As a result of a comparison of the rotations of certain aromatic tl-glucosides and their tetraacetates, it is shown to be probable that the rotations of the acetylated glucosides are influ enced by steric interactions between the aglycon group and the sugar portion of the molecule.This b ehavior is in contrast to the influences predominating in the case of the unacetylated compounds which, as shown in previous work, probably operate on the resonance of the aglycon aromatic ring or in an inductive fashion.As a test for the explanation of the anomalous positive rotations of certain of the acetylated tl-glucosides, the rotation of several of these substances in nitrobenzene solution was measured over the temperature interval 20 0 to 150 0 C.Over this temperature range, several of the glu cosides, and in particular those which show anomalous positive rotations at room temperature, exhibit a change in sign of rotation from positive to negative.The preparation and properties of the following new compounds are described: The m-nitrophenyl a-D-glucoside and its tetraacetate, the O,pand o,o'-dinitrophenyl tJ-glucoside tetraacetates, and the m-nitrobenzyl tJ-glucoside tetraacetate.The rotatory dispersion of these and other glucosides is reported for five wavelengths over the visible spectrum.
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Ward Pigman (1944) studied this question.