Do lecithin and glucose combine to form a true chemical compound?

Abstract

About a year ago I 1 reported a substance found after the evaporation of an emulsion of lecithin and glucose. This material seemed to be identical with the one previously reported by Bing 2 and others, the only point of difference being that previously it had been prepared by the evaporation of an alcoholic solution of lecithin and glucose upon the water bath while I evaporated a watery emulsion either on the water bath or in a vacuum desiccator at room temperature.

In attempting to study by the freezing-point method any changes in molecular weight which might occur, I found that some reaction took place between the benzene, which was used as a solvent, and the solute, lecithin, so that the results were entirely irregular and of no value for my purpose.

A further search for a solvent which could be used for the determination of either the freezing or the boiling point has revealed the same difficulty for a number of other solvents. In their turn ether, chloroform, carbon tetrachloride, bromoform, ethylene dibromide, acetic acid, formic acid and phenol were tried and discarded.

However, when the boiling point of a solution of “lecithin” in alcohol was determined the molecular weight of the sample of “lecithin” which I was using was consistently found to be 1,300. The high figure found would indicate an association of two molecules in the alcoholic solution. Since this “lecithin” was prepared by precipitation with acetone it probably contained considerable kephalin and consequently had for a single molecule a lower average weight than the 800 usually given (see Maclean 1 ).

There was, as perhaps might be expected, a rise in the boiling point when small amounts of glucose were added to a solution of lecithin in alcohol.