摘要:
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.
摘要:
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.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.
摘要:
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.
摘要:
The present invention relates to a process for asymmetric synthesis in the presence of a chiral catalyst comprising at least one complex of a metal of transition group VIII with ligands capable of dimerization via noncovalent bonds, such catalysts and their use.
摘要:
Process for obtaining formic acid by thermal separation of a stream comprising formic acid and a tertiary amine (I), in which a liquid stream comprising formic acid and a tertiary amine (I) in a molar ratio of from 0.5 to 5 is produced by combining tertiary amine (I) and a formic acid source, from 10 to 100% by weight of the secondary components present therein are separated off and formic acid is removed by distillation in a distillation apparatus at a bottom temperature of from 100 to 300° C. and a pressure of from 30 to 3000 hPa abs from the liquid stream obtained, the bottom discharge from the distillation apparatus being separated into two liquid phases and the upper liquid phase being recycled to the formic acid source and the lower liquid phase being recycled for separating off the secondary components and/or to the distillation apparatus.
摘要:
The invention relates to chiral phosphorus chelate compounds, to catalysts comprising such a compound such a compound as the ligand, and to asymmetric synthesis methods in the presence of such a catalyst.
摘要:
Process for obtaining formic acid by thermal separation of a stream comprising formic acid and a tertiary amine (I), in which a liquid stream comprising formic acid and a tertiary amine (I) in a molar ratio of from 0.5 to 5 is produced by combining tertiary amine (I) and a formic acid source, from 10 to 100% by weight of the secondary components present therein are separated off and formic acid is removed by distillation in a distillation apparatus at a bottom temperature of from 100 to 300° C. and a pressure of from 30 to 3000 hPa abs from the liquid stream obtained, the bottom discharge from the distillation apparatus being separated into two liquid phases and the upper liquid phase being recycled to the formic acid source and the lower liquid phase being recycled for separating off the secondary components and/or to the distillation apparatus.
摘要:
The present invention relates to a process for preparing optically active carbonyl compounds by asymmetrically hydrogenating α,β-unsaturated carbonyl compounds in the presence of optically active transition metal catalysts which are soluble in the reaction mixture and have at least one carbon monoxide ligand. The present invention especially relates to a process for preparing optically active aldehydes or ketones, in particular citronellal, by asymmetrically hydrogenating the corresponding optically active α,β-unsaturated aldehydes or ketones.
摘要:
A process for preparing optically active 2-methylalkan-1-ol of the general formula (III) comprising the following steps: (i) carbonyl-selective reduction of 2-methylalk-2-en-1-al of the general formula (I) to 2-methylalk-2-en-1-ol of the general formula (II), (ii) enantioselective hydrogenation of 2-methylalk-2-en-1-ol to the general formula (iii), (iii) increasing the optical yield of the optically active 2-methylalkan-1-ol (III) obtained in step (ii) by a lipase-catalyzed acylation reaction, where the radical R means C1-C10-alkyl.