Bromine oxidation and mutarotation measurements of the alpha- and beta-aldoses

Abstract

Rates of oxidation by bromine water, sp eci£c rotations, mutarotation coefficients , heats of activation, and other data are reported for ad glucose , i3-d-glucose, ad -galactose, ,B-d-galactose, ad -t alose, ad -mannose, ,B-d-mannose, mannose CaCh-4H20, ad -gulose CaCh-H20, ad -xylose, ad -Iyxose, ,B-d-Iyxose, a-l-arabi-nose, ,B-l-arabinose CaCl2.4H20, d-ribose, l-ribose, a-l-rhamnose, a-lact ose, ,B-lactose, and ,B-maltose. The bromine oxidation measurements reveal that the equilibrium solutions are composed for the most part of the normal alpha and beta isomers. Small quantities of other modifications appear to be present in the solutions of arabinose, galactose, talose, and ribose. F undamental cha r-acteristics of the alpha and beta sugars which furnish t he basis for the changes in nomenclature previously suggest ed by Isbell are discussed. It is shown that the sugars which appear as beta modifications under the proposed classification are oxidized by bromine more rapidly than the alpha. CONTENTS