E RING STRUCTURE OF MANNOSE . THE OPTICAL ROTATION OF 4 - GLUCOSIDO - a - MANNOSE

A comparison of the rotation of two pairs of sugars, which can not form a 1 4 ring shows that one pair gives an epimeric difference in rotation, which agrees with the value obtained from a-d-mannose (+ 30) and the normal form of glucot? while the other pair gives a value which agrees with that obtained from ^ESZJnose (-17) and the normal form of glucose. These results may be interpret ,.,1 as indicating that 4-glucosido-a-mannose and 4-galactosido-/3-mannose have structures similar to aand /3-mannose, respectively. However, regardless of the particular interpretation, the different values show that a decision between the rival ring classifications can not be reached from a comparison of the rotations of cellobiose and glucosido-mannose.