Studies in the synthesis of pure hydrocarbons

Abstract

Research into the synthesis of pure hydrocarbons received much stimulus during the war years, when the characteristics of as large a number of pure hydrocarbons as possible were needed. The present study formed part of a wide scheme for this purpose. During the work on synthesising hydrocarbons the author found that, inasmuch as the synthesis of pure hydrocarbons depended to a large extent on the Grignard reaction, it was necessary to try to obtain a better understanding of this reaction. This Thesis therefore serves two purposes. It describes the author's investigation of the abnormal reaction of Grignard reagents with carbonyl compounds, and it describes the synthesis of two hydrocarbons, 2:4: 6-trimethylheptane and 2:3:5-trimethylhexane, and the preparation of four others, believed to be new:3:4-dimethylnonane, 3:4-dimethyloctane, 2;4:5-trimethylheptane, 2:6-dimethyl-4-isobutylheptaneThe investigation of the Grignard reaction occupies the larger part of the thesis, and is devoted to a survey on some of the past work on abnormal Grignard reactions, to a discussion of the mechanisms of abnormal reactions, and the application of the author's results to these mechanisms. The author's results lead him to refute the "alcoholate" and "addition" mechanisms, and to postulate that all Grignard reagents can dissociate homolytically and heterolytically, the extent to which any Grignard reagent does so depending on the nature of the Grignard reagent and the nature of the second reactant. The author concludes that, for this reason, the mechanism of reduction of carbonyl compounds by Grignard reagents is one of free radicals, whereas that of enolisation and condensation is ionic.