Preparation cyclonite

However, attempts to prepare cyclonite from substances containing a sym-triazine ring, e.g. from N,N, N"-trichloro-cyclotrimethylenetriamine (III) (obtained by Delepine [13], by the action of hypochlorous acid on hexamethylenetetramine) were a failure. 

An attempt to prepare cyclonite by reacting the substance (III) with silver nitrite also failed, as it resulted in total decomposition of the molecule. 

The oldest and simplest method of preparing cyclonite is based on the introduction of hexamethylenetetramine (hexamine) into an excess of concentrated nitric acid, s. g. 1.50-1.52, free of nitric oxides, at 25-30°C, thereafter pouring the whole into cold water. 

HDN is one of the intermediate products obtained during preparation of Cyclonite from hexamine. It has also been proposed for use in the manufacture of an explosive, tentatively considered to be 1,3,5-trinitrohexahydro-s- triazine (Ref 7). Its use in an AN-slurry expl has been patented (Ref 12)... 

Some nitramines may be prepared without treating amines with nitric acid. The classical example is the so-called E-method of cyclonite preparation in which a nitramine is formed by dehydration of a mixture of paraformaldehyde and ammonium nitrate, i.e. without using either amine or nitric acid (this will be discussed more fully on p. 109). When a nitramine is required with a non-nitrated aromatic ring which readily undergoes nitration with nitric acid, Bamberger s method [45], involving the oxidation of diazo compounds (13), may be applied. 

This is a powerful explosive, stronger than tetryl but weaker than cyclonite. It is, however, of no practical value chiefly because its preparation is too expensive, requiring first the conversion of methylamine into urethane and then into its nitro derivative. On hydrolysis the latter yields methylnitramine. Similarly, the hydrolysis of dinitrodimethyloxamide (p. 35) leads to the formation of methylnitramine. 

Cyclonite was first prepared by Lenze [1], The method of manufacture by the nitration of hexamethylenetetramine nitrate with nitric acid is described in Henning s patent [2] of 1899. 

The author did not cite the product as an explosive — he recommended its use in medicine — but in later patents [3] he proposed the use of cyclonite in the manufacture of smokeless propellant. In 1921 Herz [4] modified Henning s method by nitrating hexamethylenetetramine itself, not its nitrate. Hale [5] described in detail the preparation of cyclonite by nitrating hexamethylenetetramine, and reported its explosive properties. 

Cyclonite (I) can be prepared by the action of concentrated nitric acid or acetic anhydride on the compound (la) at room temperature. A N-acetyl derivative of dinitro compound (XXIX) (p. 116) is obtained by the action of acetic anhydride on the compound (la) in the presence of sodium acetate. 

Vroom and Winkler believed substance (la) to be an intermediate compound in the preparation of cyclonite by the nitrolysis of hexamine. This view was shown to be incorrect by Wright, Berman and Meen [46] who proved that the substance... 

Gilpin and Winkler [51] report the following heats of nitration when cyclonite is prepared in different ways ... 

To utilize the acid for preparing hexamine dinitrate and to nitrate the dinitrate, so obtained, to cyclonite. This method was studied by T. Urbanski [53] who found, however, that the dinitrate is nitrated to cyclonite with some difficulty, part of the dinitrate remaining unchanged in the product. Since the dinitrate is not sufficiently stable, its presence in cyclonite is undesirable. Nevertheless, it may be used up for a synthesis of cyclonite by adopting a combined method, using hexamine dinitrate, ammonium nitrate and acetic anhydride. This will be discussed in later sections. 

The suspension of the ground cyclonite in water is allowed to stand in the vat for hr. The liquid is then decanted from above the cyclonite layer and allowed to run through a filter which retains any finely-divided product carried away by the water. After the liquid has been decanted the tub is filled with cold water, its contents are stirred, allowed to stand again, and then decanted. This operation is repeated three times after which the cyclonite is washed with hot water at 90-100 °C for 12 hr. After washing the liquid is decanted and the wet cyclonite is removed from the tub to the filter. The filtered cyclonite containing 10% of water, goes on to the department where explosive mixtures are prepared. 

PREPARATION OF CYCLONITE FROM HEXAMINE, NITRIC ACID AND AMMONIUM... 

The acid is allowed to run into a container of 3 m3 capacity where it is neutralized with gaseous ammonia while the temperature is raised to 70°C. The cyclonite thus formed is separated on a vacuum filter, and the filtrate is cooled when about two-thirds of the ammonium nitrate crystallizes. The latter is separated in a centrifuge, and used in the preparation of explosive mixtures. The small amounts of hexamine... 

PREPARATION OF CYCLONITE FROM SULPHAMIC ACID, FORMALDEHYDE AND... 

A method for the preparation of cyclonite from sulphamic acid, formaldehyde and nitric acid was developed in 1934 by Wolfram [38], It is known as the W-meth-od and the cyclonite so obtained is known as W-Salz . The W-method is based on the condensation of the potassium salt of sulphamic acid with formaldehyde and the nitration of the condensation product ( white salt , a Schiff s base of the type XVIII) with nitric acid. 

This mixture was prepared from 99% nitric acid and sulphuric anhydride. White salt (XVIII) was introduced to the mixture at a temperature of 30°C. The heat evolved during nitration (approximately 500 kcal per kg of cyclonite) was removed by means of a cooling coil. The cyclonite so formed was partly suspended and partly dissolved in the nitrating liquid. Addition of water completely precipitated the product which was separated on a vacuum filter. The composition of the spent acid was ... 

PREPARATION OF CYCLONITE FROM PARAFORMALDEHYDE, AMMONIUM NITRATE AND ACETIC ANHYDRIDE... 

The advantage of this method lies in the fact that the preparation of cyclonite. is accomplished without using hexamine and nitric acid so that the dangers of nitration are avoided. On the other hand acetic anhydride is required, which is rather expensive. 

It appears that apart from cyclonite, octogen (XI), a N-acetyl derivative (XXX) and a number of nitramines, mainly chain compounds, less stable than cyclonite, are also formed by this method, in side-reactions. Hence the cyclonite obtained has a relatively low melting point (190-195°C) and may be less stable than that prepared by other methods. The conduct of the reaction in the presence of boron fluoride reduces the number of by-products formed. 

Acetic anhydride is prepared from distilled acetic acid by the ketene method with ethyl phosphate as a catalyst. The water from the first cyclonite wash on the vacuum filter contains on an average 20% of acetic acid which is recovered by extraction with ethyl acetate. 

Examination of the mechanism of cyclonite formation has clarified the conditions under which various products similar in structure to cyclonite are formed. These products always accompany cyclonite prepared by method 5 and often that prepared by method 4. 

This compound sometimes occurs in an appreciable quantity in cyclonite prepared by methods 4 and 5. It is an undesirable by-product due to its high sensitiveness to impact and to its relatively poor stability, which is lower than that of cyclonite. Bachmann and Sheehan [62] found that stirring the reactants at a low temperature (e.g. 0°C) and subsequently heating the whole to 75°C favours the formation of the product (XXIII). 

The transient formation of hexamine in method 4 was confirmed by Winkler, Gillies and Williams [60] (see equation (45)) who examined the reaction mechanism of cyclonite preparation by method 4. They found that hexamine dinitrate is formed at 35°C as an intermediate product. At the same time nitric acid is evolved hence nitrolysis of hexamine dinitrate may occur, in other words the mechanism of cyclo-nite formation would be similar to that of direct nitration of hexamine with nitric acid. 

A mixture of cyclonite and octogen, rich in octogen, is best prepared by method 5, i.e. from hexamine nitrate, ammonium nitrate and acetic anhydride. A particularly large amount of octogen is formed when the product is prepared by Bachmann s method at temperatures ranging from 73 to 78°C and the mixture is then cooled to 25°C and filtered. This mixture m.p. 191-202°, contains approximately 10% of octogen. 

Homocyclonite (Homohexogen) is an homologue of cyclonite with a 7-membered ring. Wright and Myers [43] prepared it by the nitrolysis of compound XXXIV (which arises as a result of the action of formaldehyde and ammonia on ethylene-dinitramine) ... 

During World War II cyclonite was used by all the combatants to increase the power of composite explosives. Fusible mixtures of TNT with cyclonite were prepared, mainly with an admixture of aluminium, and mixtures of TNT with hexyl and cyclonite also with admixture of aluminium (pp. 271-272). 

RDX (2.14), also known as Hexogen, Cyclonite and cyclotrimethylene-trinitramine (C3H6N606), was first prepared in 1899 by Henning for medicinal use and used as an explosive in 1920 by Herz. The properties and preparation of RDX were fully developed during World War II. 

The Biazzi process has been applied to the nitration of other substances, to produce not only esters similar to nitroglycerine, but also for the preparation of such substances as PETN, cyclonite and TNT. 

Hexamethylenetetramine dinitrate ( hexamine dinitrate) itself is of no importance as an explosive. However, it plays a considerable part in the production of cyclonite by one of the methods described in Vol. III. Hexamine dinitrate is prepared from hexamine by treating it with 50- /0% nitric acid, at a temperature not above —15°C. 

Western Cartridge Co, "Engineering Laboratory Investigation of Cyclonite Process , OSRD Rept 612 (June 1942) 31) J-R- Johnson, "The Sensitivity of RDX, HMX, and RDX-HMX Mixtures , OSRD Rept 797 (Aug 1942) 32) J.R. Johnson, "Studies Relating to the Bachmann Process", OSRD Rept 800 (Aug 1942) 33) W.E. Bachmann, "Studies on the Preparation and Properties of RDX , OSRD Rept 820 (Aug 1942)... 

Of the several explosives which are preparable from formaldehyde, two are the most powerful and brisant of the solid high explosives which are suitable for military use. One of these, cyclotrimethylenetrinitramine or cyclonite, is a nitroamine and is discussed in the chapter which is devoted to those substances. The other, pentaerythrite tetranitrate or PETN, is a nitric ester. Both may be prepared from coke and air. 

The nitroamines are substituted ammonias, substances in which a nitro group is attached directly to a trivalent nitrogen atom. They are prepared in general either by the nitration of a nitrogen base or of one of its salts, or they are prepared by the splitting off of water from the nitrate of the base by the action of concentrated sulfuric acid upon it. At present two nitroamines are of particular interest to the explosives worker, namely, nitro-guanidine and cyclotrimethylenetrinitramine (cyclonite). Both are produced from synthetic materials which have become available in large commercial quantities only since the first World War, the first from cyanamide, the second from formaldehyde from the oxidation of synthetic methyl alcohol. 

Cyclonite, prepared by the nitration of hexamethylenetetramine, is derived ultimately from no other raw materials than coke, air, and water. It has about the same power and brisance as PETN, and a velocity of detonation under the most favorable conditions of about 8500 meters per second. 

This nitroso compound, which is related to Cyclonite, is prepared by treating hexamethylenetetramine with alkali metal nitrites in a dilute acid solution. 

Hexamethylenetetramine dinitrate can be prepared from hexamethylenetetramine and nitric acid of medium concentration it is an important precursor of RDX (-< Cyclonite) manufactured by the Sachmann method. 

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