Abstract:
The invention relates to a particularly economic, complete method for producing menthol, especially for the production of optically active, essentially enantiomerically and diastereomerically pure L-menthol and of racemic menthol starting from the commercially accessible, inexpensive parent material citral. The method comprises the following steps: a.1 ) catalytic hydrogenation of neral and/or geranial to form citronellal, b.1 ) cyclisation of citronellal to form isopulegol in the presence of an acidic catalyst, c.1 ) purification of isopulegol by crystallisation and d.1 ) catalytic hydrogenation of isopulegol to form menthol.
Abstract:
Alkoxides are obtained by crystallizing an alkoxide from a solution in the corresponding alcohol, wherein the alcohol is crystallized out at a pressure of at least 3 bar abs. and a temperature of at least 120°C.
Abstract:
The invention relates to novel crystalline modifications to pyraclostrobin, methods for production and use of the novel modifications for the production of plant protection agents.
Abstract:
Die Erfindung betrifft ein Verfahren zur Erzeugung von Kristallen von Menthol, insbesondere L-Menthol, dadurch gekennzeichnet, dass man eine Menthol-Schmelze durch einen Extruder führt. Die Erfindung betrifft auch Verfahren zur Herstellung von Menthol-Partikeln, bei dem man a. eine Menthol Schmelze, welche Impfkristalle von Menthol enthält, erzeugt, indem man eine Menthol Schmelze durch einen Extruder führt und b. die so erhaltene Menthol Schmelze mit mindestens einer gekühlten Oberfläche in Kontakt bringt.
Abstract:
Mixture of L- and D-enantiomers of methyl glycine diacetic acid (MGDA) or its respective mono-, di or trialkali metal or mono-, di- or triammonium salts, said mixture containing predominantly the respective L-isomer with an enantiomeric excess (ee) in the range of from 10 to 75%.
Abstract:
The invention relates to methods for producing free flowing dicarboxylic acid crystalline crops from an aqueous solution or suspension of the dicarboxylic acid in a crystallizer.
Abstract:
The invention relates to a method for isolating methyl glycine nitrile-N,N-diacetonitriles (MGDN) from an MGDN-containing aqueous emulsion with an MGDN content of 3 - 50% by weight in a crystallizer. The inventive method is characterized by (a) cooling the aqueous emulsion, starting from a temperature above the solidification point, to a temperature below the solidification point, the cooling rate in the temporal mean not exceeding 5 K/h, until substantially the total amount of the emulsified MGDN has solidified; and (b) continuing to cool the aqueous suspension obtained and/or concentrating it, the cooling rate being higher than that in step (a).
Abstract:
The invention relates to a method for producing L-menthol in solid form, especially in the form of flakes, by contacting melted L-menthol with two interspaced cooled surfaces. The invention further relates to the L-menthol in solid form obtainable by the above method, and to the use thereof for incorporation into commodities and articles of consumption of all kinds.