Purification Methods
Crystallise the hydrochloride from 3M HCl, water, and finally water/EtOH/acetone as for galactosamine hydrochloride. [Purchase & Braun Org Synth 26 36 1946, Stacey & Webber Methods in Carbohydrate Chemistry I 228 1962, Academic Press.] The salt has also been purified by dissolving in the minimum volume of boiling H2O (charcoal), filtering and adding a large excess of 95% EtOH (~4 volumes) and stirring vigorously for several hours. Collect the crystals after 4-6hours to give anomer which mutarotates ] D +100o to +72o (equilibrium, c 1, H2O). A large amount of the -anomer stays in solution. This can be precipitated from the filtrate by adding excess Et2O. The mixture of -plus -anomers has [] D +68.8o (c 4.75, H2O, mutarotating to +70.1o)[Leaback Biochemical Preparations 10 118 1963]. Note that if Et2NH is used instead of Et3N, conversion to the -anomer can be complete (see above). [Stacey et al. Methods in Carbohydrate Chemistry I 3061962, Academic Press; Beilstein 4 IV 2018.]
