Abstract
The Walden Inversion is the only phenomenon connected with optically active compounds for which a possible explanation is not forthcoming on the theories of Pasteur, van't Hoff and Le Bel. Since sign of rotatory power and configuration do not go hand in hand, there are two aspects of this problem Before it is known whether a Walden inversion has occurred it is necessary to decide whether the product and the parent compound have the opposite configuration, and there is also the detection of the causes which bring about the inversion. From a consideration of the reactions of the p-toluene-sulphinic and p-toluenesulphonic esters of 1(-)-beta-octanol and 1(-)-phenylmethylcarbinol, it is shown in the present work that each of these laevorotatory alcohols has the same configuration as its laevorotatory halide. Further, these esters are shown to undergo definite inversion reactions which probably have a relatively simple mechanism. A study of the decomposition of the chloro-formates of these two alcohols has revealed that, whilst in the absence of tertiary bases laevorotatory chlorides are produced, in the presence of these bases, dextrorotatory chlorides arise. In other words, the decompositions are not attended by inversion unless a tertiary base is present. These observations are important, particularly as this is the first time that a laevorotatory chloride has been obtained from 1(-)-beta-octanol. In order to demonstrate the unique character of this decomposition, a study has been made of the halogenation of l (-)-beta-octanol with thionyl chloride and the chlorides and oxychloride of phosphorus, both in the presence and in the absence of tertiary bases and other substances. From a consideration of the experimental results it is possible to conclude that substitution reactions in organic chemistry can be classified into two main types: type I which occurs with inversion, and during which the organic radical passes momentarily through the kationic state; and type II which occurs without inversion and in which the organic radical passes through the anionic state. It is shown that the general conclusions reached are largely in agreement with those of other workers employing different methods.