SO_4~(2-)/Sb_2O_3/SiO_2复合固体超强酸催化合成乙酸异戊酯

以乙酸和异戊醇为原料,固体超强酸SO24-/Sb2O3/SiO2作催化剂,催化合成乙酸异戊酯。考察了醇酸比、催化剂用量、反应温度与反应时间对酯化反应的影响。结果表明,乙酸异戊酯的最佳合成条件为:n(异戊醇)∶n(乙酸)=1.4∶1,催化剂用量为1.2 g,反应时间4 h,反应温度108~112℃,在此条件下酯化率可达95.7%。并用IR手段对产品进行了确证。     

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.     

Chemically Mediated Host-Plant Selection by the Milfoil Weevil: A Freshwater Insect–Plant Interaction

The milfoil weevil Euhrychiopsis lecontei is a specialist aquatic herbivore that feeds, oviposits, and mates on the invasive freshwater macrophyte Myriophyllum spicatum. We characterized the weevil's preference for M. spicatum, and through bioassay-driven fractionation, isolated and identified two chemicals released by M. spicatum that attract E. lecontei. Mass spectrometry and nuclear magnetic resonance spectroscopy were used to identify the attractive compounds as glycerol and uracil. Dose-response curves for glycerol and uracil indicated that weevil preference increased as sample concentration increased. Weevils were attracted to a crude sample of M. spicatum-released chemicals from 0.17 to 17 mg/l, to glycerol from 18 to 1800 μM (0.0017–0.17 mg/l), and to uracil from 0.015 to 15 μM (0.00014–1.4 mg/l). Although glycerol and uracil are ubiquitous, weevils are likely responding to high concentrations that are released as a result of the rapid growth of M. spicatum. Uracil concentration was greater in the exudates of M.spicatum than other Myriophyllum spp. E. lecontei was attracted to glycerol at a concentration similar to that at which terrestrial insects are attracted to sugar alcohols. This is the first example of a freshwater specialist insect being attracted to chemicals released by its host plant. Analysis of the water milfoil–weevil interaction provides further understanding as to how insects locate their host plants in aquatic systems.     

Optimization of the enzymatic production of isoamyl acetate with novozym 435 from candida antarctica

In this study the production of isoamyl acetate by esterification of isoamyl alcohol and acetic acid was carried out using immobilized C . antarctica lipase (Novozym 435) as a catalyst without any organic solvent. The esterification yield was optimized with response surface methodology. This method was used with four parameters to evaluate the effects of important variables on the esterification yield. The parameters are acid/alcohol mole ratio (0.2-0.8), enzyme amount (4-12%, w/w), temperature (30-50 °C), and reaction time (4-8 hr). It was found that the most effective parameter was acid/alcohol mole ratio. As acid/alcohol mole ratio increased at any given reaction time and amount of enzyme, ester concentration, C p (mmol ester/g mixture), increased up to an acid/alcohol mole ratio of 0.7 and thereafter decreased. The model indicated the optimum conditions for maximum esterification (3.45 mmol ester/g mixture) in the acid/alcohol mole ratio of 0.52 for 8.15% enzyme at 43.2 °C and after 5.27 hr, which were in good agreement with the experimental value (3.5 mmol ester/g mixture).     

Comparison of bio- and autocatalytic esterification of oils using mono- and diglycerides

The purpose of this study was to investigate enzymatic and autocatalytic esterification of FFA in rice bran oil (RBO), palm oil (PO), and palm kernel oil (PKO), using MG and DG as esterifying agents. The reactions were carried out at low pressure (4–6 mm Hg) either in the absence of any added catalyst at high temperature (210–230°C) or in the presence of Mucor miehei lipase at low temperature (60°C). The reactions were carried out using different concentrations of MG, and the optimal FFA/MG ratio and time were 2∶1 (molar) and 6 h, respectively, in both auto- and enzyme-catalyzed processes. With DG as the esterifying agent in the autocatalytic process, the optimal temperature was 220°C, and the optimal FFA/DG ratio was 1∶1.25. For both MG and DG, the enzymatic process was more effective in reducing FFA and produced more favorable levels of unsaponifiable matter and color in the final product. The PV of the final products were also lower (1.8–2.9 mequiv/kg) by using the enzymatic process. To produce edible-grade oil, a single deodorization step would be required after enzymatic esterification; whereas, alkali refining, bleaching, and deodorization would be required after autocatalytic treatment.     

固体超强酸在酯化反应中的应用

以Ti(OC4H9)4为原料,采用溶胶-凝胶法制备固体超强酸SO42-/WO3-TiO2,以SO42-/WO3-TiO2为催化剂,通过丁酸与异戊醇反应合成丁酸异戊酯。讨论了影响酯化率的主要因素,实验结果表明,当WO3在催化剂中的质量分数为3.0%,催化剂用量为0.6 g,醇酸摩尔比为1.5∶1,反应温度为125℃,反应时间为4.0 h时,平行实验的平均酯化率可达95.1%。该工艺具有催化剂价廉易得,催化效果好,用量少,操作简单,三废少,收率高等优点。     

对甲苯磺酸催化合成丁酸异戊酯的工艺研究

以对甲苯磺酸为催化剂,正丁酸与异戊醇为原料合成了丁酸异戊酯,讨论了醇酸物质的量比、催化剂用量、反应时间、带水剂等因素对酯化率的影响,确定了最佳工艺条件为：以0．2mol正丁酸为基准,醇酸物质的量比为1．5：1,催化剂用量为0．5g,反应时间为2h,带水剂环己烷为7．5mL,丁酸异戊酯的酯化率为95．8％。该催化剂具有催化活性高,使用量少,酯化率高,与目前工业中使用的硫酸相比,环境污染小,对设备几乎无腐蚀等优点,且对甲苯磺酸价格低廉易得,性质稳定,使用方便,是一种很有发展前景的催化剂。     

氯化铁催化合成丁酸异戊酯的研究

氯化铁作为丁酸和异戊醇的催化剂，性能优于硫酸，探讨了较好的反应条件，酯化率可达９１．６％。     

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.     

Phytotoxic Effects of Leukamenin E (an ent-kaurene diterpenoid) on Root Growth and Root Hair Development in Lactuca sativa L. seedlings

Leukamenin E, an ent-kaurene diterpenoid isolated from Isodon racemosa (Hemsl) Hara, showed phytotoxic effects on root growth and root hair development of lettuce seedlings (Lactuca sativa L.). Lower concentrations (10 μM) of leukamenin E did not affect root growth, but at concentrations higher than 50 μM, the rate was inhibited. The influence of leukamenin E on root growth rate was closely correlated with alterations in the mitotic index. A low incidence of aberrant mitosis image was observed when lettuce roots were treated with higher concentrations (100 and 200 μM) of leukamenin E. This suggests that inhibition of root growth may be due to inhibition of cell division. All tested concentrations of the diterpenoid (10 μM or more) inhibited root hair development in a dose-dependent manner. At a concentration of 80 μM, leukamenin E completely blocked root hair initiation. Application of Ag⁺—an ethylene action inhibitor—to lettuce seedlings inhibited root hair elongation similar to the diterpenoid. Enhanced root hair length was stimulated by exogenous ethephon—an ethylene-releasing agent—and could be reversed by addition of leukamenin E. This suggests that leukamenin E may act as a potential ethylene action antagonist in the inhibition of lettuce root hair development. We conclude that leukamenin E may curb root hair development by interfering with ethylene action at concentrations above 10 μM and inhibits root growth via inhibition of cell division at concentrations above 50 μM. Lan Ding and Linlin Qi contributed equally to this work.     

纳米固体超强酸SO_4（2-）/Fe_2O_3催化合成正丁酸异戊酯的研究

采用纳米固体超强酸SO42-/Fe2O3为催化剂,以正丁酸和异戊醇为原料,催化合成正丁酸异戊酯。较适宜反应条件为：正丁酸150 mmol,n（酸）∶n（醇）=1∶1.2,催化剂300 mg（占反应物总量1%）,于150-160℃回流反应3 h,产率达96.30%。     

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.     

The influence of water on the synthesis of n-butyl oleate by immobilizedMucor miehei lipase

The influence of initial water concentration on the synthesis of n-butyl oleate was investigated. The synthesis was done with immobilizedMucor miehei lipase—Lypozyme^™—at various reaction conditions. The activity of the enzyme is lower at higher amounts of water. Initial reaction rates, as well as equilibrium conversion, increase at low initial water concentration. Optimal water concentration for the activity of immobilized lipase is temperature dependent at the pressure of 1 bar. Low initial water concentration barely effects equilibrium esterification at 0.032 bar. At high initial water concentrations equilibrium conversion, as well as initial reaction rates, decrease at both pressures.     

Enzymatic esterification of (−)-menthol with fatty acids in solvent by a commercial lipase from Candida rugosa

Esterification of (−)-menthol with fatty acids in isooctane was successfully catalyzed using a commercial lipase, Lipase AY “Amano” 30 from Candida rugosa in original powder form. The esterification reactions were performed to elucidate the effects of temperature, enzyme load, molar ratio of (−)-menthol/fatty acid, and fatty acid type, keeping the (−)-menthol concentration at 200 mM. At the optimal conditions for (−)-menthol esterification, determined at a (−)-menthol/lauric acid molar ratio of 1∶1 and 35°C [1.5 g enzyme/g (−)-menthol, 0.1 g molecular sieves], the molar conversion of (−)-menthol after 48 h reached 93%. After 24h, the lowest and the highest molar conversions of fatty acids at 2∶1 molar ratio were obtained with myristic acid (71%) and margaric acid (98%), respectively. After 48 h, the molar conversions of lauric acid at molar ratios 2∶1, 1∶1, and 1∶2 were 98, 93, and 49%, respectively.     

Production of 15-, 16- and 17-hydroxy-9-octadecenoic acids by bioconversion of oleic acid withBacillus pumilus

SeveralBacillus strains were tested for their ability to hydroxylate oleic acid. Two strains—BD-174 and BD-226—converted oleic acid into a trio of hydroxy-octadecenoic acids. Bioconversion in 72–120 hr produced 5–11% of hydroxy acids relative to oleic acid as measured by gas chromatography. These acids were identified as the 15-, 16- and 17-hydroxy-9-octadecenoic acids by gas chromatography-mass spectrometry of trimethyl silyl derivatives of the product acids and their hydrogenated counterparts.     

Variation in fatty acid composition of the different acyl lipids in seed oils from fourSesamum species

Seeds from different collections of cultivatedSesamum indicum Linn. and three related wild species [specifically,S. alatum Thonn.,S. radiatum Schum and Thonn. andS. angustifolium (Oliv.) Engl.] were studied for their oil content and fatty acid composition of the total lipids. The wild seeds contained less oil (ca. 30%) than the cultivated seeds (ca. 50%). Lipids from all four species were comparable in their total fatty acid composition, with palmitic (8.2–12.7%), stearic (5.6–9.1%), oleic (33.4–46.9%) and linoleic acid (33.2–48.4%) as the major acids. The total lipids from selected samples were fractionated by thin-layer chromatography into five fractions: triacylglycerols (TAG; 80.3–88.9%), diacylglycerols (DAG; 6.5–10.4%), free fatty acids (FFA; 1.2–5.1%), polar lipids (PL; 2.3–3.5%) and steryl esters (SE; 0.3–0.6%). Compared to the TAG, the four other fractions (viz, DAG, FFA, PL and SE) were generally characterized by higher percentages of saturated acids, notably palmitic and stearic acids, and lower percentages of linoleic and oleic acids in all species. Slightly higher percentages of long-chain fatty acids (20∶0, 20∶1, 22∶0 and 24∶0) were observed for lipid classes other than TAG in all four species. Based on the fatty acid composition of the total lipids and of the different acyl lipid classes, it seems thatS. radiatum andS. angustifolium are more related to each other than they are to the other two species.     

Film materials with controlled release of biologically active substances

The properties of spun composites containing polyvinyl alcohol, a proteolytic enzyme (protease C or Terrilytin) and the high-molecular-weight antimicrobial polyhexamethyleneguanidine hydrochloride were investigated. The effect of the composition of the spinning compositions and spinning temperature on the properties of the film materials — the activity, stability, and rate of release of biologically active substances — was investigated. The possibility of obtaining polyvinyl alcohol films with controlled release of biologically active substances was demonstrated. Translated from Khimicheskie Volokna, pp. 44–48, September–October, 1998.     

杂多酸(盐)催化合成肉桂酸异戊酯的研究

以杂多酸（盐）为催化剂,３Ａ分子筛为脱水剂,肉桂酸和异戊醇为原料合成肉桂酸异戊酯,考察了醇酸比、催化剂种类、催化剂用量、反应时间对酯产率的影响。结果表明,在肉桂酸用量为０１ｍｏｌ情况下,用ＡｌＰＷ１２Ｏ４０为催化剂,催化剂用量为１００ｇ,醇酸摩尔比为２５∶１,反应时间３ｈ,反应温度１３５～１４０℃是最适宜的反应条件。酯产率超过９６％。     

Component triacylglycerols of six seed oils of malvaceae

The component triacylglycerols of six seed oils of the Malvaceae family—Gossypium barbadense (Egyptian cotton),Hibiscus cannabinus (kenaf),Hibiscus sabdarifa (roselle), two varieties ofHibiscus esculentas (okra) andAlthea rosea (ketmia, hollyhock or Egyptian hemp)—have been determined by using the lipase hydrolysis technique. The oils were found to contain triacylglycerols belonging to trisaturated (1.0–2.1), disaturated-monounsaturated (12.3–20.9), monosaturated-diunsaturated (42.3–46.6) and triunsaturated (30.1–44.2) types of triacylglycerols.     

环境友好催化合成邻苯二甲酸二异戊酯

将无机盐经 4 5 0℃焙烧制得一种不溶于水的新型固体酸催化剂T 4 5 0 ,吸附吡啶的红外光谱表明 ,催化剂表面形成了新的Bronsted酸中心。该催化剂对邻苯二甲酸酐和异戊醇的酯化活性高 ,无副反应。并得到合成DIAP的环境友好催化新工艺条件如下 :异戊醇0 5mol,邻苯二甲酸酐 0 2mol,催化剂 1g ,反应温度 185℃ ,反应时间 180min ,在此条件下收率可达 97%以上 ,且催化剂易回收 ,具有良好的重复使用性能。