【作者】 黄亚琴；

【导师】 吕效平；

【作者基本信息】 南京工业大学 ， 化学工程， 2005， 硕士

【摘要】 糖类脂肪酸酯（简称:糖酯）作为一种非离子型表面活性剂,其比较传统的制备方法是采用化学合成法,但是其复杂的工艺,低效的选择性使人们不得不寻找更为有效的方法。酶法合成糖酯就是采用脂肪酶催化有机溶剂中的糖与酰基供体（如脂肪酸或者脂肪酸酯）,使之发生酯化反应或者酯交换反应生成糖酯。酶是一种高效、专一的生物催化剂,在非水介质中能够选择性地催化糖酯合成反应,其温和、高效的独特优点已经使酶法合成糖酯受到广泛的关注。 脂肪酶在水溶液中主要用于水解,改变反应条件,可以使酶反应向酯合成方向进行。因此,酶促糖酯合成是一个可逆反应,其副产物是水,这就决定了糖酯合成反应必须在非水介质中进行,并且反应体系中必须严格控制水的含量,以抑制逆反应的发生。水含量、溶剂的性质都是影响酶反应的重要因素,其他的影响因素还有:酶的用量,酰基供体及酰基受体的选择及配比、温度等。本文重点考察了:叔戊醇和丁酮两种溶剂体系中水含量的影响,不同碳数的脂肪酸酰基供体,果糖、葡萄糖、蔗糖作为酰基受体以及酰基供受体之间的配比对反应的影响。经多次实验,得到了优化的合成条件:底物为0.09g果糖、0.192g棕榈酸（配比为1∶1.5）,溶剂为10mL丁酮,0.1g酶,20粒4A型分子筛（约0.85g/10ml丁酮）。反应46小时得到的最终平衡浓度为43.6g·L^-1,果糖转化率为97.5%,比国外减压条件下同类型的反应转化率还高(较高的果糖转化率为93%,而产物浓度不到30g·L^-1),棕榈酸的转化率为88%。固定化脂肪酶重复使用10次时,酶活仅下降19%。 将超声用于强化生物过程中酶反应这一技术近年来在国内外都有研究,专家学者对此评价颇有争议。本文在酶法合成糖酯条件优化的基础上考察了不同强度的超声对于酶反应的影响。结果发现低强度的超声对反应起促进作用,与未使用超声的反应相比:在相同的反应时间下,能够提高反应的转化率,缩短反应时间。其中,在10kHz,0.16W·m^-2声强,20kHz,9W·m^-2声强和40kHz,1W·m^-2声强下,生成的产物浓度随时间变化呈现指数形式,与未加超声反应12小时达到的浓度相比,反应时间减少了1/3。并且在10kHz,0.16 W·m^-2超声作用条件下,得到的产物浓度是不加超声作用时的3倍。而高强度的超声则不利于反应,在其它更多还原

【Abstract】 As a kind of nonionic surface-active agent, sugar ester （sugar-fatty acid ester） was commonly synthesized by the traditional chemical methods. However, these methods were limited due to complicate process and low selectivity. In recent years, great attention on the lipase-catalyzed synthesis of sugar ester has been received. It is achieved by means of esterification or transesterification catalyzed by lipase between sugar and acyl donor in organic solvent. Lipase is a kind of high efficiency and specific biocatalyst. It can catalyze the synthesis of sugar ester in non-aqueous medium.Lipase is a species of hydrolytic enzyme and is often used as hydrolysis. When condition changed, the reaction can go on in reverse direction. So in the process of synthesis, water content has to be controlled strictly to avoid reverse reaction. Water content and the nature of solvent affect the enzyme reaction evidently. In addition, other factors such as the quantity of the enzyme, the selection of acyl donor and acceptor and the ratio between them also must be considered. This paper studied with the emphasis on: （1） the effect of water content of tert-amyl alcohol and butanone as solvent, respectively; （2） when the solvent selected as butanone, the optimal water content in the system; （3） the effect of fatty acid with different numbers of carbon as acyl donor and fructose, sucrose, glucose as acyl acceptors; （4） the ratio between acyl donor and acceptors. The optimized conditions are as fllows: fructose 0.09g, palmitic acid 0.192g （the mole ratio is 1:1.5）, butanone 10mL, lipase 0.1g and 4A molecular sieve 0.85g /10mL butanone. When the reaction time up to 46h, the ultimate concentration of production reaches 43.6g·L^-1, and the conversion of fructose is 97.5%, which is higher than that from other researchers in abroad achieves in different conditions (their better results show that under decompression, the higher conversion is 93%, and the concentration of ultimate production is less than 30 g·L^-1). The conversion of palmitic acid s 88%. After used 10 times, the enzyme activities of Novozym435 only reduce 19%.Study on ultrasound-promoted lipase-catalyzed reaction was reported in the world in recent years. However, experts have different ideas. Based on the optimized conditions of the synthesis, this paper studied the effect of different intensity ultrasound on the lipase-catalyzed reaction. Our result shows that ultrasound plays an important role in lipase-catalyzed reaction. Low energy ultrasound can decreases the reaction time when getting the same yield, increases the reaction rate, and enhances the concentration of production. When 10kHz, 0.16W-m’2, 20kHz, 9W-m’2 and 40kHz, lW-m"2 are selected .is ultrasonic parameters, the overall concentration of production vs. the reaction time appears the exponential addition form. In addition, the reaction time reduces 1/3 with ultrasound operation. What’s more, when the frequency is 10 kHz and sound intensity is about 0.16W-m"2, the concentration of ester is twice more than that without ultrasonic irradiation. However, high energy ultrasound is not beneficial to vhe reaction. In the same condition, the concentration of production appears downtrend.更多还原