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1.
Maha Karra-Chaabouni Sylviane Pulvin Didier Touraud Daniel Thomas 《Journal of the American Oil Chemists' Society》1998,75(12):1201-1206
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. 相似文献
2.
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. 相似文献
3.
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. 相似文献
4.
对甲苯磺酸铜催化合成丁酸异戊酯 总被引:6,自引:0,他引:6
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。 相似文献
5.
6.
S. Bourg-Garros N. Razafindramboa A. A. Pavia 《Journal of the American Oil Chemists' Society》1997,74(11):1471-1475
(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. 相似文献
7.
Lisa N. Yee Casimir C. Akoh Robert S. Phillips 《Journal of the American Oil Chemists' Society》1997,74(3):255-260
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. 相似文献
8.
9.
Natália Paroul Luana Paula Grzegozeski Viviane Chiaradia Helen Treichel Rogério L. Cansian J. Vladimir Oliveira Débora de Oliveira 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(12):1636-1641
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 相似文献
10.
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%。 相似文献
11.
12.
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. 相似文献
13.
14.
Lisa N. Yee Casimir C. Akoh Robert S. Phillips 《Journal of the American Oil Chemists' Society》1995,72(11):1407-1408
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. 相似文献
15.
16.
B. K. De T. Chatterjee D. K. Bhattacharyya 《Journal of the American Oil Chemists' Society》1999,76(12):1501-1504
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). 相似文献
17.
18.
硫酸锆催化合成丁酸异戊酯的研究 总被引:10,自引:0,他引:10
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。 相似文献
19.
丁酸异戊酯合成中的催化剂研究 总被引:3,自引:1,他引:3
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。 相似文献
20.
S. Hari Krishna B. Manohar S. Divakar N. G. Karanth 《Journal of the American Oil Chemists' Society》1999,76(12):1483-1488
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. 相似文献