An original transesterification route for fatty acid ester production from vegetable oils in a solvent-free system

Wax ester production from a long-chain alcohol and methyl ester has been investigated with an immobilized thermostable lipase (lipozyme IM from Novo Nordisk). The transesterification reaction rate was monitored in solvent-free medium that was exclusively composed of the reactants and the enzyme. The transesterification is performed by simply mixing the two substrates in various stoichiometric amounts at a temperature range from 55 to 65°C under constant stirring in the presence of low concentrations of enzyme preparation (0.12 to 2%, w/w). Long-chain reactants produce waxes of high molecular mass that induce low solubility and high viscosity. On average, high transesterification yields are obtained (around 95%). Thermodynamic parameters involving substrate concentration and temperature have also been investigated. The balance between optimal working temperature and the molar ratio of substrates in such a complex medium appears to be 60°C, with a molar ratio methyl oleate/stearyl alcohol of 1:0.5. Substrate inhibition due to stearyl alcohol has been observed. A study of kinetic parameters has confirmed these results.     

Optimization of citrus peels D-limonene extraction using solvent-free microwave green technology

Attention is presently drawn to the development of a new and green alternative technique for the extraction of essential oil from citrus plant materials. This study was aimed at the extracting essential oil from orange and lemon peels using solvent-free microwave method. This process uses microwave-assisted hydro-diffusion technique to extract essential oil from citrus peels. Response surface methodology was used to investigate the effect of microwave power (200–1,000?W) and extraction time (10–40?min) on the essential oil yield. The oil extracted was characterized using Fourier transform infrared radiation (FTIR) and Gas chromatography–mass spectrometry analysis to determine the functional groups and chemical components present, respectively. The optimum yield of extract from orange and lemon peels were 3.7 and 2.0%, respectively at corresponding power of 1,000?W and time of 10?min. The analysis of variance results showed that the resulting models for both orange and lemon peels were significant and microwave power had greater influence on the extraction processes at both linear and quadratic levels. The FTIR analysis revealed prominent functional groups of alkenes that majorly constitute limonene compound at 1,642 and 1,643?cm^?1 for orange and lemon peels, respectively. The present process permits fast and efficient extraction, avoids water and solvent consumption, and allows substantial energy savings.     

Polyvinylpolypyrrolidone-Supported Chlorosulfonic Acid: An Efficient Catalyst for One-Pot Synthesis of Dihydropyrimidinones and Octahydroquinazolin-2,5-diones

Polyvinylpolypyrrolidone-supported chlorosulfonic acid has been successfully applied to perform one-pot reaction of arylaldehydes, urea, ethylacetoacetate, or cyclic 1,3-diketo compounds under solvent-free condition at 70°C to provide a series of dihydropyrimidinones and octahydroquinazolin-2,5-diones in good to excellent yields. The method offers several advantages such as high yield, short reaction time, simple workup, easy preparation, and reusability of the catalyst. The [PVPP-SO₃H]⁺Cl^? catalyst was characterized via Fourier transform infrared spectroscopy (FT-IR) and thermal gravimetric analysis (TGA). Moreover, the catalyst could be recycled several times without significant loss of its catalytic activity. Clean methodologies, easy work-up procedure, high yield, and simple preparation of the catalyst are some advantages of this article.     

壳聚糖基固体酸催化果糖合成5-羟甲基糠醛

以壳聚糖为原料,采用一步水热碳化和磺化法合成壳聚糖基固体酸材料(CASA),并将其用于催化无溶剂条件下果糖脱水合成5-羟甲基糠醛(5-HMF),考察了催化剂用量、反应温度、反应时间及催化剂循环利用次数对脱水反应的影响,并与甲壳素基固体酸材料(CISA)进行了催化性能比较。采用X射线衍射、扫描电镜、吡啶吸附红外光谱对CASA材料进行了结构和酸性质表征,建立了催化剂结构与性能的关系。结果表明,CASA材料含有大量的表面强Br?nsted酸性位点,因而其催化性能较CISA突出;当m(果糖)∶m(CASA)=6∶1、120℃反应5 h时,5-HMF的收率高达63.2%,且CASA可重复利用4次而无明显失活。     

无溶剂环氧涂料的抗阴极剥离性能

研究了环氧涂层抗阴极剥离性能的主要影响因素,结果表明,涂料自身性能、表面处理状况以及阴极保护电位均对涂层的抗阴极剥离性能产生影响。     

水滑石高效催化缺电子烯与胺类的共轭加成反应

The novel efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. A series of hydrotalcite-like materials were synthesized as catalyst for the conjugate addition of amines and alkenes. After optimizing the reaction conditions, ZnAl-LDHs (3︰1) was chosen as the best catalyst for the reaction. The results showed that the catalyst worked very well for the conjugate addition of amines to electron deficient alkenes with the excellent yields in several minutes. Operational simplicity, no solvent, low cost of the catalyst, high yields, reusability, excellent chemoselectivity, wide applicability are the key features of this method.     

微波辐射四氯化锡催化无溶剂合成7-羟基-4-甲基香豆素

以间苯二酚和乙酰乙酸乙酯为原料,以五水四氯化锡为催化剂,采用微波辐射技术,无溶剂合成7-羟基-4-甲基香豆素。探索了不同反应条件对产率的影响。结果表明:当n(间苯二酚)∶n(乙酰乙酸乙酯)为1∶0.8,反应温度为115℃,五水四氯化锡为2.6 g(间苯二酚为0.15 mol),辐射时间为16 min,辐射功率为500 W时,产率可达80.6%。     

无溶剂下微波辐射合成阿魏酸

以香草醛为反应底物,丙二酸为试剂,醋酸铵为催化剂,采用微波辐射技术,经Knoevenagel-Doebner反应,在无溶剂条件下合成了阿魏酸。研究了酸、醛和醋酸铵用量,微波功率和辐射时间对阿魏酸收率的影响。得到较佳工艺条件为:40 mmol香草醛、48 mmol丙二酸、4.8 mmol醋酸铵,微波功率400 W,辐射15 min。在此条件下产率为86.9%,阿魏酸的质量分数超过98%。     

软包装用无溶剂型聚氨酯复膜胶的发展概况

综述了国内外软包装用无溶剂型聚氨酯(PU)复膜胶的发展概况,并针对其面临的主要问题提出了今后的发展方向。随着人们对环保要求日趋严格,绿色环保的无溶剂型复膜胶必将在复合软包装行业中得到迅速而广泛的应用。     

3-乙酰基-4-羟基苯甲酸的合成及正交工艺优化

以4-乙酰氧基苯甲酸甲酯为原料,经无溶剂的Fries重排法合成了3-乙酰基-4-羟基苯甲酸,并对其结构进行了表征.采用L9(34)正交实验,考察了物料投料比、反应温度和反应时间等参数对目标产物收率的影响,并对重排反应机理进行了探讨.结果表明,3-乙酰基-4-羟基苯甲酸的最佳合成工艺为:n(4-乙酰氧基苯甲酸甲酯):n(...