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Title: A study of bromocortisol acetate and other organic molecules by X-ray crystal analysis
Author: Miller, R. A. L.
Awarding Body: University of Glasgow
Current Institution: University of Glasgow
Date of Award: 1968
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X-ray studies have been carried out on organic crystals which contain heavy atoms. Three structures have been successfully solved; the adduct of triphenylarsine and acetylene dicarboxylic methyl ester; the heterocyclic compound 2-(2-hydroxyethylamino)-2-thiazoline formed on reaction of 2-methylthio-2-oxazoline with 2-mercaptoethylamine; and the 9-alpha-bromo derivative of cortisol acetate. In order to obtain molecular dimensions and overall shape for the molecule, an x-ray analysis of the 9-alpha-bromo derivative of cortisol acetate was undertaken. The total structure was evident after examination of the fourth electron density map. Refinement produced a final discrepancy, R, of 13.2% and showed that the expected distortion of the molecule due to the bromine atom, had not occurred. Elucidation of the structure of the triphenylarsine adduct resulted from straightforward application of the heavy atom technique and the complete structure was assigned with certainty after the fourth three-dimensional Fourier synthesis. Subsequent refinement by Fourier and least squares methods reduced the discrepancy, R, to 14.3% The structure was found to be other than that first predicted by considering the corresponding reaction of triphenylphosphine. Two possible resonance forms have been proposed for the adduct and are supported by the results of this analysis. In the reaction of 2-methylthio-2-oxazolines and 2-mercapto-ethylamine, products with unusual properties were isolated. One such product was predicted to be a spiro compound and corroboration of this was sought from x-ray analysis of the crystal. The normal heavy atom technique failed to give a solution to the structure and the Patterson superposition method was applied. The structure was solved in this way and was refined to a discrepancy, R, of 12.1%. The structure was found to contain only one heterocyclic ring and not two as required by the proposed spiro compound. Molecular dimensions for the three structures are in favourable agreement with the expected values and with values gained from other crystal structure analyses. The various classes of bond lengths and angles have been discussed in some detail in later sections.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available