Unexpected products from the reaction of different compounds with hydrazine hydrate or aryl thiosemicarbazides

• Published in: Journal of Saudi Chemical Society Vol. 20; no. 5; pp. 547 - 552
• Main Authors: Chaaban, Ibrahim, El Khawass, El Sayeda M., Mahran, Mona A., Abd El Razik, Heba A., El Salamouni, Nehad S.
• Format: Journal Article
• Language: English
• Published: Riyadh, Saudi Arabia Elsevier B.V 01.09.2016; Saudi Chemical Society; Elsevier
• Subjects: 1-(1,4-Dihydroxynaphthalen-2-yl)ethanone; 2,5-Dihydroxyacetophenone; 2-(2,5-Dimethoxybenzylidene)propanedioate; Ethyl 2-cyano-3-(2,5-dimethoxyphenyl)propenoate; Unexpected products; Ethyl 2-cyano-3-(2,5-dimethoxyphenyl)propenoate; 1-(1,4-Dihydroxynaphthalen-2-yl)ethanone; 2,5-Dihydroxyacetophenone; 2-(2,5-Dimethoxybenzylidene)propanedioate; Unexpected products
• ISSN: 1319-6103
• DOI: 10.1016/j.jscs.2012.08.007

The reaction of 2,5-dihydroxyacetophenone I or 1-(1,4-dihydroxynaphthalen-2-yl)ethanone II with various 4-aryl thiosemicarbazides did not yield the expected 4-aryl-1-[1-(2,5-dihydroxyphenyl)ethylidene]thiosemicarbazides III nor 4-aryl-1-[1-(1,4-dihydroxy-naphthalen-2-yl)ethylidene]thiosemicarbazides IV, respectively. However, unexpected products were formed namely, N1,N2-bis[1-(2,5-dihydroxyphenyl)ethylidene]hydrazine V or N1,N2-bis[1-(1,4-dihydroxynaphthalen-2-yl)ethylidene]hydrazine VI, respectively. Also, an unexpected product N1,N2-bis(2,5-dimethoxybenzylidene)hydrazine XI was obtained when heating under reflux diethyl 2-(2,5-dimethoxybenzylidene)propanedioate VII or ethyl 2-cyano-3-(2,5-dimethoxyphenyl)propenoate VIII with 99% hydrazine hydrate in ethanol. The mechanisms of these reactions were proposed.