Synthesis and reactions of flavazoles

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Synthesis and reactions of flavazoles

Show simple item record Ramabhadran,P Dr.Madhavan Pillai, P 2014-03-24T05:49:41Z 2014-03-24T05:49:41Z 1984-07
dc.description Department of Applied Chemistry, Cochin University of Science and Technology en_US
dc.description.abstract The study deals with the production of l-phenylflavazoles with chloro, amino, hydroxy, chloromethyl, carboxamido, trichloromethyl, N-pyrrolidyl and N-pyrrolidylmethyl groups substituted at position 3. The interconversions of 3-amino, 3-hydroxy and 3-chlorol- phenylflavazoles were also investigated. Further, an unusual phenylation reaction was found to take place if stored or air-oxidised phenylhydrazine was used as the condensing agent for the formation of flavazoles from quinoxaline-2-carboxaldehyde phenylhydrazones. By this phenylation reaction 1,3-diphenyl, l-p-tolyl-3-phenyl, l-p-chlorophenyl-3-phenyl, l-p-bromophenyl- 3-phenyl and l-phenyl-3-p-tolylflavazoles were prepared. In addition to establishing the structure of the phenylation products, the reaction was shown to take place by a free radical mechanism involving phenyl radicals formed from oxidised phenylhydrazine. Also the oxidation, reduction and bromination reactions of l-phenylflavazole were investigated. The product obtained when a mixture of l-phenylflavazole and sodium borohydride in isopropanol was heated under reflux was shown to be 2-anilinoquinoxaline-3-carboxamide which when refluxed with concentrated hydrochloric acid gave the known 2-anilinoquinoxaline. New procedures were worked out for the oxidative cyclisation reactions of quinoxaline-2carboxaldehyde phenylhydrazones to l-phenylflavazoles in excellent yields using azobenzene as a dehydrogenating agent. These cyclisations were also shown to take place, though in low Yield, if the quinoxaline2- carboxaldehyde phenylhydrazones were heated above their melting points in an atmosphere containing oxygen. en_US
dc.description.sponsorship Cochin University of Science and Technology en_US
dc.language.iso en en_US
dc.publisher Cochin University of Science and Technology en_US
dc.subject Flavazoles en_US
dc.subject Ascorbic acid en_US
dc.subject Phenylation reactions en_US
dc.subject Ultraviolet adsorptions en_US
dc.title Synthesis and reactions of flavazoles en_US
dc.type Thesis en_US

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