Preparation of epoxy nitrates

Details Preparation of epoxy nitrates Preparation of epoxy nitrates

1991-03-22

1992-08-04

Evans, J. E.

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

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

549555, C07D30100, C07D30116

Patent

active

051360624

DESCRIPTION:

BRIEF SUMMARY
This invention relates to a method for the preparation of the nitrate esters of epoxy alcohols, hereinafter also referred to as epoxy nitrates.
Nitrates esters of epoxy alcohols, of which glycidyl nitrate (the nitrate ester of glycidol) is probably the best known example, have known and useful explosive properties and are also useful starting products for the preparation of various polyfunctional compounds.
Epoxy nitrates have in the past been prepared by a general method employing acyclic precursors which are first treated with mixtures of concentrated nitric and sulphuric acids to produce partly nitrated intermediates, after which the intermediates are isolated and purified and are then treated with a base to effect ring closure. Examples of such methods are disclosed in Will.Ber.Deutsch Chem.Ges. 41 1117 (1908) in which the nitration step described is the di-nitration of glycerol, and Petty and Nichols J.Amer.Chem.Soc. 76 4385 (1954) in which the nitration step described is the mono-nitration of 3-chloropropane-1,2-diol. Such multiple-step methods are tedious, may result in low yield of the final closed-ring product, and are hazardous because they require the isolation and purification, usually by distillation, of reactive nitrated acyclic intermediates.
More recently, nitrate esters of certain .alpha.-epoxy alcohols have been prepared by a single step method, described by L. T. Eremenko and A. M. Korolev, (Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya 5, 1142-1144 (1967)), which obviates many of the problems associated with the aforementioned multi-step methods. 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, after having first added the alcohol dropwise to the acid mixture. 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 is 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 and 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.
It is the object of the present invention to provide a method of preparing epoxy nitrates, and particularly nitrate esters of monohydric epoxy alcohols, which obviates at least some of the aforementioned disadvantages. More especially, it is an object of the present invention to provide a one reaction step method for producing nitrate esters of epoxy alcohols which is less hazardous than the aforementioned methods.
According to the present

REFERENCES:
patent: 3058994 (1962-10-01), Schrage
Eremenko et al., Chem. Abstr. vol. 68, No. 9, Feb. 26, 1968, 39373c.

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