Catalyst and process for preparing amides

Details Catalyst and process for preparing amides Catalyst and process for preparing amides

1997-09-10

1999-08-03

Kumar, Shailendra

Organic compounds -- part of the class 532-570 series

Organic compounds

Heavy metal containing

502162, 502439, 556 23, 564126, C07F 1500, B01J 2342

Patent

active

059327561

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to platinum phosphorus complexes and their use in a process for the hydration of nitriles to amides.
Amides such as acrylamide, acetamide and benzamide are important industrial chemicals and are used in a wide range of products. Other amides such as nicotinamide are also important as food supplements.
Known methods of making amides from nitriles include the sulphuric acid process in which acrylonitrile is hydrated using sulphuric acid at an elevated temperature and the acrylamide is then separated from the other products by the reaction of cooling.
Another method of preparing amides from nitriles is by the alkaline hydration of nitriles, optionally using a metal catalyst and this process is used to produce nicotinamide. These processes are briefly described in Ullmann's Encyclopaedia of Industrial Chemistry, 5th Edn: Vol. A1, Page 173 and in Kirk Othmer, Encyclopaedia of Chemical Technology, 3rd Edn: Vol 24, Page 67.
However, these processes, unless stringently controlled, can hydrolyse the amide to the acid and this has proved to be a difficulty in commercial operations.
To overcome this problem, enzymes have been used as catalysts, and industrially, heterogenous metal catalysts have been used, particularly to hydrolyse acrylonitrile to acrylamide.
A method of preparing amides and primary alcohols is also described in U.S. Pat. No. 4,684,751 using tertiary trialkyl phosphine complexes of platinum group metals, particularly the trimethyl phosphine complex.
In the process of this invention, nitriles are converted to the corresponding amide using, as a catalyst, a tertiary trimethyl phosphine complex of platinum in the presence of a nucleophile. However, this reaction only works effectively with some nitriles and the reaction needs to be carried out in an oxygen free atmosphere which makes it complex and difficult to operate industrially.
Methods for converting nitriles to amides using noble metal catalysts are also described in C M Jensen and W C Trogler, J Am Chem Soc 1986 108,723(1), G Villain, G Constant, A Gaset and P Kalck, J Mol, Cat. 1980 7,355(2) and T Yoshida, T Matsuda, T Okano, T Kitani and S Otsuka, J Am Chem Soc 1979 101,2027(3).
We have now discovered a class of platinum complexes of dialkyl and diaryl phosphine oxides which selectively convert nitriles to amides.
We have also discovered a method of making platinum complexes of the dialkylphosphine oxides of the invention.
According to the invention there is provided a platinum complex of dialkylphosphine of stoichiometric formula PtX(R.sub.2 POHOPR.sub.2)(PR.sub.2 OH) where R is an alkyl, alicyclic, chiral, alkylarly group or substituted alkyl, alicyclic, chiral, alkaryl group or the two R groups attached to one phosphorus atom can form a heterocyclic ring with the phosphorus atom and X is H or a halide such as chlorine or bromine.
The complexes of the invention are thought to have the structural formula ##STR1## where R and X are as defined above.
In some cases the complex can be in an equilibrium mixture with its hydroxyl form, X.dbd.OH.
Preferably R is a C.sub.1 to C.sub.5 alkyl group and more preferably a methyl group.
According to the invention there is also provided a method of hydrating a nitrile to an amide which process comprises reacting the nitrile with water in the presence of the disubstituted phosphinite complex of platinum described above.
The platinum complexes of the present invention can be formed by different methods depending on the nature of X. E.g., when X.dbd.H by reacting a platinum triphenyl phosphine complex with a secondary phosphine oxide , R.sub.2 P(O)H, where R and X are as defined above. The reaction is thought to proceed according to the reaction mechanism: ##STR2##
The reaction takes place preferably under normal conditions with regard to temperature and pressure and preferably is carried out in an inert organic solvent such a toluene; preferably the reaction is carried out under an inert atmosphere, e.g. nitrogen.
When X is a halogen by reacting a soluble platinum salt such as K.

REFERENCES:
patent: 4684751 (1987-08-01), Trogler et al.
Pidcock et al, J. Chem. Soc.(A), pp. 2080-2086, 1970.
Leeuwen et al, Organometallics, vol. 9, pp. 1211-1222, 1990.
Tetrahedron Letters; vol. 36, No. 47, Nov. 20, 1995 pp. 8657-8660.
Inorganic Chemistry; vol. 14, No. 7, 1975 pp. 17321732-1734.

Affiliated with

Also associated with

Rating

Catalyst and process for preparing amides does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Catalyst and process for preparing amides, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Catalyst and process for preparing amides will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-850822