Abstract
The transformation of β-glucosides (acetates) into α-form has been studied by using SeCl4 as a catalyser which is found by us to be effective under mild conditions.
β-Ethyl-, -methyl-, and -isopropyl-D-glucbside (acetate) were generally dissolved in purified chloroform, and SeCl4, (3 or 4 moles ratio) was added. After refluxing for a given time(10_??_12 hours), the chloroform layer was shaken with ice water, and the mixture was filtered through an active carbon layer, and then the filtrate was concentrated to a thick syrup under a reduced pressure. After addition of a small amount of water to the syrup dissolved in alcohol, the 'solution was allowed to stand for several days, then the a-glucoside crystallised was filtered, and w4is, recrystallised from alcohol. The results obtained under various experimental conditions were described.
In order to distinguish the a-form, specific rotation and melting point were employed. The crystals obtained gave respectively no depression in melting points on admixture with the a-gluco. sides (acetates) prepared from β-glucosides by using SbCl5, as catalyser.
The yields of α-methyl-, -ethyl-, and -isopropyl-D-glucoside (acetates) were 75, 45, and 60% respectively. It appears that SeCl4, gives rise to the transformation of β-glucosides under a mild action.
