Guanidine nitrate preparation

It is conveniently prepared in the laboratory by the interaction of sulphanil-amide and guanidine (from guanidine nitrate and sodium methoxide solution) the resulting guanidine salt of sulphanilamlde decomposes upon heating at 150-160° into sulphaguanidine and ammonia ... 

It is strongly recommended that our procedure1 not be used to prepare guanidine nitrate. Mixtures of ammonium nitrate and organic materials not much different from the mixture in the procedure are now used extensively as commercial explosives. The aqueous mixture of Note 101 is similar to some aqueous mixtures used in sizable quantities for rock blasting a confined mixture of this sort is especially hazardous. Only a few laboratories devoted to explosives research have the barricades and remote control devices needed to run this preparation of guanidine nitrate without risk. 

Jousselin [26] prepared nitroguanidine by the action of anhydrous nitric acid or sulphuric acid on guanidine nitrate. The preparation of this substance by the action of sulphuric acid has been developed as an industrial method for the production of nitroguanidine. The method described by Marqueyrol and Loriette [27] follows somewhat different principles. It consists in acting with anhydrous nitric acid on guanidine sulphate which, in turn, is obtained on treating dicyandiamide with sulphuric acid. 

Bourjol [59] reviewed various methods of preparing nitroguanidine from guanidine nitrate and sulphuric acid, and also carried out extensive experiments to find the most convenient laboratory method of carrying out the reaction. 

Nitroguanidine may be prepared by the nitration of guanidine salts by means of nitric acid,1 or by the action of concentrated sulfuric acid upon guanidine nitrate.2 The nitration of guanidine thiocyanate yields a product which retains a small proportion of sulfur compounds, and Lhe nitration of the sulfate requires vigorous treatment and gives poor yields. The present procedure, which yields the alpha form,3 is simple and economical, and furnishes a good yield. 

Picard V.I.Siele, "Mechanism of Formation of White Calcium Cyanamide by the Picatinny Process , PATR 2405 (1957) (Conf) 16)J.P. Picard et al, "Laboratory Pilot Plant Investigation of Picatinny Process for Producing White Calcium Cyanamide , PATR 2452 (1957) (Conf) 17)V.I.Siele et al, "Suitability of White Calcium Cyanamide for the Preparation of Guanidine Nitrate , PATR 2455 (1957) (Conf) 18)M.Blais J.P.Picard, "Effect of Various Physical Properties of Lime on the Purity of White Calcium Cyanmide Made by the Picatinny Process , PATR 2457 (1857) (Conf) 19)S. 

Guanidine nitrate is of interest to us both as an explosive itself and a component of explosive mixtures, and as an intermediate in the preparation of nitroguanidine. All other salts of guanidine require strong mixed acid to convert them to nitroguanidine, but the nitrate is converted by dissolving it in concentrated sulfuric acid and pouring the solution into water. 

On hydrolysis with dilute sulfuric acid it yields urea. On treatment with ammonium sulfide it prefers to react with the hydrogen sulfide part of the molecule to form thiourea, not with the ammonia part to form guanidine, and the reaction is the commercial source of many tons of thiourea for the rubber industry. On evaporation for crystals, the solution yields dicyandiamide which constitutes a convenient source for the preparation of guanidine nitrate. 

Preparation of a-Nitroguanidine. Five hundred cc. of concentrated sulfuric acid in a 1-liter beaker is cooled by immersing the beaker in cracked ice, and 400 grams of well-dried guanidine nitrate is added in small portions at a time, while the mixture is stirred with a thermometer and the temperature is not allowed to rise above 10°. The guanidine nitrate dissolves rapidly, with very little production of heat, to form a milky solution. As soon as all crystals have disappeared, the milky liquid is poured into 3 liters of cracked ice and water, and the mixture is allowed to stand with chilling until precipitation and crystallization are complete. The product is collected on a filter, rinsed with water for the removal of sulfuric acid, dissolved in boiling water... 

Although guanidine thiocyanate is readily prepared by this method, it is extremely deliquescent and cannot be obtained in so pure a state as guanidine nitrate. 

Cyanamide is also acted upon directly by ammonium salts in aqueous and non-aqueous solutions.17-20 Since it is of decided advantage to avoid the isolation of pure cyanamide, methods have been developed in which aqueous solutions of cyanamide are prepared from calcium cyanamide and are then permitted to react with ammonium salts. However, guanidine nitrate may also be prepared directly from commercial calcium cyanamide by the action of ammonium nitrate. This reaction takes place readily in the fused state, in concentrated aqueous solution,21 or by direct admixture of solid ammonium nitrate with calcium cyanamide and subsequent heating to 100°C.22 The latter procedure is to be preferred, since better yields are obtainable and the hazard of fusion with ammonium nitrate is obviated. The directions given for procedure B require the use of a fairly good grade of unoiled calcium cyanamide containing approximately 65 per cent CaNCN. 

Guanidine nitrate is soluble in alcohol and water. It is the precursor compound in the synthesis of - Nitroguanidine. It is prepared by fusing dicyanodiamide with ammonium nitrate. 

Guanidine picrate is sparingly soluble in water and alcohol. It is prepared by mixing solutions of guanidine nitrate and ammonium picrate. 

Guanidine nitrate, which has been prepared from dicyanodiamide and ammonium nitrate, is dehydrated under formation of nitroguanidine, when treated with concentrated sulfuric acid. Nitroguanidine can be incorporated into nitrocellulose powder, nitroglycerine powder, or diglycol dinitrate powder it is not dissolved in the powder gel, but is embedded in it as a fine dispersion. These cold (calorie-poor) powders erode gunbarrels to a much lesser extent than do the conventional hot powders. 

Nitroguanidine, 17, is another aliphatic nitramine that is used as a major constituent in triple-base propellants. It exists in two crystalline forms, the a- and 3-forms. The a -form of nitroguanidine, 17, can be prepared by reacting guanidine nitrate in concentrated sulfuric acid followed by the addition of an excess of water from which guanidine nitrate, 19, is crystallized (Eqs. 12.11 and 12.12) [4]. 

The preparation of guanidine nitrate from dicyandiamide by the action of aqua regia has been patented, but tlie rcacUon evidently depends solely upon the hydrolysis of the cyan group and does not require the use of a vigorous oxidizing agent Marqueyrol and Loriette in a French patent of September 26,... 

Guanidine thiocyanate, prepared by passing ammonia into molten ammonium thiocyanate, is converted into the sulfate. The latter can be converted to the nitrate by the action of calcium nitrate. Gluud, Keller and Schultze, Ber. ges. Kohlentech. 4, 21 (1931) [C. A. 26, 2017 (1932)]. 

A methanolic soln. of O-methylisourea added to an aq. soln. of orni-thine-Cu-nitrate, prepared from ornithine nitrate and CuCOs, allowed to stand at room temp, for 2 days, acidified with H2S04. Cu removed with H2S, and isolated as flavianate —arginine flavianate. Y 94.5%. (F. Turba and K. Schuster, H. 283, 27 (1948) guanidines from isoureas s. a. V. M. Rodionov and 0. S. Urbanskaya, >K. 18, 2028... 

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