Nonreducing units, disaccharide

It was also possible to synthesize "11 a protected disaccharide (673c) containing N,N -diacetylpurpurosainine C as the nonreducing unit. 

Lactose appears also to be oxidized as its hemiacetal by lead tetraacetate in acetic acid, to give a formyl ester (with the consumption of three to four moles of oxidant), without the liberation of any formaldehyde. In addition, with various (1 —> 4)-dihexose disaccharides at 27° in 90% acetic acid containing potassium acetate as catalyst, the nonreducing unit gives rise to one mole of free formic acid per mole, and the reducing unit is oxidized to a tetrose diformate (31), - thus suggesting the following pathway. 

For nonreducing disaccharides such as sucrose or trehalose, the position of the hemiacetal hydroxyl of each unit involved in the linkage is evident. For reducing disaccharides, the position of substitution of the nonreducing unit in the reducing unit must be determined. For this purpose the methyla-tion method has been the most valuable means. 

Hexopyranose disaccharides having a (1 —> 6)-linkage rapidly yield about five moles of formic acid per mole (see Fig. 6), that is, one from the nonreducing end and four from the reducing end-unit, and consume about six moles of oxidant per mole, the data corresponding to conversion of LVIII to LX. In the 1,4-hexopyranoses (for example, LIX), formic acid appeared... 

---