METHOD FOR PRODUCING OPTICALLY ACTIVE, RACEMIC MENTHOL
申请人:Heydrich Gunnar
公开号:US20100249467A1
公开(公告)日:2010-09-30
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 steps
a.1) catalytic hydrogenation of neral and/or geranial to give citronellal,
b.1) cyclization of citronellal to isopulegol in the presence of an acidic catalyst,
c.1) purification of isopulegol by crystallization and
d.1) catalytic hydrogenation of isopulegol to give menthol.
The present invention relates to diarylphenoxyaluminum compounds which are obtainable by reacting a bis(diarylphenol) ligand of the formula (I)
with an alkylaluminum compound and/or a complex aluminum hydride.
The invention moreover relates to the use of such diarylphenoxyaluminum compounds as catalysts.
Moreover, the invention relates to a method of producing isopulegol by cyclization of citronellal in the presence of diarylphenoxyaluminum compounds as catalysts.
The invention also relates to a method of producing menthol by cyclization of citronellal in the presence of diarylphenoxyaluminum compounds as catalysts and subsequent hydrogenation.
Die vorliegende Erfindung betrifft Diarylphenoxy-Aluminium-Verbindungen, die erhältlich sind durch Umsetzung eines Bis(diarylphenol)-Liganden der Formel (I)
mit einer Alkylaluminiumverbindung und/oder einem komplexen Aluminiumhydrid.
Die Erfindung betrifft darüber hinaus die Verwendung derartiger Diarylphenoxy-Aluminium-Verbindungen als Katalysatoren.
Darüber hinaus betrifft die Erfindung ein Verfahren zur Herstellung von Isopulegol durch Cyclisierung von Citronellal in Gegenwart von Diarylphenoxy-Aluminium-Verbindungen als Katalysatoren.
Die Erfindung betrifft auch ein Verfahren zur Herstellung von Menthol durch Cyclisierung von Citronellal in Gegenwart von Diarylphenoxy-Aluminium-Verbindungen als Katalysatoren und anschließender Hydrierung.
Method and device for separating a substance out of a solution
申请人:BASF SE
公开号:US10294182B2
公开(公告)日:2019-05-21
The present invention relates to a method for separating off a substance from a solution, in which electromagnetic radiation is radiated into the solution, an intensity of the electromagnetic radiation which has been scattered by crystals located in the solution is detected, the detected intensity is compared with a desired intensity (IS) and the temperature of the solution is regulated depending on the difference between the detected intensity and the desired intensity (IS) in such a way that the amount of this difference is reduced. If the amount of the difference between the detected intensity and the desired intensity (IS) is less than a limiting value, a crystallization method is started in which crystals of the substance are obtained which are then separated off.