Abstract  Three hydrometallurgical processes for industrial wastes treatment are presented. ?The main separation techniques are: solvent extraction, leaching-precipitation, electro-oxidation, and ion exchange. Recovery of gold from solid wastes generated in the electronic and jewellery industries consists of thermal degradation, two-stage leaching with nitric acid solution to remove silver and other metals and then with aqua regia to dissolve gold, selective solvent extraction of gold with diethyl malonate, and reduction of gold from the organic phase.

Vanadium recovery from residue ashes after burning heavy oil fractions consists of alkaline leaching of vanadium, filtration, neutralization of sodium vanadate solution, precipitation of ammonium metavanadate, drying of the precipitate, and adsorption of the remaining vanadium from the filtrate on an anionite. From the remaining ashes nickel is recovered using acidic leaching, filtration, precipitation of ammonium-nickelous sulphate, filtration, and drying.

The third process concerns processing of electroplating sludges and waste waters containing chromium and copper. The waste waters are electro-oxidized to transform Cr(III) into chromate. Then metal cations are separated on a cationite. The purified electroplating baths are recycled directly to electroplating; other solutions are first concentrated using anionite, followed by sodium chromate eluate conversion into concentrated chromic acid solution. The sludges accumulated from waste water processing by hydroxide precipitation are re-dissolved in chromic acid solution generated progressively by circulation between the dissolving and electro-oxidation steps. The concentrated chromic acid solution obtained is purified on the cationite and recycled.

Abstract  Using a malonic ester route, the first branched tandem intramolecular Diels-Alder (TIMDA) precursor, 3, was synthesized from sorbic acid in seven steps (15% overall yield). Treatment with Lewis acid catalysts (e.g., boron trifluoride etherate) affects the TIMDA reaction to afford a new fused-tetracyclic, 4, as two diastereomers (1:1). An alternative synthetic route to key intermediates used in the synthesis of linear TIMDA precursors has also been achieved.

Abstract  Tetracarboxylic acid ester was synthesized with diethyl malonate and methyl acrylate, and an amino terminated hyperbranched polymer (HBP-NH2) was prepared by reaction of a tetracarboxylic acid ester with diethylenetriamine (DETA). Hyperbranched polymer grafted chitosan (HBP-g-chitosan), a novel adsorbent material for Cr(VI) removal, was prepared from HBP-NH2 and chitosan with epichlorohydrin as crosslinking agent. The adsorbent was characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectrophotometry, and X-ray diffraction. The influence of the initial concentration of Cr(VI), the dosage of adsorbent, pH value and the coexisting anions on the adsorption performance were studied. An isotherm of the adsorption process was generated and studied by Langmuir and Freundlich models. The results showed that the Freundlich model proved to be more suitable than the Langmuir model. The adsorption kinetics were determined by pseudo-first order and pseudo-second order kinetics. In doing so, it was found that the pseudo-second order kinetic model was more reliable than the pseudo-first order kinetic model.

Abstract  A new and efficient method for the direct conversion of N-acyl oxazolidinones to a beta-keto ester is disclosed. The one-pot transformation is effected by the utilization of an excess of Lewis acid along with base and potassium ethyl malonate. This methodology has been applied to the large scale preparation of ethyl (R)-5-methyl-3-oxooetanoate. (c) 2008 Elsevier Ltd. All rights reserved.

Abstract  We describe a specific procedure for the synthesis of deuterium-labelled 2-(1-methylalkyl)succinate established via alkylation of diethyl malonate, Krapcho decarboxylation reaction with D2O and hydrolysis reaction. Two novel compounds, 2-[H-2]-2-ethylsuccinic acid and 2-(H-2-2-(1-methylheptyl)succinic acid were prepared via this synthetic route and characterized by mass spectrometry and H-1 NMR. The results showed that the 2-(1-methylalkyl)succinic acids were deuterated at the beta-position, which is considered as an important reaction centre in the anaerobic degradation of n-alkanes. (C) 2015 Chinese Chemical Society and Institute of Materia Medics, Chinese Academy of Medical Sciences. Published by Elsevier B.V. All rights reserved.

Abstract  Diffusion, permeation, and equilibrium sorption coefficients have been determined using a sorption gravimetric technique for methyl acetoacetate, ethyl acetoacetate, methyl benzoate, ethyl benzoate, methyl salicylate, isobutyl salicylate, and diethyl malonate into tetrafluoroethylene/propylene copolymer membranes in the temperature range 25-70 degrees C. The sorption kinetics process has been characterized by first-order rate constants and penetration velocities. From a temperature dependence of the transport coefficients, the activation parameters have been estimated. It is observed that the values of the transport coefficients for the systems of this study depend on the nature of the penetrant molecules rather than on their molecular sizes. On the whole, the mechanism of solvent transport into the copolymer membranes used here follows nearly the Fickian trend. (C) 1994 John Wiley and Sons, Inc.

Abstract  The reaction of barium or strontium metal in ammonia gas-saturated THF with two equivalents of dimethyl malonate (dmalH) in the presence of tetraethylene glycol dimethyl ether (tetraglyme) or 1,1,4,7,7-pentamethyldiethylenetriamine (pmdt) yields Ba(dmal)(2)(tetraglyme) (1), Ba(dmal)(2)(pmdt) (2). Sr(dmal)(2)(tetraglyme) (3). and Sr(dmal)(2)(pmdt) (4) as colorless crystals in reasonable yields (45-52%). These complexes have been characterized by spectroscopic methods (IR and H-1- and C-13-NMR) and elemental analysis data. Molecular structures of 1, 3, and 4 have been determined by X-ray diffraction studies and have revealed that they are monomeric and the tetraglyme or pmdt ligand wraps around a central metal atom in a meridional plane with the dmal ligands on opposite sides of this plane. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract  Fluorine smoothly attacks quinuclidine-trifluoroborane, quinuclidine-pentafluorophosphorane, and quinuclidine-sulfur trioxide in acetonitrile at -35 degrees C to give the corresponding N-fluoroquinuclidinium salts NFQ(+)X(-) (X(-)=BF4-, PF6-, and FSO3- respectively; Q = quinuclidine). Like its tetrafluoroborate analogue (NFQ(+)BF(4)(-)), the hexafluorophosphate NFQ(+)PF(6)(-) can also be prepared by direct fluorination of quinuclidine in the presence of the appropriate sodium salt (NaPF6). An alternative route to the tetrafluoroborate involves treatment of NFQ(+)F(-) with boron trifluoride. A comparative study of site-specific electrophilic fluorination of methoxybenzene [--> 1-fluoro-2- and 4-methoxybenzene], 2-hydroxynaphthalene (--> 1-fluoro-2-hydroxynaphthalene and 1,1-difluoro-2-oxo-1,2-dihydronaphthalene),2-nitropropan-2-yl-lithium (--> 2-fluoro-2-nitropropane) and diethyl sodio(phenyl) malonate [--> diethyl fluoro(phenyl) malonate] with all of the NFQ(+) X(-) salts mentioned above, plus the triflate (X(-) = CF3SO3-), revealed that the hexafluorophosphate and triflate are the most easily-handled and effective reagents.

Abstract  The complexing properties of four dimalonate and one diester calix[4]arene derivatives toward alkali and alkaline earth cations have been investigated in acetonitrile by means of UV spectrophotometry. Mononuclear complexes have been detected for all the complexes except in the case of ligands 4 and 5 with Na+ and Ca2+ where a biligand species (ML2) is present. This later stoichiometry was also confirmed by H-1-NMR and FAB(+) MS methods. In the case of ligand 3 and Sr2+ we observed the formation of both mono and binuclear species (ML, (ML)-L-2). Particular selectivities have to be noted from the unique complexation of Na+ and Ba2+ by ligand 2 and Rb+ by ligand 3 toward the two series of cations. The complexation is predominantly dependent on the bulkiness of the cavity and the cation size.

Abstract  The paper considers the possibility of increasing the sensitivity of semiconductor adsorption sensors using photon laser stimulation of low power. The results of experiments on the detection of vapors of malonic ester to semiconductor sensors manufactured on the basis of tin dioxide with various doping impurities with the use of laser irradiation and without it. The mechanism of photon stimulation was proposed and its effect was examined on the kinetics of adsorption and an increase the indicator effect.

Abstract  The bubble points for (triethyl orthoformate + diethyl malonate) at T = (373.15, 383.15, and 393.15) K and at p = 13.33 kPa, measured with an inclined ebulliometer are presented. The experimental results are analyzed using the UNIQUAC equation with the temperature-dependent binary parameters with satisfactory results. Experimental vapour pressures of triethyl orthoformate are also included. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract  Novel P*-chiral P,N-bidentate ligands were synthesized by treatment of ferrocene-based imino alcohols with chlorophosphites derived from (S)-2-anilinomethylpyrrolidine or (S)-prolinol. Metal chelate complexes with the ligands [Rh(CO)(PN)Cl] and [Pd(PN)(allyl)]X-+(-) (X- = BF4-, Cl-, I-, CH12B11-) - were obtained and all new compounds were fully characterized by H-1, C-13, P-31 NMR, IR, MS (El, Cl, FAB, ESI and plasma desorption techniques) and X-ray analysis (imino alcohol 2d and complex 7). P*-Chiral diamidophosphites gave up to 97 % ee in the Pd-catalysed allylic substitution of 1,3-diphenylallyl acetate with dimethyl malonate and paratoluenesulfinate. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Abstract  Ring-opening of N-(PhF)serine-derived cyclic sulfamidate 17 was achieved with different nucleophiles (beta -keto esters, beta-keto ketones, dimethyl malonate, nitroethane, sodium azide, imidazole, and potassium thiocyanate) to prepare a variety of amino acid analogs. Two different pathways for ring opening of 17 were elucidated: direct nucleophilic displacement, as well as beta -elimination followed by Michael addition. Furthermore, beta -keto ester and beta -keto ketone products 18k,18m, and 18i were converted to prolines and pyrazole amino acids.

Abstract  Rhodium complexes, in the presence or absence of PEt3, catalyse the carbonylation of CH2I2 to dialkylmalonates in the presence of alcohols (ROH, R = Me, Et, Pr-i, Bu) with side products from reactions in EtOH being CH2(OEt)(2), EtI and traces of EtCO2Et and EtOAc. The active species when using PEt3 is shown to be [RhI(CO)(PEt3)(2)], formed via [Rh(OAc)(CO)(PEt3)(2)] from [Rh-2(OAc)(4). 2MeOH] and PEt3. Mechanistic studies show that the first step of the catalytic cycle is oxidative addition of CH2I2 to give [Rh(CH2I)I-2(CO)(PEt3)(2)], but that insertion of CO into the Rh-CH2I bond gives an iodoacyl complex which is unstable. The analogous [Rh(COCH2X)X-2(CO)(PEt3)(2)], (X = Cl or Br) have been synthesised by oxidative addition of XCH2COX to [RhX(CO)(PEt3)(2)] and fully characterised (by X-ray crystallography, for X = Cl). [Rh(COCH2Br)Br-2(CO)(PEt3)(2)] has also been formed from reaction of [Rh(COCH2Cl)Cl-2(CO)(PEt3)(2)] with excess NaBr. However, the analogous reaction with NaI does not give the iodoethanoyl complex, but rather [RhI3(CO)(PEt3)(2)] and its decomposition products. It is proposed that [Rh(COCH2I)I-2(CO)(PEt3)(2)] is unstable towards loss of I- to form the ketene complex, [RhI2(CH2 = C = O)(CO)(PEt3)(2)]I, which is transformed into [Rh(COCH2CO2Et)I-2(CO)(PEt3)] by nucleophilic attack of ethanol at the central C atom, followed by CO insertion into the Rh-C bond. An analogue, [Rh(COCH2CO2Et)Cl-2(CO)(PEt3)(2)], has been isolated by oxidative addition of EtO2CCH2COCl across [RhCl(CO)(PEt3)(2)], and characterised both spectroscopically and crystallographically. In refluxing ethanol, [Rh(COCH2CO2Et)Cl-2(CO)(PEt3)(2)] produces diethylmalonate and [RhCl(CO)(PEt3)(2)], thus completing the catalytic cycle. Possible pathways of deactivation of the catalyst to give [RhI3(CO)(PEt3)(2)] are discussed. One involves the reaction of ketene with ethanol to give EtOAc, whilst the others involve protonation of the Rh-Z bond in [RhZI(2)(CO)(PEt3)(2)] (where Z = CH2I, CH2CO2Et or H) by HI. The isolation of CH2DCO2Et, when carrying out the reaction in EtOD, is consistent with all of these deactivation pathways except protonation of [RhHI2(CO)(PEt3)(2)]. (C) 1998 Elsevier Science S.A. All rights reserved.

Abstract  The kinetics of oxidation of esters by chromic acid has been investigated in acetic acid-water mixtures in the presence and absence of oxalic acid. In the absence of oxalic acid, the reaction is overall second order, first order in each reactant. The reaction rates are independent of the added salts, while in the presence of oxalic acid the rate of oxidation increases. The products are identified and activation parameters have been calculated.

Abstract  Bromomethyl cyclopent-1-enyl sulfone and bromomethyl cyclohex-1-enyl sulfone reacted with dimethyl malonate and malononitrile sodium salts in THF at 20-50A degrees C to give products of Michael-induced Ramberg-Backlund reaction, functionalized derivatives of methylidenecyclopentane and methylidenecyclohexane. Reactions of bromomethyl hex-1-en-1-yl sulfone and bromomethyl hept-1-en-1-yl sulfones with the same sodium enolates followed the Michael-induced ring closure pattern with formation of tetrahydrothiophene 1,1-dioxide derivatives containing allylmalonic acid derivatives as impurities. Factors responsible for the different reaction pathways of cyclic and acyclic bromomethyl sulfones are discussed.

Abstract  P*-Chiral diamidophosphite ligand-assisted Pd-catalyzed Tsuji-Trost reaction between dimethyl malonate and prochiral 3-acetoxy-1,3-diphenylpropene in organic solvents using potassium carbonate as the base affords the substitution product in quantitative yields and with enantioselectivities up to 99% ee.

Abstract  Palladium-catalyzed potassium carbonate-assisted reaction between diethyl malonate and allyl acetate in the presence of 1,3-dialkylimidazolium ionic liquids (ILs) as solvents or phase transfer catalysts affords major monoallylation product, whereas in the presence of 1,2,3-trialkylimidazolium or quaternary ammonium/phosphonium ILs diallylation product is preferably formed. These procedures are extended to some other CH-acids and allylic acetates.

Abstract  Coating sol solutions were prepared from anhydrous ethanol solutions of Ta(OC2H5)5. With the addition of high-purity acetic acid, Ta(OC2H5)5 was partially hydrolyzed by trace amounts of water in the acetic acid used and further condensation took place. Among the sol solutions obtained, the solution (A) containing 1.2 mol% Ta(OC2H5)5 together with acetic acid at its molar ratio of 1.5 to Ta(OC2H5), was transparent and stable on storage for two months. When chelating agents (diethyl malonate, acetylacetone, ethyl acetoacetate and ethyl acetate) were added to one of the starting solutions, the agents (especially diethyl malonate) were found to remain in gels when the solution was dried at room temperature. Among these gels, one containing acetylacetone crystallized at the highest temperature of about 830-degrees-C on heating.

Ta2O5 gel thin films were prepared from the solution (A) by the drop-coating method, the solution was dropped on a substrate to spread over and evaporate. Preparation under dry nitrogen (approximately 0% relative humidity) gave a transparent gel film at room temperature. DTA analysis revealed that, on heating in air, the gel film crystallized around 840-degrees-C which was higher by about 100-degrees-C than the crystallization temperatures of the other gels prepared under high relative humidities. On heating under nitrogen atmosphere, the exothermic peak of crystallization at 840-degrees-C decreased extremely to be replaced by a weak exothermic peak (appearing) at 1000-degrees-C. Preparation test under different relative humidities and substrate temperatares showed that transparent gel films were obtained regardless of substrate temperatures under low relative humidities, while only at somewhat elevated substrate temperatures under high humidities.

Abstract  The coordination of transition metals to organic fragments can yield complexes with fascinating and unexpected binding patterns. The study of metal-benzyl complexes has demonstrated the feasibility of η(3)-coordination, which results in a dearomatized ring. These complexes also offer insight into reaction mechanisms as proposed intermediates in catalytic cycles. In this Review we discuss the synthesis and characterization of these complexes with late transition metals and the subsequent development of catalytic benzylic functionalization methods, including asymmetric variants.

Abstract  alpha,beta-Unsaturated acetylenic -hydroxyketones have been shown to react with ethyl acetoacetate in a Michael-addition fashion and subsequently undergo cyclization followed by dehydration to give substituted furans with a predictable regiospecificity. The yields were good to excellent. A mechanism for the transformation is proposed, and this mechanism explains why furan formation does not take place when the same unsaturated ketones are treated with -methylated acetoacetate and diethyl malonate. [Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications (R) for the following free supplemental resource: Full experimental and spectral details.]

Abstract  The rhenium hydroxy and methoxy carbonyl complexes [Re-2(mu-OR)(3)(CO)(6)](-) (R=H or Me) have been studied by negative-ion electrospray mass spectrometry (ESMS). The complexes undergo facile exchange reactions with protic compounds, including alcohols and phenols. With dimethyl malonate, ester hydrolysis occurs giving carboxylate-containing complexes, and with H2O2 or (BuOOH)-O-t, oxidation to ReO4- occurs. The feasibility and extent of these reactions can conveniently, rapidly, and unambiguously be determined by electrospray mass spectrometry, and is dependent on the acidity and steric bulk of the protic compound. The results also suggest that the complexes can be used as versatile starting materials for the synthesis of a wide range of analogous [Re-2(mu-OR)(3)(CO)(6)](-) complexes by simple reaction with an excess of the appropriate alcohol. By varying the applied cone voltage the fragmentation pathways have been investigated; the hydroxy complex undergoes dehydration followed by CO loss, whereas for the methoxy complex beta-hydride elimination (and CO loss) is observed, with confirmation provided by deuterium labelling studies. Under ESMS conditions, the neutral complexes [Re-2(mu-OR)(2)(mu-dppf)(CO)(6)] [R=H or Me; dppf=1,1'-bis(diphenylphosphino)ferrocene] undergo substantial solvolysis and hydrolysis to give mainly mononuclear species; simple parent ions (e.g. [M+H](+)) are not formed in appreciable abundance, probably due to the lack of an efficient ionisation pathway.

Abstract  Novel liquid crystalline malonic ester monomer was synthesized from malonyl dichloride and disperse red 1, a photoresponsive group. The monomer was polymerized with 1,6-dibromohexane, 1,8-dibromooctane, 1,10-dibromo-decane, 1,12-dibromododecane, alpha,alpha'-dibromo-p-xylene, alpha,alpha'-dibromo-m-xylene, or alpha,alpha'-dibromo-o-xylene in the presence of sodium hydride to give seven kinds of novel poly(malonic esters) with two symmetrical photoresponsive groups in the side chain. The resulting polymer films were found to be excellent as reversible optical information recording media for data storage and retrieval through a trans-cis isomerization of azobenzene group by Ar laser irradiation. The sensitivity of data recording was dependent not only on the thickness of the polymeric thin film but also on the intensity of laser beam. (C) 2002 Elsevier Science B.V. All rights reserved.

Abstract  We report an efficient process for the synthesis of diethyl malonate (DEM) and other malonates through the palladium-catalyzed carbonylation of chloroacetates. Excellent selectivity (96?%) and yield (94?%) were obtained without the formation of Pd black. For the first time, a weakly alkaline buffer was used to control the selectivity for DEM in the reaction and we discuss the relationship between the buffer medium and selectivity in the reaction. The combination of anisole as the solvent and a Na2HPO4/NaH2PO4 buffer was beneficial for completely restraining the phase-transfer-catalyzed substitution of DEM with ethyl chloroacetate, as well as accommodating the proposed [(PPh3)2PdI]-[Bu4N]+ intermediate, by providing a suitable environment for its stable existence. We achieved the highest efficiency in the catalytic cycle by fine-tuning the balance between the rates of oxidative addition and reductive elimination; moreover, we synthesized a recoverable heterogeneous polymer-bound Pd catalyst in 85?% yield that could be reused without an appreciable loss in activity over four cycles.