催化加氢制备低氯漂白紫胶及其表征  

Preparation of Bleached Low-chlorine Shellac by Catalytic Hydrogenation and Its Structural Characterization

作　　者：廖亚龙[1] 柴希娟[1] 

机构地区：[1]昆明理工大学材料与冶金学院,云南昆明650093

出　　处：《林产化学与工业》2008年第5期100-104,共5页Chemistry and Industry of Forest Products

基　　金：昆明理工大学校基金(200810)

摘　　要：制备和表征了在食品及制药业中广泛使用的天然低氯漂白紫胶。通过在次氯酸钠漂白改性后的紫胶碱性溶液中加入N i-Fe二元金属催化剂,升温至90℃后,通入氢气,氢气流速为50 mL/m in,进行加氢离解反应240 m in,脱除漂白过程中加成到紫胶分子环状萜烯酸双键上的结合氯,从而获得低氯天然漂白紫胶。借助有机元素分析仪、红外光谱及紫外光谱表征了制备的产物结构,探索了催化加氢制备低氯漂白紫胶的反应机理。结果表明:制备的产物氯质量分数为0.44%,同催化加氢脱氯前的2.54%相比不到1/5;在催化加氢过程中主要发生取代反应,漂白过程中结合到紫胶分子上的氯被氢依次取代。Bleached natural shellac with low chlorine content, which had been widely used in food industry and pharmacy, was prepared and characterized. The bleached natural shellac product with low chlorine content was prepared by means of catalytic hydrogenation of the bleached shellac in the presence of Ni-Fe binary-metal catalyst and hydrogen. Most of chlorine bonded to the double bond of terpenic acids of shellac and compacted in the molecule of shellac were eliminated by sodium hypoehlorite bleach- ing under the conditions of Ni content 2.91%, catalyst quantity 8 g/L, H2 flow rate 50 mL/min, and reaction temperature 90℃ for 240 min. Moreover, the mechanism of catalytic hydrogenation in preparation of the products was elucidated by the aid of structure characterization of the products through elementary analysis, infrared spectrometry, and ultraviolet speetrophotometry. It was demonstrated that chlorine content in the final product could reach 0.44 % under optimum conditions, chlorine content in the final product was 1/5 of that before deehlorination by catalytic hydrogenation, and chlorine compacted in the molecule of shellac was substituted by hydrogen.

关 键 词：催化加氢 二元金属 脱氯 漂白紫胶 表征 

分 类 号：TQ351.0[化学工程]