Carbon exchange in hot alkaline degradation of glucose

The decomposition of 1-C-13-D-glucose, 6-C-13-D-glUeose, and 1-C-13-sodium lactate has been studied in hot (145+/-3 degreesC) alkaline (3.5 M) sodium hydroxide solution in order to understand the mechanisms of carbon exchange in the alkaline degradation of glucose. The results show that in the formation of lactate from glucose the carboxylate (COO-) carbon is formed preferentially from C1 carbons but methyl (CH3) carbon is formed preferentially from C6 carbons. However, on further decomposition of lactate to ethanol and carbonate, C-13-labeled carboxylate (COO-) is scrambled equally among carbonate and both carbons in product ethanol molecules. In the production of glycolate, the labeled C1 carbon mainly ends up as carboxylate (COO-) carbon, while for C6-labeled glucose the labeled carbon mainly ends up as alcoholic (CH2OH) carbon. In the production of acetate and formate there is also discrimination between C1 and C6 label.