成脎和成腙反应速率反应产物的比较

Comparison of Osazone and Hydrazone of Glucose and Fructose in Speed and Product

为分析成脎和成腙反应的机理,用苯肼、2,4-二硝基苯肼与5%葡萄糖、果糖溶液作用,检测其反应速率,再通过质谱和薄板层析检测其反应产物。结果表明:成脎反应产物多,反应速率快,葡萄糖、果糖成脎时间分别是5.3min、2.4min,葡萄糖和果糖的成脎反应都发生在C1和C2位,为双取代反应,反应产物两种以上;成腙反应速率慢、产物少,2,4-二硝基苯肼与葡萄糖、果糖溶液反应成腙时间均在24h或更长,反应分别发生C1或C2位上,为单取代反应,反应产物仅1种。分析表明:羰基试剂的空间效应和电子效应影响这两种糖的单双取代和反应速率,影响产物的数量和种类。

In order to analyze the reaction mechanism of becoming osazone and hydrazone,they are prepared by using phenyl hydrazine,2,4-dinitrophenyl hydrazine and 5% glucose solution containing fructose as reagents.Their reaction speed is tested,and then the reaction products are detected through mass spectrometry and thin layer chromatography (TLC) method.The experiments results showed that many products are formed,the reaction speed is fast.The reaction time of glucose and fructose are 5.3 minutes and 2.4 minutes respectively,reacting in C1 and C2,which are disubstituted reaction.The products are two or more.The time of becoming 2,4-dinitrophenylhydrazones of glucose and fructose are 24 hours or longer in C1 or C2 respectively,which are Mono-substituted reaction.The product is only one.The analysis shows that Mono-substitution and disubstitution,the reaction time,quantity and kinds of products of these two kinds of sugar are influenced by steric effect and electronic effect of carbonyl reagent.