The catalytic effects of acetic acid-water mixtures on the mutarotation of α-d-glucose, and a comparison with the racemisation of 1-trans-αγ-dimethylglutaconic acid in acetic acid-water mixtures (1946)
AuthorsChapman, L. P. J.show all
When crystalline α-d-glucose prepared by crystallisation from cold concentrated acetic acid is dissolved in water its specific rotation is 113.4°, but slowly changes to 52.5°; β-d-glucose has an initial specific rotation of 17.5° which also changes to 52.5°. This phenomenon of mutarotation is shown by a number of reducing sugars such as lactose and fructose. Lippmann and Simon first realised that a sugar having a cyclic (pyranose or furanose) structure should exist in two modifications differing in configuration about carbon atom one; Armstrong showed the structural relationship of α- and β-glucose to α- and β-methyl glucoside respectively; while Hudson and Lowry showed that mutarotation was due to the establishment of an equilibrium between the two forms in solution.