Preparation of nitratoalkyl-substituted cyclic esters

Details Preparation of nitratoalkyl-substituted cyclic esters Preparation of nitratoalkyl-substituted cyclic esters

1991-03-22

1992-09-08

Evans, J. E.

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

549511, 549513, C07D30100, C07D30506, C07D30504

Patent

active

051459744

DESCRIPTION:

BRIEF SUMMARY
This invention relates to the preparation of nitratoalkyl-substituted cyclic ethers, and in particular to the preparation of nitratoalkyl-substituted oxiranes and oxetanes, from hydroxyalkyl-substituted cyclic ethers.
It is known that nitratoalkyl-substituted cyclic ethers can be prepared directly from their corresponding hydroxyalkyl-substituted precursors.
One such known preparative route is described by L T Eremenko and A M Korolev, (Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya 5, 1142-1144 (1967)). This single step method consists of reacting an .alpha.-epoxy alcohol with a 16:26 w/w mixture of 100% nitric acid and acetic anhydride at a temperature of -10.degree. C. for 20 minutes. However, although a high yield of epoxy alcohol is recoverable from the water-quenched reaction mixture (for example a yield of 81% of glycidyl nitrate is reported from glycidol), this method also has several disadvantages.
One disadvantage of the method of Eremenko and Korolev is that it requires the use of an unstable and potentially dangerous nitrating mixture (nitric acid and acetic anhydride) which is known to generate internally the unstable explosive acetyl nitrate. Such mixtures when containing more than 50% by weight of nitric acid in acetic anhydride are especially dangerous, having been shown by T A Brown & J A C Watt (Chemistry in Britain 3(11), 504 (1967)) to act as detonating explosives. For safety reasons the content of nitric acid in the mixture must therefore be maintained at considerably below 50% by weight. Since the method of Eremenko and Korolev requires a molar excess of nitric acid (a molar excess of about 60% is reported) to ensure the nitration reaction goes to completion, then this excess has to be matched by an even greater quantity by weight of acetic anhydride. This relatively large quantity of acetic anhydride present in the reaction mixture represents a wasted component, since it does not take part in the primary nitration reaction but is nevertheless consumed, mainly by conversion to acetic acid during the course of the reaction and the subsequent quenching of the reaction mixture in aqueous solution. This in turn creates the problems of disposing large quantities of waste acid.
A further disadvantage of the method of Eremenko and Korolev is that even after several washings with aqueous solutions, the epoxy nitrate products are found to be contaminated with appreciable amounts (2.5% w/w reported) of dinitro acetates.
A further known method in the field of the present invention is described in U.S. Pat. No. 3,058,994, in which nitratoalkyl-substituted oxetanes are prepared by the slow addition of a slight molar excess of N.sub.2 O.sub.5 in organic solvent to a stirred, cooled mixture of an hydroxyalkyl-substituted oxetane. Nitric acid is formed as a byproduct from the exothermic reaction involved. Although this method reportedly produces good yields of nitratoalkyl product, it is not readily adapted to large scale manufacturing processes and leads to the presence of increasing quantities of potentially explosive nitratoalkyl product within the exothermic reaction mixture which slowly build up as the N.sub.2 O.sub.5 is added. Furthermore, the analogous reaction with more reactive hydroxyalkyl-substituted oxiranes (glycidol, for example) has been shown in published European Patent Application No EP-0223441-A1 to produce rapid rupturing of the oxirane ring and so prevents isolation of a corresponding nitratoalkyl-substituted oxirane product.
It is one object of the present invention to provide a method of nitration which ovecomes at least some of the disadvantages mentioned above and is applicable to the preparation of both nitratoalkyl oxetanes and nitratoalkyl oxiranes. It is a further object of the invention to provide a method whereby the yield and purity of the nitratoalkyl cyclic ether products is improved over those reported in the methods described above.
Accordingly, the present invention provides a process for the preparation of a nitratoalkyl-substituted cyclic ether which compris

REFERENCES:
patent: 3058994 (1962-10-01), Schrage
patent: 3549687 (1970-12-01), Bachman et al.
Eremenko et al. Chem. Absts. vol. 68, No. 9, Feb. 26, 1969, 39373c.

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