QYH-1型印花糊料——Ⅰ.以2-氯乙醇作醚化剂的反应机理

QYH-1 PRINTING PASTE Ⅰ. MECHANISM OF REACTION USING ETHYLENE CHLOROHYDRIN AS AGENT OF ETHERIFY

QYH—1型印花糊料系羟乙基淀粉,其取代度大于0.5,用2-氯乙醇作醚化剂时,一般认为,以NaOH作催化剂,2-氮乙醇直接与淀粉反应生成羟乙基淀粉。我们在实验中发现:当2-氯乙醇加到淀粉与NaOH的悬浮液中后,2-氯乙醇立即与氢氧化钠反应生成环氧乙烷,而后生成的环氧乙烷与淀粉反应生成羟乙基淀粉,这是反应的主要机理。反应效率约为65％,副反应生成的乙二醇约为34％。

QYH-1 printing paSte is hydroxyethyl starch, Its degree of subs-titution(DS) is more than 0.5. When the 2-ethylene chlorohydrin is used as agent of etherify, in the present of sodium hydroxide, the generally agreed mechanism of reaction is that the ethylene chlorohydrin reacted with starch to produce hydroxyethyl starch. A main mechanism of reaction was discoverd: as ethylene chlorohy-drin is added to slurry of starch and sodium hydroxide, it react with NaOH to form ethylene oxide. It react with starch to produce hydroxy ethyl starch. The efficiency of reaction is about 65％. The ethylene glycol which is formed by side reaction is about 34％.