Modifications in the nitric acid oxidation of D-mannose: X-ray crystal structure of N,N'-dimethyl D-mannaramide.

ABSTRACT

Nitric acid oxidation of D-mannose was carried out under an oxygen atmosphere using a computer controlled reactor. The process represents a catalytic oxidation of D-mannose with oxygen as the terminal oxidant. The crude oxidation product was esterified with methanolic HCl and the esterified product directly converted to crystalline N,N'-dimethyl-D-mannaramide with methylamine. Treatment of the diamide in aqueous sodium hydroxide gave solid disodium D-mannarate. The X-ray crystal structure of N,N'-dimethyl-D-mannaramide was determined as a model for the repeating D-mannaramide units of stereoregular poly(alkylene-D-mannaramides). Disodium D-mannarate was prepared as a precursor of esterified D-mannaric acid for use as a reactive diacid monomer to prepare poly-D-mannaramides.