Halogenated Hydrocarbon Solvents Research Articles

Xenobiotic transporters and kidney injury.

Renal proximal tubules are targets for toxicity due in part to the expression of transporters that mediate the secretion and reabsorption of xenobiotics. Alterations in transporter expression and/or function can enhance the accumulation of toxicants and sensitize the kidneys to injury. This can be observed when xenobiotic uptake by carrier proteins is increased or efflux of toxicants and their metabolites is reduced. Nephrotoxic chemicals include environmental contaminants (halogenated hydrocarbon solvents, the herbicide paraquat, the fungal toxin ochratoxin, and heavy metals) as well as pharmaceuticals (certain beta-lactam antibiotics, antiviral drugs, and chemotherapeutic drugs). This review explores the mechanisms by which transporters mediate the entry and exit of toxicants from renal tubule cells and influence the degree of kidney injury. Delineating how transport proteins regulate the renal accumulation of toxicants is critical for understanding the likelihood of nephrotoxicity resulting from competition for excretion or genetic polymorphisms that affect transporter function.

Kinetic study of hydrogen transfer from benzyl alcohol to aliphatic aldehydes catalysed by heterogenised ruthenium(II) catalysts

AbstractAliphatic aldehydes were reduced to corresponding alcohols by transfer hydrogenation in the presence of Ru(II) complexes bound to swellable polymer matrices. Benzyl alcohol was used as hydrogen donor because of its strong hydrogen donor ability. The kinetics of the reaction has been measured between 100 and 140°C. The results showed that reaction rate depended on the structure of aldehydes and concentrations of aldehyde. Also reaction rate depended on the concentration of hydrogen donor, and on the amount of catalyst. The reaction proceeded efficiently in halogenated hydrocarbon solvents. The metal leaching was different for different catalytic runs and it was most pronounced in the first catalytic run. The observed activation energy, Ea = 18 ± 1 kcal/mol was obtained, suggested that process in predominantly chemically controlled reaction. A general reaction mechanism and rate equation have been proposed.

Hydrogen transfer from cyclohexanol to aromatic aldehydes catalyzed by heterogenized ruthenium(II) complexes bound to swellable polymer matrices

Abstract Aromatic aldehydes can be reduced to corresponding alcohols by hydrogen transfer from cyclohexanol in the presence of Ru(II) complexes bound to swellable polymer matrices. The kinetics of the reaction has been measured between 100 and 140 °C. The process was shown to depend on the structure of aromatic aldehydes, on the concentrations of aldehyde and hydrogen donor, and on the amount of catalyst. The reaction proceeded efficiently in halogenated hydrocarbon solvents. The metal leaching and deactivation of the catalyst was studied. The metal leaching was different for subsequent catalytic runs and it is most pronounced in the first catalytic run. The IR spectra study for the catalyst deactivation showed that catalyst deactivation may be ascribed to the formation of metallic units bound to two carboxylate groups. This problem can be prevented by esterifying the groups. An apparent activation energy, Ea = 22 ± 1 kcal/mol was obtained, which suggests that the catalytic process involves predominantly a chemically controlled reaction. A general reaction mechanism and rate equation have been proposed.

One-Dimensional Coordination Polymers of Dihydrobis(1,2,4-triazol-1-yl)borate Ruthenium(II) Complex

Increasing interest in coordination and organometallic polymers lies in the various intriguing properties of welldesigned inorganic polymer materials. A variety of attempts have been made to synthesize multidentate ligands which can bridge various metal centers. Ambidentate poly(triazolyl)borate ligands [HnB(tz)4-n] − (n = 1 and 2, tz = 1,2,4triazol-1-yl) are good candidates for multidimensional network topologies. It was revealed that both the exodentate (4-position) and endodentate (2-position) nitrogen atoms of the triazolyl rings have comparable electron density to coordinate competitively to metal centers from the theoretical calculation and the N NMR study. It was frequently observed that the poly(triazolyl)borate ligands induce metal ions to form multidimensional coordination polymers through the coordinations of exodentate N atoms whose electron density is higher than the endodentate N atoms. However, in the case of [HB(tz)3] −, tridentate chelated monomers M[η-HB(tz)3]2 (M = Fe, Co, Cu and Zn) are exclusively isolated, and these results are explained by a combination of chelate and kinetic effect. Discrete Ag and Cu complexes bearing a bidentate dihydrobis(1,2,4triazolyl)borate through endodentate coordination such as Cu(L)n[η-H2B(tz)2] (L = aryl phosphines, n = 1 or 2), Ag(L)2[η-H2B(tz)2] (L = aryl phosphines), Ag(dppf)[ηH2B(tz)2] (dppf = 1,10-bis(diphenylphosphino)ferrocene) and their polymeric derivatives were recently reported. In these cases, however, the dihydrobis(1,2,4-triazolyl)borate ligands coordinate to the same type of ions to constitute 1D homometallic polymer networks. In order to develop efficient heterometallic polymeric systems whose physicochemical properties can be systematically tuned, we are pursuing to prepare discrete mononuclear complexes bearing anionic dihydrobis(1,2,4-triazolyl)borate ligands through endodentate coordinations instead of exodentate coordinations. Discrete complexes having a ligand (or ligands) through a bidentate coordination of the two endodentate N atoms could potentially serve as metalloligands for the engineering of 1D modular structure through additional coordinations of the exodentate N atoms to two other transition metal moieties. Recently we were able to prepare discrete mononuclear Fe[HB(tz)3]2·ClO4 and Ag(L)(PPh3) (L = hydrotris(3,5-dimethyl-4-(4-pyridyl)pyrazolyl)borate) to use them as building blocks for novel 3D or 2D functional networks. On the other hand, the reaction between Mn(TPP)·ClO4 and K[H2B(tz)2] only afforded a discrete mononuclear Mn(TPP)(H2O)[η-H2B(tz)2] instead of 1D polymeric structures because of a steric bulk of TPP ligand (TPP is 5,10,15,20-tetraphenylporphine). Here we report a new metalloligand having a dihydrobis(1,2,4-triazolyl)borate, RuH(CO)(PPh3)2[η-H2B(tz)2] (1) and its successful applications to 1D supramolecular systems through self-assembly. Because 1 might have catalytic activities for the hydrogenation of ketones and aldehydes under hydrogen atmosphere, the 1D polymers of 1 could be used as recyclable heterogeneous catalysts. The compound 1 was obtained in good yield from the reaction of RuHCl(CO)(PPh3)3 10 with K[H2B(tz)2] 2 (Figure 1). The compound 1 was fully characterized by H and P{H} NMR, IR, and elemental analysis. A triplet resonance signal of the hydride ligand from H NMR and a singlet peak of two P atoms from P{H} NMR clearly indicate that the proposed structure of 1 which is an ideal geometry as a metalloligand. The entire coordination environment is same to the crystallographically characterized RuH(CO)[P(p-Tolyl)3]2[η-H2B(tz)2] and RuH(CO)(AsPh3)2[η-H2B(pz)2] (pz is pyrazol-1-yl). Unlike other insoluble dihydrobis(triazolyl)borate derivatives, the monomer 1 shows a good solubility in halogenated hydrocarbon solvents. The reactions of 1 with 1 or 2 equivalent Cu(OAc)2·H2O afford well-defined 1D heterometallic polymers {[Cu2(OAc)4][1][Cu(η-OAc)2][1]}n (2) and {[1][Cu2(OAc)4]·(CH2Cl2)2}n (3), respectively, which contain lantern-type dicopper moieties, Cu2(OAc)4. 12 Single crystal x-ray crystallographic studies of 2 and 3 confirm the

Reaction of halogenated hydrocarbon solvents with tertiary amines: Spectrophotometric and conductimetric study

AbstractHalogenated hydrocarbon solvents, SolvCl, (dichloromethane, chloroform, and 1,2‐dichloroethane) react with various types of tertiary amines, A, such as tri‐n‐buthylamine, tropane derivatives (tropine and atropine) and quinine generating a quaternary ammonium salt, N‐halogenalkylammonium chloride (SolvA+Cl−). Some tertiary amines, as well as secondary and primary amines, cannot react with these solvents. This reaction has been detected and studied by both conductivity and visible spectrophotometry measures—the latter after adding a small quantity of a dye, such as bromocresol green (BCGH2), bromophenol blue (BPBH2), or tetrabromophenolphthaleinethyl ester (TBPEH). Both study methods permit the determination of the kinetic parameters, and they are in good agreement. The monoprotic TBPEH is the dye of the simplest mechanism, useful to study kinetics of amines of uncertain behavior as quinine, while BPBH2 is the best dye for quantitative determinations. Kinetics for this reaction are of first order for both amine, A, and solvent, SolvCl; activation energy, Ea, and frequency factor are also determined. Rate constants increase with the amine basicity and with a reduction in the number of the halogen atoms present in the solvent. This reaction is slow but not negligible and must be considered a side reaction of these universally used solvents. © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36:500–509, 2004

Two-photon-absorption-induced accumulated thermal effect on femtosecond Z-scan experiments studied with time-resolved thermal-lens spectrometry and its simulation

Accumulated thermal effect (ATE), which can be an artifact in femtosecond closed-aperture Z-scan measurements, was investigated by varying the repetition rate of the incident pulse for a dye solution in CHCl3. It was found that the measurement is affected by two-photon-absorption-induced ATE, even at a low repetition rate of 1 kHz. The relaxation time of the ATE was found to be tens of milliseconds by time-resolved thermal-lens experiments and simulations, which is consistent with the observed repetition-rate dependence of the Z-scan measurements. The simulations for various commonly used solvents also exhibited that the ATE can be prominent in hydrocarbon and halogenated hydrocarbon solvents and inconspicuous in alcohols and water.

Functional equivalence of industrial metal cleaning processes comparison of metal cleaning processes within LCA

In an LCA case study, the three most frequent industrial metal cleaning technologies were assessed: Cleaning based on aqueous cleaning agents, non-halogenated hydrocarbon solvents and halogenated hydrocarbon solvents. Beside optimisation analysis, the comparison of the cleaning processes was a main goal of the study. The function of metal cleaning processes can be described with a set of parameters called functional parameters. In order to compare different cleaning processes within LCA, it is a precondition that all relevant functional parameters be equivalent. However, metal cleaning processes from different companies normally differ in most of the functional parameters and, thus, are not functionally equivalent. Therefore, it is necessary to calculate the material and energy flows of the processes corresponding to a reference function as a basis for comparison. This can be achieved by simulating the processes according to the functional parameters with the help of a process model. For a general comparison of the technologies, it is also necessary to consider the assessed machines having the same level of optimisation and the same scale.

Cyclopolymerization of Diethyl Dipropargylmalonate and Triethyl Dipropargylphosphonoacetate by Molybdenum Pentachloride

The cyclopolymerization of two dipropargyl monomers having different functionality (diethyl dipropargylmalonate, triethyl dipropargylphosphoneacetate) was carried out by molybdenum (V) chloride catalyst system in chlorobenzene at 60°C. The polymerizations were well proceeded to give a high polymer yield (85–98%). The number average molecular weights (An of poymers were in the range of 46000–97000. These polymers were completely soluble in aromatic and halogenated hydrocarbon solvents and easily casted into a homogeneous polymer film. Various instrumental analyses such as NMR (1H- and 13C-), IR, GPC, and UV-visible spectroscopies indicated that the present polymers have a highly conjugated polymer backbone structure. The tensile strength and failure strain of polymer film generally increased as the feed ratio of diethyl dipropargylmalonate in copolymer increased. On the other hand, the char yield of polymers increased significanly as the feed ratio of triethyl dipro-pargylphosphonoacetate in copolymer increased.

Organic contaminants in sewage sludge and their ecotoxicological significance in the agricultural utilization of sewage sludge

The screening of sewage-sludge for organic pollutants was carried out in the state of Brandenburg, Germany. Samples were taken both in summer and winter. The waste water treatment plants were classified in three groups depending on the types of sewage treated (domestic, municipal and industrial waste water). The content of polychlorinated terphenyls, naphthalenes, chloropesticides, halogenated hydrocarbon solvents, aromatic hydrocarbon solvents (BTEX), chlorobenzenes, polyaromatic hydrocarbons, phenols, chlorophenols, phthalates, petroleum hydrocarbons, surfactants, organotin compounds and 2,4-dichloroaniline was estimated. Data from terrestrial ecotoxicology were used to estimate tolerable levels of soil contamination. This yields the so-called “standard values” for concentrations of organic pollutants in sewage sludge. The concentrations of most pollutants in sewage sludge were found to be below the standard value. However, surfactant and toluene concentrations exceeded the standard value.

N-Octanol-water partition coefficients, aqueous solubilities and Henry's law constants of fatty acid esters

The aqueous solubility and n-octanol-water partition coefficient of fifteen fatty acid esters are determined by the RP-HPLC method. Aqueous solubilities decrease from 5.7 × 10 −5 M for methyl caprate to 5.3 × 10 −12 M for methyl behenate while the log K ow's increase from 4.4 to 10. Special attention is given to satisfying the statistical assumptions underlying the establishment of the calibration line. Residual plots show that in this case small systematic errors are introduced rapidly even if the selected substances for the calibration line are similar in their physical properties to the fatty acid esters. Combining previously determined vapour pressure data with the estimated solubility values allows for the estimation of Henry's law constants. Although the calculated values are not very accurate, it can be concluded that they are in general lower than those of the halogenated hydrocarbon solvents.

Polymerization of 1‐ethynylcyclohexene by tungsten and molybdenum‐based catalysts

Abstract1‐Ethynylcyclohexene, an acetylene derivative having cyclohexenyl substituent, was polymerized by various W‐ and Mo‐based catalysts. WCl6‐EtAlCl2 catalyst system was found to be very effective for this polymerization. The effects of the monomer‐to‐catalyst mol ratio, the initial monomer concentration, the temperature, and the cocatalysts for the polymerization of 1‐ethynylcyclohexene by WCl6 were investigated. The catalytic activity of Mo‐based catalysts was found to be similar to that of W‐based catalysts. The polymer structure was identified to have a conjugated polymer backbone carrying a cyclohexenyl substituent. The resulting polymers were light‐brown powder and completely soluble in aromatic and halogenated hydrocarbon solvents such as chlorobenzene, benzene, chloroform, carbon tetrachloride, etc. Studies of the thermal properties and morphology of poly(1‐ethynylcyclohexene) were also carried out. © 1995 John Wiley & Sons, Inc.

Detection and Identification of Side Reactions of Halogenated Hydrocarbon Solvents with Amines of Pharmaceutical Interest by Secondary Processes to the Neutralizations of Sulphonphthaleinic Dyes with These Amines

The neutralization reactions between amines and diprotic acid dyes in organic solvents generate (dye-, amineH+) and [dye2-, (amineH+)2] ion associates that show two absorption bands in the visible spectrum. An unidentified third absorption band; which appears with a high amine concentration, proves that halogenated hydrocarbon solvents (dichloromethane, chloroform, 1,2-dichloroethane, and carbon tetrachloride) give side reactions with amines (atropine, tropine, quinine, ephedrine, and ajmaline) that generate a quaternary ammonium salt, N-halogenalkylammonium halide ([N(+)-RX,X-]). The molecular weight of the quaternary ammonium salt is the sum of the amine and that of the solvent. The (N(+)-RX,X-) ion associated reacts with [dye2-, (amineH+)2] by substitution reactions, forming (dye2-, amineH+, N(+)-RX) and (dye2-, (N(+)-RX)2] ion associates that justify the third absorption band. The amine-solvent side reactions are of first order with respect to the amine, being very slow processes with rate constant values from 399.4 h-1 (tropine-dichloromethane reaction) to 15.8 h-1 (atropine-1,2- dichloroethane reaction). Rate constants increase with the basicity of the amine measured in the halogenated hydrocarbons employed. Rate constants also increase with a reduction in the number of the halogen atoms present in the halogenated solvent. The new visible absorption band that appears in the amine-dye neutralization gives a quick colorimetric test to bring to light this kind of side reaction in these solvents.

Polymerization of Cyclohexene Oxide By Organoaluminum Compounds

Abstract The polymerization of cyclohexene oxide (CHO) by various organoaluminum compounds such as R3Al (R = Me, Et, i-Bu), Et2AlCl, and EtAlCl2 is reported. Ethyl-substituted aluminum compounds were found to be very effective for this polymerization. As more chlorine atom is substituted on the aluminum atom, the polymer yield was increased though the molecular weight was decreased. The polymer yields at varying monomer-to-catalyst mole ratios (M/C) were similar (80–93%). The temperature and solvent effect for the present polymerization were also studied. The present poly(CHO) was a less stereoregular (atactic) isomer, regardless of catalysts and polymerization conditions. The resulting poly(CHO) was a white powder ad was soluble in aromatic and halogenated hydrocarbon solvents such as benzene, chlorobenzene, CCl4, chloroform, etc.

The corrosion of aluminium in halogenated hydrocarbon solvents

The behaviour of aluminium in 1,1,1-trichloroethane has been examined to determine conditions for the initiation of so-called bleeding corrosion and reasons for continued activity. Aided by the use of supporting electrolyte to enhance solution conductivity, it is evident that little reaction between aluminium and the solvent proceeds unless the air-formed film is mechanically damaged. However, mechanical damage per se is insufficient to allow continued reaction; thus, sufficiently high anodic potentials are also required in polarization studies. In natural immersion studies, the onset of bleeding corrosion is associated with a marked anodic excursion in potential, with dramatic net cathodic currents developed for specimens that were originally anodically polarized. Mechanisms for such behaviour suggest the requirement to sustain sufficiently large regions of bare metal, where solvent reduction outstrips repassivation in the inevitable presence of water in the solvent.

Voltammetry of oxorhenium(V) complexes containing the [O=Re−OR] core and substituted pyridine ligands

Compounds of the general formula [ORe(OR)Cl2(PPh3)2] and [ORe(OEt)Cl2(PPh3)(py)], where R=alkyl or aryl and py=a substituted pyridine, were synthesized and their voltammetric behaviour investigated. For the former, the electron-transfer mechanism was observed to be dependent on solvent. In dry MeCN, a quasi-reversible oxidation and a reduction followed by a chemical reaction was observed. There were indications of nucleophilic attack on electrochemically generated [ORe(OEt)Cl2(PPh3)2]+, forming an unstable species whose reduction potentials were strongly dependent on the identity of the nucleophile. Voltammetric and spectroscopic observations of the oxorhenium(V) alkoxypyridine complex indicate the pyridine to be labile in halogenated hydrocarbon solvents but not in Me2CO, MeCN, or CCl4. Electrochemical generation of [ORe(OEt)Cl2(PPh3)(ClxCyHz)]+ (x=1,2, or 3; y=1 or 2; z=2,3, or 4) appears to be followed by transfer of a hydrogen atom from the solvent to form [(HO)Re(OEt)Cl2(PPh3)]+. Various pyridine complexes of this type were preparedvia substitution reactions under mild conditions. Varying the reaction conditions allowed the synthesis oftrans-dioxotetrapyridyl complexes in excellent yield.

Preparation of soluble TiCl 3 catalysts by reduction of TiCl 4 with organoaluminium compounds and their use for copolymerization of ethylene with propylene

Reductions of TiCl 4 by organoaluminium compounds were carried out in hydrocarbon and halogenated hydrocarbon solvents using various ethers as donor. Under appropriate conditions, TiCl 4 was quantitatively reduced by trialkylaluminium to give a homogeneous black solution of TiCl 3· 1 3 AlCl 3· ether complex. Catalyst systems of the soluble TiCl 3 and Al( i-Bu) 3 (cocatalyst) showed high catalytic activities for random copolymerization of ethylene with propylene. The resulting copolymers were superior elastomers with low crystallinity and had outstandingly high tensile strength and elongation at break in comparison with copolymers prepared from a conventional VOCl 3 Al( Et) 1.5 Cl 1.5 catalyst system. Characterization data of copolymers suggest that the excellent tensile properties are due to microblock-type sequences of ethylene and propylene in a polymer chain.

Preparation of soluble [(TiCl4+MgCl2) � phosphate] and soluble [(TiCl3-O-MgCl) � phosphate] catalysts and their use for copolymerization of ethylene with propylene

TiCl4 and MgCl2 were dissolved in hydrocarbon or halogenated hydrocarbon solvents using phosphate or phosphonate donor. Mg(OH)Cl reacted with TiCl4 with HCl gas evolution above 100°C in the presence of phosphate or phoshonate donor, and a homogeneous solution of [TiCl3-O-MgCl2] complex was obtained. The soluble catalysts and triisobutylaluminium as co-catalyst showed high activities for the copolymerization of ethylene with propylene. The copolymers obtained were rubbery and possessed very low crystallinities.

Preparation of soluble TiCl3 catalysts by reduction of TiCl4 with Grignard reagents and their use for copolymerization of ethylene with propylene

Preparations of soluble TiCl3 catalysts by reduction of TiCl4 with some types of Grignard reagents were carried out in halogenated hydrocarbon solvents by using appropriate ethers as donor. The soluble TiCl3·MgX2·ether complex catalysts and triisobutylaluminum as co-catalyst showed high activities for the copolymerization of ethylene with propylene. It was first found that the soluble TiCl3·MgX2·ether complex catalysts enhance the activities for the copolymerizations in the same manner as solid titanium catalysts supported on MgCl2 which show high activities for homopolymerizations of olefin monomers. The copolymers obtained possessed low crystallinities. Also, the copolymers seem to contain microblock sequences and have outstandingly high tensile strength and elongation at break compared to copolymers by the conventional VOCl3/Al(Et)1.5Cl1.5 catalyst system.

Preparation of Soluble TiCl3 Catalysts and Their Use for Copolymerization of Ethylene with Propylene

Abstract The solubilization of TiCl3 catalysts in organic solvents was carried out to enhance the activity for random copolymerization of ethylene with propylene. β-TiCl3 · 1/3AlCl3 was solubilized in halogenated hydrocarbon solvents by using an appropriate ether as donor. α-TiCl3 free from AlCl3 was found to be soluble in the presence of a VCl4 or VOCl3 ligand and a suitable ether. The solubilized TiCl3 catalysts showed high catalytic activities for the copolymerization using trialkylaluminum compounds as a cocatalyst. The copolymers obtained possessed low crystallinities. Also, the copolymers seem to contain a microblock type of sequences and outstandingly high tensile strength and elongation at break compared to copolymers by conventional VCl4 and VOCl3 catalysts.

Sedimentological Analysis of a Contaminated Groundwater Aquifer

The use of sedimentological reservoir analysis techniques adapted from standard oilfield practice can improve the efficiency and reduce the costs of the evaluation of groundwater aquifers and the design of restoration programs. An evaluation/restoration program at a site in California drilled over 200 test wells in about 750 ac. All wells were logged lithologically and with wireline. The shallow aquifer is a complex braided alluvial floodplain deposit of Late Quaternary age. Analysis demonstrates depositional and erosional responses to periodic hinterland uplifts and to changing climatic conditions. Channel, overbank, lacustrine, and minor deltaic deposits can be recognized. The aquifer architecture has been interpreted to explain the movement of fuel and halogenated hydrocarbon solvents in the sediments and water. Routine engineering geology techniques and hydrologic tests were used to evaluate contamination and to design experimental restoration processes. As demonstrated here, sedimentological techniques show promise in reducing the costs and time required for this type of study. The abundant detailed data will be used in an attempt to develop a microcomputer-based expert system for rapid preliminary analyses of similar aquifers or reservoirs.