Structural Analysis of Cellulose Derivatives by ¹H- and ¹³C-NMR Spectroscopy

Abstract

Reaction of cellulose with propylene oxide (P0) under base-catalyzed conditions produces hydroxypropylcellulose (HPC) HPC thus obtained was a high molecular weight polymer (Mn =18000-163000, Mw=37000-366000). We analyzed its structure by ¹H- and ¹³C-NMR, and assigned the C2, C3and C6 peaks in the ¹³C-NMR spectra by comparing the chemical shift differences between before and after the addition of PO, then obtained the MS (Molar Substitution) and DS (Degree of Substitution). As a result, the order of the relative reactivity of PO toward the hydroxy group was 6-OH > 2-0H > 3 -0H, which was same to the generally accepted order of the reactivity in the literature. It wa s also found that distribution of PO in HPC differed by quantity of oxidant in making an adjustment of molecular weight of HPC.