摘要:
The present invention relates to a process for preparing carboxamides by hydrolysing carbonitriles in the presence of a catalyst comprising manganese dioxide, wherein the reaction mixture added to the catalyst comprising manganese dioxide has a pH in the range of 6.0 to 11.0 and the hydrolysis is performed in the presence of an oxidizing agent. The present invention further relates to a process for preparing alkyl (meth)acrylates, the process having a hydrolysis step according to the process described above.
摘要:
Continuous process for preparing alpha-hydroxycarboxylic esters, in which the reactants reacted are alpha-hydroxycarboxamide with an alcohol in the presence of a catalyst to obtain a product mixture which comprises alpha-hydroxycarboxylic ester, ammonia, unconverted alpha-hydroxycarboxamide and alcohol, and catalyst; wherein a′) reactant streams comprising, as reactants, an alpha-hydroxycarboxamide, an alcohol and a catalyst are fed into a pressure reactor; b′) the reactant streams are reacted with one another in the pressure reactor at a pressure in the range of 1 bar to 100 bar; c′) the product mixture which results from step b) and comprises alpha-hydroxycarboxylic ester, unconverted alpha-hydroxycarboxamide and catalyst, and also ammonia and alcohol, is discharged from the pressure reactor; and d′) the product mixture is depleted in alcohol and ammonia by distilling off ammonia at a pressure which is constantly kept greater than 1 bar without the aid of additional stripping media. The continuous process can be employed particularly advantageously on the industrial scale.
摘要:
The present invention relates to processes for preparing alkyl (meth)acrylates, comprising the steps of transesterifying an alkyl α-hydroxycarboxylate with (meth)acrylic acid to obtain alkyl (meth)acrylates and α-hydroxycarboxylic acid, and dehydrating the α-hydroxycarboxylic acid to obtain (meth)acrylic acid.
摘要:
The present invention relates to a catalyst for reacting carbonitriles with water, wherein the catalyst comprises at least 60% by weight of manganese dioxide with an empirical formula MnOx where x is in the range from 1.7 to 2.0, and at least one plasticizer. The present invention further relates to a process for preparing the catalysts detailed above and to a process for preparing carboxamides by reacting carbonitriles with water in the presence of the present catalyst.
摘要:
The present invention relates to processes for transesterification, comprising the steps of A) mixing an organic acid a) with an ester b) and B) transferring the alcohol radical of the ester b) to the acid a) to obtain the ester of the acid a) and the acid of the ester b), step B) being carried out in a still.
摘要:
Alpha-hydroxycarboxylic esters are prepared by a continuous process in which alpha-hydroxycarboxamide is reacted with an alcohol in the presence of a catalyst to obtain a product mixture which contains alpha-hydroxycarboxylic ester, ammonia, unconverted alpha-hydroxycarboxamide and alcohol, and catalyst; wherein reactant streams containing an alpha-hydroxycarboxamide, an alcohol and a catalyst are fed into a pressure reactor. The reactant streams are reacted with one another in the pressure reactor at a pressure in the range of 1 bar to 100 bar; and the product mixture is depleted in alcohol and ammonia by distilling off ammonia at a pressure which is constantly kept greater than 1 bar without the aid of additional stripping media. The continuous process can be employed particularly advantageously on the industrial scale.
摘要:
The present invention relates to a process for preparing alkyl(meth)acrylates, characterized in that the process has a step in which a cyanohydrin is hydrolysed with an enzyme whose residual activity after the conversion of methacrylonitrile in the presence of 20 mM cyanide ions at 20° C. after 30 min is at least 90% of the residual activity of the enzyme which has been used under otherwise identical conditions in the absence of cyanide ions.
摘要:
The present invention relates to processes for transesterification, comprising the steps of A) mixing an organic acid a) with an ester b) and B) transferring the alcohol radical of the ester b) to the acid a) to obtain the ester of the acid a) and the acid of the ester b), step B) being carried out in a still
摘要:
In a device for the installation of a compression sleeve around a blood vessel, including a guide element for holding the blood vessel, and a carrier for holding the compression sleeve in a bent-open state in which the carrier and the compression sleeve are supported at the distal end of the installation device, the installation device includes a push element for pushing the compression sleeve off the carrier while the blood vessel is disposed in the bent-open compression sleeve so that, upon its release from the carrier, the compression sleeve extends tightly around the blood vessel.
摘要:
A system and method for delivering a surgical clip to a surgical site within a patient's body to compress body tissue is disclosed. In one embodiment for the system of the present invention, the system includes an endoscopic device that has an endoscope cap disposed on a distal end of the endoscopic device. A surgical clip is removably disposed on an outside surface of the endoscope cap. A deployment device is associated with the surgical clip for deploying the surgical clip from the endoscope cap to the body tissue that is to be compressed.