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为解决羧甲基羟丙基瓜尔胶(CMHPG)合成过程中副产物多,容易糊化的问题。以丙酮为反应介质,甲醇钠为催化剂代替乙醇、异丙醇为介质,氢氧化钠为催化剂。探讨了工艺条件对产品的影响,找出了较佳工艺条件。结果表明,合成较佳工艺条件为:环氧丙烷与瓜尔胶质量比为0.2︰1、氯乙酸与瓜尔胶质量比为0.4︰1,反应时间为160 min;前者催化剂与瓜尔胶质量比为0.2︰1、反应温度为45～50℃,后者催化剂与瓜尔胶质量比为0.3︰1,反应温度为65～70℃。乙醇、异丙醇为介质,氢氧化钠为催化剂合成产品的羧甲基取代度为0.43,羟丙基取代度为0.36,粘度为1 120 mPa.s;以丙酮为反应介质,甲醇钠为催化剂合成产品羧甲基取代度为0.48,羟丙基取代度为0.37,粘度为1 030 mPa.s。
To solve the carboxymethyl hydroxypropyl guar (CMHPG) synthesis process more by-product, easy to gelatinization problem. Acetone as the reaction medium, sodium methoxide as a catalyst instead of ethanol, isopropanol as a medium, sodium hydroxide as a catalyst. The influence of process conditions on the product is discussed, and the better process conditions are found out. The results showed that the optimum conditions for the synthesis were as follows: the mass ratio of propylene oxide to guar gum was 0.2︰1, the mass ratio of chloroacetic acid to guar gum was 0.4:1, and the reaction time was 160 min. The former catalyst and guar gum quality The ratio of 0.2: 1, the reaction temperature of 45 ~ 50 ℃, the latter catalyst and guar gum mass ratio of 0.3: 1, the reaction temperature is 65 ~ 70 ℃. Ethanol and isopropanol as medium, sodium carboxymethyl substitution degree of 0.43, hydroxypropyl substitution degree of 0.36 and viscosity of 1 120 mPa · s with sodium hydroxide as catalyst. Using acetone as reaction medium and sodium methoxide as catalyst The carboxymethyl substitution degree of the synthesized product was 0.48, the hydroxypropyl substitution degree was 0.37 and the viscosity was 1 030 mPa.s.