Goals Of Green Chemistry Research Articles

Ultrasound-assisted, low-solvent and acid/base-free synthesis of 5-substituted 1,3,4-oxadiazole-2-thiols as potent antimicrobial and antioxidant agents.

One of the goals of green chemistry is to use environmentally friendly solvents or remove and reduce the volume of harmful spent solvents. In this study, a novel process for the synthesis of 5-substituted 1,3,4-oxadiazole-2-thiol derivatives was proposed via ultrasound-assisted reaction of aryl hydrazides with CS2 (1:1 molar ratio) in some drops of DMF in the absence of basic or acidic catalysts. They were produced in good to excellent yields under easy workup and purification conditions. In order to prove the usefulness of the prepared compounds, their antioxidant, antibacterial, and antifungal potentials were screened by DPPH free radical scavenging, serial twofold microdilution and streak plate methods. Acceptable to significant inhibitory activities were observed with synthesized heterocycles. The results showed that 5-(4-fluorophenyl)-1,3,4-oxadiazole-2-thiol (3c) is an broad-spectrum antimicrobial agent. Many of them displayed remarkable antioxidant properties comparable to standard controls (ascorbic acid and α-tocopherol). Synthesized 1,3,4-oxadiazoles are also potent candidates to treat cancer, Parkinson, inflammatory, and diabetes diseases. Eighteen 5-substituted 1,3,4-oxadiazole-2-thiol derivatives as potent antimicrobial and antioxidant agents were prepared via a new, efficient and green procedure.

GREEN PESTICIDES (ADVANTAGES AND PROBLEMS OF IMPLEMENTATION)

Currently, the excessive use of pesticides has caused environmental problems and become a subject of deep reflection, both for the public and for scientists. Since pesticides are harmful to ecosystems and human health, there is a need to study pesticides that meet the goals of green chemistry to varying degrees, meaning they are safe, effective and biodegradable with minimal environmental disturbance. The implementation of biopesticides is a new and advanced tool for creating natural products safe for humans and the environment. This makes the commercial appeal of green pesticides interesting, but their introduction raises questions on the development of a system of safety criteria and regulation.

Green Chemistry: Principles, Applications, and Disadvantages

This work provides an overview on applicability of 12 principles of green chemistry. Green chemistry is a term that indicates the creation of chemical products and procedures that reduces the use and production of harmful materials. The goals of green chemistry for protecting the environment can be achieved via several main directions. Some of them are bio-catalysis, use of alternative repeatable raw materials (biomass), alternative reaction solution (such as ionic liquids, supercritical fluids, water), alternative reaction circumstances (microwave activation) as well as to new photocatalytic reactions. Moreover, keep natural resources on earth without using harmful materials is the main objective of green chemistry. By changing patterns of consumption and production, steps are being taken to decrease the pollution and harmful waste, which considered being one of the important goals of green chemistry. Also, it was found that, it is so serious to develop alternative technologies that are safer for both human health and the environment to prevent any further damage to human health and the environment such as reducing release of dangerous chemicals to air leading to reduce damage to lungs. In addition, design safer chemical found to be a good opportunity to improve some chemical methods via producing cleaner and cheaper products in industrial processes when harmful chemicals are replacing with biological enzymes. For all the reasons outlined here, in this review, 12 principles of green chemistry are outlined with their applications, where shows how green chemistry reduces the impact of chemical processes on the environment and how their benefit can be achieved. And, also disadvantages of 12 principles are discussed, as well.

Investigation of the carbon dioxide adsorption behavior and the heterogeneous catalytic efficiency of a novel Ni-MOF with nitrogen-rich channels.

MOFs have attracted remarkable attention as solid sorbents in CO2 capture processes for their low-energy post-combustion. In this paper, a new Ni-based MOF, Ni4(TATB)1.5(EtO)3.5(NEt3)4, was synthesized and characterized using various physicochemical techniques. The efficiency of the as-prepared Ni-MOF as a solid sorbent for CO2 capture was investigated, and acceptable adsorption was exhibited. Furthermore, this Ni-MMOF was used as a catalyst in toluene selective oxidation, for eliminating a volatile organic compound, with tert-butyl hydroperoxide as an oxidant in the absence of organic solvents. The obtained results indicated that Ni-MOF has good catalytic activity and could be reused three times without considerable loss of its catalytic activity. This study highlights the great potential of developing MOFs to achieve green chemistry goals with the removal of hazardous liquid and gas compounds such as toluene and CO2.

Deep eutectic solvent an efficient reaction medium for the synthesis of chromeno pyrazolo and indazolo phthalazine derivatives

AbstractThe volatile, harmful and hazardous solvents have impact on human health, all organisms and environment. To reduce the use of hazardous volatile solvents, there is need to develop the alternative green reaction medium for organic transformations and is the main goal of green chemistry. The green solvent should be nonvolatile, nontoxic, biodegradable and biorenewable. Considering these parameters, herein, we have reported an efficient and environmentally benign green synthesis of chromeno pyrazolo and indazolo phthalazine derivatives in deep eutectic solvent. The present protocol contains excellent yield of the product, short reaction time, operation simplicity, reusability of solvent and no need of further purification.

Targeted Development of Sustainable Green Catalysts for Oxidation of Alcohols via Tungstate-Decorated Multifunctional Amphiphilic Carbon Quantum Dots.

Achieving green and sustainable chemical processes by replacing organic solvents with water has always been one of the green chemistry goals and a challenging topic for chemists. However, the poor solubility of organic materials is a major limitation to achieving this goal, especially in alcohol oxidation. In this contribution, the development and design of amphiphilic catalysts via abundant, safe, cheaper, and more biocompatible sources have received notable attention. To this purpose, herein, our group successfully synthesized a new multifunctional amphiphilic carbon quantum dot (CQD) composed of 1-aminopropyl-3-methyl-imidazolium chloride ([APMim][Cl]), dodecylamine (DDA), and citric acid (CA) (denoted as CQDs@DDA-IL/Cl) using a one-pot hydrothermal route. The CQDs@DDA-IL/Cl was then utilized as an amphiphilic stabilizer for anchoring tungsten ions using an anion-exchange method (marked as CQDs@DDA-IL/W). The CQDs@DDA-IL/W as a reusable catalyst selectivity mediated the oxidation of alcoholic substrates with stoichiometric H2O2 in water solvent. The extraordinary performance of our catalyst was attributable to the coexistence of ionic liquid (IL) and DDA upon the surface of the CQDs@DDA-IL/W, which plays a main duty in the hydrophobic/hydrophilic balance, and significantly increase the catalyst compatibility in the aqueous medium with the purpose of removing organic solvents. As a result, the great mass transfer occurs in the two-phase medium using this amphiphilic nanocatalyst without any phase transfer catalyst (PTC) or other additives. The 100% selectivity, excellent turnover number (TON) and turnover frequency (TOF), high yield, almost complete and fast conversion of alcohol to the desired aldehydes and ketones without more oxidation, and easy and no-trouble isolation of product and catalyst are outstanding features of this catalytic system.

Determination of Cr(III) and Cr(VI) in water by dual-gel electromembrane extraction and a microfluidic paper-based device

A major goal of green chemistry is to avoid the use of toxic organic solvents. In particular, there are few green methods allowing extraction and quantification of chromium species in environmental samples. Here, we developed home-made, dual-gel electromembrane extraction combined with a microfluidic paper-based analytical device for the simultaneous determination of Cr(III) and Cr(VI) in water, without using any organic solvent. The positively charged Cr(III) and negatively charged Cr(VI) migrated selectively into the cathodic (pH 2.0) and anodic (pH 3.0) aqueous acceptor phases, respectively. After extraction, the anodic acceptor phase containing Cr(VI) was analyzed directly by a microfluidic paper-based analytical device, after the addition of the diphenylcarbazide colorimetric reagent. The cathodic acceptor phase containing Cr(III) was mixed with Ce(IV) to oxidize Cr(III) to Cr(VI), and then, Cr(VI) ions were detected on the microfluidic paper-based analytical device after adding diphenylcarbazide. Under the optimized conditions, limits of detection of 2.0 and 3.0 ng/mL and extraction recoveries of 58.8% and 83.3% were achieved for Cr(VI) and Cr(III), respectively.

In vitro and in silico protein corona formation evaluation of curcumin and capsaicin loaded-solid lipid nanoparticles

Nanotechnology has been an important tool for the production of nanoparticles with controlled release of drugs for therapeutic applications. Here, we produced solid lipid nanoparticles (SLN) loaded with curcumin and capsaicin (NCC) following the overarching goals of green chemistry. Currently, besides evaluating the composition, and size of these, it is necessary to understand the interactions between nanoparticles and the biomolecules present in the biological medium. For this, assays were conducted in order to evaluate the potential formation of the protein ‘corona’, and to better understand the results obtained in vitro, we also performed an interaction study, in silico, between the NCC components and the main serum protein, albumin. In the first hour of contact between the NCC and the culture medium showed fluctuation in the diameter of the NCC. However, after 24 and 48 h of the incubation period, all NCC concentrations showed an increase in size, which can be attributed to plasma protein adsorption. Since, hard corona takes a few seconds, while the soft corona can be formed in minutes up to a few hours. On the other hand, best docking binding-poses of interaction for the formed docking complexes evaluated suggest interactions following the docking affinity like free energy FEB (Tween 80-bovine serum albumin) ≈ FEB (Span 80-bovine serum albumin) showing a pharmacodynamic pattern based in non-covalent hydrophobic interactions with the bovine serum albumin binding-site. Our in silico results clarify and reinforce our in vitro findings of corona formation, which represents the real interaction with cell membranes in vivo.

Palladium‐Containing and Metal‐Free Supported Dendrons As Catalysts in Multistep Conversion of Oxygenates to Fuels

AbstractThis article reports a three‐step process: 1) the hydrogenation of phenol, 2) aldol condensation between the cyclohexanone produced in reaction 1 and an aldehyde, and 3) hydrogenation of the aldol reaction product. This is achieved using palladium containing supported dendrons for reactions 1 and 3 and non‐metal containing supported dendrons for reaction 2. Palladium/dendron‐OMS catalyzes the phenol hydrogenation with a cyclohexanol yield of 85 %, the parent dendrons (no Pd) catalyze the Aldol reaction with over 80 % yield in some cases, and the Pd‐dendron samples can be used to hydrogenate the aldol coupling product at high yields, not dissimilar from what one observes from aqueous phase reforming (APR). The operating conditions of low temperature and low‐pressure hydrogen in aqueous media are consistent with green chemistry goals.

Ni@Zeolite-Y Nano-Porous: Preparation and Application as a High Efficient Catalyst for Facile Synthesis of Quinoxaline, Pyridopyrazine, and Indoloquinoxaline Derivatives

In this research, by a simple and modified method, nanoporous of Ni(II) ion loaded Y-type zeolite (NNZ) was designed and applied as a novel highly efficient catalyst for the synthesis of quinoxalines, pyrido[2,3-b]pyrazines, and indolo[2,3-b]quinoxalines 3a-s. These heterocycles were obtained through a one-pot condensation reaction of aryl-1,2-diamines with 1,2-diketones or the isatin in the presence of catalytic amount of Ni@zeolite-Y in ethanol or acetic acid at room temperature giving good to excellent yield. The structure of entitled catalyst was identified with FT-IR spectroscopy, Energy Dispersive X-ray (EDX), Scanning Electron Microscopy (SEM) and Brunauer-Emmett-Teller (BET) analysis. This method has some advantages such as the use of inexpensive, safety, stable and recyclable catalyst, high yields, short reaction times, and easy isolation of the product. It can be claimed that this approach in simplicity covers the goals of green chemistry.

Fe3O4@BNPs@SiO2-SO3H as a highly chemoselective heterogeneous magnetic nanocatalyst for the oxidation of sulfides to sulfoxides or sulfones.

To achieve green chemistry goals and also to reduce the cost of catalysts as well as to avoid producing toxic wastes and show the importance of separation and recycling of catalysts from the reaction medium, in this work, we describe the preparation and characterization of magnetic acidic boehmite nanoparticles as a heterogeneous catalyst, which is called Fe3O4@BNPs@SiO2–SO3H. This catalyst works efficiently in the selective oxidation of sulfides to sulfoxides or sulfones in the presence of H2O2 as a green oxidant. It can easily be separated from the reaction medium by using an external magnet and it was recycled 6 times without loss of magnetic catalytic properties.

Ionic Liquids for Clean Biocatalytic Processes

Background: Biocatalysis has many attractive features in the context of green chemistry, due to the high efficiency of chemical transformations and the renewable character of the enzymes used. Since the beginning of this century, ILs have emerged as exceptionally interesting non-aqueous reaction media for biotransformations because of their unique solvent properties, headed by their negligible vapour pressure and their exceptional ability to maintain enzymes in active and stable conformations. However, the goal of green chemistry is much more than simply replacing hazardous solvents with environmentally benign ones, and it is necessary to devise new clean methodologies that will fulfil the sustainable requirements for efficient transformations of substrates, product recovery and the reuse of all the elements of the reaction system. Results: The use biocatalyst in IL/scCO2 biphasic systems was the first approach forward to develop integral green chemical processes in non-aqueous environments. The combination of these sustainable tools provides synergies in both biocatalyst performance (i.e. improved activity and enantioselectivity, enhanced stability, etc.), and the genuine separation technologies of nearly pure products. Sponge-Like Ionic Liquids (SLILs) were recently reported as a new platform for green biocatalytic chemical processes using straightforward technologies. These SLILs are a new class of hydrophobic ILs based on cations with long alkyl side-chains (e.g. 1-octadecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, ([C18mim][NTf2], etc.), which behaves as a sponge-like system by switching from liquid to solid phase as the temperature changes. Thus, such ILs are able to dissolve (“soak up”) hydrophobic compounds as a liquid phase, and products can then be “wrung out” by centrifugation of the resulting solid phase after cooling. Based on this property, clean biocatalytic processes for the production of nearly pure compounds of high added value (e.g. geranyl acetate, anisyl acetate, biodiesel, monolaurin, etc.) can be easily designed by the coupling of both biotransformation and separation steps, in a sustainable approach of high potential for practical applications at industrial level. Conclusions: The use of biocatalytic approaches in green non-conventional reaction media holds much promise for the development of a sustainable chemical manufacturing industry. The combination of enzymes with multiphase neoteric systems (SLILs, ILs and/or scCO2) should be explored in the near future, as a clear strategy for developing integral new green multi-catalytic synthetic processes of industrial interest (e.g. pharmaceutical drugs). Keywords: Biocatalysis, clean processes, ionic liquids, sponge-like ionic liquids, green chemistry, terpene, biodiesel, anisyl acetate, lipases.

Fe3O4@chitosan‐bound picolinaldehyde Cu complex as the magnetically reusable nanocatalyst for adjustable oxidation of sulfides

As ecological and environmental demands for sustainability are one of the most strategic landscapes in the green chemistry, recent chemical researches have been directed toward eco‐friendly catalysts. Further advancement in this area has presented magnetically recoverable nanocatalyst. Herein, Cu‐based nanocatalyst was synthesized via reaction of picolinaldehyde and amine group of immobilized chitosan on the magnetic nanosupport, and followed by metallation. The prepared nanocatalyst was characterized by a variety of techniques. FT‐IR analysis demonstrated the favored coating of chitosan‐based Cu complex over Fe3O4 nanoparticles. The scanning electron microscopy and transmission electron microscope techniques confirmed nano‐sized of the catalyst. Fe3O4 nanoparticles and the nanocatalyst fit the X‐ray diffraction pattern of standard magnetite. High thermal stability of the nanocatalyst was determined by the TGA analysis. The inductively coupled plasma atomic emission analysis technique specified content of Cu was 0.62 mmol/g. Magnetic properties were analyzed by the vibrating sample magnetometer study. Regarding green chemistry goals, the applicability of this nanocatalyst was tested in the oxidation of sulfides derivatives. The nanocatalyst exhibited high catalytic activity and selectivity in the oxidation of sulfides to the corresponding sulfoxide (without over‐oxidation of sulfides to sulfones) under green conditions. Based on the magnetic properties (alluded to the Fe3O4 component), the nanocatalyst could be easily recovered from the reaction mixture using an external magnet, and reused up to four times without noticeable deterioration in its performance. Moreover, the other merits such as high yields, mild reaction condition, use of stable and green oxidant and eco‐friendly procedure made this nanocatalyst as a valuable catalyst in practical synthesis. © 2017 American Institute of Chemical Engineers Environ Prog, 37: 1626–1631, 2018

Air Quality of the Black Sea Region: Local and Long Range Transported Pollutants

Catalysis has manifested its role as a fundamental tool in pollution prevention. While catalysis has long been utilized in increasing efficiency, yield, and selectivity, it is now also recognized as accomplishing a wide range of green chemistry goals. Air pollutants produced by industrial and man-made emissions possesses a unique property that it could affect regional and global receptors. Measuring and defining the levels of pollutants and its sources whether it is local, regional or global should precede the precautions and measures that should be taken to reduce the levels of a particular pollutant. In this article the air quality at the Black Sea region of Turkey is being discussed. Moreover, it endeavors to locate the possible sources of the different pollutants at local, regional and long range transported scales. About 196 rainwater samples were collected over the Black Sea region of Amasra between 1995-1999 and analyzed for major and trace ions. Although statistical tools do provide information on the type of sources and processes affecting the site, they do not provide information on where these sources are located. A back trajectory has to be included in the evaluation to incorporate geographical information in analytical results. To compute the PSCF for each ion the back trajectories were computed using ECMWF model, which is an isentropic 3-D model. Then number of 1 hour-long segment of the 3.5 daylong trajectories in each defined sub-region is determined. This study shows that, the Black Sea region receives different amounts and types of anthropogenic pollutants via long-range transport according to trajectory models. The highest PSCF values for H + are calculated for central Europe and Russia have fairly high contribution to observed free acidity in our samples. The main source areas for SO 4 2- were found to be central Europe and Northwestern Turkey (Marmara region or Istanbul–Kocaeli industrial area). Normal 0 false false false RU X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Обычная таблица; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:8.0pt; mso-para-margin-left:0cm; line-height:107%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:Calibri,sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:Times New Roman; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;} Catalysis has manifested its role as a fundamental tool in pollution prevention. While catalysis has long been utilized in increasing efficiency, yield, and selectivity, it is now also recognized as accomplishing a wide range of green chemistry goals. Air pollutants produced by industrial and man-made emissions possesses a unique property that it could affect regional and global receptors. Measuring and defining the levels of pollutants and its sources whether it is local, regional or global should precede the precautions and measures that should be taken to reduce the levels of a particular pollutant. In this article the air quality at the Black Sea region of Turkey is being discussed. Moreover, it endeavors to locate the possible sources of the different pollutants at local, regional and long range transported scales. About 196 rainwater samples were collected over the Black Sea region of Amasra between 1995-1999 and analyzed for major and trace ions. Although statistical tools do provide information on the type of sources and processes affecting the site, they do not provide information on where these sources are located. A back trajectory has to be included in the evaluation to incorporate geographical information in analytical results. To compute the PSCF for each ion the back trajectories were computed using ECMWF model, which is an isentropic 3-D model. Then number of 1 hour-long segment of the 3.5 daylong trajectories in each defined sub-region is determined. This study shows that, the Black Sea region receives different amounts and types of anthropogenic pollutants via long-range transport according to trajectory models. The highest PSCF values for H+ are calculated for central Europe and Russia have fairly high contribution to observed free acidity in our samples. The main source areas for SO 4 2- were found to be central Europe and Northwestern Turkey (Marmara region or Istanbul–Kocaeli industrial area). Normal 0 false false false RU X-NONE X-NONE <w:LsdException Locked=false Priority=

Capillary electrophoresis method for the simultaneous determination of carbohydrates and proline in honey samples

A capillary electrophoresis method with indirect UV detection for the simultaneous determination of three carbohydrates (fructose, glucose and sucrose) and the amino acid proline in honey samples was developed. This method included the use of a background electrolyte consisting of 10mM sodium benzoate and 1.5mM cetyltrimethylammonium bromide, pH12.4. Under optimal capillary electrophoresis conditions, the separation of the investigated substances was achieved in less than 5min and single dilution of each sample was employed. The detection limits for fructose, glucose and sucrose were 0.58gL−1, 0.67gL−1 and 0.12gL−1 respectively, and 0.72mgL−1 for proline. Precision measurements calculated in terms of %RSD in the range of 0.92 to 5.43%, were obtained. The proposed method was applied to honey samples from Argentina and Sweden and enables the determination of the three carbohydrates and the amino acid proline. The results show that the proposed method is simple, requires short analysis times, low consumption of reagents and sample, minimum waste and that there is no need to perform any sample pre-treatment. This method is a good alternative to carry out the quality control of honey samples. Finally, it is a promising methodology for achieving green chemistry goals.

Metal-cellulose catalytic systems for biodiesel preparation and reductive stabilization

Development of green processes is of the most important field of today’s research, with direct impacts on future generations, contributing to environmental and economic technologies. In this sense, the use of biomass is an attractive way in search of the green chemistry goals. This manuscript presents the modification of cellulose in order to complex tin, palladium and nickel cations, and the use of the obtained material as a catalyst for biodiesel preparation and partial hydrogenation. Reactions yields for soybean transesterification and hydrolysis and soybean fatty acids esterification using Sn (II) complexed with modified cellulose rendered yields up to 55%, 93% and 95%, respectively. Partially hydrogenation leading to monounsaturated chains were achieved using palladium and nickel derivatives under mild conditions (10bar; 80°C). These highly efficient catalytic systems could be recovered at the end of the process and reused without any loss of catalytic activity.

The chronic effects of lignin-derived bisphenol and bisphenol A in Japanese medaka Oryzias latipes

One of the ultimate goals of green chemistry is to produce greener and more environmentally friendly chemicals to replace the existing toxic chemicals. In this study, Japanese medaka were exposed to 1.5mg/L of bisphenol A or lignin-derived bisphenol for 60 days, and the expressions of various biochemical markers, effects on reproduction, and histopathology were evaluated. The results showed that concentrations of liver vitellogenin of LD-BP exposed males were approximately 125% higher compared to the control males. Total number of eggs from the BPA and LD-BP exposed fish was approximately 47% (p<0.001) and 25% (p<0.05) less than the control fish, respectively. Total number of brood was lower from the BPA (46%, p<0.05) and LD-BP (17%, p<0.05) exposed fish than that of the control fish. Relative to the control fish, catalase and glutathione-S-transferase were significantly affected by the two chemicals in all tested tissues. BPA and LD-BP caused lipid peroxidation in all the tested tissues. Furthermore, acetylcholinesterase and α-glucosidase activity were significantly inhibited. Histopathological analysis showed that both the testis and ovary were mildly damaged by both chemicals. LD-BP affected medaka slightly more severe than BPA except on the reproduction, which was most likely due to different uptake, translocation, binding to targets and metabolism. Our results demonstrated that chronic exposure to both chemicals caused several adverse effects to medaka. Further research on the toxicity of LD-BP to other aquatic organisms is needed before substitution of traditional BPA with LD-BP can be recommended.

N-Propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride-SBA-15 (SBA-DABCO) as basic mesoporous catalyst for the synthesis of 1,4-dihydropyridine hetrocyclic compounds

Regarding the green chemistry's goals, the development of mesoporous silica materials as attractive candidates in the search for supporting of catalysts is currently a subject of increasing interest. Therefore, in the present research n-propyl-4-aza-1-azoniabicyclo[2.2.2]octane chloride-SBA-15 (SBA–DABCO) was used as a basic catalyst for the synthesis of 1,4-dihydropyridine (DHP) derivatives from one pot, three-component condensation of aromatic aldehydes, ammonium acetate and ethylacetoacetate under solvent-free at 80°C. This method offers several advantages, including high yield, short reaction time, simple work-up procedure, ease of separation and recyclability of the catalyst, as well as the ability to tolerate a wide variety of substitutions in the reagents.

Reducing Isozyme Competition Increases Target Fatty Acid Accumulation in Seed Triacylglycerols of Transgenic Arabidopsis

One goal of green chemistry is the production of industrially useful fatty acids (FAs) in crop plants. We focus on hydroxy fatty acids (HFAs) and conjugated polyenoic FAs (α-eleostearic acids [ESAs]) using Arabidopsis (Arabidopsis thaliana) as a model. These FAs are found naturally in seed oils of castor (Ricinus communis) and tung tree (Vernicia fordii), respectively, and used for the production of lubricants, nylon, and paints. Transgenic oils typically contain less target FA than that produced in the source species. We hypothesized that competition between endogenous and transgenic isozymes for substrates limits accumulation of unique FAs in Arabidopsis seeds. This hypothesis was tested by introducing a mutation in Arabidopsis diacylglycerol acyltransferase1 (AtDGAT1) in a line expressing castor FA hydroxylase and acyl-Coenzyme A:RcDGAT2 in its seeds. This led to a 17% increase in the proportion of HFA in seed oil. Expression of castor phospholipid:diacylglycerol acyltransferase 1A in this line increased the proportion of HFA by an additional 12%. To determine if our observations are more widely applicable, we investigated if isozyme competition influenced production of ESA. Expression of tung tree FA conjugase/desaturase in Arabidopsis produced approximately 7.5% ESA in seed lipids. Coexpression of VfDGAT2 increased ESA levels to approximately 11%. Overexpression of VfDGAT2 combined with suppression of AtDGAT1 increased ESA accumulation to 14% to 15%. Our results indicate that isozyme competition is a limiting factor in the engineering of unusual FAs in heterologous plant systems and that reduction of competition through mutation and RNA suppression may be a useful component of seed metabolic engineering strategies.

Sulfonic acid-functionalized silica-coated magnetic nanoparticles as an efficient reusable catalyst for the synthesis of 1-substituted 1H-tetrazoles under solvent-free conditions.

Regarding green chemistry goals, silica-coated magnetite nanoparticles open up a new avenue to introduce a very useful and efficient system for facilitating catalyst recovery in different organic reactions. Therefore, in this paper the preparation of sulfonic acid-functionalized silica-coated magnetic nanoparticles with core-shell structure (Fe3O4@silica sulfonic acid) is presented by using Fe3O4 spheres as the core and silica sulfonic acid nanoparticles as the shell. The catalyst was characterized by infrared spectroscopy, scanning electron microscopy, X-ray diffraction analysis, dynamic light scattering, thermogravimetric analysis and vibrating sample magnetometry. Nanocatalyst can be recovered using an external magnet and reused for subsequent reactions 6 times without noticeable deterioration in catalytic activity.