The Specific Rotation of Melezitose

Most of the values reported for the specific rotation of melezitose lie between Ca n +88.1 and +88.8°, as reckoned for anhydrous melezitose by the observers. Richtmyer and the writer found +88.5 in 

The Scission of Anhydro Rings of the Ethylene Oxide Type. 47 

Tables of Properties of Anhydro Sugars and Their Derivatives. 69 

It is to be noticed that although the anhydro ring of levoglucosan is stable to alkali (Tanret s preparative method consisted in the heating of aromatic j9-D-glucosides with aqueous alkali), it readily undergoes scission in the presence of acid. An isomeric glucose anhydride prepared in 1912 by E. Fischer showed, however, very different properties. 

Fischer, having succeeded in replacing the bromine atom in methyl 6-bromo-triacetyl-/3-D-glucoside by the amino group, endeavored in collaboration with Zach to effect the removal of the bromine, as well as the acetyl groups, by the treatment of the compound with barium hydroxide, 

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Most of the values reported for the specific rotation of melezitose lie between [qQd +88.1° and +88.8°, as reckoned for anhydrous melezitose by the observers. Richtmyer and the writer48 found [a]D20 +88.5° in water (c, 2) for melezitose monohydrate, CwHjjOu-HaO. Their experience showed that powdered melezitose dihydrate and anhydrous melezitose are transformed rapidly in the air to the stable monohydrate it thus seems doubtful whether the water content of the samples in the older studies was accurately known, and it now appears likely that the samples were essentially melezitose monohydrate. The value [oQn80 +88.5° for melezitose monohydrate corresponds to [a]o 0 +91.7° for anhydrous melezitose, and to [c ]d20 +85.6° for melezitose dihydrate. 

The data on the specific optical rotation, X-ray diffraction, and on the octa-acetate of the melezitose product were obtained by Professor C. S. Hudson, Dr. Hewitt G. Fletcher, Jr., and Dr. Nelson K. Richtmyer of the Laboratory of Chemistry and Chemotherapy, National Institutes of Health. 

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