Method for producing optically active, racemic menthol

US8318985B2 · kind B2 · utility

Assignee

• BASF SE

Inventors

• Gunnar Heydrich · Schifferstadt, DE
• Gabriele Gralla · Mannheim, DE
• Matthias Rauls · Ludwigshafen, DE
• Joachim Schmidt-Leithoff · Mannheim, DE
• Klaus Ebel · Lampertheim, DE
• Wolfgang Krause · Münstermaifeld, DE
• Steffen Oehlenschläger · Ludwigshafen, DE
• Christoph Jäkal · Schifferstadt, DE
• Marko Friedrich · Lorsch, DE
• Eike Johannes Bergner · Schriesheim, DE
• Nawid Kashani-Shirazi · Ilvesheim, DE
• Rocco Paciello · Bad Dürkheim, DE

Key dates

• Filing date: Nov 13, 2008
• Grant date: Nov 27, 2012
• Expiry date: Aug 28, 2029

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07C2601/16
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

The present invention relates to a particularly economic overall method for producing menthol, specifically for producing optically active, essentially enantiomerically and diastereomerically pure L-menthol and racemic menthol, starting from the starting material citral which is available inexpensively on an industrial scale. The method comprises the following stepsa) catalytic hydrogenation of neral and/or geranial to give citronellal,b) cyclization of citronellal to isopulegol in the presence of an acidic catalyst,c) purification of isopulegol by crystallization andd) catalytic hydrogenation of isopulegol to give menthol.