Preparation of Tetranitromethane

It would appear that the chief product of the action of acetylene on nitric acid is an intermediate compound which becomes tetranitromethane when the solution is heated with sulphuric acid. 

The object to be attained in the commercial manufacture is the maximum yield of tetranitromethane calculated on the weight of nitric-acid and the volume of acetylene used should be absorbed. 

Experiments have shown that for the first named object the most favourable concentration of the nitric acid is between 90 and 97.5 per cent, strength and that approximately 3 litres of acetylene per 100 grams of nitric acid diluted to this strength is the best proportion to use. For the second object is is useful to work at a raised temperature, the absorption occurring at about 40° C. at which temperature about 90 per cent, of the acetylene may be absorbed and the yield also improved. 

It has been found that the addition of mercury or a mercury salt to the nitric acid, for instance mercuric nitrate added to the extent o 0.2 to 0.6 per cent, of the weight of nitric acid, increases the proportion of acetylene absorbed, without, however, improving the percentage yield at ordinary temperatures, though at 30°-40° C. the percentage yield is much increased as well as the proportion of acetylene absorbed. 

When the acetylene has been absorbed by the nitric acid, and operation performed in any apparatus adapted to bring gas and liquid into contact with each other and to withstand nitric acid, the liquid is 

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For the preparation of tetranitromethane on the laboratory scale Chattaway s method [68] is commonly used. It consists in treating acetic anhydride with fuming nitric acid at room temperature or below. After a few days the homogeneous solution is poured into water, causing the oily tetranitromethane to separate. 

In addition to the initial reaction between nitric acid and acetic anhydride, subsequent changes lead to the quantitative formation of tetranitromethane in an equimolar mixture of nitric acid and acetic anhydride this reaction was half completed in 1-2 days. An investigation of the kinetics of this reaction showed it to have an induction period of 2-3 h for the solutions examined ([acetyl nitrate] = 0-7 mol 1 ), after which the rate adopted a form approximately of the first order with a half-life of about a day, close to that observed in the preparative experiment mentioned. In confirmation of this, recent workers have found the half-life of a solution at 25 °C of 0-05 mol 1 of nitric acid to be about 2 days. ... 

Nitroisoxazolines were prepared from ALalkoxy-3,3-dinitroisoxazolidines by thermally induced P-elimination. For example, isoxazolidines 42 synthesized by a three-component reaction of tetranitromethane with two equivalents of alkenes 41, were converted into isoxazolines 43 by heating in boiling chlorobenzene <06S706>. 

The synthesis and chemistry of iodonium thiophene derivatives have been studied <00AM133, 00TL5393>, for example, the preparation of 46 involved the ipso substitution of 2-stannylthiophene 45 <00CC649>. A similar ipso substitution of 2-stannylbenzo[b]thiophene 47 with tetranitromethane gave 2-nitrobenzo[ >]thiophene (48) . 

However, in our opinion, the rigorous assignment of products to covalent nitronic esters rather than to their structural isomers, which are true nitro compounds or ionic salts, is a more important and complex problem This problem involves difficulties, because ambident anions of nitro compounds (which are evident precursors of nitronates) have comparable O- and C-nucleophilicities and, therefore, the resulting substrates can belong to any of the above mentioned series. Incorrect structure assignments of derivatives of polynitro compounds prepared from tetranitromethane were made in former studies. In addition, the structures of nitronates assigned to some products in early studies, should not have been accepted without the use of modem spectral methods. 

Condensed 1,3,2-dioxazoles are produced by the reaction of A-phenyliminophosphorane and 9,10-phenanthreno-and 1,2-naphthoquinones (Scheme 7). Photochemical addition of tetranitromethane to aromatic compounds is still in use for the preparation of 1,3,2-dioxazolidines 22 and 23 but in low yields. 

Of all the women chemists, Phyllis Violet McKie24 of the University College of Wales, Bangor, one of Orton s protegees, seems to have been the most productive during the war period. McKie was part of the team at Bangor producing paraldehyde.25 In addition, she devised a new method for the preparation of the explosive tetranitromethane for the Ministry of Munitions, and she studied methods of preparation of saccharin and vanillin for war purposes.26 Orton reported back to the War Committee ... 

To this there was added 54 g tetranitromethane which had been pre-cooled to 0 deg C. Stirring was continued for exactly 2 min, and then the reaction was quenched by the addition of a cold solution of 16.8 g KOH in 300 mL H20. Stirring was continued until the temperature had again been lowered to near 0 deg C. The product was removed by filtration. Extraction of the filtrate with CH2CI2 and removal of the solvent provided additional nitrostryrene, for a combined yield of 50.7 g with a mp of 103 deg C due to the presence of a small amount of free myristicinaldehyde. A recrystallization from MeOH produced 1 -(3-methoxy-4,5-methylenedioxyphenyl)-2-nitropropene with a mp of 109-110 deg C. This material was completely adequate for the above-described reduction to MMDA. The conversion of this nitropropene to myristicinaldehyde is an alternative to the lengthy synthesis given above), and can be used in the preparation of LOPHOPHINE. 

The preparation of nitromethane at laboratory is the nitration of cyanide acid with mixed acid at 10-30 °C to obtain trinitro acetonitrile, and then trinitromethane after hydrolysis and acidification. You can also obtain trinitromethane salt after treatment of tetranitromethane with basic solution. In industry to produce trinitromethane catalyzed by mercuric nitrate, acetylene is nitrated with fuming nitric acid, and the resulting trinitromethane is dissolved in excess nitric acid, then concentrated sulfuric acid was added trinitromethane is nitrated into tetranitrom-ethane because tetranitromethane is insoluble in acid mixture, trinitromethane and tetranitromethane can be separated [32]. The separated liquid is treated with base to generate trinitromethane salt, and trinitromethane can be produced after acidification. Main reactions mechanism are ... 

Tetranitromethane is of explosion whose oxygen balance is 49 % with explosion heat of 1,892 J/g. The pure tetranitromethane is of poor sensitivity that cannot be detonated by even 10 g special as booster. However, it is violently explosive when it is mixed with combustible material at almost zero oxygen balance, and it has a small critical diameter (thickness) and significant detonation and shock sensitivity. Such explosives are generally prepared when they are needed and the quantity addresses the requirement exactly regarding the safety considerations. Table 7.14 lists the detonation properties of tetranitromethane and certain combustible compounds at zero oxygen balance. 

Cyclic and acyclic silyl enol ethers can be nitrated with tetranitromethane to give ct-nitro ketones in 64-96% yield fEqs. 2.42 and 2.43. " The mechanism involves the electron transfer from the silyl enol ether to tetranitromethane. A fast homolydc conphng of the resultant cadon radical of silyl enol ether with NO leads tn ct-nitro ketones. Tetranitromethane is a neutral reagent it is commercially available or readdy prepared. " ... 

Safety aspects of the preparation from halotrinitromethanes or tetranitromethane by treatment with methyl iodide are improved by use of an aprotic solvent (DMF, DMSO or HMPA) in diethyl ether or carbon tetrachloride at 30-60°C. 

Cyclic nitroalkenes are prepared from cyclic ketones via nitration of vinylstannanes with tetranitromethane in DMSO, as shown in Eq. 2.36, where DMSO is a critical choice of solvent for replacing tin by nitro at the unsaturated carbon. The conversion of ketones to vinylstannanes... 

As useful as tetranitromethane is as a charge-transfer nitrating agent, it is generally too unreactive to effect the comparable electrophilic nitration of most aromatic donors, except the most electron-rich ones. Thus in order to make the direct comparison between the photochemical and thermal nitration of the same ArH, we now turn to the A-nitropyridinium acceptor (PyNOj) as the alternative nitrating agent (Olah et al., 1965, 1980). For example, PyNO can be readily prepared as a colourless crystalline salt, free of any adventitious nitrosonium impurity, and used under essentially neutral conditions. Most importantly, the electrophilic reactivity of this... 

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