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
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...
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| Language: | en |
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University of Canterbury. Chemistry
2013
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| Online Access: | http://hdl.handle.net/10092/8512 |
| Summary: | 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. |
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