Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.661828
Title: Studies in steric hindrance, with special reference to the aromatic iodo-chlorides
Author: Shedden, Thomas
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1936
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Abstract:
An examination of the formation of the aromatic iodo- chlorides has been carried out. Difficulty was experienced in the isolation of the dichlorides of certain diortho -substituted iodo -compounds. Further, quantitative experiments have shown that this difficulty is due, in some cases, to the instability of the dichloride and to the appearance of side reactions. Therefore the quantitative results cannot be taken as being fundamental until experiments have been carried out taking all these factors into consideration. The quantitative results have shown, however, that no ¿eneral hindrance to the reaction has been encountered. From scale diagrams of diortho-substituted iodobenzene molecules this is to be expected. Only in two cases - with the compounds 4.6- dibromo -2- nitro -iodobenzene and 4- iodo -3 :5- dinitrotoluene - has an appreciable retardation of the reaction occurred. It is not certain whether this is due solely to steric causes. No difference in reactivity of substituted a- and i3- iodonaphthalenes has been observed. The dichlorides of ¡3- iodonaphthalenes have proved to be very unstable. It was shown, in the case of 1;6- dibromo- t3- iodonaphthalene, that decomposition is accompanied by nuclear chlorination. One new iodine derivative in the benzene series and two in the naphthalene series have been isolated. Several hitherto unknown dichlorides have been described. In the course of a brief examination it has been shown that, whereas a- substituted aceto -¡3- naphthalides are easily hydrolysed using alcoholid hydrochloric acid, 3- substituted aceto -a- naphthalides are resistant to this reagent. Finally, condensation experiments have been carried out with certain substituted thiobenzoic acids. The method adopted for the preparation of the unknown o- chloro- and o- bromo- thiobenzoic acids is suggested as a general method for the preparation of mono - substituted" thio- acids. More vigorous methods were found necessary for the preparation of the new 2:4:6 - tribromo- thiobenzoic acid. In the course of this part of the research two new substituted dibenzoyl disulphides and several new substituted benzanilides were isolated. New lines for future research have been suggested.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.661828  DOI: Not available
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