紫胶色酸酯的制备工艺优化

对紫胶色酸分子中的羧基先进行甲酯化，然后再用醋酸酐进行乙酰化，最后制备得到了紫胶色酸酯。通过单因素及正交试验确定了紫胶色酸酯的制备工艺条件为：紫胶色酸1.0 g、对甲苯磺酸用量为紫胶色酸质量的5.0%、甲酯化时间36 h、醋酸酐用量1.0 mL、三乙胺用量2.5 mL。在此条件紫胶色酸的酯化率为81.3%，标准偏差为0.67%。通过傅里叶变换红外光谱、紫外-可见吸收光谱表征表明紫胶色酸酯中酯基及烷基的吸收峰变强；通过差示扫描量热仪及热重分析测定，表明紫胶色酸酯的熔融温度为68 ℃，温度高于198 ℃时出现热分解。紫胶色酸酯的色价为121，可溶于大多数有机溶剂，脂溶性增强，其在1 L菜籽油可溶解0.340 g，保存28 d后，油样呈红色，且澄清无沉淀，保存率达96.2%，说明其稳定性良好，对油脂类物质染色效果好，具有潜在的应用价值和前景。

Optimized Preparation of Laccaic Acid Ester Using Orthogonal Array Design

Laccaic acid is one of the most valuable shellac products and improvement of its solubility is a strong impetus for its development and utilization. In this study, laccaic acid ester was prepared from laccaic acid by two sequential reactions, namely esterification with methanol and acylation with acetic anhydride. The reaction conditions were optimized using one-factor-at-a-time method and orthogonal array design as follows: 36 h estertification of 1.0 g of laccaic acid in the presence of 5.0% (relative to laccaic acid) p-toluenesulfonic acid, and acylation with 1.0 mL of acetic anhydride in the presence of 2.5 mL of triethylamine. Under these conditions, the esterification rate reached 81.3% with standard deviation (SD) of 0.67%. The presence of ester and alkyl groups in the obtained product was confirmed by FTIR and UV-Vis spectroscopic analyses. The melting temperature of the laccaic acid ester was 68 ℃ as demonstrated by DSC analysis, and temperature higher than 198 ℃ caused its decomposition. The color value of the laccaic acid ester was 121. It could be dissolved in most organic solvents, especially oils. Its solubility in rapeseed oil reached 0.340 g/L, and the oil sample was red in color and remained clear without precipitation after 28 d of storage, with a retention rate of 96.2%. The laccaic acid ester was proven to have good stability and solubility indicating its promising application potential.