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|Title:||Reactivity of aromatic compounds in detritiation.|
|Authors:||Bancroft, Keith Charles Colbery.|
|Presented at:||University of Leicester|
|Abstract:||The literature on the mechanism of electrophilic aromatic hydrogen- exchange reactions is reviewed. A number of mono-tritiated polynuclear aromatic hydrocarbons and substituted benzenes have been prepared and their rates of detritiation in anhydrous trifluoroacetic acid have been measured. The deactivating effect of the halogens on the meta position has been determined in the [2-3H]-4-halogenoanisoles and (2-3H]-4-halogeno-toluenes; some interaction between the methoxy group and the medium being noted for the former series. Concurrent de-iodination accompanying the detritiation of [2-3H]-4-iodoanisole has been observed. Partial rate factors in detritiation have been determined for the 2-, and 3- positions in toluene and in diphenylmethane; the 1-, 3-, and 4- positions in fluorene; the 1-, 2-, 3-, and 4- positions in phenanthrene; the 2-position in 9,10-dihydrophenanthrene; and the 9-position in anthracene. These results are compared with other aromatic substitutions, such as halogenation and nitration; and with calculated reactivity data: some inconsistencies have been noted. A preliminary study has been made of the rate of detritiation of o- and p- tritiatedw-phenyl-n-alkyltrimethylsilanes, Ph(CH2)nSiMe3 (where n = 1 to 4). Because of various side reactions it proved possible to measure the rate of detritiation of only the two n = 4 compounds by the normal technique. A modified technique made possible measurements on the tritiated benzyltrimethylsilane. The rates of detritiation and de-t-butylation of [3-3H]-t-butylbenzene in trifluoroacetic acid - aqueous perchloric acid at 25° have been measured. The effect of the de-alkylation reaction on the rate of detritiation has been considered.|
|Rights:||Copyright © the author. All rights reserved.|
|Appears in Collections:||Theses, Dept. of Chemistry|
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