Process for the producing of pentenenitriles

Details Process for the producing of pentenenitriles Process for the producing of pentenenitriles

1997-09-15

1998-11-10

Richter, Johann

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

Organic compounds

Nitriles

C07C25300

Patent

active

058346163

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to a process for the preparation of pentenenitriles. Pentenenitriles, more particularly 3-pentenenitrile and 4-pentenenitrile, can result in adiponitrile by reaction with hydrogen cyanide.
The invention more specifically consists of a process for the preparation of pentenenitriles by the use, in the vapour phase, of 2-methylglutarimide and/or of ethylsuccinimide and/or of their precursors, in the presence of an acidic solid catalyst chosen in particular from acidic molecular sieves, acidic clays, bridged clays (or pillared clays), bulk oxides and acidic phosphates.
During the preparation of adiponitrile by hydrocyanation of butadiene, with the intermediate production of pentenenitriles, large amounts of methylglutaronitrile and ethylsuccinonitrile are inevitably obtained. These by-products currently have only very few industrial outlets and must largely be incinerated.
It is therefore entirely desirable to enhance the value of such by-products and this is one of the aims of the present invention. This is because the compounds employed in the present process, 2-methyl-glutarimide and/or ethylsuccinimide, as well as their precursors, can be prepared from methylglutaronitrile or from ethylsuccinonitrile.
2-Methylglutarimide can be employed directly or in the form of one of its precursors, such as in particular 4-cyanovaleramide, 2-methyl-4-cyano-butyramide, 4-cyanovaleric acid or 2-methyl-4-cyanovaleric acid.
Likewise, ethylsuccinimide can be employed directly or in the form of one of its precursors, such as in particular 3-cyanovaleramide, 2-ethyl-3-cyanopropionamide, 3-cyanovaleric acid or 2-ethyl-3-cyanopropionic acid.
2-Methylglutarimide and its precursors are the most important and the preferred substrates among those which can be employed in the present process, in particular because of the higher proportion of methylglutaronitrile available and because of the better results which they provide.
2-Methylglutarimide can be prepared, for example, by reaction of methylglutaronitrile with dodecanoic acid, as described in an article in the Journal of Organic Chemistry, 36, pages 3050 et seq. (1971). It can also be prepared by reaction of methylglutaric acid with ammonia, as described in another article in the Journal of Organic Chemistry, 22, pages 1728 et seq. (1957).
The acidic molecular sieves employed are in particular acidic zeolites of pentasil structure, such as, for example, ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-48, mordenite or ferrierite, and acidic zeolites of faujasite structure, such as, for example, zeolite X or zeolite Y.
The zeolites of pentasil structure are more particularly zeolites of ZSM-5, ZSM-12, ZSM-11, ZSM-22, ZSM-23, ZSM-48, mordenite and ferrierite type having the general formula (I) expressed in terms of ratios of oxides: tri- and tetravalent metals, M being at least in part a hydrogen atom,
The zeolites of faujasite structure are more particularly those having the general formula (II) expressed in terms of ratios of oxides: tetravalent metals, M being at least in part a hydrogen atom,
The zeolites used in the context of the invention are preferably those in the formula (I) or (II) of which the oxide used in combination with silica is that of a trivalent metal, in particular Al or Ga.
Preference is generally given to the acidic zeolites in the formula (I) or (II) of which M is chosen from hydrogen, NH.sub.4, alkali metals, such as, for example, Na, K, Li, Rb or Cs, alkaline-earth metals, such as, for example, Be, Mg, Ca, Sr or Ba, rare-earth metals, such as, for example, La or Ce, or transition metals, such as, for example, Fe.
For a more detailed description of acidic clays, reference may be made to Patent FR-A-2,622,575, which is incorporated in the present text by reference.
Preference is given, in the process of the invention, to the use of smectites, such as, for example, montmorillonites, beidellites, nontronites, hectorites, stevensites and saponites.
Bridged clays, which can be used as catalysts in the present process, are clays between th

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Journal of Organic Chemistry, vol. 36, No. 20, 1971, "Nitrile Synthesis via the Acid-Nitrile Exchange Reaction", pp. 3050-3051.
Liebigs Annalen Der Chemie, vol. 716, 1968, F. Becke et al, Uber die Einwirkung von Carbonsauren auf Nitrile, pp. 78-82.
Chemical Abstracts, vol. 101, No. 3, 16 Jul. 1984, Columbus, Ohio, Abstract No. 22606, Rao et al, p. 529.

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