Basf Aktiengesellschaft

Carsten Groning

Klaus Ebel

Johann-Peter Melder

Joaquim Henrique Teles

Gerd Kaibel

Toni Dockner

Reinhard Kemper

Markus Frede

Gisela Hieber

Regina Schneider

Bernd Ruge

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.

Process for the preparation of 2,4-dimethylpyrrole

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.

Preparation of glyoxal monoacetals

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, and

Aqueous phase process for preparing N-substituted imidazoles

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,

Preparation of 1,2,4-triazolium salts and 1,2,4-triazolines

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Carsten Groning