Hydrazides from ureas

Allophanyl hydrazide has been prepared previously as the hydrochloride by the zinc-hydrochloric acid reduction of 1-nitrobiuret.1 The new procedure2,3 outlined here entails the hydrazinolysis of allophanic esters in alcoholic solution. Excellent yields (80 to 84%) of allophanyl hydrazide are obtainable with a minimum of difficulty using readily available starting materials. The methyl and ethyl allophanates are prepared from urea and the corresponding chlorocarbonic esters.4... 

Anthranilic acid hydrazides (104), prepared from lA and hydrazines,are used as precursors for quinazolines, benzotriazinones, and benzotriazepines. Cyclization of 104 with formic acid gives 3-amino-quinazolone (105) 3-aminoquinazolinedione (106) is obtained from urea and the unsubstituted hydrazide 104(R = = H), while ring closure... 

Maleic hydrazide (149), produced on a large scale as a herbicide, can be obtained, according to a patent, from a simple diaziridine, which on an industrial scale could be less expensive than hydrazine hydrate. In the proposed manufacture of diamide (150) from a diaziridine and urea it must be taken into account that the reaction of urea is preceded by solvolytic hydrazine formation, which probably proceeds under the reported conditions (several hours, 70-80 °C, acidic media) (79AHC(24)63). 

A mixture of 13.6 gm (0.1 mole) of isonicotinic acid hydrazide, 16.6 gm (0.28 mole) of urea, and 40 ml of water is refluxed for 8 hr while ammonia is being evolved. The solid product which separates on cooling is dissolved in 10% sodium hydroxide solution, treated with charcoal, filtered, and acidified with 10% hydrochloric acid to pH 6.0. The white crystalline product that separates is purified by recrystallization from water to afford 17.0 gm (94%) of colorless shining needles, m.p. 244°C dec. ([30] m.p. 243°C dec.). 

The azide 465, obtained from the hydrazide 462 with sodium nitrite in 50% acetic acid, afforded the carbamates 466 in refluxing alcohol. The presence of traces of water resulted in the formation of the urea 467 as by-product. 

Reaction of aromatic or heterocyclic amines with formaldehyde and urea or phenylthioureas gave 2-(oxo)thioxohexahydro-l,3,5-triazines 90. Regioselective cyclization and isomerization of propargylthio-l,2,4-triazinones were achieved to give the fused heterocycles 91-93. Cyclization of isatin 3-thiosemicarbazones gave 94 which can be alkylated to 95 . The imidazotriazepines 96 were obtained from heating a mixture of hydrazide and ortho-ester. 

Carbonyl azides are usually obtained from the hydrazides, although in principle they can also be prepared directly from the carbonyl chlorides and sodium azide. They are frequently used as intermediates for synthesis of isocyanates, urethanes, ureas, amines, etc., and are often used in such work without isolation. 

This compound, however, was unavailable, since sufficient quantities ofhippuryl urea, which Curtius had formerly prepared from hippuric ester and urea, could not be obtained from hippurazide and urea. They therefore attempted to make the azide of benzoylcarbamic acid by the action of hydrazine on benzoylurea, but the only product which they obtained was the hydrazide of benzoic acid. The benzoic acid radical is therefore very easily eliminated from the urea molecule, the molecule of benzoylcarbamic acid hydrazide, being hydrolysed according to the equation... 

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