Phosphine inhibition

Details Phosphine inhibition Phosphine inhibition

1990-05-29

1991-01-08

Lechert, Jr., Stephen J.

Explosive and thermic compositions or charges

Containing free phosphorus or binary compound of phosphorus

102335, 1491096, C06G 3900

Patent

active

049832344

DESCRIPTION:

BRIEF SUMMARY
The present invention relates to inhibiting phosphine release from phosphorus by use of certain radical compounds.
Phosphorus finds a wide variety of applications in industry, for instance in matches, pyrotechnics and munitions and as an oxidation inhibitor in some plastics. Generally the red allotrope is favoured over the white allotrope because of its greater stability in air and easier handling characteristics. However, a major difficulty with red phosphorus is that, on storage, there is a gradual release of phosphine which is toxic by inhalation and which can, in turn, give rise to diphosphine which is spontaneously flammable in air. In pyrotechnics and munitions, phosphine liberated by the red phosphorus charge may diffuse through the device, even through elastomeric seals, and can give rise to corrosion of essential working parts, presumably after it has been oxidised to phosphoric acid and phosphates. Phosphine is also liberated by white and black phosphorus.
It has now surprisingly been discovered that certain compounds, when admixed with phosphorus, will reduce the rate at which phosphine is liberated thus prolonging the shelf-life of munitions and other products containing phosphorus and reducing the hazards presented by manufacturing processes involving phosphorus.
The compounds in question are quinonic compounds and sulphur analogues thereof, which are mono- and fused bi- and tri-cyclic compounds bearing at least a first and second substituent, the first and second substituents each being selected from oxo and thioxo, the second substituent being located on the same ring and ortho or para to the first substituent, other than anthraquinone or a substituted anthraquinone.
The quinonic compounds and their sulphur analogues defined above will hereafter be referred to as "radical inhibitors".
The radical inhibitors used in the present invention may bear further substituents in additions to the first and second substituents defined above. Suitably, any such further substituents are selected from nitro, halo, for instance chloro, and alkyl, for instance tertiary butyl, substituents.
Preferably the first and second substituents are the same and most preferably the first and second substituents are both oxo.
The fused bicyclic radical inhibitors comprise two fused aromatic rings and the fused tri-cyclic radical inhibitors comprise three aromatic rings.
With tri-cyclic radical inhibitors it is prefered that the first and second substituents are both located on a ring fused to both the other two rings.
Particular examples of the mono- and fused bi- and tri-cyclic compounds useful in the invention are:
Preferences within this list are in accordance with those stated above. The most preferred compounds, in terms of ability to diminish phosphine emission from red phosphorus, are 1,4-naphthaquinone and 1,4-benzoquinone.
When used to inhibit phosphine emission from white phosphorus, the radical inhibitor is selected having regard to the solubility of the radical in water since white phosphorus is normally stored under water.
The present invention therefore provides a composition comprising phosphorus, preferably red phosphorus, and a minor proportion of at least one radical inhibitor as hereinbefore defined.
The amount of radical inhibitor incorporated in the phosphorus will depend to a certain extent on the degree to which phosphine emission must be inhibited and especially on the degree to which the useful properties of phosphorus are diminished by inclusion of the radical inhibitor. It could be envisaged that for certain applications relatively large amounts of radical inhibitor could be tolerated, whereas for pyrotechnic and munitions applications based on a red phosphorus charge, the compositions should not contain less than 90% red phosphorus by weight based on the total weight of the composition. For ease of handling and to improve stability, red phosphorus as supplied (i.e., "ex-works") usually contains a small amount of water and/or oil. Typically about 1.25% w/w of a light mineral oil is added to imp

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patent: 3899375 (1975-08-01), Palmer
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patent: 4187207 (1980-02-01), Cerny et al.
patent: 4423025 (1983-12-01), Ledford
patent: 4900518 (1990-02-01), McLeod et al.

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