Showing papers in "Green and Sustainable Chemistry in 2011"

(2-Hydroxyethyl)ammonium Lactates—Highly Biodegradable and Essentially Non-Toxic Ionic Liquids

Abstract: (2-Hydroxyethyl)ammonium lactates have been prepared by reactions of the corresponding (2-hydroxyethyl) amines with lactic acid and characterized by their 1H NMR, IR, and mass spectra. They have been quantita- tively analyzed by HPLC, and their water contents have been determined by the Karl-Fischer method. The title salts are low-melting solids or viscous liquids, and they belong to the class of polar, hydrophilic ionic liquids. The toxicity and chemical and biological degradation of the synthesized ionic liquids have been evaluated by methods described in European Standards. The measurements showed these ionic liquids to be highly biodegradable and only slightly toxic substances. Condensation reactions of benzaldehyde with ethyl cyanoacetate and with acetophenone have been performed in these materials as solvents. The possibility of simultaneously applying these ionic liquids as both solvents and catalysts for the mentioned reactions has been demonstrated, as well as repeated use of the same ionic liquid for a number of condensation reactions without any purification.

Phase-Transfer-Catalyzed Intramolecular Hydroaryloxylation and Hydroamination of C≡C Triple Bonds: An Efficient Synthesis of Benzo[ b ]furan and 3-Methyleneisoindoline-1-one Derivatives

Abstract: Phase-transfer-catalyzed intramolecular cyclization reaction of forming benzo[b]furan and 3-methyleneisoin- doline-1-one derivatives has been developed. The cyclization reaction of propargylic carbonates was also de- scribed under metal-free condition and the reaction was reported by Pd and Ni before. The reaction condi- tions and the scope of the process are examined. The catalysts are cheap and environmentally friendly and the substrates are readily available and the procedure is simple, rapid, and general. The development of C-O and C-N bond formation processes via an overall structural isomerization represents the most atom-eco- nomical approach.

A Green Microwave-Assisted Synthesis of New Pyridazinium-Based Ionic Liquids as an Environmentally Friendly Alternative

Abstract: A green microwave-assisted procedure for the preparation of a series of fifteen new N-alkylpyridazinium ionic liquids with different functionality in the alkyl chain is described. For the first time, target ionic liquids were prepared using standard methodology and under microwave irradiation in short duration of time with quantitative yields. In most cases, the microwave-assisted reaction is an environmentally friendly alternative to traditional methods.

Preparation of α-Bromoketones and Thiazoles from Ketones with NBS and Thioamides in Ionic Liquids

Abstract: Ketones smoothly reacted with NBS in the presence of a catalytic amount of ptoluenesulfonic acid to give α-bromoketones in good yields in typical ionic liquids, such as [bmim]PF6 and [bmpy]Tf2N, and the ionic liquids could be repeatedly used for the same reaction after the extraction of the α-bromoketones. Then, the one-pot conversion of ketones into thiazoles by the treatment with NBS, and subsequently with thioamides could be also carried out in [bmim]PF6 and [bmpy]Tf2N, respectively Thus, [bmim]PF6 and [bmpy]Tf2N could be used as recyclable reaction media for the preparation α-bromoketones and thiazoles from ketones.

Highly Regio-Selective Synthesis of β-Amino Alcohol by Reaction with Aniline and Propylene Carbonate in Self Solvent System over Large Pore Zeolite Catalyst

Abstract: The nucleophilic ring opening of epoxides with amines is a well known route for the synthesis of β-amino alcohols. The use of carbonates offers significant advantages over epoxides as they are far less hazardous materials, safe for handling, do not require high-pressure equipment and most notably the possibility of solvent less reactions. In this work, utilization of zeolite as host catalyst in the reaction media for synthesis of β-amino alcohols without using solvent is reported.

Recovery of In Situ-generated Pd Nanoparticles with Linear Polystyrene

Abstract: Palladium nanoparticles generated in situ for Suzuki coupling reactions and aerobic alcohol oxidation in water were recovered completely using linear polystyrene. The resultant polystyrene-stabilized palladium nanoparticles were shown to be reusable without any loss of activity.

An environmentally Benign Synthesis of 2-Cyanomethyl-4-Phenylthiazoles under FocusedMicrowave Irradiation

Abstract: An improved environmentally benign procedure for synthesis of substituted 2-cyanomethyl-4-phenylthia- zoles under focused microwave irradiation using glycerol as solvent has been carried out. The method allows the synthesis of products in excellent yields with short reaction times and the work-up is easy. This approach can be applied to the preparation of a variety of derivatives.

Cerium (IV) Ammonium Nitrate (CAN) Mediated Reactions IV. A Highly Efficient Synthesis of N,N’-Diarylsubstituted Formamidines in Water at Ambient Temperature

Abstract: A green, simple and highly efficient synthesis of N,N-diarylsubstituted formamidines has been developed employs reaction of triethylorthoformate (TEO) with aromatic amines catalyzed by cerium (IV) ammonium nitrate (CAN) in water at ambient temperature. This method offers the advantages of proceeding under environmentally friendly technique with high yields and simplicity either in conducting the reaction or handling the products.

Asymmetric Reduction of Heteroaryl Methyl Ketones Using Daucus carota

Abstract: Asymmetric reduction of the heteroaryl prochiral ketones to corresponding chiral alcohols by Daucus carota was studied. The study highlights selective bioreduction of different substituted heteroaryl ketones (1a - 1j) to their respective chiral alcohols (2a - 2j) using plant dehydrogenase enzymes present in Daucus carota in good yields (60% - 95%) and enantioselectivity (76% - 99%) with S-form configuration. The results obtained confirm that the membrane bound dehydrogenase enzyme has broad substrate specificity and selectivity in catalyzing both six and five membered heteroaryl methyl ketones. The present methodology demonstrates promising and alternative green route in the synthesis secondary chiral alcohols of biologically importance in a simple, inexpensive and eco-friendly process.

Comparison of Cellulose Decomposition by Microwave Plasma and Radio Frequency Plasma

Abstract: Biomass conversion by plasma has the advantage of mainly producing gaseous products, H2, CO and CO2. Though the thermal plasma has been used for this conversion, the plasma temperature is too high to be unfit for the conversion biomass. The temperature of cold plasma, however, is lower under 3000 K. It expects to be adequate for biomass conversion. Cold plasma can be obtained with irradiation microwave (2.45 GHz) or radio frequency (13.5 MHz) under reduce gas pressure. Therefore, in present study, the effective decomposition of cellulose by microwave plasma (MWP) and radio frequency plasma (RFP) is examined. The conversion of cellulose by MWP (XMWP) is higher than that by RFP (XRFP), irrespective of the reaction time. XMWP and XRFP reach 92.8 wt% at 10 min and 68.1 wt% at 30 min. The maximum yield of gaseous products (Ygas) by MWP is 85.1 wt% at 10 min, higher by 23.2 wt% than Ygas by RFP at 30 min. The amount of H2 and CO obtained by MWP is 18.0 mmol/g and 23.5 mmol/g, it is larger than that obtained by RFP. Comparing the relationship between conversion and yield, Ygas of MWP is slightly higher than that of RFP under X of 60 wt%, and both Ygas is almost same over 60 wt%. The amount of H2 and CO obtained by MWP is larger by 9.3 mmol/g and 9.6 mmol/g than that obtained by RFP. C, H and O element in cellulose is mainly distributed to H2 and CO by MWP. RFP mainly distributes H and O element to the other gases without H2 and CO. In addition, a large amount of C element is remains in the residue. Those results is found that MWP was more suitable for cellulose gasification than RFP, since MWP can highly convert C, H and O element to H2 and CO by higher energy of microwave frequency in comparison with radio frequency.

Cu(II) Extraction in Ionic Liquids and Chlorinated Solvents: Temperature Effect

Abstract: Room temperature ionic liquids have been currently used in liquid/liquid extraction processes in order to substitute conventional organic solvents. In this paper, a series of chlorinated solvents and 1-alkyl-3-me- thylimidazolium-based ionic liquids were selected to study the extraction efficiency of a lipophilic polya- mine 1,1,7,7-tetraethyl-4-tetradecyldiethylenetriamine (TE14DT) towards the model ion Cu(II) in such dif-ferent media. The effect of temperature on the extraction efficiency was also investigated. The metal ion par-tition was found to be strongly dependent on both the nature of the solvent and on the working temperature. The viscosity of ionic liquids and the water content in ionic liquid were found to affect the extraction effi-ciency of TE14DT. The chemical nature of the cation of ionic liquids, and in particular the alkyl chain length on imidazolium ring, also seemed to be important in determining the efficiency of the extraction process. Finally, preliminary experiments on back-extraction of Cu(II) ions from ionic liquid also revealed interesting hints to the development of a continuous transport process.

Poly Ethylene Glycols as Efficient Media for the Synthesis of β-Nitro Styrenes from α, β-Unsaturated Carboxylic Acids and Metal Nitrates under Conventional and Non-Conventional Conditions

Abstract: Poly ethylene glycols (PEG-200, 400, 600, 4000 and 6000) supported reactions were conducted with certain α, β-unsaturated acids in presence of metal nitrates under solvent free (solid state) and mineral acid free conditions. The reactants were ground in a mortar with a pestle for about 30 minutes. The aromatic acids underwent nitro decarboxylation and afforded β-nitro styrene derivatives in very good yield while α, β-unsaturated aliphatic carboxylic acids gave corresponding nitro derivatives. Addition of PEG accelerated rate of the reaction enormously. Reaction times substantially decreased from several hours to few minutes followed by highly significant increase in the product yield. Among the several PEGs PEG-300 has been found to be much more effective than other PEGs.

Lipophilic Optical Supramolecular Nano Devices in the Aqueous Phase

Abstract: Nano micelles of sodium dodecyl sulphate in water were prepared as local lipophilic media for the organisation of interacting chromophores. Such arrangements were controlled by peripheric substituents to operate either as isolated chromophores or as skew oriented pairs where H-type transitions cause hysochromic absorption and J-type transitions bathochromic fluorescence. As a consequence, large Stokes' shift could be obtained.

Simple and Practical Aerobic Oxidation of Alcohols Catalyzed by a (μ-Oxo)tetraruthenium Cluster *

Abstract: A (μ-oxo)tetraruthenium cluster showed high catalytic activity for a simple and practical aerobic oxidation of alcohols to aldehydes and ketones under 1 atm of O2 or air. After the reaction, this cluster catalyst was re- covered from the reaction mixture, and we believe that this (μ-oxo)tetraruthenium cluster acts as an active catalytic species throughout the reaction.

Degradation and Detoxification of Banana Postharvest Treatment Water Using Advanced Oxidation Techniques

Abstract: The elimination and detoxification of water contaminated with the principal commercial fungi-cides—thia- bendazole (Textar 60 T) and imazalil sulphate (Fruitgard IS 7.5)—used in the postharvest treatment of bananas was successfully achieved through the use of advanced oxidation processes (AOPs). The techniques tested were heterogeneous photocatalysis with TiO2 and TiO2-activated carbon (TiO2-CA) and Fenton and photo-Fenton processes. The evolution of fungicide concentration during degradation was studied together with mineralization and toxicity levels. When treated with any of the methods under study, the water meets the conditions stipulated by the legislation currently in force for its reuse in irrigation. However, this study proposes that the Fenton process is the best option for treatment of this type of water due to the efficiency of its reactions and its low economic cost.

The Synergy of Combined Use of DMSO and Bronsted Acid (Ionic Liquid) as a Catalyst ——Part I: Efficient Niementowski synthesis of modified quinazolinones

Abstract: A new rapid and versatile approach using Ionic liquid/DMSO as a chemical reagent for the synthesis of fused heterocyclic compounds in a highly efficient way is described. This method offers the advantages of proceeding in neutral conditions, giving high to excellent isolated yields (83–92%) for Niementowski synthesis with easy workup procedure. The inherent Bronsted acidity of ionic liquid and high polarity of both IL and DMSO resulted in a significant enhancement in the reaction rate.

An Efficient and Rapid Synthesis of 2-Amino-4-Arylthiazoles Employing Microwave Irradiation in Water

Abstract: A facile, high yielding green chemical synthetic protocol adaptable to the parallel synthesis of a library of potentially bioactive 2-amino-4-arylthiazoles is reported herein. The methodology involves the condensation of various aracyl bromides with N-arylthioureas under MWI using water as solvent, to yield pure products (81%-97%) in very short reaction times (1-20 min).

Combination of Transition Metals-(2,4-Pentanedionate) and P2O5 as a Regioselective Catalytic System for Nitric Acid Nitration of Ar-Himachalene

Abstract: A practical system of metals-(2,4-pentanedionate) (M(acac)n (M= Fe, Zn, Co and V)) and P2O5 in the pres- ence of HNO3 catalyzes regioselective nitration of ar-himachalene 1 to mono-nitro-ar-himachalene 2 in mod- erate to high yields. Under mild conditions, the selectivity of nitration of 1 to 2 is excellent compared to the classical method using the nitro-sulphuric mixture HNO3/H2SO4, both mono- and di-nitro-ar-himachalene 2 and 3 are obtained. The reaction offers a very good method for the preparation of nitro-aromatic compounds and provides a useful entry to new functionalized terpenic products.

Solar Thermochemical Reactions IV: Unusual Reaction of Nitrones with Acetonitrile Derivatives Induced by Solar Thermal Energy

Abstract: The behaviour of cyanothioacetamide 1 and the acetonitrile derivatives 6 and 10, respectively, towards the nitrones 2a-i induced by free solar thermal energy is reported. Structures and reaction mechanisms are also discussed.

Preparation of BiVO4@Fiber Composites and the Photocatalytic Property for Degradation of Organic Dyes under Visible-Light

Abstract: In this article, a novel BiVO4@fibers composite photocatalyst was prepared by a process that monoclinic scheelite BiVO4 nano/micro particles were in situ formated onto fiber materials. The structure, morphology and photophysical properties of the composite materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis diffuse reflectance spectroscopy, respectively. The immobilization of BiVO4 photocatalyst on fibers reduced the particle size of the photoactive phase, and a few visible-light absorption abilities. The decomposition of a non-biodegradable dye Red FN-3G was selected to examine the photocatalytic activity of the composite photocatalyst. It was found that the formation of composite materials of BiVO4 with fibers didn’t decrease the photocatalytic activity with comparison to that of pure BiVO4. Moreover, it demonstrated that when adjusting the dye solution into about pH = 3, the highest efficiency of dye degradation over the fiber composite material can be obtained.

Resolution of Alcohol Racemate by Oil

Abstract: Vegetable oil was successfully used as solvent and acyl donor in the kinetic resolution of several secondary alcohol racemates yielding high enantioselectivities. Using vegetable oil as solvent and acyl donor allowed easy separation of the pure alcohol enantiomer by extraction with methanol, by distillation under reduced pressure, or by column chromatography.

Selective and Clean Cyclohexene-Promoted Oxidation and Photooxidation by Air

Abstract: A simple and environmentally friendly selective procedure for cyclohexene-promoted photooxidation of p-xylene, ethylbenzene, and cumene by air in the presence of a pristine or oxidized carbonaceous material is reported. Depending on the catalyst and conditions, the reaction yields either of the following industrially important products: 4-methylbenzyl hydroperoxide, 4-methylbenzoic acid, 1-phenylethyl hydroperoxide, 2-phenyl-2-propanol, acetophenone with high selectivity and practical extent of conversion. Exposure the reaction mixture to ambient light further increased the yields. Improved performance of oxidized graphite has demonstrated the potential of surface modification for the design of novel carbonaceous catalysts.

Eco-friendly Synthesis of Cyclododecanone from Cyclododecatriene

Abstract: An eco-friendly synthesis of cyclododecanone (CDON) from cyclododecatriene (CDT) is described. Selec- tive epoxidation of CDT with hydrogen peroxide using hexadecyl trimethyl ammonium heteropolyphospha- totungstate [(n-C16H33NMe3)3PW4O16, HAHPT] as catalyst and water as solvent followed by the hydrogena- tion on Raney nickel catalyst gave cyclododecanol (CDOL). The latter was oxidized with hydrogen peroxide using HAHPT as catalyst and a mixture of water and t-butanol as solvent to afford CDON. The total yield was 53.4% under the optimum reaction conditions.

Synthesis of Novel Bis-enaminones by KHSO4-assisted Facile Michael Addition-elimination Reaction of 3-(dimethylamino)-1-phenylprop-2-en-1-ones with Diamines in Water

Abstract: 3-(Dimethylamino)-1-phenylprop-2-en-1-ones (formylated acetophenones) 1 reacted with aliphatic diamines in water assisted by KHSO4 to give bis-enaminones 2a-h in good yields. Compound 1 also reacted with o-phenylenediamine under similar conditions to produce bis-enaminones 3 instead of benzodiazepines 4 in excellent yields.

Anaerobic Biotransformation of Nitro-Compounds to Amines by Bovine Rumen Fluid

Abstract: Microorganims of the bovine rumen fluid biocatalyzed the reduction of nitro-compound substrates to yield the respective amines. This enzymatic process, using ruminal contents, has rarely been reported in associa- tion with the bioreduction of nitro groups. The biotransformation reactions catalyzed by this system were de- pendent of both the electronic characteristics and the area/volume of the nitro-substrates confirming the processes are enzymatic. The semi-preparative scale biotransformation went by in good yield showing the rumen fluid may be employed in the synthesis of amines under very mild conditions and, moreover, it may have application in the bioremediation of nitro-compounds.

Solar Thermochemical Reactions IV: Unusual Reaction of Nitrones with Acetonitrile Derivatives Induced by Solar Thermal Energy

Abstract: The behaviour of cyanothioacetamide 1 and the acetonitrile derivatives 6 and 10, respectively, towards the nitrones 2a-i induced by free solar thermal energy is reported. Structures and reaction mechanisms are also discussed.

Efficient Isolation of an Anti-Cancer Sesquiterpene Lactone from Calomeria amaranthoides by Steam Distillation

Abstract: An efficient method of isolating an anti-cancer sesquiterpene lactone, eremophila-1(10)-11(13)-dien-12,8?- olide, was developed from fresh Calomeria amaranthoides plant material on the basis of its non-polar vola-tile property. Steam distillation of fresh plant material gave a high recovery of sesquiterpene-rich oil, 0.56%, compared with the estimated 0.66% calculated from solvent extraction of dried plant material. The ses-quiterpene-rich oil containing 58% of the sesquiterpene lactone was fractionated by the short-column vac-uum chromatography method, using minimal stationary-phase and solvent, to give the sesquiterpene lactone 95% purity, yield 41%.

Halogen Exchange in Near-Critical Water

Abstract: Bromoaromatics are ubiquitous in chemistry, and their manufacture is often wasteful. Halogen exchange under hydrothermal conditions constitutes a viable alternative for their synthesis in some cases. The prepara-tion of 1,2-dibromobenzene and 1-bromo-2-chlorobenzene from 1,2-dichlorobenzene, by treatment with hy-drobromic acid in hydrothermal media at temperatures ranging from 240?C to 320?C was investigated as a viable alternative to de novo synthesis. The effects of temperature, exchange duration and the presence of Fe3+ salts on product yields are discussed. Yields for both targeted haloarenes of up to 37% and 48%, respec-tively, were achieved, with very limited formation of 1,3- and 1,4-dihalobenzene isomers. A mechanism for halogen exchange was proposed.