Acid hydrazide

Acid hjdrazides from esters. Meth and ethyl esters react with hydrazine to give acid hydrazides ... 

Place 1 0 ml. of hydrazine hydrate (CAUTION corrosive chemical) in a test-tube fitted with a short refiux condenser. Add 10 g. of the methyl or ethyl ester dropwise (or portionwise) and heat the mixture gently under refiux for 15 minutes. Then add just enough absolute ethanol through the condenser to produce a clear solution, refiux for a further 2-3 hours, distil oflF the ethyl alcohol, and cool. Filter oflF the crystals of the acid hydrazide, and recrystallise from ethanol, dilute ethanol or from water. 

Thiazole carboxylic acid hydrazides were prepared in a similar way (444, 445). Thus by refluxing thioacetamide or thiobenzamide with y-bromoaceto acetic ester arylhydrazones (83) for several hours in alcohol the 4-carboxythiazole derivatives (84) listed in Table II-ll were obtained (Scheme 36) (656). This reaction is presumed to proceed via dehydration of the intermediate, thiazoline-S-oxide. 

Thiazolecarboxylic acid hydrazides are prepared by the same general methods used to prepare amides, that is, by treating acids, esters, amides, anhydrides, or acid halides with hydrazine or substitued hydrazines. For example, see Scheme 21 (92). The dihydrazides are obtained in the same way (88). With diethyl 2-chloro-4,5-thiazoledicarboxylate this reaction gives the mono hydr azide monoester of 2-hydrazine-4,5-... 

TABLE IV-4, THIAZOLECARBOXAMIDES AND THIAZOI.ErARBOXYUC ACID HYDRAZIDES... 

Hydrazides and Related Compounds. Substitutioa of the hydroxyl group ia carboxyhc acids with a hydraziao moiety gives carboxyhc acid hydrazides. la this formal sease, a number of related compouads faU within this product class although they are aot aecessatily prepared this way. Table 5 lists some of the more common of these compouads (82). 

Sulfonic acid hydrazides, RSO2NHNH2, are prepared by the reaction of hydraziae and sulfonyl haUdes, generally the chloride RSO2CI. Some of these have commercial appHcations as blowiag agents. As is typical of hydrazides generally, these compounds react with nitrous acid to form azides (26), which decompose thermally to the very reactive, electron-deficient nitrenes (27). The chemistry of sulfonic acid hydrazides and their azides has been reviewed (87). 

All the sulfonic acid hydrazides are made from hydrazine or semicarbazide and the appropriate sulfonyl chloride in the presence of an HCl acceptor such as ammonia. 

The reactions of amides fall into hydrolysis, dehydration and degradation (to amines) acid hydrazides and acid azides undergo additional reactions. 

Claisen ester condensation, 6, 279 Thiazolecarboxylic acid chlorides reactions, 6, 279-280 Thiazolecarboxylic acid hydrazides synthesis, 6, 280 Thiazolecarboxylic acids acidity, 6, 279 decarboxylation, 6, 279 reactions, S, 92 6, 274 Thiazole-2-carboxylic acids decarboxylation, S, 92 Thiazole-4-carboxylic acids stability, S, 92 Thiazole-5-carboxylic acids decarboxylation, S, 92 Thiazole-4,5-dicarboxylic acid, 2-amino-diethyl ester reduction, 6, 279 Thiazole-4,5-dicarboxylic acids diethyl ester saponification, 6, 279 Thiazolediones diazo coupling, 5, 59 Thiazoles, 6, 235-331 ab initio calculations, 6, 236 acidity, S, 49 acylation, 6, 256 alkylation, S, 58, 73 6, 253, 256 analytical uses, 6, 328 antifogging agents... 

Degradation of acid hydrazides or acyl azides to amine or amine derivatives. 

Amides are stable compounds. The lower-melting members (such as acetamide) can be readily purified by fractional distillation. Most amides are solids which have low solubilities in water. They can be recrystallised from large quantities of water, ethanol, ethanol/ether, aqueous ethanol, chloroform/toluene, chloroform or acetic acid. The likely impurities are the parent acids or the alkyl esters from which they have been made. The former can be removed by thorough washing with aqueous ammonia followed by recrystallisation, whereas elimination of the latter is by trituration or recrystallisation from an organic solvent. Amides can be freed from solvent or water by drying below their melting points. These purifications can also be used for sulfonamides and acid hydrazides. 

Cyanoacetic acid hydrazide [140-87-4] M 99.1, m 114.5-115°. Crystd from EtOH. 

Dipping solution Dissolve 1 g isonicotinic acid hydrazide (4-pyridinecarboxylic acid hydrazide, isoniazide) in 100 ml ethanol and add 500 gl trifluoroacetic acid [1] or 1 ml glacial acetic acid. 

Spray solution Dissolve 0.8 g isonicotinic acid hydrazide in 200 ml methanol and add 1 ml hydrochloric acid (25%) [6] or glacial acetic acid [2]. 

Isonicotinic acid hydrazide forms fluorescent hydrazones with ketosteroids. 

In conditions of base catalysis, the acetylenylpyrazolecarboxylic acid hydrazides, as opposed to benzene derivatives, are more difficult to cyclize compared with the benzoic acid derivatives and are isomerized only after heating in alcohol in the presence of KOH, forming not five- but six-membered lactams. The yields of pyri-dopyrazoles were 80-90% (Scheme 133 Table XXVIII) (85IZV1367 85MI2). 

TABLE XXIX. l-Methyl-l,6-dihydropyrazolo[3,4-(i]pyridazm-7-ones Prepared by Cyclization of 4-(Alkyn-1 -yl)pyrazole-5-carboxylic Acid Hydrazides [85IZV1367 85MI2]. 

The 3-oxidotriazolopyridinium zwitterions 245 fail to react with DMAD unless magnesium bromide is present, when ring opening occurs (2000H(53 265) (Section IV.F). The thiol 268 adds methyl acrylate as expected the resulting ester is converted via the acid hydrazide, to an oxadiazole (89IJC(B)170). 

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