueous solutions which still contain other acids, by a method in which the aqueous solution is mixed with an organic nitrogen compound at as high as 50.degree. C., the phases are separated, and the glyoxylic acid is extracted from the organic phase with water, at a higher temperature.

Abstract: A process for the preparation of carbonyl compounds by oxidation of alcohols in the gas phase with a gas containing oxygen in the presence of catalysts containing copper and silver.

Abstract: A process for the preparation of carbonyl compounds by oxidation of alcohols in the gas phase with a gas containing oxygen in the presence of catalysts containing copper or silver and a phosphorus compound that is volatile under the conditions of the reaction, the ratio of the mass of phosphorus to the mass of the alcohol being less than 0.5 ppm.

Abstract: An aqueous glyoxal solution is decolorized by a process in which the said solution is passed over granulated active carbon which is arranged in a fixed bed and whose differential pore radius distribution has a maximum of from 10 to 100 A, the Peclet number being from 500 to 5000, the decolorized glyoxal solution is discharged, the active carbon bed is then regenerated by treating it with an aqueous solution of an alkaline agent and then with an aqueous acid, and further glyoxal solution to be decolorized is passed over the active carbon regenerated in this manner.

Abstract: Imidazoles which carry a hydroxymethyl radical on a carbon atom of the imidazole ring are prepared by treating a 1-hydroxymethylimidazole, which is unsubstituted in one or more of the positions 2, 4 and 5 of the imidazole ring, with an anion exchanger.

Abstract: Aqueous solutions of glyoxal which contain acids are purified by treatment with a solution which contains from 20 to 60% by weight of a tertiary amine and from 80 to 40% by weight of an alcohol which is not infinitely miscible with water, the treatment being carried out by mixing the two solutions during a residence time of less than 5 minutes.

Abstract: A process for the preparation of 1-substituted imidazoles by reacting an .alpha.-dicarbonyl compound with ammonia, an aldehyde and a primary amine in an aqueous medium, in a single stage, at 20.degree.-150.degree. C.

Abstract: A process for the preparation of 4-methylimidazoles by reacting methylglyoxal with ammonia and an aldehyde in aqueous solution, wherein the reaction is carried out at a pH of above 7 and either the reactants are all brought into contact simultaneously or the aldehyde and the methylglyoxal are added simultaneously to the aqueous ammonia solution.