Polar and Non-Polar Valency in Organic Compounds

Abstract

THERE is an increasing tendency on the part of organic chemists to apply the Berzelius dualistic theory, in a modified form, to organic compounds. In many theories of valency, individual groups are considered to be more or less electropositive or electronegative, and it is possible to arrange these groups, approximately, in a table of descending electropositive character. A difficulty which arises in examining this conception is to visualise the transference of anything less than one electron between the group and the remainder of the molecule. There appear to be at least two kinds of forces operating between atoms in a molecule, which can be designated as polar and non-polar. The polar character of the valency in the majority of salts is definite; there is experimental evidence for the transference of electrons in these substances. The non-polar forces are particularly in evidence in the linkings of organic compounds, and it is extremely unlikely that transference takes place to an appreciable extent here. Without entering into a discussion of the nature of the non-polar forces, which may be electromagnetic, there are two explanations which may be given of the undoubted positive and negative relationships of groups in organic compounds. In the first place, there may be a partial transference of an electron between the group and the residue of the molecule, or alternately there may be a varying concentration of polar molecules in the typically non-polar substance.