Showing papers in "Green Chemistry in 2002"

TL;DR: Ionic liquids, defined here as salts with melting temperatures below 100 °C, evolved from traditional high temperature molten salts and were observed as far back as the mid 19th century.

TL;DR: Several ionic liquids appear as an alternative to conventional organic solvents, providing comparable or higher rates and, in some cases, improved enantioselectivity.

TL;DR: This paper explores several metrics commonly used by chemists and compares and contrasts these metrics with a new metric known as reaction mass efficiency and uses an economic analysis of four commercial pharmaceutical processes to understand the relationship between metrics and the most important cost drivers in these processes.

TL;DR: In this paper, a series of low-cost ionic liquids containing methyl and ethyl-sulfate anions can be easily and efficiently prepared under ambient conditions by the reaction of 1-alkylimidazoles with dimethyl sulfate and diethyl sulfate.

TL;DR: New families of quaternary ammonium, 1-methyl-3-alkylimidazolium dicyanamide (dca, N(CN)2−) anion are reported in this paper.

TL;DR: In this paper, the authors present a halogen-free and relatively hydrolysis-stable ionic liquid, 1-n-butyl-3-methylimidazolium ([bmim]) [n-C8H17OSO3].

TL;DR: A short summary of possible methods for the preparation of immobilised ionic liquids (ILs) is presented in this article, where the differences in the resulting heterogeneous catalysts are discussed and examples for the use of these catalysts in organic reactions are given.

TL;DR: In this article, a number of small molecules were simulated in dimethylimidazolium chloride at 400 K and the local structure was analyzed through ranked radial distribution functions and three dimensional probability functions, and the interaction energy with anions and cations determined.

TL;DR: The reaction of cyclopentadiene with methyl acrylate has been investigated in a range of ionic liquids and the origin of the endo-selectivity for the reactions and associated rate enhancements has been attributed to a hydrogen bond formed between the cation of the ionic liquid and the methyl acid as mentioned in this paper.

TL;DR: In this article, the ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate (TFL), 1-butyl-3methyloride hexafluorophosphate (H3M) and 1-methyl-3 methylimide-drug-drug (MMD) tetrafloborate, were used for the selective removal of sulfur-containing compounds from transportation fuels such as gasoline at room temperature.

TL;DR: A review of the environmental impact of lubricants and lubrication, from a chemical perspective, is given in this paper, which is intended to give an overview of our current understanding and to provide some specific examples of how optimising lubricant chemistry can contribute to reducing the Environmental impact of human activities.

TL;DR: In this article, a preliminary assessment of the radiation stability of 1,3-dialkylimidazolium cation based ionic liquids containing nitrate and chloride anions has been performed.

TL;DR: The metathesis of natural oils and fats and their derivatives is a clean catalytic reaction that can be considered as an example of green chemistry as discussed by the authors, using this reaction, oleochemical feedstocks can be converted into valuable chemical products, directly or in only a few reaction steps.

TL;DR: In this article, the first molecular simulation study of 1-n-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], a widely studied ionic liquid, is reported.

TL;DR: In this paper, the authors used solvatochromic measurements to determine energy of transition (EoT) values and Kamlet-Taft solvent parameters (α, β, π*) for the relatively hydrophobic RTIL 1-butyl-3-methylimidazolium hexafluorophosphate, [bmim]+[PF6]−, as a function of temperature (10−70 °C) and water content (50 ppm or less water, "dry" or 2% water (v/v), "w

TL;DR: In this article, supercritical carbon dioxide is efficiently converted to dimethyl carbonate (DMC) via the reaction with methanol in the presence of a catalytic amount of dialkyltin oxide or its derivatives.

TL;DR: In this paper, it was shown that the selectivity to benzaldehyde is strongly dependent on the level of chloride ion, which leads to the formation of dibenzyl ether, and the amount of water present in the ionic liquid determines the extent of benzoic acid formation.

TL;DR: In this paper, it was shown that Diels-Alder reactions occur in high yield in novel Lewis acidic ambient temperature ionic liquids composed of choline chloride-MCl2 (1:2) (M = Zn or Sn).

TL;DR: In this paper, retroaldol condensation of glucose occurred preferentially relative to dehydration and isomerization under low water density conditions in supercritical water, and glycolaldehyde was successfully produced without any catalyst.

TL;DR: In this paper, hydrogen sulfate and tetrakis(hydrogensulfato)borate ionic liquids have been synthesized and characterised and the results clearly demonstrate an interplay of acidity and solubility effects caused by the ionic liquid additive.

TL;DR: In this paper, the solubility of water in the hydrophobic 1-alkyl-3-methylimidazolium hexafluorophosphate (alkyl = butyl, hexyl, and octyl) ionic liquids, can be significantly increased in the presence of ethanol as a co-solute.

TL;DR: In this paper, a facile and efficient synthesis of 1,1-diacetates from aldehydes with acetic anhydride has been carried out in excellent yield in the presence of H2NSO3H.

TL;DR: Aromatic electrophilic substitution reactions such as benzoylation and acetylation catalysed by metal triflates have been conducted in an ionic liquid, [bmim][BF4] (bmim = 1-butyl-3-methylimidazolium) as discussed by the authors.

TL;DR: In this article, it has been demonstrated that ionic liquids based upon substituted imidazolium cations may be used as alternative solvent media for the selective oxidation of alcohols to aldehydes and ketones.

TL;DR: In this paper, the condensation reaction of 4-oxo-(4H)-1-benzopyran-3-carbaldehydes and of aromatic aldehydes with 3-methyl-1-phenylpyrazolin-5-4H-one were carried out in an ionic liquid, ethylammonium nitrate, at room temperature in shorter times with higher yields of 78−92 and 70−75%, respectively, than found using conventional procedures.

TL;DR: In this paper, the preparation and characterization of a series of novel salts, based on the N-methyl-N-alkylpyrrolidinium or quaternary ammonium organic cations coupled with sulfonate type anions, namely the mesylate (CH3SO3−) and tosylate (CH 3C6H4SO3+) anions are reported.

TL;DR: A combination of silica modified sulfuric acid and sodium nitrite in the presence of wet SiO2 was used as an effective oxidizing agent for the oxidation of dihydropyridines to their corresponding pyridine derivatives under mild and heterogeneous conditions in moderate to excellent yields as discussed by the authors.

TL;DR: In this article, a case study with biodegradable and eco-friendly Naturally occurring Cassia angustifolia (CA) seed gum was evaluated against the chemical coagulant polyaluminium chloride (PAC) for its coagulation ability to remove colour from synthetic dye solutions, which was found to be a good working substitute alone or in conjunction with a very low dose of PAC for decolourisation of acid and direct, but not for reactive dye solutions.

TL;DR: A Grignard-type reaction of phenylacetylene with aldehydes was developed via alkynyl C-H activation under aqueous conditions catalyzed by a bimetallic Ru-In system in water as mentioned in this paper.

TL;DR: The synthesis of 2-methyl-2-naphthyl ketone and propylene glycol using different acid solid catalysts has been successfully carried out by acetalization reaction as mentioned in this paper.