5- Methyl-3-isoxazole carboxylic acid hydrazide

Eqn. (a) shows the interaction between benzaldehyde and 5-methyl-3-isoxazole carboxylic acid hydrazide in the presence of ethanol at 4°C to 3neld l-benzylidene-2 (5-methyl-3-isoxazolylcarbonyl) hydrazine (I) with the elimination of one mole of water as indicated above. 

Chemicals Required. Benzaldehyde 80 g Ethanol [95% (v/v)] 750 ml 5-Methyl-3-isoxazole-carboxylic acid hydrazide 72 g l-Benzylidene-2-(5-methyl-3-isoxazolylcarbonyl) hydrazine 11.5 g Anhydrous Solvent Ether 500 ml Pure LiAlH 1.85 g Ethyl acetate 25 ml Benzene 20 ml Methanol q.s. 

Isocarboxazid Isocarboxazid, 2-benzylhydrazid-5-methyl-3-isoxazolecarboxylate (7.2.6), can be synthesized from acetylacetone, which on nitrosation with nitrous acid gives 5-methyl-isoxazol-3-carboxyhc acid (7.2.2). Esterification of this product gives the ethyl ester of 5-methyl-isoxazol-3-carboxyhc acid (7.2.3). The synthesized ester (7.2.3) is further reacted with benzylhydrazine, to give isocarboxazide (7.2.6), or with hydrazine, which forms 5-methyl-isoxazol-3-carboxylic acid hydrazide (7.2.4). Reacting the latter with benzaldehyde gives hydrazone (7.2.5), which is further reduced to the isocarboxazide (7.2.6) [46,47]. 

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