An object of the present invention is to provide a method for manufacturing an optically active menthol having fewer steps, which generates less environmentally polluting waste because a catalytic reaction is involved in all of the steps, and is capable of saving a production cost. The present invention relates to a method for manufacturing an optically active menthol, including the following steps: A-1) asymmetrically hydrogenating at least one of geranial and neral to thereby obtain an optically active citronellal, B-1) conducting a ring-closure reaction of the optically active citronellal in the presence of an acid catalyst to thereby obtain an optically active isopulegol, and C-1) hydrogenating the optically active isopulegol to thereby obtain an optically active 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.
METHOD FOR PRODUCING OPTICALLY ACTIVE ISOPULEGOL AND OPTICALLY ACTIVE MENTHOL
申请人:TAKASAGO INTERNATIONAL CORPORATION
公开号:US20150329452A1
公开(公告)日:2015-11-19
A method for producing an optically active isopulegol includes asymmetrically isomerizing a specific compound in the presence of a ruthenium catalyst and a base, thereby giving an optically active citronellal, and selectively cyclizing the optically active citronellal in the presence of an aluminum catalyst. The aluminum catalyst is obtained by reacting a specific hydroxy compound and at least one aluminum compound selected from a specific alkylaluminum compound, a specific hydride aluminum compound, a specific linear aluminoxane and a specific cyclic aluminoxane.
Described is a process for manufacturing aromatic polyesters by reacting an aromatic dicarboxylic adic dichloride with an alkali metal salt of a bisphenol in an aqueous solution which comprises adding 0.01 to 100 mol %, based on the total monomer quantity, of an acid halide into the reaction system.
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.