Abstract

The hydrolysis of three hydroxypropyl methylcellulose samples with varying degrees of polymerization by aqueous solutions of trifluoromethanesulfonic acid with a concentration of 1, 2, 3, and 4% at a temperature of 80, 90, 100, and 110°C in a microwave reactor is studied. The completeness of hydrolysis is estimated by ¹³C NMR spectroscopy of the disappearance of the signal the acetal carbon atom. It is shown that the concentration of acid has the greatest influence on the hydrolysis rate, the effect of temperature increase is not so strong, and the effect of reaction time is even smaller. Using ¹³C NMR spectroscopy, substitution parameters at the second, third, and sixth positions (DS^C-2, DS^C-3, and DS^C-6) are determined, the amount of methyl (DS^Me) and hydroxypropyl groups (DS^HP) is estimated, and the total degree of substitution (DS^total) is calculated.

中文翻译：

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三氟甲磺酸水解羟丙基甲基纤维素并随后通过13 C NMR光谱测定化学结构

摘要

在微波反应器中，在80、90、100和110°C的温度下，用浓度分别为1、2、3和4％的三氟甲磺酸水溶液水解三种聚合度不同的羟丙基甲基纤维素样品是研究。通过乙缩醛碳原子信号消失的¹³ C NMR光谱估计水解的完整性。结果表明，酸的浓度对水解速率影响最大，温度升高的影响不那么强，反应时间的影响甚至更小。使用¹³ C NMR光谱，在第二，第三和第六位置（DS ^C-2，DS ^C-3和DS ^C-6确定），估算甲基（DS ^Me）和羟丙基（DS ^HP）的量，并计算总取代度（DS ^total）。