HYDROGENOLYSIS OF CARBOHYDRATES: IV. 1,2-O-ISOPROPYLIDENE-D-GLUCOFURANOSE

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Abstract
1,2-O-isopropylidene-D-glucofuranose was treated with hydrogen at 180 °C. and 2900 p.s.i. using copper chromium oxide catalyst and dioxane as solvent. The major isolated products were a hexanediol (2.4%), a mixture of hexanetriols (6.5%), a hexanetetrol (4.3%), and an isopropylidene-aldohexose (4.2%) which differed from the starting material. The latter product yielded L-idose on hydrolysis, showing clearly that isomerization of carbon 5 of monoacetone-D-glucose occurs under the reaction conditions used.The diol and the major components of the triol mixture were found to possess a 1,2-glycol group which was derived mainly from the 5,6-glycol group of the original monoacetone-D-glucose. Thus, hydrogenolysis of 1,2-O-isopropylidene-D-glucofuranose-l-C14 afforded the 1,2-hexanediol and mixed triols containing only about 30% of the total specific activity in carbon 1. The tetrol was shown to be 1,2,5,6-hexanetetrol. The results suggest that the carbon–oxygen bonds at carbons 5 and 6 of isopropylidene-D-glucose are least prone to hydrogenolysis and that those at carbons 3 and 4 are most readily cleaved.