Parameters affecting the synthesis of geranyl butyrate by esterase 30,000 from Mucor miehei

The factors affecting the synthesis of geranyl butyrate by esterase 30,000 of Mucor miehei were studied in a solvent-free system. The effects of substrate molar ratio, temperature, agitation speed, and initial addition of water were investigated. The equimolar ratio was most interesting for ester production in batch. There were no diffusion limitations, and the reaction could be realized at low agitation. The catalytic activity of the enzyme was irreversibly deactivated at 60°C, and the initial addition of water decreased the rate of conversion after 75 h of reaction. The enzyme activity increased with increased linear chainlength of the acid and was also affected by the alcohol structure. Esterase 30,000 gave the highest conversion of butyric acid with hexanol and terpenic alcohols (citronellol, nerol) and the lowest with the secondary alcohol (2-hexanol). Finally, five other industrial enzymatic preparations were investigated for their ability to synthesize geranyl butyrate and to hydrolyze olive oil. We observed, for the lipase from Rhizopus javanicua, that there is no relationship between hydrolytic and synthetic activities; this example shows that the hydrolytic lipase activity data cannot predict the capability of lipases in esterification reactions.     

Five-factor response surface optimization of the enzymatic synthesis of citronellyl butyrate by lipase IM77 from Mucor miehei

Response surface methodology (RSM) and a five-level-five-factor central composite rotatable design (CCRD) were used to evaluate the effects of synthetic variables, such as reaction time (3 to 27 h), temperature (25 to 65 °C), enzyme amount (10 to 50%), substrate molar ratio of citronellol to butyric acid (1∶1 to 1∶3), and added water amount (0 to 20%) on molar percent yield of citronellyl butyrate by direct esterification, using lipase IM77 from Mucor miehei. Reaction time and temperature were the most important variables. Substrate molar ratio had no effect on percent molar conversion. Based on contour plots, optimal synthetic conditions were these: reaction time 24 h, temperature 60°C, enzyme amount 20%, substrate molar ratio 1∶1.5, and added water 0%. The predicted molar conversion value was 100%. An actual experimental value of 98% molar conversion was obtained.     

Enzymatic synthesis of geranyl acetate inn-hexane withCandida antarctica lipases

Geranyl acetate is an important flavor and fragrance compound. Two immobilizedCandida antarctica lipases, SP382 and SP435, were investigated for their use in the synthesis of geranyl acetate by direct esterification. Yields between 95 and 99% molar conversion were obtained with 2 and 15% (w/w reactants) of SP435 and SP382 lipases, respectively. Optimum yields were obtained at 0.1M acetic acid and 0.12M geraniol after 16-h incubation. No inhibitory effect was observed at increasing concentrations of geraniol. Addition of 60% (w/w reactants) water led to 50 and 60% reduction in the esterification activity of SP382 and SP435 lipases, respectively. The best yields were obtained at added water contents between 0–5% (w/w reactants). Solvents with a logP value of 0.85 or more gave reaction yields of more than 80% molar conversion. Higher logP values did not necessarily lead to higher conversion yields. The immobilized lipase SP382 was still active after reusing ten times in the direct esterification reaction.     

对甲苯磺酸铜催化合成丁酸异戊酯

研究了由对甲苯磺酸与氧化铜反应制得的对甲苯磺酸铜作为催化剂,合成丁酸异戊酯,其最佳反应条件为：醇酸物质的量比1．4：1．0,反应时间1．5h,催化剂用量0．2％（以丁酸的物质的量计）,反应温度120～140℃,酯化率达到99％以上。对甲苯磺酸铜制备容易,使用后处理简单,可以重复使用。     

苯磺酸铜催化合成丁酸异戊酯

以苯磺酸铜作催化剂，环己烷作共沸带水剂，由正丁酸和异戊醇制备丁酸异戊酯。着重讨论了该反应的各种影响因素，找出了较佳的反应条件：丁酸0．167mol，n(醇)：n(酸)=1．1：1，催化剂用量为1．0％(以丁酸的摩尔分数计)，反应2．5h，85℃～90℃，环己烷5mL，酯化率可达98．0％。催化剂重复使用了8次，没有出现明显失活现象，酯化率仍达90．2％。     

Synthesis of (Z)-3-hexen-1-yl butyrate in hexane and solvent-free medium using Mucor miehei and Candida antarctica lipases

(Z)-3-Hexen-1-yl butyrate is an important flavor and fragrance compound as it represents the model of a natural herbaceous (green) note. Two immobilized lipases from Mucor miehei (Lipozym IM) and from Candida antarctica (Novozym 435) were investigated for their use in the synthesis of (Z)-3-hexen-1-yl butyrate by direct esterification in n-hexane. To determine optimal conditions for esterification, we examined the following parameters: temperature, amount of lipase, acid/alcohol ratio, and absence of solvent. In n-hexane, bioconversion yields reached 95 (after 4 h) and 92% (after 6 h) for, respectively, Lipozym IM [17 (w/w reactants)] and Novozym 435 [2% (w/w reactants)]. In the absence of solvent, at 60°C, Novozym 435-catalyzed esterification afforded the title compound in 80% yield. Up to 250 g (in hexane) and 160 g (without solvent) of ester were easily prepared, in a single operation, at a laboratory scale, in few hours, using 2% (w/w reactants) lipase.     

Lipase PS-catalyzed transesterification of citronellyl butyrate and geranyl caproate: Effect of reaction parameters

Pseudomonas sp. lipase PS was immobilized by adsorption and tested for its ability to catalyze the synthesis of citronellyl butyrate and geranyl caproate by transesterification in n-hexane. The reaction parameters investigated were: enzyme load, effect of substrate concentration, added water, temperature, time course, organic solvent, pH memory, and enzyme reuse. Yields as high as 96 and 99% were obtained for citronellyl butyrate and geranyl caproate, respectively, with 300 units (approx. 15% w/w of reactants) of lipase PS. Increasing amounts of terpene alcohol inhibited lipase activity, while excess acyl donor (triacylglycerol) concentration enhanced ester production. Optimal yields were obtained at temperatures from 30–50°C after 24-h incubation time. Yields of 90 and 99% were obtained for citronellyl and geranyl esters, respectively, with 2% added water. Solvents with log P values ≥ 2.5 showed the highest conversion yields. pH 7 and 6–8 seemed to be ideal for citronellyl butyrate and geraniol caproate, respectively. The lipase remained active after reusing 12 times.     

硫酸氢钠催化合成丁酸异戊酯

以硫酸氢钠为催化剂，正丁酸与异戊醇为原料合成了丁酸异戊酯。最佳合成条件：以0.2mol正丁酸为基准，醇酸摩尔比1．2，甲苯15mL，催化剂用量2．0g，反应时间30min，酯收率达96．84％。     

Production of geranyl propionate by enzymatic esterification of geraniol and propionic acid in solvent‐free system

Background: This work reports the optimization of geranyl propionate production by esterification of geraniol and propionic acid in a solvent‐free system using a commercial lipase as catalyst. For this purpose, a sequential strategy was performed applying two experimental designs. Results: The operating conditions that optimized geranyl propionate production were determined to be 40 °C, geraniol to propionic acid molar ratio of 3:1, 150 rpm and 10 wt% of enzyme, with a resulting reaction conversion of about 93%. After determining the optimum reaction parameters, a kinetic study was carried out evaluating the influence of substrates molar ratio, enzyme concentration and temperature on reaction conversion. Results obtained in this step allow one to conclude that an excess of alcohol (acid to alcohol molar ratio of 1:6), relatively low enzyme concentration (5 wt%), temperature of 40 °C and substrates molar ratio of 1:1 afforded nearly complete reaction conversion after 30 min of reaction. Conclusion: New experimental data on enzymatic esterification of geraniol and propionic acid for geranyl propionate production are reported in this work, showing a promising perspective of the technique to overcome the well‐known drawbacks of the chemical‐catalyzed route. Copyright © 2010 Society of Chemical Industry     

对甲苯磺酸催化合成丁酸正戊酯

以对甲苯磺酸为催化剂,正丁酸与正戊醇为原料催化合成丁酸正戊酯。较系统地研究了酸醇量比、催化剂用量、带水剂用量及反应时间等条件对收率的影响。结果表明：在固定正丁醇用量为0.2mol的情况下,在n（正丁酸）：n（正戊醇）=1：1.4,催化剂占反应物料总量2.5%,带水剂环己烷的用量为6mL,反应时间2.5h的优化条件下,产品收率可达83.3%。     

Synthesis of monoterpene esters by alcoholysis reaction with Mucor miehei lipase in a solvent-free system

The syntheses of geranyl acetate and citronellyl acetate by alcoholysis reaction catalyzed by immobilized lipase from Mucor miehei was studied for the first time in a solvent-free system. Reactions were carried out at a terpene alcohol/acyl donor molar ratio of 1:5 with Lipozyme at 10% of the total weight of the reactants in a solvent-free system. Incubations were carried out at 55 to 60°C for ethyl and butyl acetates as acyl donors, whereas for methyl acetate the incubation temperature was 40 to 45°C. Excess concentration of acyl donor increases the percentage of geranyl acetate and citronellyl acetate, while excess of terpene alcohol concentration decreases the same. Yields from 75 to 77% molar conversion (90 to 98% conversion, w/w) were obtained after 8 to 28 h of reaction time.     

Pseudomonas sp. lipase-catalyzed synthesis of geranyl esters by transesterification

Pseudomonas sp. lipase was immobilized by adsorption onto five supports and tested for its ability to synthesize geranyl esters by transesterification using short-chain triacylglycerols as acyl donors. Reaction mixtures were prepared in 2 mL ofn-hexane, 0.1 M geraniol, 0.03M triacylglycerol, and 200 units of lipase, and incubated at 30°C and 200 rpm for 24 h. Overall, glass beads were the best support. Geranyl acetate and caproate performed best with Duolite (77.5 and 95.3%, respectively). Geranyl butyrate and caprylate performed best with polyvinylpyrrolidone, (80.2 and 95.5%, respectively). Values for nonimmobilized enzyme also were obtained. Immobilization improved yields, with geranyl caproate exhibiting best results.     

丁酸异戊酯合成工艺研究

以环己烷为带水剂,采用微波辐射技术,在对甲苯磺酸的催化下,快速合成了丁酸异戊酯。探讨了原料配比、反应时间、催化剂用量、微波功率等参数对酯化率的影响。在适宜工艺条件下,酯化率可达99％以上。     

Synthesis of geranyl and citronellyl esters of coconut oil fatty acids through alcoholysis by Rhizomucor miehei lipase catalysis

Synthesis of geranyl and citronellyl esters of mixed fatty acids has been investigated by alcoholysis of coconut oil (CNO) using Rhizomucor miehei lipase. CNO fatty acid esters of geraniol and citronellol have unique mild flavors that can be used in food materials. Both geraniolysis and citronellolysis of CNO produce flavor esters in good yield. Depending on substrate concentration the molar yield is more than 50%. The optimized reaction conditions were: pressure, atmospheric; temperature, 50°C; incubation period, 5 h; and Lipozyme, 10% (w/w).     

壳聚糖硫酸盐催化合成丁酸异戊酯的研究

以壳聚糖硫酸盐作催化剂,丁酸和异戊醇为原料合成了丁酸异戊酯。采用正交实验法对影响反应的因素进行了考察。结果表明,该反应的优化条件为n(醇)∶n(酸)=2.0∶1,催化剂用量为反应混合物总量的1.5%(质量分数),带水剂环己烷15 mL,回流反应60 min,酯化率可达98.4%,并且催化剂可以多次重复使用。     

硫酸锆催化合成丁酸异戊酯的研究

以硫酸锆催化剂催化合成了丁酸异戊酯,确定了酯化反应优化条件。实验结果表明,催化剂的催化活性高,反应条件温和,方法复合,收率优良,催化剂可再生重复使用。     

丁酸异戊酯合成中的催化剂研究

评述了利用硫酸、对甲苯磺酸、氨基磺酸、强酸性阳离子交换树脂、六水三氯化铁、二水二氯化锡、十八水硫酸铝、十二水合硫酸铁铵、一水硫酸氢钠、固体超强酸、杂多酸和沸石分子筛等催化剂催化合成丁酸异戊酯的方法。     

Lipase-catalyzed synthesis of isoamyl butyrate: Optimization by response surface methodology

Immobilized lipase from Mucor miehei (Lipozyme IM-20) was employed in the esterification of butyric acid and isoamyl alcohol to synthesize isoamyl butyrate in n-hexane. Response surface methodology based on five-level, five-variable central composite rotatable design was used to evaluate the effects of important variables—enzyme/substrate (E/S) ratio (5–25 g/mol), acid concentration (0.2–1.0 M), alcohol concentration (0.25–1.25 M), incubation period (12–60 h), and temperature (30–50°C)—on esterification yield of isoamyl butyrate. In the range of parameters studied, the extent of esterification decreased with temperature, lower E/S ratios, and incubation periods. Excess acid and alcohol concentrations (i.e., acid/alcohol >1.4 or alcohol/acid >1.4) were found to decrease yield probably owing to inhibition of the enzyme by acid or alcohol, the former being more severe. The optimal conditions achieved are as follows: E/S ratio, 17 g/mol; acid concentration, 1.0 M; incubation period, 60 h; alcohol concentration, 1.25 M; and temperature, 30°C. With these conditions, the predicted value was 1.0 M ester, and the actual experimental value was 0.98 M.