Tetryl preparation

They prepared tetryl by treating dimethylaniline with a 20-fold volume of nitric acid, s.g. 1.52 at —5 to 0°C. 

The two commercial methods of preparing Tetryl via nitration of dimethylaniline, or production of diriitromethylaniline and its subsequent nitration, were described under Nitration" in Vol 8, N71-L to N72-L. Because the first of these reactions involves the oxidation of a methyl group it is highly exothermic and great care must be exercised to control the reaction temp. The second process proceeds with less gas evolution than the first and is less likely to be violent. In the lab, high purity Tetryl can be obtained by nitrating dimethylaniline with nitric acid (not mixed acid) in the presence of inert solvents such as dichloromethane, chloroform or carbon tetrachloride (Ref 18)... 

Nobel mixed nitroglycerine with nitrocellulose to form a gel. Mertens first prepared tetryl. 

Before proceeding to describe the manufacture of the nitramines, RDX and Tetryl, a few general remarks about the preparation of nitramines... 

Pagowski (Ref 6) proposes an effective OB (again undefined in CA) and claims a linear correlation of effective OB and detonation velocity Mustafa Zahran (Ref 8) prepared a series of substituted Tetryls, Pentyls, Hexyls Nonyls. For each series they claim a correlation between the Martin Yallop corrected OB, and impact or friction sensitivity, and Trauzl Block "power . 

The tests with the 12-kW system in Demo II successfully confirmed that this technology is capable of destroying the components (nitrocellulose and nitroglycerine) of M28 propellant. For tetrytol, the destruction of TNT and tetryl was good. However, recalcitrant intermediate products were formed during the treatment of tetrytol, which AEA was still evaluating at the time the Demo II report was prepared (NRC, 2001b). 

Other explosives, such as 2,4,6-trinitroanisole (7),33b.226 2,4,6-trinitroaniline (picramide), and tetryl (101), ° are conveniently prepared from the nitration of the corresponding 2,4-dinitro derivatives, which in turn, are prepared from the reaction of 2,4-dinitrochlorobenzene with the appropriate nucleophile. 

A important exception is the synthesis of the practical high explosive known as tetryl (8), prepared by treating A, A-dimethylaniline (90) with nitric acid, mixed acid or acetic... 

Tetryl (8) can be prepared from the nitration-oxidation of A, A-dimethylaniline (90) with a variety of nitrating agents and conditions, including the use of a large excess of 70 % nitric... 

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. 

The empirical equation for the preparation of tetryl from dimethylaniline is as follows ... 

Recently, T. Urbanski and Semenczuk [8] made it clear that tetryl may be safely prepared by nitrating dimethylaniline with nitric acid, s.g. 1.40. Essential safety precautions for the procedure are ... 

T. Urbanski and Semenczuk found that tetryl prepared with nitric acid alone is of high purity, possibly because it is not contaminated with 2,4,6-f.initro-N-methyl-aniline formed from tetryl as a result of the loss of the N-nitro group on heating with sulphuric acid, present in an ordinary nitrating mixture. 

Tetryl prepared in this way was contaminated by the following substances ... 

In technical operations dimethylaniline is employed as a starting material chiefly because it is obtainable more easily and is much cheaper than methylaniline. Moreover, tetryl prepared from dimethylaniline is purer than that from methylaniline. Hence the preparation of tetryl from dimethylaniline is more economic, in spite of the greater consumption of nitric acid by dimethylaniline which uses up nitric acid to oxidize one of the N-methyl groups. The yield is not higher than 80%, due to the side-reactions. 

Since methylamine prepared from methyl alohol and ammonia has become available commercially, the preparation of tetryl from dinitromethylaniline obtained from chlorodinitrobenzene and methylamine has been widely used. 

Tetryl crystallizes in the form of crystals which are colourless immediately after preparation and crystallization but which rapidly turn yellow under the influence of diffused light. The technical product is usually pale yellow. 

Such a product may be prepared by various methods, e.g. by mixing a coarse crystalline substance derived from crystallization in benzene with a fine crystalline one obtained by the precipitation of tetryl with water from an acetone solution. Another method (according to Crater [22]) consists of pouring the benzene solution into water heated to above the boiling point of benzene. Alternatively, crystallization from dichlorethane (according to Rinkenbach and Regad [23]) may produce an acceptable form of tetryl. 

Crystallization from acetone. Tetryl may be crystallized from acetone by cooling, but crystallization by precipitation with water is preferable, as this permits removal of traces of acid and gives a very fine crystalline product which, when mixed with the product prepared by crystallization from benzene, forms a free-flowing mixture. The plant is, in principle, similar to that represented in Fig. 10, except that separation is unnecessary and a much larger crystallization vessel is needed to hold both the solution and the added water. 

According to the German (Griesheim) method [60] tetryl is manufactured in two stages first dinitromethylaniline is prepared and this is then nitrated. 

Romburgh [3] was the first to prepare this substance both by nitrating ethyl-aniline and by nitrating diethylaniline. It is comparable to tetryl in its physical and chemical properties. As an explosive it is weaker than tetryl. Its sensitiveness to impact and its explosive power, measured in the lead block, are somewhat greater than those of picric acid. 

An explosive called tetryl was also being developed at the same time as picric acid. Tetryl was first prepared in 1877 by Mertens and its structure established by Romburgh in 1883. Tetryl (1.3) was used as an explosive in 1906, and in the early part of this century it was frequently used as the base charge of blasting caps. 

During World War II, an improved process was developed for producing petroleum naphthas ensuring unlimited quantities of toluene. Purification techniques were improved for TNT. Composites mixtures of TNT-PETN, TNT-RDX, TNT-tetryl, TNT-ammonium picrate, TNT aluminium, etc., were prepared. 

Tetryl (7.2) can be prepared by dissolving dimethylaniline in sulfuric acid and adding nitric and sulfuric acids at 70 °C as shown in Reaction 7.2. 

Preparation of Tetryl. Twenty grams of dimethylaniline is dissolved in 240 grams of concentrated sulfuric acid (d. 1.84), the temperature being kept below 25°, and the solution is allowed to run from a separatory funnel drop by drop into 160 grams of 80 per cent nitric acid (d. 1.46), previously warmed to 55° or 60°, while this is stirred continuously and kept at a temperature between 65° and 70°. The addition requires about an hour. After all has been added, the stirring is continued while the temperature of the mixture is maintained at 65° to 70°. The material is allowed to cool the solid matter is collected on an asbestos filter, washed with water, and boiled for an hour with 240 cc. of water while further water is added from time to time to replace that which boils away. The crude tetryl is filtered off, ground under water to pass a 150-mesh sieve, and boiled twice for 4 hours each time with 12 times its weight of water. The solid is dried and treated with benzene sufficient to dissolve all readily soluble material. The solution is filtered and allowed to evaporate spontaneously, and the residue is recrystal-... 

The nitration of aniline in the presence of a large amount of strong sulfuric acid results wholly in the formation of m-nitro-aniline, but the similar nitration of dimethylaniline gives principally a mixture of the ortho- and para-derivatives. Mono-methylaniline stands between aniline and dimethylaniline in respect to the orienting effect of its amino group it yields a considerable amount of the m-nitro- compound—and dimethylaniline is preferred for the preparation of tetryl. Commercial dimethylaniline contains a certain amount of monomethylaniline, from which it is extremely difficult to free it, and this in the manufacture of tetryl is converted in part into 2,3,4,6-tetranitro-phenylmethylnitramine, or m-nitrotetryl, pale yellow, almost white, crystals from benzene, m.p. 146-147.087... 

The ethyl analogue of tetryl was first prepared by van Rom-burgh,101 who procured it both by nitrating monoethylaniline and by nitrating diethylaniline, and reported that it melts at 96°. The present writer has found that the pure material, recrystallized twice from nitric acid (d. 1.42) and once from alcohol, melts at 94°. It is comparable to tetryl in its chemical reactions and in its explosive properties. 

At the time of the first World War the methyl alcohol which was needed for the preparation of tetryl was procured from the distillation of wood. It was expensive and limited in amount. Formaldehyde was produced then, as it is now, by the oxidation of methyl alcohol, and a demand for it was a demand upon the wood-distillation industry. Formaldehyde was the raw material from which methylamine was produced commercially, and the resulting methylamine could be used for the preparation of tetryl by the alternative method from dinitrochlorobenzene. It was also the raw material from which certain useful explosives could be prepared, but its high price and its origin in the wood-distillation industry deprived the explosives in question of all but an academic interest. With the commercial production of synthetic methyl alcohol, the same explosives are now procurable from a raw material which is available in an amount limited only by the will of the manufacturers to produce it. 

At a time when the only practicable methods for the preparation of nitromethane were the interaction of methyl iodide with silver nitrite and the Kolbe reaction from chloracetic acid, the explosive was far too expensive to merit consideration. The present cheap and large scale production of nitromethane by the vapor-phase nitration of methane and of ethane has altered the situation profoundly. Trimethylolnitromethane trinitrate is an explosive which can now be produced from coke, air, and natural gas. Nitromethane too has other interest for the manufacturer of explosives. It may be used as a component of liquid explosives, and it yields on reduction methylamine which is needed for the preparation of tetryl. 

A number of by-products are formed in the preparation of Tetryl (Ref 34). Commercial dimethylaniline contains some methylaniline, which is nitrated to 2,3,4,6-tetranitrophenylnitramme (also called m-nitroethyl) which in turn is readily hydrolyzed to the substance below ... 

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