Reactions of The Thiosemicarbazones

Burns, Robert (1925) Reactions of The Thiosemicarbazones. PhD thesis, University of Glasgow.

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The investigation described in the following pages forms one portion of an extensive research programme being carried out in the Department of Organic Chemistry of The Royal Technical College. The work is under the general supervision of Professor Forsyth J. Wilson and includes the reactions of the semicarbazones and semioxamazones as well as those of the thiosemicarbazones. Neuberg and Neimann (Ber. 1902, 35, 2049) have shown that the thiosemicarbazones C:N.NH.CS.NH2, possess the property of forming metallic derivatives, one of the hydrogen atoms being replaced by an equivalent of silver, copper, or mercury. The present investigation was undertaken to determine if, by the action of halogenated compounds, the hydrogen atom replaceable by metal could be replaced by alkyl or other substituents. The known metallic derivatives were found to be unsuitable for this work and the sodium derivative of acetone thiosemicarbazone was the starting material chiefly employed. The reactions of the sodium derivative with ethyl bromide, propyl bromide, n-butyl bromide, benzyl chloride and allyl iodide were investigated, with the result that a new series of S-alkylated thiosemicarbazones has been obtained. The products of hydrolysis of these S-alkylated compounds have also been examined. An attempt was made to prepare an optically active thiosemicarbazone by the action of 1-menthyl chloroacetate on the sodium derivative but the product obtained proved to be a thiohydantoin derivative of a new type; a ring closure having been effected. This rather interesting result led to the investigation of the action of the sodium derivative on the esters of halogenated acids. In the case of the esters of chloroacetic acid, ethyl α-bromopropionate, ethyl α-bromo-n-butyrate, and ethyl bromophenylacetate the products of the reaction were found to be derivatives of 2. 4 diketotetra-hydrothiazoles of the type The products of hydrolysis of these cyclic compounds were also examined. The esters of β-halogenated acids do not yield a six membered ring but were found to lose hydrogen halide with formation of the esters of the corresponding unsaturated acid. The cases investigated were those of ethyl β-bromo-n-butyrate and ethyl β-bromo-β-phenylpropionate with acetone sodio thiosemicarbazone. The action of the esters of y-halogenated acids was found to proceed as in the ease of those of the β-halogenated acids; ethyl y-chloro-n-butyrate, ethyl y-chlorvalerate, and ethyl y-chloroisocaproate yielding esters of unsaturated acids by loss of hydrogen halide. The reaction between ethyl ω-bromo-o-toluate, CH2Br which may be regarded as a y-halogenated acid ester, and acetone sodio thiosemicarbazone was found to proceed exactly as in the case of the alkyl halides; the structure of the product, as deduced from a study of the products of hydrolysis, being analogous. Another attempt to obtain an optically active thiosemicarbazone by the action of 1-dimethylchlorosuccinate on the sodium derivative gave a solid of low melting point which did not contain sulphur or nitrogen and was not, therefore, further investigated. Ethyl chlorocarbonate and phenyl chlorocarbonate have been found to react with the sodium derivative of acetone thiosemicarbazone in benzene suspension, with formation chiefly of the 1-carbethoxy or 1-carbophenoxy thiosemicarbazide R.OOC.NH.NH.CS NH2. Carbon dioxide is also formed, together with varying amounts of diethyl carbonate or diphenyl carbonate and the carboethoxy or carbophenoxy derivative of the thiosemicarbazone. The action of iodine on the sodium derivative of acetone thiosemicarbazone was tried but was found to give negative results; ethylene dibromide also failed to react. Preliminary work on the action of the amines on the thiosemicarbazones showed that aniline reacts with acetone thiosemicarbazone at 160 C. with vigorous evolution of ammonia and formation of a resinous product which could not be purified. Benzylamine reacts with acetone thiosemicarbazone at 140-145C , ammonia is evolved and a mixture of products formed, while with acetophenone thiosemicarbazone benzylamine reacts at a temperature of 130-135 C. with formation chiefly of the corresponding 4-benzyl thiosemiearbazone C:N.NH.CS. NHCH2.C6H5; a yield of 60% of the theoretical being obtained.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Organic chemistry
Date of Award: 1925
Depositing User: Enlighten Team
Unique ID: glathesis:1925-81036
Copyright: Copyright of this thesis is held by the author.
Last Modified: 31 Mar 2020 11:37

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