Preparation from Carbohydrazide

Preparation from Carbohydrazide. One hundred seventeen grams of carbohydrazide (1.3 mols) and 108 ml. of 12 M hydrochloric acid (1.3 mols) are mixed in a 400-ml. beaker equipped with a mechanical stirrer and a 360° thermometer. The mixture is heated slowly on a hot plate with constant stirring. At first, there is vigorous effervescence, which may cause spattering, but this gradually subsides as evaporation continues. The temperature rises to about 215° and remains there for approximately an hour. Heating is stopped when the temperature rises above 220°. The over-all time of reaction is 4 hours. To the cooled melt, 125 ml. of water is added, and the mixture is heated to effect solution of soluble by-products (principally hydrazine hydrochloride). After the solution has cooled to room temperature, the urazine is filtered and washed with water, ethanol, and ether. The yield of dry product is 55 g. (73%)- The product melts with decomposition at 271 to 272°. 

1200 ml. of 0.1 M hydrochloric acid at 95°, filtering, and cooling to room temperature with constant stirring. The urazine crystallizes in the form of large, brilliant, white crystals it is filtered and washed with water, ethanol, and ether. The product weighs about 44 g. (80% yield based on the crude product) and melts wdth decomposition at 275°. 

Twenty-six and six-tenths grams of carbohydrazide-lV-carboxamide (0.2 mol) and 16.7 ml. of 12 M hydrochloric acid (0.2 mol) are heated together in a 200-ml. beaker until the temperature of the mixture rises to 210°. This usually requires between 60 and 90 minutes. The melt is then cooled and treated with 35 ml. of water. The suspension is heated briefly to effect complete solution and is then cooled to room temperature. The crystalline urazine is filtered and washed with water, ethanol, and ether. The product weighs about 11.5 g. (50% yield) and melts with decomposition at 270 to 272°. Purification is effected by recrystallization from 0.1 M hydrochloric acid, as described above. 

Urazine melts with decomposition at 276°, but it is quite stable over long periods of time at 110°. It is soluble in water to the extent of 0.32 g./lOO g. at 0° and 4.02 g./lOO g. at 65°. It is difficultly soluble in alcohol and completely insoluble in boiling acetic acid and in ether. 

Urazine reduces ammoniacal silver nitrate but does not reduce Fehling solution. When shaken with benzaldehyde, it reacts readily to form 4-benzalaminourazole, CeHsCH-C2H2N402, which melts at 253°. 

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The derivatization of DCCH to a carboxylic acid required conversion of the acid to acid chloride using thionyl chloride before reaction with the carbohydrazide group. To evaluate the chemiluminescent characteristics of this coumarin compound, the amide derivative of DCCH was isolated by preparative TLC. Although CL was observed from this product, detection limits were not determined because of the difficulty in quantitative transfer from TLC plates. 

Pellizzari and Roncagliolo2 prepared this compound by reaction of carbohydrazide in dilute acetic acid with 2 mols of potassium cyanate and also by condensation of carbohydrazide- A-carboxamide hydrochloride with 1 mol of cyanate. The former procedure does not give a pure product, probably because of the preferential formation of the less soluble carbohydrazide-A-carboxamide. The latter reacts wjth hydrochloric acid to form the hydrochloride, which is water-soluble. Prior condensation of carbohydrazide to form the A-carboxamide is advantageous, since the hydrochloride of this compound will undergo further reaction with cyanate to give the desired product by precipitation from water. When the procedure outlined below is followed, it is not necessary to recrystallize the carbohydrazide-A, A -dicarboxamide unless an extremely pure material is desired. 

The Curtius reaction of l,2,5-thiadiazole-3-carbohydrazide (79) proceeded normally and in high yield to the ethyl urethane (80, R = Et). The ethyl urethane, however, resisted acid hydrolysis and was extensively decomposed by base. The benzyl urethane (80, R = CH2Ph), on the other hand, was smoothly hydrolyzed to the amine with aqueous acid. Attempts to prepare 1,2,5-thiadiazole-3,4-dicarboxazide from the dihydrazide resulted in an unstable product which exploded violently. ... 

A similar method was applied when preparing exclusively the [5,1-/)]-isomer from 2-hydrazino-l-methylpurinone. A useful access involved the treatment of nitrous acid and 4-amino-2-hydrazinopyrimidine-5-carbohydrazide (315) giving 5-amino-6-azidocarbonyltetrazolo[l,5-u]pyrimidine 316. Subsequent heating and cyclization converted it to the corresponding isocyanate 317 and tetrazolo[5, l-a]purin-7-one 318, respectively (86H1899) (Scheme 92). 

Apart from the above applications, hydrazine hydrate is also used in preparing organic derivatives, like hydrazones and hydrazides such as carbohydrazide (CH), oxalyl dihydrazide (ODH), malonic acid dihydra-zide (MDH), tetra formal tris azine (TFTA) and so on, from the corresponding ketones and aldehydes. Hydrazones have been investigated as solid fuels in hybrid rockets [40]. The hydrazides have been exploited as combustible fuels with metal nitrate oxidizers in the preparation of nanocrystalline oxide materials [41]. 

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