Reduction Of CCl4 Research Articles

Biomimetic siRNA nanogels for regulating macrophage polarization and promoting osteogenesis

BackgroundBone fracture regeneration poses significant clinical challenges due to complications such as delayed healing, nonunion, and the limitations of current treatments. ObjectiveThis study introduces a novel therapeutic approach utilizing biomimetic nanogels to silence the Ccl4 gene, aiming to promote bone repair by regulating macrophage polarization. MethodsThe nanogels, composed of tannic acid (TA) and small interfering RNA (siRNA), were designed for targeted gene delivery. ResultsIn vitro findings indicate that siRNA-mediated Ccl4 reduction significantly improves M2 macrophage polarization, which, in turn, promotes osteogenic differentiation of bone marrow-derived mesenchymal stem cells. Increased expression of osteogenic markers and enhanced mineral deposition were observed. The nanogels demonstrated optimal particle size, stability, and cellular uptake, and biocompatibility assays confirmed their non-toxicity. ConclusionThis study underscores the potential of targeted siRNA delivery in modulating immune responses to enhance bone regeneration, offering promising treatment options for complex bone healing scenarios.

New Mechanism via Dichlorocarbene Intermediate for Activated Carbon-Mediated Reductive Dechlorination of Carbon Tetrachloride by Sulfide in Aqueous Solutions.

Although activated carbon (AC) is widely used as an adsorbent and barrier for contaminated sediment remediation, little attention has been paid to its mediation effects on reductive dechlorination of chlorinated solvents by commonly presenting sulfide. Here, we reported that highly porous, graphitized AC (250 mg L-1) suspended in deoxygenated aqueous solutions could increase the pseudo-first-order rate constant of sulfide-induced dechlorination of carbon tetrachloride (CCl4) by more than 1 order of magnitude. Carbon disulfide (CS2) was the only main product, with no production of chloroform or dichloromethane. The minimum promotion of CCl4 reduction observed with electro-conductive but nonporous graphite and a microporous but electro-insulative resin (XAD-4) indicates that graphitic carbons and micropores both play key roles in AC-mediated dechlorination of CCl4 by sulfide. The detection of dichlorocarbene (:CCl2) by free radical trapping experiments combined with the high suitability of the Langmuir-Hinshelwood model led us to propose a new mediation mechanism: CCl4 molecules adsorbed within the deep regions of AC micropores formed by graphitic carbons accept two electrons transferred from sulfide to form :CCl2, which is impeded from hydrolysis and hydrogenolysis by the hydrophobic micropore and further reacts with sulfide to generate CS2. Consistently, the production of :CCl2 was very low when AC was replaced with graphite or XAD-4. The proposed mechanism was further validated by the enhanced mediation effects of another two carbonaceous materials (template-synthesized mesoporous carbon and covalent triazine-based framework) that are electro-conductive and have well-developed micropore structures. These findings highlight the importance of pore properties of carbonaceous materials as mediators or catalysts for reductive dechlorination reactions and shed light on the development of coupled adsorption-reaction systems for remediation.

A trinuclear chromium(iii) chlorocarbyne.

Reduction of CCl4 by CrCl2 in THF afforded a trinuclear chromium(iii) carbyne [CrCl(thf)2]3(μ3-CCl)(μ-Cl)3. The chlorocarbyne complex reacted with aldehydes to afford chloroallylic alcohols and terminal alkynes. The mechanistic study proposed two competitive pathways via an α-chlorovinyl intermediate.

Post-treatment of melatonin with CCl4 better reduces fibrogenic and oxidative changes in liver than melatonin co-treatment.

Therapeutic effects of melatonin (MEL) in targeting CCl4 -induced liver fibrosis has been widely known, but there is no study comparing oxidative and fibrogenic changes in co- and post-treatment of MEL with CCl4 , which was further aimed in this experiment. Male SD rats were injected with CCl4 (1 mL/kg/i.p./daily) dissolved 1:1 in olive oil for 1 month. Some animals received MEL (20 mg/kg/i.p./daily) diluted in 1 mL PBS in combination with CCl4 (co-treatment), and some rats were treated with MEL, beginning with injection of the last dose of CCl4 for one month (post-treatment). The groups were control, CCl4 , CCl4 -co vehicle, CCl4 -post vehicle, post-CCl4 , MEL co-treatment, and MEL post-treatment. MEL post-treatment group showed significantly lower lipid deposition, serum malondialdehyde (MDA), serum alanine aminotransferase (ALT), and liver hydroxyproline. This group also had low expressions of Bax and transforming growth factor-β1 (TGF-β1). MEL post-treatment group revealed higher sera levels of albumin, superoxide dismutase (SOD) and glutathione peroxidase (GPx). Expression levels of metalloproteinase-13 (MMP-13) and Bcl2 was also higher in this group (P ≤ 0.05 vs co-treatment). Results of the present study indicated that MEL post-treatment is more powerful in reduction of CCl4 -induced liver fibrosis through reduction of oxidative stress and maintenance of matrix balance.

Radical Chain Reduction of CCl4 Initiated by Illumination of SPEEK Solutions.

Efficient reduction of CCl4 took place upon exposure to 350-nm photons of aqueous solutions containing sulfonated poly(ether etherketone) (SPEEK) as a sensitizer and either poly(vinyl alcohol) (PVA) or HCO2H/HCO2- buffer. The photoreaction formed chloride ions whose concentration increased linearly with time in solutions free of O2, whereas slower reductions occurred in the presence of air. Utilization of formate buffer as the H-atom donor yielded photoreactions at least 10 times faster than those in the presence of PVA and generated CHCl3 as another reaction product. The quantum yield of chloride ion formation, ø(Cl-), was found to be a function of both the SPEEK concentration and concentration of formate buffer. Whereas the quantum efficiency increased steadily with decreasing solution acidity, a drastic surge in the reaction rate occurred in neutral solutions. ø(Cl-) first increased rapidly to a maximum value exceeding 1 at pH 7.3 and then decreased thereafter. The dependence of r(Cl-) on (I0)1/2, where I0 is the light intensity, and the occurrence of postirradiation formation of Cl- through the reduction of CCl4 in the dark are further evidence that the photoreaction proceeded by a chain process. Several of the kinetic features were rationalized by means of a mechanism involving the α-hydroxy radicals of SPEEK and •CCl3 as chain carriers.

Therapeutic Potential of Selenium Treated Stem Cells for the Reduction of Liver Fibrosis

Mesenchymal Stem Cells (MSCs) therapy is an alternative way to treat liver fibrosis. The aim of the current study is to enhance the therapeutic potential of MSCs by pretreated with selenium for the reduction of CCl4 induced liver injury. Male Balb/C mice were treated with CCl4 (1.0 μL/g) intraperitoneally, twice a week for 4 weeks. Mouse MSCs were cultured and then pretreated with 15 ng/ml selenium for 24 hrs. The untreated and selenium pretreated MSCs were transplanted into CCl4 injured mice. After two weeks of MSCs transplantation, mice were observed for liver regeneration. The morphological result showed that selenium treated MSCs have significant therapeutic effect in reduction of CCl4 induced injured as compared to untreated MSCs. Biochemical and histopathological result also revealed significant reduction in serum ALT and bilirubin level, collagen content in selenium treated MSCs group as compared to untreated MSCs. Reverse transcriptase PCR result at mRNA level also confirm the antifibrotic effect of selenium treated MSCs on liver fibrosis as evidenced by decreasing the expression level of apoptotic marker and enhancing hepatocyte marker. Thus it is concluded that selenium treated MSCs have a strong therapeutic effect on the reduction of liver fibrosis in CCl4 mice model.

Hepatoprotective activity of aerial parts of Erythrina crista-galli

Hepatoprotective activity was measured for Erythrina crista-galli extract as well as fractions. Fractions II and III have shown a remarkable protective effect against CCl4-induced hepatocyte injury. This was evidenced by their ability to significantly ameliorate CCl4-induced elevation in ALT and AST levels. This is supported by the notion that pretreatment of hepatocytes with either Erythrina crista-galli extracts or fractions significantly alleviated CCl4- induced GSH and SOD depletion and replenished CCL4 reduction of TAC. Hepatoprotective activity mechanism is attributed at least in part, to the free radical scavenging and antioxidant activity of the phenolic compounds present in the extract proved by the phytochemical screening of the fractions.

Analgesic, antipyretic, nephritic and antioxidant effects of the aerial parts of Bassia eriophora (Family: Chenopodiaceae) plant on rats

ObjectiveTo study analgesic, antipyretic, renal and antioxidant effects of the aerial parts of Bassia eriophora (Family: Chenopodiaceae) (B. eriophora), a wild plant in Saudi Arabia. MethodsAlcoholic extract (90%) of the aerial parts of B. eriophora was tested for analgesic, antipyretic, nephritic and antioxidant activities, to show their therapeutic potential. For analgesic effect, hot plate and writhing methods were used while for antipyretic effect, rectal temperature method was used. The renal protective effects and antioxidant properties were determined through CCl4-intoxicated animal method. ResultsAnimals treated with dose of 250 and 500 mg/kg body weight, after 90 min showed significant analgesic effect (8.10 ± 0.18 and 8.10 ± 0.12) respectively, comparable to indomethacin (9.18 ± 0.22) in hot plate method, while in writhing method, the percentage reduction accounted for 55.14% and 68.38% at the dose of 250 and 500 mg/kg body weight respectively. The antipyretic effect using rectal temperature method after 90 min, at the dose of 500 mg/kg body weight was 35.66 ± 0.13, comparatively more effective than indomethacin (35.10 ± 0.22). The significant reduction of CCl4 on elevated creatinine, urea, uric acid, Ca, Na and K as well as increase on the depleted total protein after administration of the plant extract, indicated the safe use in kidney dysfunctions. The normalization of changed CCl4 intoxication, malondialdehyde and nonprotein sulfhydryls levels designated antioxidant nature of this plant. The histopathological evaluation of the kidney also revealed that B. eriophora alcoholic extract may prevent the occurrence of kidney lesions. ConclusionsB. eriophora may have analgesic, antipyretic and antioxidant activities, and may be safely used in renal toxicity conditions. Furthermore, pharmacological and clinical studies were required before therapeutic use.

A low temperature reduction of CCl4 to solid and hollow carbon nanospheres using metallic sodium

Carbon nanospheres are obtained by reacting metallic sodium at 100 °C with tetrachloromethane under a flow of N2 gas at ambient pressure. The product consisted of both hollowed and solid carbon spheres, ranging between 20 and 300 nm in size and comprised of concentrically oriented, disordered graphitic fragments. The maximum surface area recorded for this nanostructured carbon is 830 m2 g−1. Morphological, structural, and chemical analysis of the product is carried out with HR-TEM, BET surface area, XPS, XRD, and Raman spectroscopy. The formation of the spherical shape of the carbon nanoparticles is discussed based on direct observations of the reaction at the interfacial phase boundary.

Electrocatalytic dechlorination of volatile organic compounds at a copper cathode. Part I: Polychloromethanes

The electrochemical reductive dehalogenation of CCl4, CHCl3, CH2Cl2 and CH3Cl was investigated at Cu in dimethylformamide (DMF). The principal aim of the study was to check whether Cu has good electrocatalytic properties and is stable to fouling in preparative-scale electrolyses. All polychloromethanes (PCMs) have been investigated by cyclic voltammetry in DMF+0.1M Pr4NBF4 in order to evaluate the reduction mechanism and the catalytic activity of Cu. The electrochemical reduction of CCl4 and CHCl3 has also been studied by controlled-potential electrolysis in DMF+0.1M Pr4NBF4 both in the absence and presence of H2O or CH3CO2H, using chromatographic techniques to determine the intermediates and final products of the process. Cu exhibits a good electrocatalytic activity, in some cases the positive shifts of the reduction potentials with respect to GC being comparable with those at Ag, which is considered to be one of the best candidates for environmental applications in dehalogenation reactions. The results point out that the reduction mechanism at Cu is similar to what was already observed for Ag on which reduction of PCMs takes place through two competing reaction pathways: hydrodehalogenation and hydrogenolysis of carbenes. The proton availability of the medium affects drastically both the catalytic effect of Cu and the distribution of reduction products. The presence of an added proton donor promotes the hydrodehalogenation pathway, enhancing the concentration of intermediate PCMs and the final yield of methane, which is the main product of the exhaustive electrolysis.

Outer Sphere Electroreduction of CCl4 in 1-Butyl-3-methylimmidazolium Tetrafluoroborate: An Example of Solvent Specific Effect of Ionic Liquid

Electrodics of CCl4 reduction in 1-butyl-3-methylimmidazolium tetrafluoroborate [BMIM][BF4] room temperature ionic liquid (RTIL) is reported. A convolutive analysis of the cyclic voltammograms suggests that CCl4 electroreduction follows stepwise (outer sphere) dissociative electron transfer pathway, rather than the sticky dissociative (inner sphere) electron transfer, as in the case of conventional organic solvents. This difference in the mechanism of electron transfer initiated bond cleavage is attributed to the solvent specific effects, namely, stabilization of CCl4*- intermediate radical anion in RTIL, which in turn decreases the electron transfer rate and thus the carbon-halogen bond cleavage rates. Electroreduction of CCl4 in RTIL through outer sphere electron transfer would be a promising pathway for its direct conversion to methane.

Controlling Reduction Potentials of Semiconductor-Supported Molecular Catalysts for Environmental Remediation of Organohalide Pollutants

The spectroscopic and redox properties of iron(lll) protoporphyrin chloride (hemin) and cobalt(lll) meso-tetra-(4-carboxyphenyl) porphyrin chloride (CoTCP) were quantified in fluid solution and when anchored to mesoporous nanocrystalline TiO2 thin films. Surface binding was well-described by the Langmuir adsorption isotherm model from which adduct formation constants of 10(5) M(-1) and limiting surface coverages of 10(-8) mol/cm2 were abstracted. In acetonitrile and dimethyl sulfoxide electrolytes, TiO2 binding was found to induce a substantial negative shift in the M(III/II) formal reduction potentials. In DMSO electrolyte, the Co(III/II) and Fe(III/II) potentials were -559 and -727 mV versus ferrocenium/ferrocene (Fc+/Fc) and shifted to -782 and -1063 mV, respectively, after surface binding. The Bronsted acidity of the TiO2 surface was found to correlate with the measured reduction potentials. For TiO2 pretreated with aqueous solutions from pH 4-9, the Co(III/II) potential showed a -66 mV/pH unit change, while the Fe(llI/II) potential of hemin changed by -40 mV/pH from pH 1 to 14. Spectroelectrochemical data gave isosbestic, reversible spectral changes in the visible region assigned to M(III/II) redox chemistry with lambda(iso) = 410, 460, 530, 545, 568, and 593 nm for CoTCP/TiO2 and lambda(iso) = 408, 441, 500, 576, and 643 nm for hemin/TiO2. In aqueous solution, the CoTCP reduction potentials were also found to be pH dependent upon surface binding, with CoTCP = -583 mV and CoTCP/TiO2 = -685 mV versus Fc+/Fc at pH 6. For CoTCP/TiO2, the aqueous pH dependence of the potentials was -52 mV/pH. The rate constant for heme/TiO2 reduction of CCl4 increased from 3.9 +/- 0.7 x 10(-4) to 2.0 +/- 0.1 x 10(-3) s(-1) when the pH was raised from 4 to 8.

Reduction of CCl4 by Iron Powder in Aqueous Solution

Abstract·CCl3 radicals formed in the first step of the CCl4 degradation react with iron powder to form an intermediate with an Fe–C σ bond. In the absence of iron powder, ·CCl3 radicals formed by γ‐irradiation react with 2‐propanol in a chain reaction toward dechlorination. When the irradiated solution contains iron powder, the iron scavenges the ·CCl3 radicals, thus inhibiting the chain reaction. The minor product of the dechlorination of CCl4 by iron powder in aqueous solution is CH4, contrary to the results reported in the literature for the electrochemical reduction of CCl4 on iron electrodes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Ab Initio Study of Carbon−Chlorine Bond Cleavage in Carbon Tetrachloride

Chlorinated solvents in groundwater are known to undergo reductive dechlorination reactions with Fe(ll)-containing minerals and with corroding metals in permeable-barrier treatment systems. This research investigated the effect of the reaction energy on the reaction pathway for C-Cl bond cleavage in carbon tetrachloride (CCl4). Hartree-Fock, density functional theory, and modified complete basis set ab initio methods were used to study adiabatic electron transfer to aqueous-phase CCl4. The potential energies associated with fragmentation of the carbon tetrachloride anion radical (CCl4-) into a trichloromethyl radical (CCl3) and a chloride ion (Cl-) were explored as a function of the carbon-chlorine bond distance during cleavage. The effect of aqueous solvation was investigated using a continuum conductor-like screening model. Solvation significantly lowered the energies of the reaction products, suggesting that dissociative electron transfer was enhanced by solvation. The potential energy curves in an aqueous medium indicate that reductive cleavage undergoes a change from an inner-sphere to an outer-sphere mechanism as the overall energy change for the reaction is increased. The activation energy for the reaction was found to be a linear function of the overall energy change, and the Marcus-Hush model was used to relate experimentally measured activation energies for CCl4 reduction to overall reaction energies. Experimentally measured activation energies for CCl4 reduction by corroding iron correspond to reaction energies that are insufficiently exergonic for promoting the outer-sphere mechanism. This suggests that the different reaction pathways that have been observed for CCl4 reduction by corroding iron arise from different catalytic interactions with the surface, and not from differences in energy of the transferred electrons.

High-temperature electrocatalysis using thermophilic P450 CYP119: dehalogenation of CCl4 to CH4.

The use of a thermophilic cytochrome P450, CYP119, in electrocatalytic dehalogenations of C1 halocarbon solvents is studied. Temperature stable enzyme-modified electrodes were constructed using sol-gel and polymeric surfactant approaches. CYP119 deposited in a dimethyldidodecylammonium poly(p-styrene sulfonate) (DDAPSS) film has good retention of electrochemical activity up to 80 degrees C. At potentials approaching the FeII/I couple, the CYP119/DDAPSS films demonstrate high catalytic dehalogenations of the C1 chloromethanes CCl4, CHCl3, and CH2Cl2. Product analysis identified mixtures of sequentially dechlorinated products up to methane; no evidence for radical-coupled products was observed. The yield of methane from the CYP119-catalyzed reduction of CCl4 is increased 35-fold from 25 degrees C to 55 degrees C. In combination with the lack of C2 products, the facility of an overall eight-electron reductive dehalogenation suggests that the substrate is constrained within the protein during electrocatalytic turnover.

Mechanisms and products of surface-mediated reductive dehalogenation of carbon tetrachloride by Fe(II) on goethite.

Natural attenuation processes of chlorinated solvents in soils and groundwaters are increasingly considered as options to manage contaminated sites. Under anoxic conditions, reactions with ferrous iron sorbed at iron(hyro)xides may dominate the overall transformation of carbon tetrachloride (CCl4) and other chlorinated aliphatic hydrocarbons. We investigated mechanisms and product formation of CCl4 reduction by Fe(II) sorbed to goethite, which may lead to completely dehalogenated products or to chloroform (CHCl3), a toxic product which is fairly persistent under anoxic conditions. A simultaneous transfer of two electrons and cleavage of two C-Cl bonds of CCl4 would completely circumvent chloroform production. To distinguish between initial one- or two-bond cleavage, 13C-isotope fractionation of CCl4 was studied for reactions with Fe(II)/ goethite (isotopic enrichment factor epsilon = -26.5% percent per thousand) and with model systems for one C-Cl bond cleavage and either single-electron transfer (Fe(II) porphyrin, epsilon = -26.1 percent per thousand) or partial two-electron transfer (polysulfide, epsilon = -22.2 percent per thousand). These epsilon values differ significantlyfrom calculations for simultaneous cleavage of two C-Cl bonds (epsilon approximately equal to -50 percent per thousand), indicating that only one C-Cl bond is broken in the critical first step of the reaction. At pH 7, reduction of CCl4 by Fe(II)/ goethite produced approximately 33% CHCl3, 20% carbon monoxide (CO), and up to 40% formate (HCOO-). Addition of 2-propanol-d8 resulted in 33% CDCl3 and only 4% CO, indicating that both products were generated from trichloromethyl radicals (*CCl3), chloroform by reaction with hydrogen radical donors and CO by an alternative pathway likely to involve surface-bound intermediates. Hydrolysis of CO to HCOO-was surface-catalyzed by goethite butwastoo slow to account for the measured formate concentrations. Chloroform yields slightly increased with pH at constant Fe(II) sorption density, suggesting that pH-dependent surface processes direct product branching ratios. Surface-stabilized intermediates may thus facilitate abiotic mineralization of CCl4, whereas the presence of H radical donors, such as natural organic matter, enhances formation of toxic CHCl3.

Thermodynamics and Kinetics of Carbon Deposition from Mixtures of Hydrogen and Carbon Tetrachloride

The thermodynamics and kinetics of pyrolytic carbon deposition via hydrogen reduction of CCl4 were studied. Thermodynamic analysis of the C–Cl–H system was used to determine the compositions of the gas and condensed phases at CCl4 : H2 = 1 : 4 to 1 : 90, temperatures from 700 to 1400 K, and a pressure of 105 Pa. The reactions leading to the formation of solid carbon in the H2–CCl4 system were considered, and the deposition parameters were optimized in terms of carbon yield.

Carbon tetrachloride dechlorination by the bacterial transition metal chelator pyridine-2,6-bis(thiocarboxylic acid).

A reaction pathway is proposed to explain the formation of end products during defined chemical reactions between carbon tetrachloride (CCl4) and either metal complexes of pyridine-2,6-bis(thiocarboxylic acid) (PDTC) or pure cultures of Pseudomonas stutzeri KC. The pathway includes one-electron reduction of CCl4 by the Cu(II):PDTC complex, condensation of trichloromethyl and thiyl radicals, and hydrolysis of a labile thioester intermediate. Products detected were carbon dioxide, chloride, carbonyl sulfide, carbon disulfide, and dipicolinic acid. Spin-trapping and electrospray MS/MS experiments gave evidence of trichloromethyl and thiyl radicals generated by reaction of CCl4 with PDTC and copper. Experiments testing the effects of transition metals showed that dechlorination by PDTC requires copper and is inhibited by cobalt but not by iron or nickel. PDTC was shown to react stoichiometrically rather than catalytically without added reducing equivalents. With added reductants, an increased turnover was seen along with increased chloroform production.

Electrolytic Reduction of CCl4—Effects of Cathode Material and Potential on Kinetics, Selectivity, and Product Stoichiometry

Carbon tetrachloride (CCl4) was reductively transformed via electrolysis at metal cathodes consisting of pure Ag, Al, Au, Cu, Fe, Ni, Pd, and Zn. Primary products included CHCl3, CH2Cl2 and CH4. Traces of CH3Cl, C2H4, C2H6, C3H8, and other unidentified products were also observed in headspace samples. CHCl3 was reduced to CH2Cl2 and CH4 under the same experimental conditions, although at a slower rate. CH2Cl2 was essentially stable during the course of these experiments (ks < 0.05 L/m2 · min). CCl4 reduction was first order in the bulk liquid phase concentration. Pseudo-first-order rate constants were a function of cathode material, pH, and applied cathode potential (Ec) in the range −1.4 V ≤ Ec ≤ −0.4 V vs. SHE. At all electrodes, reaction rates conformed to Butler-Volmer kinetics, modified to account for mass transfer limitations. Under comparable conditions, the kinetics of CCl4 electrolysis at Ni and Cu electrodes were superior to those of transformation using any other metal tested. At Ec = −0.6 and −0.8 V, rate constants for CCl4 reduction at a Cu electrode decreased with increasing pH in the range 2 < pH < 6. At Ec ≤ −1.2 V, reduction was limited by mass transfer to the electrode surface and was independent of cathode material and pH. Electrode efficiency (ratio of dehalogenation rate to total electrolytic current) for CCl4 reduction was inversely related to the material-dependent exchange current density for hydrogen gas generation, suggesting that production of H2 (g) is the most significant competitive reaction under the conditions of the experiments. Based on efficiency considerations, the electrode materials were ordered Zn > Cu > Fe > Ni. Key words: Reductive dehalogenation; carbon tetrachloride; groundwater remediation; electrolysis

Reductive Dechlorination of Carbon Tetrachloride Using Iron(II) Iron(III) Hydroxide Sulfate (Green Rust)

The reductive dechlorination of CCl4 and CHCl3 in the presence of the synthetic sulfate form of green rust (GRSO4), FeII4FeIII2(OH)12SO4yH2O, at pH ∼ 8 and room temperature was investigated. Reduction of CCl4 produces CHCl3 and C2Cl6 as main chloroaliphatic products, while GRSO4 is oxidized to magnetite (Fe3O4). The formation of C2Cl6 indicates a coupling reaction between trichloromethyl radicals in the suspension. Chloroform was much less susceptible than CCl4 to reductive dechlorination by GRSO4 showing reduction rates approximately 100 times less than for reduction of CCl4. The transformation of CCl4 by GRSO4 can be described by pseudo-first-order reaction kinetics with respect to formation of chloride. At room temperature the rate expression is given as: d[Cl-]/dt ≅ −d[CCl4]/dt = r·kobs[Fe(II)]GR, where kobs is in the range (0.47 × 10-5)−(2.18 × 10-5) s-1 for CCl4 concentrations above its aqueous solubility. This narrow range may be due to the constant CCl4(aq) concentration owing to buffering of the...