Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Patent
1995-05-30
1996-09-17
Jordan, Charles T.
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
568924, 568944, C07C24102
Patent
active
055570151
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method of preparing hydrazine nitroform and more particularly to a method of preparing hydrazine nitroform in a pure and stable form which renders the hydrazine nitroform suitable in particular as a solid propellant.
High-energy solid oxygen oxidizers that are suitable for use as propellant have long been searched for. Suitable compounds should possess a high density, be thermally stable and exhibit high impact resistance, both alone and in mixtures with other compounds.
In the 1960s it was already found that hydrazine nitroform (HNF), alternatively referred to as hydrazine nitroformate or hydrazine nitroformiate, is a very strong oxidizer which renders this compound useful as fuel. The compound has a high energetic value, so that it is particularly suitable as a solid propellant.
It has been found that this compound, contrary to the suggestion of the structural formula NH.sub.2 NH.sub.2.HC(NO.sub.2).sub.3, is thermally stable. Indeed, most nitroform compounds decompose rapidly at room temperature or even below room temperature.
The compound is relatively impact resistant and, even when mixed with aluminum, no reduction of the impact resistance arises. This is of importance because hydrazine nitroform, as described in U.S. Pat. No. 3,307,985, is often mixed with aluminum, among others, to improve the properties regarding its performance as a solid propellant. Aluminum, but also magnesium, beryllium or other metals, is then employed as powdery fuel compound.
Methods of preparing hydrazine nitroform have long been known. U.S. Pat. No. 3,297,747 describes a method of preparing hydrazine nitroform through dissolving nitroform in alcohol and slowly, dropwise adding hydrazine thereto. The hydrazine nitroform formed then precipitates as a salt. This salt can be isolated by means of filtration and optionally be further purified by recrystallization from a solution in a short chain alcohol, such as isopropyl alcohol. The yield of hydrazine nitroform achieved by means of this method is 50%.
Such a method is also described in U.S. Pat. No. 3,378,594, where equimolar amounts of hydrazine (hydrated or non-hydrated) are mixed with nitroform at 0.degree. C. to 50.degree. C. and atmospheric pressure. Water can be present as solvent and is then present in large amounts. Preferably, however, the method is effected in the presence of an organic solvent such as methanol.
In the Encyclopedia of Explosives and Related Items, S. M. Kaye, vol 8, page M78-M80 (1978) a method for preparing HNF is described, in which hydrazine is mixed with nitroform in water. The end product can also be prepared by adding anhydrous hydrazine to nitroform in isopropyl alcohol.
However, as appears from numerous publications from the 1960s and 1970s, the hydrazine nitroform produced in this way did not exhibit the desired stability. As described in U.S. Pat. No. 3,418,183, the hydrazine nitroform tends to form bubbles, or, as it is called, the hydrazine nitroform `gasses`. This tendency to `gas` is attributed to impurities of the hydrazine nitroform produced. It appears from U.S. Pat. No. 3,378,595 that the stability of the hydrazine nitroform depends on the ratio of the hydrazine to the nitroform and on the purity of nitroform and solvent.
One possibility of preventing hydrazine nitroform from `gassing` could be to purify the hydrazine nitroform. However, this option is laborious and hence expensive.
Accordingly, to sufficiently ensure stability, it proved necessary to always add stabilizers. A great deal of research was focused on finding a stabilizer which, in small amounts, is capable of stabilizing the hydrazine nitroform to a sufficient degree.
Publications which can be mentioned in this connection include the above-mentioned U.S. Pat. No. 3,418,183, where anhydrides of dicarboxylic acids are proposed, U.S. Pat. No. 3,658,608, where nitroguanidine is proposed, and U.S. Pat. No. 3,384,674, disclosing the addition of non-volatile aldehyde compounds such as benzaldehyde for increasing the stability of hydrazine nitroform
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Hordijk Arie C.
Mul Johannes M.
Zee Fransiscus W. M.
Aerospace Propulsion Products B.V.
Hardee John R.
Jordan Charles T.
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