United States Patent Office Patented Mar

3,125,606 United States Patent Office Patented Mar. 17, 1964 1. 2 involves the reduction of tetranitromethane which is 3,125,606 PROCESS FOR THE MANUEFACTURE OF readily available from the nitration of acetylene, ketene NTROFORMAN TSSAYS |Dargens and Levy, Compt. rend., 229, 1081 (1949, Donald J. Gover, Bowie, Md., Joseph C. Dacons and or acetic anhydride IOrg. Syn., vol. 21, p. 105 or as a Darrel V. Sickman, Washington, D.C., and Mariora E. by-product in the manufacture of trinitrotoluene in accord Hill, Kensington, and Mortimer J. Kamlet, Silver Spring, ance with the process described in U.S. Patent No. 1,632 Md., assigaors to the United States of America as rep 959 to R. H. Gärtner. A variety of reagents have been resented by the Secretary of the Navy employed in this reduction of the tetranitromethane but No Drawing. Filed Jan. 12, 1959, Ser. No. 786,437 there are disadvantages attendant to the use of each. 7 Claims. (C. 260-644) O Thus potassium ethylate Hantzsch and Rickenberger, (Granted under Title 35, U.S. Code (1952), sec. 266) Ber., 32, 629 (1899) and sodium methylate Macbeth, The invention described herein may be manufactured Ber., 46, 2537 (1913) give the corresponding alkyl ni and used by or for the Government of the United States trates as hazardous by-products. The use of hydrazine is of America for governmental purposes without the pay attended by the formation of toxic hydrazoic acid Schul ment of any royalties thereon or therefor. 5 theis and Schimmelschmidt, supra) while alkaline hydro This invention relates to a new and improved process gen peroxide involves the use of an expensive and danger for the preparation of nitroform and the salts of nitro ous reagent. High cost or poor yields militate against the form. More specifically, the invention relates to a process use of ammonia Pietet and Genequard, Ber., 36, 2225 whereby one of the nitro groups of tetranitromethane is I1903)], sodium sulfite Muraour, Bull, soc. chim., replaced by a hydrogen, sodium or potassium or other 20 I435, 367 (1924), potassium ferrocyanide Chatta light metal to produce nitroform or a salt of nitroform. Way and Harrison, Journ. Chem. Soc., 1916, 171 or Nitroform, trinitromethane, CHNO3, has been found aqueous alkaline solutions of glycerol (Macbeth and Orr, useful as an intermediate in the preparation of a wide Journ. Chem. Soc., 1932,534). variety of compounds which have been found useful as Tetranitromethane has also been reduced to nitroform high explosives and propellants. For example, 2,2,2- 25 by the agency of aqueous potassium hydroxide Schmidt, trinitroethyl-4,4,4-trinitrobutyrate has been prepared by Ber., 52, 400 1919). The usefulness of this process is first reacting free nitroform with formaldehyde and an reduced, however, by the simultaneous hydrolysis of the acrylic compound such as acrylic acid or acrylamide and tetranitromethane to potassium carbonate with the corre then reacting the mixture of 2,2,2-trinitroethanol and sponding reduction in the yield of the desired nitroform 4,4,4-trinitrobutyric acid obtained as one of the products 30 product in accordance with the following equations: of the first reaction with sulfuric acid. This compound, CINO24-2KCH->KCNO)--KNO-HO II 2,2,2-trinitroethyl-4,4,4-trinitrobutyrate, hereinafter re CINOla-I-2KOH->K2CO3--4KNO-3H2O (II) ferred to as TNETB, is a castable explosive having a melt The relative yields of the two sets of products formed in ing point of 93 C. and may be employed alone or in these competing reactions depends on the concentrations explosive mixtures as a substitute for TNT with improved of the tetranitromethane and the potassium hydroxide and results as may be seen from the following table compar it has been found that a potassium hydroxide concentra ing the two compounds. tion greater than 7 N and a molar ratio of potassium hy Table I droxide to tetranitromethane greater than 100 to 1 is re 40 quired to obtain a potassium nitroform yield higher than improvement 80% while a 92.3 yield of potassium nitroform requires TNETB TNT. T.NETB/TNT,percent 14 N KOH. Such high concentrations of KOH are clearly prohibitive. Crystal density, glec------------- .78 1.65 8 It is, therefore, an object of the present invention to Cast density, g.fcc- - 1.70 .56 9 45 provide a new and useful process for the production of Percent oxygen- -- 58.0 42.8 32 G. Oxygen?cc.--- .03 0.70 47 nitroform and the salts of nitroform which is commercially Oxygenbalance: feasible and which does not involve the use of extreme to CO, percent--------------- --21 -8 29 to CO3, percent.-------------- -4 -47 43 ambient conditions or hazardous or expensive reagents and Detonation velocity meters,sec. 8,450 7, 054 20 Fragmentation velocity ft.fsec--- 4,440 3,680 21 does not produce hazardous by-products. Heat of detonation, cal. lg.com 50 Another object is to provide a new and useful process putedl-------------------------- 1,524 934 55 Underwater effects, equivalent for the production of nitroform and the salts of nitroform weights: in high yield from low cost reagents. ShockWave------------------ 1, 18 0.87 36 Other objects and the attendant advantages of the in Bubble energy---------------- 1.16 1.00 16 vention will become apparent to those skilled in the art 55 as the invention is disclosed in the following detailed The salts of nitroform are useful as intermediates in the description. - preparation of TNETB and in the preparation of nitro The above objects are achieved in accordance with the form itself as hereinafter described. invention by subjecting tetranitromethane to the action of Several methods are known for the preparation of a light metal salt of nitrous acid in aqueous or aqueous nitroform and the salts of nitroform. Orton and McKee 60 alkaline solution. Applicants have discovered that the Journ. Chem. Soc., 1920, 283 prepared tetranitrometh nitrite anion, alone or in conjunction with other alkaline ane by the nitration of acetylene and in so doing isolated materials converts tetranitromethane to nitroform anion small amounts of nitroform which they suggested might in aqueous or aqueous organic solvents in accordance be an intermediate in their process. Schulteiss and Schim with the following equation: melschmidt (PB 47730, B.I.O.S. 709 adapted this process 65 to the production of nitroform by stopping the reaction at CENO24--NO-->CNO) --NO III) the nitroform stage and extracting the mixture with nitro In the presence of alkali, the nitrite anion is catalytic in gen dioxide at 0° C. Because of the extreme conditions its effect and is regenerated in accordance with the fol and complex equipment required, however, this process lowing equation: has never been effectively utilized for the production of 70 nitroform. NO--2OH-->NO --NO---HO IV Another method for producing nitroform and its salts In the presence of chemically equivalent quantities of 3,125,606 3. 6. hydroxide and nitrite ions, the rate of the reaction lead decomposition of the product to take place. A typical ing to the nitroform salt is many orders of magnitude reaction gives yields of 95 to 100% in 2% to 3% hours greater than the reaction leading to the formation of the at the preferred temperatures. Since the reduction is carbonate. The conversion of the tetranitromethane un not strongly exothermic, no difficulty is involved in tem der these conditions to the nitroform salt is, therefore, perature control. essentially quantitative with only negligible by-product The reaction of the invention goes equally well in formation of potassium carbonate. The reaction proceeds dilute or concentrated solutions but high concentrations rapidly in good yields so as to minimize the effects of are preferred in order to make maximum use of available undesirable side reactions. reactor capacity. For a typical preparation in a solvent The reaction of the invention proceeds in aqueous O consisting of 50% methanol and 50% water at 50 C. solvents but most rapidly in mixed aqueous organic Sol the optimum concentrations are 2% moles each of sodium vents in which the tetranitromethane is soluble. The re nitrite, sodium bicarbonate and tetranitromethane per action of the invention for example gives equally good liter of solvent. Two factors determine the upper limit yields in aqueous and in aqueous methanolic solutions of the concentrations which can be used. These are 1 but since the solubility of tetranitromethane in Water is 5 the solubility of the inorganic reactants and 2 the limited the reaction proceeds more slowly in this medium. explosive nature of the intimate mixtures of tetranitro The incorporation of an organic solvent, such as methanol, methane with organic fuels at higher concentrations of enhances the rate of the reaction by increasing the Solu tetranitromethane. In the typical preparation described bility of the tetranitromethane. However, above an op above the tetranitromethane is initially not completely timum concentration of the organic solvent, e.g. 40 to 50 20 miscible with the remainder of the mixture and vigorous percent by volume of methanol, the inorganic reactants stirring is required. However, after from about 15 to become insoluble. Since the function of the organic about 45 minutes the reaction mixture coalesces to a solvent is merely to increase solubility, any solvent for single phase and the stirring may be discontinued. tetranitromethane which is also miscible with Water may The order of addition of the reactants to the reaction be employed. Aqueous solutions of methanol and diox 25 mixture is not important, however, if an alkaline salt is ane have been employed in the reaction of the invention employed in conjunction with the nitrous acid salt the with equally good results.

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