Synthesis of green nanocatalysts and industrially important green reactions

Abstract

There is a growing interest in applying green chemistry for nanocatalysis applications. On the basis of a Scifinder Scholar search, the field of applying green chemistry to catalysis with nanoparticles has undergone an explosive growth from year 2002 to present. It can be seen that green chemistry applied to nanocatalysis is a relatively hot area with much room for growth. I discuss several review articles written about the use of green nanocatalysts as well as green reactions. I discuss studies involving the synthesis of green nanocatalysts and application of metal nanocatalysts in green reactions. I have organized the discussion of green nanocatalysts by the type of nanoparticles that are synthesized and used as catalysts. I have organized discussions of green reactions by the type of green reaction that is being conducted. Overall, our review article discusses developments in new types of green nanocatalysts as well as developments in green catalytic reactions.     

Naturally derived green bio-additives

During the last few years, special attention has been paid by the lubricant industry towards vegetable oil-based lubricants due to their biodegradability, renewability and excellent tribological properties. But to maintain the biodegradability of the final lubricants, the additive in the lubricants must also be biodegradable. Hence, in our present work, multifunctional lubricating oil additive based on castor oil has been investigated as a less toxic, feasible alternative to traditional petroleum based additives. Homopolymer of castor oil and its copolymer with α-pinene were synthesized by a thermal method using azobisisobutyronitrile as a radical initiator. Characterization of the prepared polymers was performed by spectral analysis and gel permeation chromatography (GPC). Additive performances of each of the prepared polymers as viscosity index improvers/viscosity modifiers and pour point depressants were carefully evaluated. Photo micrographic image was used to study the effectiveness of the additives as pour point depressants. Thermogravimetric analysis (TGA) was conducted to investigate the thermal response of the additives at high temperature. Finally, biodegradability of all the polymers was tested against fungal pathogen by the disc diffusion method and soil burial test. The study illuminated excellent additive performances of the polymers and thus their potential for acting as entirely naturally derived green bio-additives for lube oil.     

Deconstructing green fluorescent protein

Green fluorescent protein (GFP) has been reassembled from two pieces, a large fragment 214 amino acids in length that is produced recombinantly (GFP 1-10) and a short synthetic peptide corresponding to the 11th stave of the beta-barrel that is 16 amino acids long (synthetic GFP 11), following a system developed by Waldo and co-workers (Cabantous, S.; et al. Nat. Biotechnol. 2005, 23, 102-7) as an in vivo probe for protein association and folding. We demonstrate that the reassembled protein has identical absorption and excited-state proton transfer dynamics as a whole protein of the identical sequence. We show that the reassembled protein can be taken apart and the peptide replaced with a different synthetic peptide designed to perturb the chromophore absorption. Thus, this semisynthetic reassembly process offers a general route for studying the assembly of the beta-barrel as well as the introduction of unnatural amino acids.     

Production of malachite green oxalate and leucomalachite green reference materials certified for purity

Malachite green oxalate (MG oxalate) and leucomalachite green (LMG) have been prepared and certified as pure reference materials. The purities of MG oxalate and LMG were assessed by high-performance liquid chromatography–diode array detection (HPLC–DAD), nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry (DSC), Karl Fischer titration, ashing and thermogravimetric analysis (TGA). MG oxalate was purified by supercritical fluid extraction (SFE). Prior to purification, commercial MG oxalate purity was estimated to be about 90%. The main impurities present in SFE-purified MG oxalate were identified and quantified using HPLC–DAD. The main impurities were found to be monode-MG (monodemethylated MG oxalate synthesis impurity), 4-(dimethylamino)benzophenone (4-DMABP), MG-carbinol and LMG. The homogeneity of both reference materials was also determined. Issues associated with the stability of LMG and MG oxalate in solution forced an extensive study investigating different parameters i.e. solvent, acid, analyte concentration and temperature. MG oxalate (100 μg/mL) was found to be stable in acetonitrile containing 1% v/v glacial acetic acid for at least 155 days and LMG (100 μg/mL) was stable in acetonitrile for at least 133 days. The final purity value for MG oxalate was 94.3 ± 1.4% m/m at the 95% confidence interval (or 67% m/m if MG cation is reported). For LMG, the certified purity was found to be 98.8 ± 0.8% m/m at the 95% confidence interval. Figure Calibration reference materials for malachite green and leucomalachite green, certified for purity, are essential in characterising these key analytes in a fish matrix reference material     

Some aspects of green solvents

Chemical solvents constitute around 80% of the total volume of chemicals used in many important chemical processes, especially fine chemical manufacturing. Unfortunately, these solvents are often volatile organic compounds from petroleum resource bearing several health and environmental risks. Numerous researchers take these two aspects as a reason to search for novel green solvents to replace the conventional ones. As a consequence, there are an increasing number of publications dealing with green solvents. In this review, we discuss the definition and accuracy of the term “green solvent”. We explain our urgent request for application-oriented research in this field. Finally, we point out some promising and interesting kinds of solvents, solvent systems and solubilization concepts for a successful research towards “greener solvents”.     

Pectin from green kenaf bast

A technology is proposed for obtaining from kenaf bast and flax bast a food pectin the physicochemical indices of which correspond to proposed requirements.Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 193–197, March–April, 1995. Original article submitted October 18, 1994.     

基于离子液体的绿色催化过程

离子液体为构建绿色催化反应过程提供了新途径.本文简要评述了离子液体在几个代表性催化反应中的研究进展,如CO2羰基化、烷基化、酯交换、氧化、CO2加氢、共聚以及PET降解等;分析讨论了离子液体的特点和优势,如提高反应活性、降低废物排放以及简化分离等,并对离子液体催化反应的未来发展方向进行了展望.     

免标记比色核酸适配体传感器同步快速检测孔雀石绿和无色孔雀石绿

研究以双特异性核酸适配体A3作为传感探针、纳米金（AuNPs）为指示剂、NaCl溶液为聚集诱导剂,构建了一种新型的免标记AuNPs比色生物传感器,可实现水产品中孔雀石绿（MG）和无色孔雀石绿（LMG）的同步、快速、可视化检测。该方法的检测原理是核酸适配体A3对MG和LMG有双特异性识别能力,可作为MG和LMG理想的识别受体。它可通过静电作用吸附到AuNPs表面,保护AuNPs并抑制高盐溶液诱导的聚集,AuNPs溶液颜色不变,即为红色;当加入靶标MG或LMG后,该核酸适配体能够与靶标特异性结合,并从AuNPs表面上解离,AuNPs失去保护作用而在高盐溶液诱导下发生聚集,溶液颜色由红变蓝。根据颜色变化,可通过肉眼定性或通过光谱仪定量分析MG和LMG的残留量。该方法首先将50 μL的核酸适配体A3（终浓度150 nmol/L）与150 μL的AuNPs（终浓度1.25 nmol/L）混合,室温孵育6 min。随后加入50 μL待测液,室温孵育30 min。最后加入50 μL NaCl（终浓度150 mmol/L）,4 min后观察溶液颜色变化,并分别测定MG和LMG在520 nm和650 nm下的吸光度值。结果表明,在最佳反应条件下,该方法能够特异性检测MG和LMG,而对磺胺嘧啶（SDZ）和硝基呋喃妥因（NFT）无交叉反应;当MG、LMG的浓度为0~17.5 μmol/L时,吸光度比值与靶标浓度呈现良好的线性关系,相关系数（R ² ）分别为0.9938和0.9715。MG和LMG的检出限分别为6.93 nmol/L和6.38 nmol/L,加标回收率分别为88.60%~93.30%和101.80%~107.00%,相对标准偏差（RSD）分别为2.27%~3.55%和2.62%~3.75%。该方法操作简单,快速和灵敏,可为水产品中MG和LMG的同步快速检测提供一种新方法。     

The effects of cooking on residues of malachite green and leucomalachite green in carp muscles

The effects of various cooking methods (boiling, baking and microwaving) on residues of malachite green (MG) and its major metabolite, leucomalachite green (LMG), in incurred carp muscles were investigated. Moreover, the stability of MG and LMG standard solutions under boiling in water and in oil was examined. The MG and LMG residues in cooked meat were determined by liquid chromatography with visible and fluorescence detectors. The results showed that in muscles cooked by boiling or baking MG concentration was reduced by 54% in 15 min while LMG was stable in these conditions. By microwave cooking MG residues were reduced by 61% after 1 min. Microwaving was the only method of cooking when a loss of LMG was observed (40% in 1 min). Both MG and LMG standard solutions were stable in boiling water at 100 degrees C. In cooking oil, MG was reduced by 49% after 10 min and less than 3% of the original MG remains after 90 min at 150 degrees C. No losses of LMG were observed over a time period of 120 min in cooking oil at 150 degrees C. Upon increasing the temperature to 210 degrees C and holding for 120 min, MG was rapidly reduced by 97% after 10 min. LMG under the same conditions was reduced by 18% after 10 min. No further loses of MG and LMG were observed after 120 min. The findings of this investigation show that the high temperature does not guarantee a full breakdown of residue of MG and LMG which may occur in carp muscles.     

Dried biomass of green algae and its matrix matching with green parts of higher plants

Literature data for the content of matrix elements in dry biomass of green algae have been compared with those for green parts of higher plants. The data were evaluated by means of frequency histograms and box-and-whisker plots. With two exceptions (Fe, P), the spread of the data values for a given element was broader for higher plants than for algae. Distribution of the data was asymmetric, in most cases with long right-hand tails. All outliers found (average 5.6% for algae, 9.1% for higher plants) lay above the bulk of the data values. In all cases, there was either partial or (mostly) complete overlap of the ranges for algae with those for higher plants. While the question of matrix-matching of reference materials prepared from algal biomass with samples from green parts of higher plants can exhaustively be answered only after a similar comparison of the composition of matrix compounds, the content of the main matrix elements is certainly not doubtful.     

Nanomaterials and catalysis for green chemistry

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聚甲基丙烯酸钠辅助的金纳米颗粒的绿色制备

利用聚甲基丙烯酸钠的弱还原性和螯合作用,建立了一种水溶性金纳米颗粒合成的新方法.借助紫外可见分光光度计和透射电子显微镜对金纳米颗粒进行了表征,初步讨论了反应物浓度以及反应温度对产物的影响.     

Three-phase electrochemistry for green ethylene production

The electrochemical conversion of greenhouse gases (mainly CO₂ and CH₄) into ethylene has attracted worldwide attention. Compared with thermal cracking and dehydrogenation ethylene production processes, electrochemical ethylene production is an energy-saving and environmentally friendly process with high atom and energy economies. Great efforts have been made in enhancing the performance of electrochemical CO_x reduction and alkane dehydrogenation reactions in recent years. The complicated interactions between gas reactants, electrolytes, and catalysts force the three-phase interface mass transfer process an important issue in determining the electrochemical activity and product selectivity. Herein, we summarize the recent progresses on electrochemical ethylene production. Special attention has been paid to the principles for the design of gas–liquid–solid and gas–solid–solid three-phase interfaces and their influence on the electrochemical CO_x reduction and alkane dehydrogenation reactions. The comprehensive understanding of those different ethylene production reactions together from the perspective of the three-phase interface-related mass transfer process would provide new insights into the design of advanced electrochemical cells for green ethylene production.