Synthesis and characterization of methyl xylan

The synthesis of methyl xylan using methyl chloride and methyl iodide as etherifying agent under varying reaction conditions was studied. The reaction of xylan with an excess of methyl chloride under pressure in the presence of 40% aqueous NaOH led to a methyl xylan with a degree of substitution (DS) of 0.94. The conversion of xylan with methyl iodide yielded DS values of about 0.5 independent of the molar ratio of methyl iodide to anhydroxylose unit homogeneously in 25% aqueous NaOH or after addition of acetone leading to a heterogeneous slurry. The DS and the distribution of the substituents were determined by means of one and two-dimensional NMR spectroscopy.