Basf Aktiengesellschaft

Carsten Gr&ouml;ning

Klaus Ebel

Gerd Kaibel

Reinhard Kemper

J&ouml;rg Therre

Markus Frede

Helmuth Menig

Gerhard Fritz

Rainer Dietz

J&uuml;rgen Koopmann

A process for the preparation of 2,4-dimethyl-3,5-bisalkoxycarbonylpyrrole is described, in which an acetoacetic alkyl ester is nitrosated to give the 2-nitrosoacetoacetic alkyl ester, the nitroso compound is reduced using hydrogen in the presence of a noble metal catalyst to give the amine, and the resulting amino compound is condensed without isolation in the presence of the corresponding non-nitrosated acetoacetic alkyl ester to give the 2,4-dimethyl-3,5-bisalkoxycarbonylpyrrole. The process makes it possible to work under conditions which are milder than in the prior art and to avoid the formation of by-products.

Process for the preparation of 2,4-dimethyl-3,5-bisalkoxycarbonylpyrrole

In a process for the preparation of methylglyoxal dimethyl acetal from methylglyoxal and methanol in the presence of an acidic ion exchanger, water is introduced in an amount sufficient to form an acidic reaction mixture in which the acetal product and water form an azeotropic mixture, with or without the retention of some methanol reactant. After subjecting a single phase acidic reaction mixture to an azeotropic distillation, it will separate into two distinct liquid phases with a simple recovery of the acetal product from the aqueous phase.

Preparation of methylglyoxal dimethyl acetal

Growing community of inventors

Mannheim, Germany

Carsten Gröning

Growing community of inventors

Mannheim, Germany

Carsten Gr&ouml;ning

Carsten Gröning