酶催化合成混合型蔗糖酯的研究

脂肪酸蔗糖酯是一种非离子表面活性剂，可用于日用化工、食品工业、医药行业等方面。过去多以碱性物质为催化剂，在较高温度由脂肪酸和蔗糖合成。由于脂肪酸及蔗糖在较高温度下不稳定，导致脂肪酸蔗糖酯产率降低，产品质量低下。近年来，利用脂肪酶为催化剂在较低温度下催化合成脂肪酸蔗糖酯的研究引起了人们的兴趣。     

甘油单脂肪酸酯合成中催化剂的研究进展

综述了非离子表面活性剂甘油单脂肪酸酯合成过程中所用催化剂的研究进展以及几种可以用于甘油单脂肪酸酯合成的新型催化剂类型,即非离子碱、离子交换树脂、介孔材料、金属氧化物和各种脂肪酶催化剂,并对各自的催化效果及优缺点作了比较。     

生物表面活性剂催化合成蔗糖酯及其应用

蔗糖酯是一种有效的食品添加剂,它可由蔗糖与脂肪酸酯或甘油酯在碱性催化条件下由有机溶剂法或无溶剂法合成得到,报道了蔗糖酯的合成,分离和应用进展,还论述了生物表面活性剂作为均相催化剂在蔗糖酯合成中的作用。     

生物技术在油脂化工方面的应用进展

利用微生物产生的脂酶为生物催化剂,在温和条件(常压、常温)下使油脂转化为脂肪酸单甘酯、脂肪酸甲酯、烷基葡萄糖苷脂肪酸等油脂化工产品.与化学工艺相比,生物催化技术选择性好,副反应少,产物纯度高,能源消耗低,尤其是对于多不饱和脂肪酸衍生物,可以避免较高温度下氧化、聚合等副反应,不仅可以简化提纯工艺,而且有助于提高产品收率与质量.本文简要介绍近期国外化学工作者利用商品脂酶制剂为生物催化剂,通过醇解反应制备高产率、高纯度单甘酯;通过酸解反应,制取富含多不饱和脂肪酸的甘油酯;通过酯化反应,合成脂肪酸甲酯、烷基葡萄糖苷脂肪酸酯.     

蔗糖脂肪酸酯合成新技术

蔗糖脂肪酸酯是一种国际上公认的食品添加剂,具有广泛的应用范围。蔗糖脂肪酸酯的合成路线及工艺随着人们对产品要求的提高不断改进。中科院上海有机化学所采用了生物表面活性剂作为均相催化剂,并用无溶剂法合成了蔗糖酯,使蔗糖酯的合成达到了国际先进水平。     

乙酸苄酯和乙酸苯乙酯的合成研究

研究了氨基磺酸催化酯化合成乙酸苄酯和乙酸苯乙酯。此工艺反应时间短、能耗低、产品纯度高、产率良好、无三废污染 ,优于文献方法。     

酯化合成单甘酯的催化剂研究进展

单甘酯作为一种高效的表面活性剂,大量应用于食品、医药、塑料等行业。综述了酯化合成单甘酯过程中所用催化剂的研究进展,介绍了几种酯化合成单甘酯的催化剂,包括沸石分子筛、离子交换树脂、固体超强酸、金属氧化物、脂肪酶等,并对它们的催化效果和优缺点做了比较。     

固体氯化物催化合成氯乙酸系列酯

固体氯化物催化合成氯乙酸系列酯牛梅菊（聊城师范学院化学系，聊城２５２０５９）氯乙酸脂肪酸酯是合成农药、医药、染料和阳离子表面活性剂季铵盐的重要原料，广泛应用于有机合成工业＂＇。工业生产氯乙酸脂肪酸酯，通常采用硫酸作催化剂，但硫酸的氧化性使酯化反应易生...     

碳酸钾催化合成海藻糖脂肪酸酯

海藻糖脂肪酸酯是非离子生物表面活性剂,它具有可降解、无毒、无污染、在极端环境下稳定性强等优势。本文工艺采用食品添加剂乙二醇作为溶剂,由海藻糖和脂肪酸酯原料酯交换反应合成海藻糖脂肪酸酯,工艺简单,生产成本低,过程中采用食品级原料,易于食品工业化生产。该工艺合成海藻糖脂肪酸酯转化率在90%以上。     

Candida sp. 99-125脂肪酶及其在化学品合成中的应用

传统的酯化或转酯化产品的合成通常需要高温、强酸、强碱等相对苛刻的条件,脂肪酶由于其生物催化过程具有高效、高选择性、条件温和和环境友好等特点,在化学品的合成中越来越受到人们的关注。本课题组开发了一种可以用于酯类合成的新脂肪酶,并且实现了该酶的工业化生产。来源于Candida sp. 99-125的脂肪酶在非水相中对酯化和转酯化反应具有高效的催化活性和稳定性。本文介绍了该脂肪酶的发酵生产及其在中长链脂肪酸酯、二元酸酯、维生素A棕榈酸酯、手性化合物以及生物柴油等多种化学品的合成中的应用。     

Solvent‐free preparation of phytosteryl esters with fatty acids from butterfat in equimolecular conditions in the presence of a lipase from Candida rugosa

BACKGROUND: Enzymatic esterification of phytosterols with fatty acids from butterfat in equimolecular conditions to produce phytosteryl esters was performed in solvent‐free medium. Commercial and immobilized Candida rugosa lipases were used as biocatalysts for the reaction. RESULTS: By this methodology, under simple and mild reaction conditions (without solvents, 50 °C and short reaction times), 94% and 99% (w/w) of phystosteroyl esters were obtained in 48 h and 9 h with the commercial and the immobilized lipase, respectively. The effects of temperature, fatty acid specificity, enzyme amount and residual activity of each lipase were also evaluated. CONCLUSIONS: The phytosteryl esters from butterfat produced in this study are expected to have lower melting point, improved oil and fat solubility and bioavailability compared to that of their corresponding free phytosterols. Copyright © 2008 Society of Chemical Industry     

Enzymatic synthesis of steryl esters of polyunsaturated fatty acids

Steryl esters of long-chain fatty acids have water-holding properties, and polyunsaturated fatty acids (PUFA) have various physiological functions. Because steryl ester of PUFA can be expected to have both features, we attempted to synthesize steryl esters of PUFA by enzymatic methods. Among lipases used, Pseudomonas lipase was the most effective for the synthesis of cholesteryl docosahexaenoate. When a mixture of cholesterol/docosahexaenoic acid (3:1, mol/mol), 30% water, and 3000 units/g of lipase was stirred at 40°C for 24 h, the esterification extent attained 89.5%. Under the same reaction conditions, cholesterol, cholestanol, and sitosterol were also esterified efficiently with docosahexaenoic, eicosapentaenoic, arachidonic, and γ-linolenic acids.     

Estersynthesen mit Lipasen

Synthesis of Esters by Lipases Lipases belong to the enzymatic class of hydrolases and catalyse both the hydrolysis and synthesis of esters at the interface between water and insoluble substrate. Esterification by lipases is possible at ambient temperature and at neutral pH under normal pressure in simple reaction vessels. Lipases have potential uses in the preparation of wax esters, fragrances, ester oligomers and other compounds. Ester synthesis by lipases may be performed either batch-wise or continuously. Examples for stereoselective esterification have been reported e.g. in the selective preparation of l-menthylester from dlmenthol. Regio-specific lipases, catalysing transesterification of position 1 and 3 of the triglyceride, are applied to the production of valuable products such as cocoa butter substitutes. Transesterification of triglycerides and methanol results in fatty acid methyl esters.     

Lipase-catalyzed synthesis of waxes from milk fat and oleyl alcohol

A screening of five lipases was carried out for the synthesis of wax esters from stoichiometric amounts of oleyl alcohol and milk fat in which long-chain fatty acid content (myristic acid, palmitic acid, stearic acid, and oleic acid) represents 70% of the total fatty acid fraction. The lipases from Alcaligenes sp. and Chromobacterium viscosum both allowed for the best ester synthesis (around 60%) within 2 and 48 h, respectively. Enzeco® Lipase Concentrate gave 30% ester yield within only 2 h. During the time period of 166 h, less than 20% ester synthesis was obtained with Lipozyme? 10,000L whereas Enzeco® Lipase XX did not catalyze the reaction. Owing to commercial availability, the food-grade Enzeco® Lipase Concentrate preparation was selected for further experiments with a view to improve wax synthesis. Wax yields were compared for three substrate molar ratios, i.e., 0.5:1, 1:1, and 1.5:1 (alcohol/fatty acid). For 0.5:1 and 1.5:1 substrate molar ratios, the addition of water increased ester yields while the effect of silica gel addition was shown to be minor. The best improvement was obtained at a substrate molar ratio of 1.5:1 with addition of water, leading to 59% wax ester synthesis.     

Lipase-catalyzed synthesis of kojic acid esters in organic solvents

Kojic acid is an inhibitor of bacteria, viruses, and fungi. It is used for inhibiting the browning effect of tyrosinase in the food and cosmetic industries. To improve its lipophilic properties, Pseudomonas cepacia lipase and Penicillium camembertii lipase were used for catalyzing the esterification of kojic acid to synthesize kojic acid monolaurate and kojic acid monooleate. These products showed a 69.5% inhibitory effect on tyrosinase in hydrophobic organic solvent. The yields of kojic acid esters were affected by enzymes, substrates, organic solvent, and temperature. Lauric and oleic acids were the best substrates for esterification among various fatty acids tested. CaCl₂ and MnCl₂ stimulate Pseudomonas cepacia lipasecatalyzed esterification by 7.0%. On the contrary, MgCl₂, SrCl₂, and ZnCl₂ inhibited the reaction. The best pH of buffer for lipase pretreatment was pH 6.0. Pseudomonas and Penicillium lipases can be reused for the synthesis of kojic acid esters. After reaction at 40°C for 10 d, the Penicillium and Pseudomonas lipases still retained 57.0% and 92.0% of their initial activities, respectively.     

Enzymatic production of alkyl esters through alcoholysis: A critical evaluation of lipases and alcohols

This paper focuses on a detailed evaluation of commercially available immobilized lipases and simple monohydric alcohols for the production of alkyl esters from sunflower oil by enzymatic alcoholysis. Six lipases were tested with seven alcohols, including straight and branched-chain primary and secondary alcohols. The reactions were conducted in a batch stirred reaction vessel using stoichiometric amounts of substrates under solvent-free conditions. Dramatic differences in alcoholysis performance were observed among the different lipases. For most of the alcohols, Novozym 435 produced the highest yield of FA alkyl esters, with yields well over 90% for methanol, absolute ethanol, and 1-propanol. Overall, 96% ethanol was the preferred alcohol for all lipases except Novozym 435, and ethanolysis reactions reached the maximal conversion efficiency. Increasing the water content in the system resulted in an increased degree of conversion for all lipases except Novozym 435. The secondary alcohol 2-propanol significantly reduced the alcoholysis reaction with all lipases; however, the branch-chain isobutanol was more advantageous than linear 1-butanol for Novozym 435, Lipozyme RMIM, and Lipase PS-C. Many commercial immobilized lipases are highly efficient and promising for the production of alkyl esters, offering high reaction yields and a simple operation process.     

Lipase-Catalyzed Synthesis of Fatty Acid Pyridylcarbinol Ester for the Analysis of Seed Lipids

Numerous derivatives of fatty acids (FA), including esters of methanol/3‐hydroxymethylpyridine or dimethyloxazoline, are used for the analysis of FAs in biological specimens. Picolinyl derivatives are frequently prepared for structural determination by gas chromatography–mass spectrometry (GC‐MS) since they provide characteristic fragments. The ester can be prepared by chemical methods‐multistep methodologies or basic transesterification. Microbial lipases catalyze a number of transesterification reactions, and their catalytic activities are often stable at extreme conditions. Although these characteristic features may be useful in the application of typical FA structure analysis by picolinyl ester, detailed studies have not been reported. To address the problems, a simple and quantitative methodology for the synthesis of picolinyl esters from lipids has been developed. It involves the transesterification with Novozym 435 (Novozymes Biopharma US Inc., Franklinton, USA), resin‐immobilized lipase from Candida antartica in toluene. Mild reaction conditions allow for complete derivatization of perilla seed oil in 30 min at 50 °C. The procedure was further studied with various TAGs and fatty wax from 17 plants. The optimized procedure was as follows; 1 mg lipid and 20 mg catalyst in 2 mL toluene at 50 °C for 1 h. Quantitative analysis of marker FAs was performed with the proposed method. The results coincided well with those from potassium t‐butoxide‐catalyzed reaction. The optimized method, however, was not applicable for the determination of some epoxy FAs, fatty wax, and parinaric acid.     

Lipase-catalyzed reactions involving thia fatty acids and ester derivatives

Enzymatic hydrolysis of synthetic methyl 5-, 9-, and 12-thiastearates in aqueous media withCandida cyclindracea or porcine pancreatic lipases gave the corresponding fatty acids in 70–100% yield. Hydrolysis of the 3- and 4-positional isomers gave only 15–25% of the free thia fatty acids, suggesting discrimination against these isomers by lipases. No lipolysis was achieved with methyl 2-thialaurate under a range of reaction conditions. Esterification of the 3-, 4-, 5-, 9-, and 12-thiastearic acids withn-butanol inn-hexane using Lipozyme (immobilizedRhizomucor miehei) as the biocatalyst gave the corresponding butyl esters in 80–95% yield. Interesterification (acyl exchange) of triolein with methyl 9-thiastearate in the presence of Lipozyme showed the incorporation of 9-thiastearoyl chain at only one of the α-positions of triolein. In the case of methyl 2-thialaurate, no lipase-catalyzed acyl exchange reaction was possible. This study showed that the position of the sulfur atom in thia fatty esters affects the lipase-catalyzed hydrolysis and interesterification reactions.     

Fatty methyl ester hydrogenation to fatty alcohol part I: Correlation between catalyst properties and activity/selectivity

Fatty alcohols, derived from natural sources, are commercially produced by hydrogenation of fatty acids or methyl esters in slurry-phase or fixed-bed reactors. One slurry-phase hydrogenation of methyl ester process flows methyl esters and powdered copper chromite catalyst into tubular reactors under high hydrogen pressure and elevated temperature. In the present investigation, slurry-phase hydrogenations of C₁₂ methyl ester were carried out in semi-batch reactions at nonoptimal conditions (i.e., low hydrogen pressure and elevated temperature). These conditions were used to accentuate the host of side reactions that occur during the hydrogenation. Some 14 side reaction routes are outlined. As an extension of this study, copper chromite catalyst was produced under a number of varying calcination temperatures. Differences in catalytic activity and selectivity were determined by closely following side reaction products. Both activity and selectivity correlate well with the crystallinity of the copper chromite surface; they increase with decreasing crystallinity. The ability to follow the wide variety of side reactions may well provide an additional tool for the optimized design of hydrogenation catalysts.     

固体酸催化废油酯制备脂肪酸丁酯

研究以废油酯为原料在固体酸催化作用下与丁醇酯交换反应制备脂肪酸丁酯的过程,采用气相色谱对脂肪酸丁酯的含量进行分析。考察了醇油摩尔比、催化剂用量、反应温度和反应时间对酯化反应转化率的影响。结果表明,该反应的最适宜工艺条件为：醇油摩尔比16∶1,催化剂用量1.2%,反应温度115℃,反应时间4 h。废油酯在最优工艺条件下,经过酯交换反应得到的转化率超过83%。