Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1986-03-06
1989-04-11
Hines, Robert V.
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
564124, 564126, 564127, C07C10208
Patent
active
048208728
DESCRIPTION:
BRIEF SUMMARY
It is known to make amides of the formula RCONH.sub.2 where R is a hydrocarbon group having 1 to 10 carbon atoms by hydrolysis of the corresponding nitrile RCN by water in the presence of a solid catalyst. A wide range of catalysts have been proposed and are reviewed in, for instance, U.S. patent specification 3,997,606. However most recent literature concentrates on the use of copper as the catalyst, usually Raney copper.
The emphasis throughout the literature is on providing a catalyst having the maximum activity, so as to achieve the highest rate of conversion from nitrile to amide.
It is well established in the literature that it is desirable to include activators to improve the activity of the catalyst. For instance U.S. Pat. No. 3,381,034 descrives the use of a mixture of zero valent, monovalent and divalent copper, the ionic copper being introduced as cupric chloride, sulphate or cyanide and two examples show the use of acetic acid with cuprous chloride.
In U.S. patent specification 3,911,009, the use of Raney or other suitable copper in combination with dissolved promoters selected from copper sulphate, copper nitrate, copper chloride and copper salts of lower fatty acids was described. Copper nitrate was shown to be a very active activator and copper acetate was shown to be less effective.
In European Patent Specification No. 78178, we described how the activity of the Raney copper could be improved by partially oxidising it, before utilisation in the reactor, by contact with oxygen, peroxide, iodate, chlorate, bromate or nitrate, the hydrolysis of the nitrile preferably being conducted in the presence of a copper nitrate or other suitable promoter for increasing activity.
Various other processes have been described. For instance in European Patent Specification No. 37178 activity of a copper catalyst is maintained by electrolysis under conditions such that the catalyst has from 0.75 to 12.5 monolayers of ionic copper on its surface. It is shown in the specification that the activity of the catalyst decreases at lesser or higher amounts of ionic copper.
It is recognised in the literature that the catalyst becomes deactivated during prolonged use and that this deactivation can be due to oxidation. See for instance U.S. patent specification No. 3,886,213. It is also recognised that deactivated catalyst can be regenerated. For instance in U.S. patent specification No. 3,642,894 deactivated catalyst is oxidised and then reduced.
It has been thought to be satisfactory to conduct the hydrolysis in the presence of deactivated catalyst provided that fresh, active, catalyst is also present. Thus fresh, active Raney or other copper catalyst may be charged continuously or intermittently to the reactor over a prolonged period and water, acrylonitrile and any dissolved promoter (for instance copper nitrate) may be charged continuously. Acrylamide is removed continuously. All or some of the catalyst may remain in the reactor. Typically the process is conducted until the amount of used or "stale" catalyst in the reactor is so high that it is necessary to terminate the reaction, discharge the used catalyst from the reactor, and restart the process.
Many of the hydrolysis processes are exemplified in the literature as being conducted at, for instance, 70.degree. C. but of course the hydrolysis proceeds faster at higher temperatures and in U.S. 3,911,009 temperatures up to 150.degree. C. are proposed and in U.S. 3,381,034 a temperature of 125.degree. C. is exemplified.
Although the known processes can give good conversions, a problem that has been encountered is that during a prolonged run the formation of by-products tends to increase. For instance when starting from acrylonitrile, the formation of ethylene cyanohydrin and .beta.-hydroxy propionamide starts to increase after prolonged operation. Removal of these impurities from the end product is inconvenient. Their origin has not been clear and so, as soon as a reactor started producing unacceptable quantities of by-products, it has been necessary to close down t
REFERENCES:
patent: 3642643 (1972-02-01), Habermann
patent: 3670020 (1972-06-01), Moore
patent: 3804897 (1974-04-01), Haefele et al.
patent: 3911009 (1975-10-01), Yoshimura
patent: 4056565 (1977-11-01), Matsuda
patent: 4365091 (1982-12-01), Masaaki et al.
patent: 4543423 (1985-09-01), Farrar et al.
"The Influence Of The pH Of An Aqueous Solution Of Acrylonitrile . . . " by I. O. Mikhailishin et al. Chemical Technology, 1983 No. 3, The Lvov Polytechnic Institute.
Benn Gerald
Farrar David
Flesher Peter
Allied Colloids Ltd.
Hines Robert V.
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