Since this thesis is concerned mainly with a study of optical activity of diphenyl derivatives, the various methods of preparation of diphenyl derivatives are given in the General Introduction. The thesis is divided into two parts: Part I is concerned mainly with the reactions of certain benzidine bases with ketones and Part II, the major portion, with diphenyl derivatives of interest from the point of view of optical activity. In this summary, pages to which cross reference has been given contain the main conclusions of this thesis. Part I is subdivided into three sections: the Introduction, the Theoretical Section and the Experimental Section. The Introduction gives an account of previous relevant work, experimental and theoretical, and furnishes a background to the actual work undertaken. The latter, together with certain theoretical aspects, is discussed in the Theoretical Section. Part I was undertaken in order to provide further information on a subject briefly referred to by Reddelien (page 27 ) namely, the reactions of aromatic ketones with benzidine bases. At the same time, it was intended to gain some information on the prospects of optical resolution of appropriately substituted benzidine derivatives by means of the formation of diastereoisomeric anils with optically active ketones. Benzidine condensed with acetophenone and benzophenone to form the corresponding di-anils, o-tolidine reacted similarly with acetophenone but not with benzophenone, and o-dianisidine did not react with either acetophenone or benzophenone. These observations are discussed (page 39) from a theoretical stand point with reference to the effects of ortho methyl and meth-oxyl groups on analogous anil condensations of benzenoid amines. Benzoin reacted with benzidine, o-tolidine and o-dianisidine to form didesyl-derivatives, which in contrast to the di-anils, were extremely resistant to hydrolysis. In addition to the action of nitrosyl chloride on benzidine, the anil condensations of certain other benzidine derivatives were also studied. Ketone anil formation was found to be unsuited for the optical resolution of benzidine derivatives because of the high reaction temperatures and the relative insolubility of the products while the difficulty of hydrolysis of didesyl derivatives precluded the use of optically active benzoin for the same purpose. Part II is concerned with the preparation of diphenyl derivatives of stereochemical interest; three new dibromodi-methylbenzidines were the subject of optical resolution experiments. This part is sub-divided into four sections; the Historical Section, the Introduction, the Theoretical Section and the Experimental Section. The Historical Section, which does not contain any original work performed by the author, consists of a fairly extensive historical review of the stereochemistry of diphenyl derivatives. The Introduction, which likewise does not contain any of the author's experimental work completes the presentation of the facts and theories leading to the original research. The Introduction also deals with general methods of preparation of compounds analagous to those dealt with in the original work which follows in the Theoretical and Experimental Sections. The original work and its theoretical significance are | discussed in the Theoretical Section. In this Section also, mention is made of certain improvements in existing methods of preparation of previously known compounds. (Abstract shortened by ProQuest.)