Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1996-11-25
1998-07-07
Dees, Jose G.
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
502301, C07C20900, B01J 2500
Patent
active
057771669
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/FR94/01478 Dec. 16, 1994.
The present invention relates to the huge field of the catalytic reduction of nitriles, in particular of mononitriles and/or dinitriles, to monoamines, diamines or aminonitriles by use of Raney catalysts doped with one or a number of additional metal elements.
More precisely, the subject of the present invention is a process for the hydrogenation of nitriles to amines, for example of mononitriles and/or dinitriles to monoamines and/or diamines, using a catalyst of Raney nickel type doped with at least one additional metal element chosen from group IVb of the periodic classification and resulting from an Ni/Al/doping element(s) metallurgic precursor alloy.
The reduction of nitriles to amines, for example of dinitriles to diamines, is a chemical conversion which assumes the greatest importance in the chemical industry because amines, and in particular diamines, are compounds which are often used as reactive monomers in polycondensation reactions, for example with other bifunctional monomers. A particularly illustrative example of this large-scale industrial dimension is that of adiponitrile, which is capable of being hydrogenated to hexamethylenediamine. This last compound is one of the basic monomers in the manufacture of polyamide-6,6, the economic importance of which is known.
This reduction of nitriles to amines must also be understood as comprising the conversion of dinitriles to aminonitriles, for example of adiponitrile to aminocapronitrile, it being possible for the latter to be converted to caprolactam by cyclizing hydrolysis. Caprolactam itself is also a fundamental compound in the chemistry of polymer fibers, since it constitutes the monomer of polyamide-6.
The hydrogenation of nitriles to amines is conventionally carried out with the catalytic support of, optionally doped, Raney nickel. These catalysts are prepared by leaching the aluminium from aluminium-rich Al/Ni alloys, in strongly alkaline medium. The catalysts obtained consist of agglomerates of nickel crystallites having a high specific surface and a variable residual aluminium content.
Modification of the structural and electronic factors of Raney nickel, by addition of metals to the nickel/aluminium alloy, has already been envisaged. The addition of a doping agent is conventionally carried out by introduction into an Ni/Al precursor alloy in the molten state. It relates to metallurgic doping. Thus, the doping of Raney nickel with various metal promoters (Fe, Co, Cr, Mn, V, Mo, Zr, Ta or Ti), as well as their effects as regards the activity, selectivity and stability of the catalyst, form the subject of a rich scientific and techical literature.
The article by Freidlin et al. (Russian Chemical Review, Vol. 33, No. 6, June 1964) relates to the catalytic reduction of dinitriles and lists a certain number of doped Raney catalysts used under varied hydrogenation conditions (temperature, hydrogen pressure (P.sub.H.sbsb.2), reaction medium). Mention is particularly made of Raney nickels doped with chromium, copper and titanium. With Raney Ni doped with chromium, the hydrogenation is carried out in acetic anhydride in the presence of NaOH at a temperature of 50.degree. C. and a hydrogen pressure of approximately 0.35 MPa to obtain a selectivity of 77% for diamine from adiponitrile. As regards Raney Ni doped with titanium, the reaction medium contains butanol and ammonia, the temperature is from 140.degree. C. to 180.degree. C., the hydrogen pressure approximately 14 MPa and the selectivity for diamine is 60% from dicyanobenzene. It also appears that the doping elements (such as Ti) are present in an amount greater than or equal to 4% by weight with respect to the nickel.
It is observed that the selectivities obtained in the hydrogenations of dinitriles using doped Raney Ni described in this prior document are relatively low. In addition, in certain cases, the reaction conditions, such as the temperature and the hydrogen pressure, are at such high levels that they are harmful to the conve
REFERENCES:
patent: 3862911 (1975-01-01), Chabert
patent: 4248799 (1981-02-01), Drake
Russian Chemical Reviews, Uspekhi Khimii, vol. 33, 1964.
Chemical Abstracts, vol. 92, No. 22, Jun. 2, 1980, Abst. #92:182869v.
Cordier Georges
Fouilloux Pierre
Laurain Nathalie
Spindler Jean-Francis
Dees Jos,e G.
Pryor Alton
Rhone-Poulenc Chimie
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