Abstract: A process for the preparation of 2,4-dimethylpyrrole is described in which a 2,4-dimethyl-3,5-bisalkoxycarbonylpyrrole is refluxed with from 10 to 30% strength aqueous alkali metal hydroxide solution until the solid has passed into solution, the reaction mixture is neutralized with acid and the mixture is refluxed further until decarboxylation is complete. The process makes it possible to work under significantly milder, less aggressive conditions than are known from the prior art.

Abstract: Unsaturated cyclic ethers of the formula I ##STR1## whereZ is --(CHR.sup.4).sub.q -- or --(CHR.sup.4).sub.q --O--,q is 0, 1, 2 or 3 andR.sup.1,R.sup.2,R.sup.3,R.sup.4 are hydrogen or C.sub.1 -C.sub.4 -alkylare prepared by reacting diols of the formula II ##STR2## where Z, R.sup.1, R.sup.2 and R.sup.3 are as defined above, in the liquid phase at from 150 to 300.degree. C. in the presence of a cobalt-containing supported catalyst which has not been activated by reduction before use and comprises cobalt and a noble metal selected from the group consisting of platinum, palladium, rhodium, iridium, ruthenium, osmium, rhenium or a mixture thereof applied by sol impregnation on an inert support, wherein the supported catalyst is doped with sulfur. Sulfur-doped supported catalysts comprising cobalt and noble metals are also provided.

Abstract: A process for preparing glyoxal monoacetals of the formula I, ##STR1## where R.sup.1 and R.sup.2, which can be identical or different, are C.sub.1 -C.sub.4 alkyl or C.sub.2 -C.sub.4 alkenyl involves reacting a mixture of glyoxal and glyoxal bisacetals of the formula II, ##STR2## where R.sup.1 and R.sup.2 have the meaning given above, with an excess of an alcohol of the formula R.sup.1 OH or R.sup.2 OH or mixtures of these in the presence of an acid catalyst until reaction equilibrium is achieved.

Abstract: A process for preparing substituted imidazoles of the formula I ##STR1## R.sup.1, R.sup.2 and R.sup.3 are identical or different and are each hydrogen, halogen, NO.sub.2, CN or a C.sub.1 -C.sub.20 -hydrocarbon radical which is unsubstituted or substituted by one or more halogens or R.sup.1 and R.sup.2 together are members of a 3- to 20-membered hydrocarbon ring which is unsubstituted or substituted by one or more halogens and/or C.sub.1 -C.sub.8 -alkyl groups and which may contain 1, 2 or 3 heteroatoms from the group consisting of nitrogen, oxygen and sulfur, andR.sup.4 is a C.sub.1 -C.sub.20 -hydrocarbon radical which is unsubstituted or substituted by one or more halogens,comprises using an aqueous phase of the imidazoles of the formula II ##STR2## where R.sup.1, R.sup.2 and R.sup.3 are as defined above with compounds of the formula IIIR.sup.4 --O--R.sup.5 IIIwhereR.sup.4 is as defined above andR.sup.5 is hydrogen or R.sup.4, it being possible in the latter case for the two R.sup.

Abstract: A process for the preparation of 1,2,4-triazolium salts Ia ##STR1## where R.sup.1, and R.sup.2 and R.sup.3 are C-organic radicals, it being possible for R.sup.2 and R.sup.3 to be connected to give a 5- to 8-membered ring,R.sup.4 is hydrogen or an organic radical andA is an equivalent of an anion, by reacting an amidrazone II ##STR2## with a carboxylic acid IIIR.sup.4 --COOH IIor a functional derivative (IIIa) of this acid, an anion A being formed from III or IIIa which, optionally, can be replaced by another anion. The triazolium salts have great industrial importance as catalysts for the preparation of acyloine from aldehydes.