近化学专业毛细管法测定固体有机物熔点的因素分析及其验证

Analysis and Improvement of the Determination of Melting Point of Organic Matter by Capillary Method in Chemical Specialit

大学基础有机化学实验的微型化越来越受到人们的重视。针对台州学院医药化工学院近化学专业开设的有机实验毛细管法在有机物熔点测定中所暴露出的不足,以尿素和苯甲酸熔点测定为例,从样品研磨尺寸、装填高度、装填抖动次数、样品纯度、升温速率等5个方面对影响2种常见固体有机物的熔点测定因素进行了试验。结果表明,对于2种固体试样测试,磨细至2 mm左右,毛细管的最佳装填高度为3~4 mm;起始温度设置低于物质熔点的标称值前5℃;升温速率0.6~1.0℃/min时为佳。采用优化后的方法测定其熔点,准确度和精密度均符合有机化学基础试验要求,值得在地方高校应用型本科专业推广。

The microminiaturization of basic organic chemistry experiments in university has been paid more and more attention. According to the shortcomings exposed in the organic experiment of determining melting point of organic matter by capillary method in pharmaceutical and chemical engineering school of Taizhou university, from 5 aspects including sample grinding size,loading height, filling vibrating times, sample purity and heating rate, the factors affecting the determination of the melting point of solid organic matter were analyzed. The results showed that for solid samples, the best loading height of capillary was 3~4 mm, and the initial temperature was 5 ℃ below the nominal value of melting point. The faster the heating rate was, the higher the melting point value was, and the worse the reproducibility of data was. The accuracy of the melting point measured by the optimized method is higher, and the experimental demonstration effect is more obvious.