摘要:
In a process and an apparatus for avoiding encrustations in reactors or crystallizers (13), such as industrial crystallizers for suspensions (11), points of incidence (4) for the excitation of ultrasonic oscillations by sonotrodes (3) which are connected to electromechanical converters (2) are provided on the walls (6, 21) and on the base (7) of the crystallizer (13). The ultrasonic frequency is generated at high-frequency generators (1).
摘要:
The present invention relates to a process for crystallizing small particles with a narrow particle size distribution. The crystals of the invention are obtained by introducing ultrasound into a solution or suspension of the substance to be crystallized while simultaneously adjusting a particular specific stirring power.
摘要:
A process for preparing guanidine derivatives, in particular creatine, is described and entails an O-alkylisourea salt and a primary or secondary amine being reacted in the presence of crystals of a guanidine derivative.
摘要:
The invention relates to a process for isolating methylglycinenitrile-N,N-diacetonitrile (MGDN) from an aqueous emulsion which comprises MGDN and has an MGDN content of 3-50% by weight in a crystallizer, comprising the steps: (a) the aqueous emulsion is, starting from a temperature above the solidification point, cooled to a temperature below the solidification point, the cooling rate averaged over time not exceeding 5 K/h, until substantially the entirety of the emulsified MGDN has solidified, (b) the resulting aqueous suspension is cooled further and/or concentrated, and the cooling rate may be greater than in step (a).
摘要:
The present invention relates to novel crystalline modifications of pyraclostrobin, to processes for their preparation and to the use of the novel modifications for preparing crop protection compositions.
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 preparing enriched isopulegol by crystallization from a melt comprising isopulegol. The invention relates specifically to a process for preparing enantiomerically enriched n-isopulegol proceeding from optically active isopulegol having a relatively low enantiomeric excess by crystallization from the melt. The invention further relates to a process for preparing menthol proceeding from enantiomerically and/or diastereomerically enriched n-isopulegol prepared by crystallization from the melt.