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In this paper, we report a unified approach to N-substituted and N,N-disubstituted benzothiazole (BT) sulfonamides. Our approach to BT-sulfonamides starts from simple commercially available building blocks (benzo[d]thiazole-2-thiol and primary and secondary amines) that are connected via (a) a S oxidation/S-N coupling approach, (b) a S-N coupling/S-oxidation sequence, or via (c) a S-oxidation/S-F bond formation/SuFEx approach. The labile N-H bond in N-monoalkylated BT-sulfonamides (pKa (BTSO2N(H)Bn) = 3.34 ± 0.05) further allowed us to develop a simple weak base-promoted N-alkylation method and a stereoselective microwave-promoted Fukuyama-Mitsunobu reaction. N-Alkyl-N-aryl BT-sulfonamides were accessed with the help of the Chan-Lam coupling reaction. Developed methods were further used in stereo and chemoselective transformations of podophyllotoxin and several amino alcohols.

The novel enantiopure synthesis of protected proline-cysteine analogs by means of 1,3-dipolar cycloaddition of homochiral thiazolines and azomethine ylides is described. The important role of the oxidation state of the sulfur atom of the dipolarophile in such reaction is demonstrated affecting strongly the regioselectivity and reactivity of the 1,3-dipolar cycloaddition. Mono-oxidized sulfur atom (sulfoxide group) and di-oxidized (sulfone group) led to 2,3 regio-addition whereas reactions starting from non-oxidized sulfur atom resulted in the 2,4 addition. Besides, sulfur oxidized thiazolines reacted smoothly upon heating in an organic solvent media but the non-oxidized sulfur thiazoline required metal catalysis. Diastereofacial selectivity was observed to be independent of the oxidation state of the sulfur atom but controlled by the bulky tert-butyl group at the thiazoline ring. The highly substituted and functionalized enantiopure pyrrolidine-thiazolidine bicyclic compounds are considered as novel (homo)cysteine-proline analogs with important properties to discover. Enantiopure proline-cysteine analogs were obtained by 1,3-dipolar cycloaddition between homochiral thiazolines and azomethine ylides. The reactivity and regioselectivity are controlled by the oxidation state of the thiazoline sulfur atom. Sulfoxide and sulfone groups led to 2,3 addition whereas reactions starting from the thioether group resulted in 2,4 addition. Diastereofacial selectivity is controlled by the bulky tert-butyl group at the thiazoline ring., The authors thankfully acknowledge MINECO (Ministerio de Economía y Competitividad, grant CTQ2013-40855-R) and Gobierno de Aragon-FEDER (Grupo Aminoácidos y Péptidos E19_20R; FEDER 2014–2020‘Construyendo Europa desde Aragón’), for the financial support provided to this work. J. G.-V. thanks the Gobierno de Aragón–FSE for a pre-doctoral Grant.

Plants need hormone substances to regulate a plethora of responses during their life cycle. One major hormone class is called auxin, which is involved in many developmental processes. Besides the major auxin indole-3-acetic acid, there are other auxin-like molecules present in some, but not in all plants, an example would be chlorinated IAA in legumes. Among these are also the auxins with longer chains, indole-3-propionic acid and indole-3-butyric acid. The auxin-dependent growth response is dependent on the concentration of the compound. While lower concentrations are mainly growth promoting, high concentrations are actually inhibiting some developmental processes. Therefore, tight control of the auxin concentration is essential for proper growth and development. This can be achieved by altering the amount of active auxin via transport, biosynthesis, degradation or reversible conjugation to small molecules. In addition, plants use auxin during their interaction with the environment, for example during abiotic stresses such as salt, temperature or water stress to adapt the growth responses specifically. Furthermore, auxin is involved in the development of plant disease symptoms, such as tumor growth or aberrant tissue formation. However, together with other plant hormones such as salicylic acid auxin can also modulate disease progression or resistance in different plant – microbe combinations.

Methoxyanilines are aniline derivatives that are important chemical precursors for numerous Dye and Pharmaceuticals industries. Wastewater containing methoxyanilines have high toxicity and carcinogenic properties and if discharged without prior treatment into fresh water resources, can result in possible detrimental eff ;ects to aquatic life and public health. Therefore, in this work Fenton-like oxidation was evaluated for the degradation of 2-methoxyaniline (2-MA) and 4-methoxyaniline (4-MA) separately using abundantly available Laterite soil as an alternative source of iron against commercially procured iron (CI) in Fenton-oxidation. Parameters like hydrogen peroxide (H2O2), iron and initial methoxyanilines concentration were investigated for each of the methoxyanilines in separate experiments. For initial methoxyanilines concentration of 0.5 mM, the maximum methoxyanilines removal of 83.28 ± 0.26% and 86.34 ± 0.34% and COD removal of 71.91 ± 0.31% and 72.64 ± 0.29% for 2-MA and 4-MA at pH 3 and pH 2.5 was attained at laterite soil iron [LSI] of 0.05 mM respectively. From kinetic studies of 2-MA and 4-MA, reaction time was estimated to be 360 min. Degradation with LSI was found to be slower and lesser than CI, but is comparable and can be applied as a replacement of CI for treatment of wastewater containing toxic and incalcitrant chemicals.

The synthesis of rare macrocyclic alkynediyl sulfides by a Cu-catalyzed Csp -S cross-coupling is presented. The catalytic protocol (Cu(MeCN)4 PF6 /dtbbpy) promotes macrocyclization of peptides, dipeptides and tripeptides at ambient temperature (14 examples, 23→73 % yields) via thiols and bromoalkynes, and is chemoselective with regards to terminal alkynes. Importantly, the underexplored alkynediyl sulfide functionality incorporates a rigidifying structural element and opens new opportunities for diversification of macrocyclic frameworks through S oxidation, halide addition and azide-alkyne cycloaddition chemistries to integrate sulfones, halides or valuable fluorophores (7 examples, 37→92 % yields).

A series of monometallic and bimetallic Cu/Mg oxide-based structured catalytic sorbents were synthesized by impregnation of extruded activated carbon honeycombs and tested for the purification of simulated biogas from H2S at room temperature. Dynamic H2S (100ppmv) removal tests were run at short contact time under moist conditions in the presence of O2 to compare sulfur capture capacities and to investigate kinetic aspects of the oxidation reactions involved in the mechanism at varying the composition of the active phase. Fresh, exhausted and thermally regenerated honeycomb catalytic sorbents were characterized by N2-adsorption, PSD, XPS, TG-MS to shed light on the specific nature of S-species formed upon catalytic oxidation, the maximum capacity and the efficacy of a simple thermal regeneration treatment at 600 °C. Under moist conditions, the surface chemistry resulted dominated by the basic nature of MgO, and bimetallic CuMg catalytic sorbents show fast H2S removal rates and large S-capacity coupled to easy and complete regenerability.

The remediation of surface water contaminated with domestic purpose kerosene (DPK) using Fenton’s oxidation was investigated at ambient temperature for effectiveness at optimum conditions established. Results obtained from optimization studies for the Fenton’s oxidation employed for the study were 250000 mg/L H2O2 and 300 mg/L FeSO4 at ambient temperature with pH of samples adjusted to 3.0. At the end of the chemical remediation, the Fenton’s oxidation was found to be rapid with the reaction being exothermic and followed second order kinetics. About 44.4% of the total petroleum hydrocarbon (TPH) as kerosene removal efficiency was achieved after 90 minutes. The reaction also followed a pseudo-first order kinetics with the rate constant of 3x102 mol-1cm3min-1.

Direct catalytic selective oxidation of H2S to sulfur at low temperature has been drawing attention. Molybdenum carbide (Mo2C), in which the excess occupied orbitals provide more back-donation chan...

The relationship between marrow adipose tissue (MAT) and bone health is poorly understood. We used running exercise to ask whether obesity-associated MAT can be attenuated via exercise and whether this correlates with gains in bone quantity and quality. C57BL/6 mice were divided into diet-induced obesity (DIO, n = 14) versus low-fat diet (LFD, n = 14). After 3 months, 16-week-old mice were allocated to an exercise intervention (LFD-E, DIO-E) or a control group (LFD, DIO) for 6 weeks (4 groups, n = 7/group). Marrow adipocyte area was 44% higher with obesity (p

Knowledge of the manganese oxidation states of the oxygen-evolving Mn 4 CaO 5 cluster in photosystem II (PSII) is crucial toward understanding the mechanism of biological water oxidation. There is a 4 decade long debate on this topic that historically originates from the observation of a multiline electron paramagnetic resonance (EPR) signal with effective total spin of S = 1/2 in the singly oxidized S 2 state of this cluster. This signal implies an overall oxidation state of either Mn(III) 3 Mn(IV) or Mn(III)Mn(IV) 3 for the S 2 state. These 2 competing assignments are commonly known as “low oxidation (LO)” and “high oxidation (HO)” models of the Mn 4 CaO 5 cluster. Recent advanced EPR and Mn K-edge X-ray spectroscopy studies converge upon the HO model. However, doubts about these assignments have been voiced, fueled especially by studies counting the number of flash-driven electron removals required for the assembly of an active Mn 4 CaO 5 cluster starting from Mn(II) and Mn-free PSII. This process, known as photoactivation, appeared to support the LO model since the first oxygen is reported to evolve already after 7 flashes. In this study, we improved the quantum yield and sensitivity of the photoactivation experiment by employing PSII microcrystals that retained all protein subunits after complete manganese removal and by oxygen detection via a custom built thin-layer cell connected to a membrane inlet mass spectrometer. We demonstrate that 9 flashes by a nanosecond laser are required for the production of the first oxygen, which proves that the HO model provides the correct description of the Mn 4 CaO 5 cluster’s oxidation states.

Because of the production of chlorine species in leachate during Fenton’s oxidation, harmful disinfection byproducts (DBP) can be formed but this has not been well studied before. Herein, we have investigated five classes of DBP: trihalomethanes, haloacetic acids, haloacetonitriles, haloketones, and halonitromethanes during Fenton’s oxidation of landfill leachates. The results show that the DBP concentration increased with the increase of [H2O2]: [Cl−] ratio due to the increased concentration of chlorine species. The highest total DBP concentration was 4860 μg L-1 at [H2O2]: [Cl−] = 4.0 and the lowest was 84 μg L-1 at [H2O2]: [Cl−] = 0.25. Both the DBP concentration and DBP toxicity increased with the increase of the [H2O2]: [Fe2+] ratio, because of the increased concentration and lifetime of the chlorine species. Most of the DBP were formed during the first minute of the reaction and stayed stable up to 3 h, indicating that DBP may not be preferred targets of hydroxyl radicals in the presence of a large amount of organics. In most cases, trihalomethanes dominated the DBP concentration, while haloacetonitriles dominated the total additive toxicity. This study has provided important implications to understand DBP formation during Fenton’s oxidation.

Employing organic redox mediators (ORMs) as mobile catalyst into the electrolyte system has been selected as an important strategy to lower the charging overpotentials in lithium-oxygen (Li-O2) batteries. Careful choice of molecular designs of ORMs can also tailor their redox potential and rate of electron-transfer to improve the catalytic efficiency. However, the stability of ORMs in Li–O2 cells was scarcely studied. In here, catalytic efficiency and stability of several important ORMs are assessed through in situ gas analysis and reactivity tests with singlet oxygen. Some well-known ORMs are detrimentally decomposed during the first cycle in Li–O2 cells, whereas nitroxyl-radical-based ORMs bear the most stable and efficient response. Analogous nitroxyl-radical derivatives further increase round-trip energy efficiency and electron-transfer kinetics. This study also emphasizes the evaluation of chemical stability of ORMs, which are mandatory for the long-term cyclability in Li–O2 cells. references W.-J. Kwak, H. Kim, H.-G. Jung, D. Aurbach, Y.-K. Sun, J. Electrochem. Soc. 2018, 165, A2274–A2293. W.-J. Kwak, H. Kim, Y. K. Petit, C. Leypold, T. T. Nguyen, N. Mahne, P. Redfern, L. A. Curtiss, H.-G. Jung, S. M. Borisov, S. A. Freunberger and Y.-K. Sun, Nat. Commun., 2019, 10, 1380.

Elemental S oxidation in soil is a microbially mediated process and is hypothesised to be influenced by changes to soil chemical properties such as acidity and ionic strength, which may arise from co-granulation with macronutrients or elemental S oxidation itself. Soil incubation was conducted with a sandy soil from South Australia to assess the effect of acidification and increased ionic strength on bacterial abundance and community composition and on elemental S oxidation during a 14-week incubation at 25 °C and 70% field capacity. Prior to incubation, the soil was treated with HNO3 to bring the pH to 6.7–4.4 or with KH2PO4 to increase the ionic strength by 0–0.7 M. Elemental S was applied at 200 mg kg−1 air-dried soil. Acidification or increased ionic strength had no or little effect on elemental S oxidation but decreased the abundances of 16S ribosomal deoxyribonucleic acid (rRNA) and soxB genes and changed the bacterial community composition. A second experiment with two other soils also showed that acidification did not, or only slightly, decreased elemental S oxidation, even though acidification strongly reduced 16S rRNA and soxB gene abundances in one of the soils. This study suggests that shifts in bacterial population brought about by temporary changes in pH and ionic strength, as may occur around fertiliser granules, have no or little effect on elemental S oxidation, indicating that the S-oxidising bacterial community in these agricultural soils contains functionally redundant taxa, which responded to changing conditions.

The operation conditions for the implementation of the Fenton process are of utmost importance because there are problems related to the proportion of H2O2 dosage to COD and Fe2+ dosage to the specified H2O2 amount. The relevant lite-rature shows that COD/H2O2 ratios range between 0.0084 and 113.9. Similarly, the COD/Fe2+ ratio varies between 0.079 and 292.6, while the H2O2/Fe2+ ratio varies between 0.09 and 287. Moreover, the ratio of the maximum value to the minimum value used in the operations on the basis of COD is 13560 for COD/ /H2O2 (0.0084-113.9), 2210 for COD/Fe2+ (0.079-174.7), and finally 3190 for H2O2/Fe2+ (0,09-287). The aim of this study was to re-evaluate these values that significantly differ from each other with specific emphasis on textile wastewater and considering stoichiometric ratios. Results showed that values ranging between 0.43 and 4.0 for COD/H2O2 and those ranging between 0.75 and 3.0 for H2O2/Fe2+ are more suitable. The results showed that in a Fenton process con-ducted by dosing H2O2 at different times, the TOC reduction efficiencies inc-reased from 80.8 up to 88.9%. Similarly, the color reduction efficiency also rose from 96.5 to 98.7%. This article has been corrected. Link to the correction 10.2298/CICEQ170425016E

In this study, the relevance of Fenton’s reaction for the treatment of urban anaerobically digested sludge was investigated. In a first part, the impact of the oxidation process on the improvement of the sludge dewaterability was studied. In a second part, the removal of heavy metals from the sludge was examined. Fenton’s reaction was carried out with increasing concentrations of Fe2+ and H2O2 in 1:10 and 1:1 ratios. Dewaterability of the raw sludge was highly improved: the addition of 36 mM Fe2+ and 360 mM H2O2 led to specific cake resistance (SCR) and capillary suction time (CST) reductions of 99.8% and 98.8%, respectively. Indeed, under these conditions, SCR and CST of respectively 1.04 × 1011 m kg−1 and 18.5 ± 0.2 s were measured, and the treated sludge could be considered as having ‘good dewaterability’. A significant impact was also observed on the removal of heavy metals from the sludge. After 1-h oxidation, Cd, Cr, Cu, Pb and Zn could be removed by 81.1 ± 0.1%, 25.1 ± 0.1%, 87.2 ± 1.1%, 77...

The present study investigates the applicability of Fenton's oxidation for the treatment of a highly refractory, viscous, bulk drug industry effluent. The effluent is found to behave as a Newtonian fluid, thrice as viscous as water. Fenton's oxidation experiments on the undiluted effluent are conducted in accordance with central composite design (CCD), considering the operating factors of pH (3–11), FeSO4 dosage (3–15 g L−1), H2O2 dosage (7–19 mL L−1), and treatment time (30–150 min). The treatment yielded a maximum total organic carbon (TOC) reduction of 28% at neutral pH, FeSO4, and H2O2 dosages of 9 g L−1 and 13 mL L−1, respectively, for 150 min of operation. The maximal treatment efficacy observed at neutral pH is explained by the non-radical mechanism of Fenton's oxidation, and further correlated with viscosity and type of fluid (here, Newtonian), as judged from the generated viscosity profiles. Upon comparison with previous effluent samplings, differing treatment efficacies are observed for different fluid types, that is, Newtonian and non-Newtonian (shear thinning), with the latter obtaining twice the TOC reduction, under similar experimental conditions. Hence, the effect of viscosity and fluid type on the effectiveness of Fenton's oxidation treatment is experimentally validated and discussed.

A lab scale bubble reactor (BR) configuration was employed to evaluate the degradation of gaseous toluene by Fenton’s oxidation under semi-batch mode operation (i.e., with continuous gas bubbling in the liquid phase where organics oxidation is carried out). A parametric study was performed for evaluating the effect of Fenton’s process operating parameters, such as temperature and concentration of Fe2+ and H2O2, in the removal of toluene from the gas stream. The maximum amount of toluene transferred (0.041 mol per liter of solution) was reached when the optimal conditions ([Fe2+] = 2.5 mM, [H2O2] = 20 mM, and T = 25 oC, at pH 3.0) were used after 120 min of reaction, yielding the highest average toluene absorption rate (5.78 × 10−6 mol/L.s). The treatment of the gas stream increased, however, the organic load in the aqueous phase, so a subsequent treatment stage of the liquid was performed. Additionally, a scale-up of the sequential gas-liquid treatment for a bubble column reactor (BCR) was carried out for several cycles, up to almost 20 h. This strategy, making use of the Fenton’s process for treating the toluene gas stream, with intermediate liquid oxidation, allowed to reach more gas treatment stages, while providing a final effluent that is non-toxic (0.0 % of inhibition of Vibrio Fischeri) and biodegradable.

Methods for the preparation of thiophene S-oxides, their roles in thiophene metabolism, and the structures and chemical reactivity of these compounds, are discussed.

Applications of Fenton's oxidation of landfill leachate is limited by both high reagent requirements and a large amount of sludge generation. To address those issues, forward osmosis (FO) and humic acid (HA) recovery were incorporated with Fenton's treatment. In the FO, leachate was concentrated by 3.2 times in 10 hours using a 5-M NaCl draw solution. The HA recovery increased from 1.86 to 2.45 g L−1 at pH 2 after FO concentration, mainly because of the replacement of O in the HA structure by other inorganics (i.e., Cl, Na, K) with higher molecular weights. Due to the movement of alkalinity causing species (i.e., HCO3−, CO32-) to the draw side driven by a concentration gradient, the H2SO4 requirement per g of recovered HA and per g of removed COD decreased by 46.4% and 17.1%, respectively. The HA recovery also decreased sludge generation by 30%. At a dimensionless oxidant dose of 0.5, the proposed system reduced the overall requirement of H2SO4 by 25.2%, NaOH by 34.6%, and both FeSO4.7H2O and H2O2 by 35%, compared to the standalone Fenton's treatment of raw leachate. Those results have demonstrated that the proposed system could greatly decrease the leachate volume, lower the reagent requirements, and reduce the sludge production towards sustainable leachate treatment.

Mice that were heterozygous dominant for the enu1 and enu2 mutation in phenylalanine monooxygenase/phenylalanine hydroxylase (PAH) resulted in hepatic PAH assays for S-carboxymethyl-L-cysteine (SCMC) that had significantly increased calculated K

In the presence of acetic acid, the effects of pH, processing time, addition of Fe2+ and H2O2 on dye wastewater treatment were studied. Experimental results showed that in the presence of acetic acid, when the pH value was 4, the processing time was 30.0min, addition of ferrous sulfate was 4.8g/L, and addition of hydrogen peroxide was 56mL/L, the treatment effect was the best, COD removal rate reached 51.0%. Further studied of the effect of the presence of acetic acid on Fenton’s oxidation of dye wastewater, the results showed that without of acetic acid, the COD removal rate was higher than that with acetic acid. And the effect of Fenton's reagent on oxidation of dye substances was interfered by the presence of acetic acid.

We examined the feasibility of Cr(OH)3(s) oxidation mediated by surface catalyzed Mn(II) oxidation under common groundwater pH conditions as a potential pathway of natural Cr(VI) contaminations. Dissolved Mn(II) (50 μM) was reacted with or without synthesized Cr(OH)3(s) (1.0 g/L) at pH 7.0-9.0 under oxic or anoxic conditions. Homogeneous Mn(II) oxidation by dissolved O2 was not observed at pH ≤ 8.0 for 50 days. At pH 9.0, by contrast, dissolved Mn(II) was completely removed within 8 days and precipitated as hausmannite. When Cr(OH)3(s) was present, this solid was oxidized and released substantial amounts of Cr(VI) as dissolved Mn(II) was added into the suspension at pH ≥ 8.0 under oxic conditions. Production of Cr(VI) was attributed to Cr(OH)3(s) oxidation by a newly formed Mn oxide via Mn(II) oxidation catalyzed on Cr(OH)3(s) surface. XANES results indicated that this surface-catalyzed Mn(II) oxidation produced a mixed valence Mn(III/IV) solid phase. Our results suggest that toxic Cr(VI) can be naturally produced via Cr(OH)3(s) oxidation coupled with the oxidation of dissolved Mn(II). In addition, this study evokes the potential environmental hazard of sparingly soluble Cr(OH)3(s), which has been considered the most common and a stable remediation product of Cr(VI) contamination.

A simple rapid method is proposed to determine cefazolin in neat substances and powders for preparing injection solutions based on the preliminary oxidation of the preparation in weak acidic media by potassium peroxomonosulfate to respective S,S′-dioxide followed by its determination by oscillographic polarography. The concentration of the title material in the cefazolin substance was found to be 96.7%, RSD = 3%, δ= 2.4% and in the powder, 97.7%, RSD = 3%, δ = 2.3%.

Advanced oxidation processes (AOPs) have been increasingly applied to emergent pollutants degradation. Although, homogeneous reaction by classical Fenton enables amoxicillin degradation, high iron catalyst concentrations are needed, raising environmental concerns. This work proposed an innovative and cheap solution to degrade amoxicillin by combining microwave with Fenton’s reaction. The main operational parameters were optimized step-by-step (hydrogen peroxide and ferrous ion concentration and microwave power). Amoxicillin oxidation was significantly improved over classical Fenton’s reaction. In fact, in less than 5 min (P = 162 W, [H2O2]0 = 2.35 mg L−1, [Fe2+]0 = 95 μg L−1) amoxicillin was no longer detected in the reaction system. A semi-empirical kinetic model was proposed to predict the two-stage decay curves at any conditions within the studied parameters and the adequacy of the model was statistically evaluated.

A series of nuevamine aza-analogues were prepared in moderate to good yields in two reaction steps. The synthetic strategy involves an isonitrile-based multicomponent reaction, including an aza-Diels–Alder cycloaddition and Pictet–Spengler reaction as postcondensation.

The results of thermal study and mechanism of the oxidation process of synthetic Ag2S in air are presented in this article based on the comparative analysis of DTA and XRD results, as well as by constructed phase stability diagrams (PSD) for the Ag-S-O system.

Ranitidine hydrochloride (RNH), chemically known as A-dimethyl-5-[2-(l- methylamino-2-nitro-vinyl)-ethylthiomethyl]furfuryl amine hydrochloride, is an antiulcer drug and its oxidation-kinetic study is of much significant in understanding its mechanistic chemistry in redox reactions. Consequently, the kinetics of oxidation of RNH by sodium N-chloro-p-toluenesulfonamide (chloramine-T or CAT) have been examined in HC104 and NaOH media at 298 K. The stoichiometry and oxidation products of RNH - CAT reaction are the same in both media, however, their kinetic patterns were found to be different. The reaction rate exhibits first-order kinetics with respect to [CAT]O and [RNH]O in both media. The rate of reaction increases with increase in [H+], but it decreases with respect to [OH -] with a slope of unity in both the cases. Decrease of the dielectric constant of the medium decreases the reaction rate in both media. Variation of the ionic strength of the medium, and addition of /7-tolucncsul foil amide or NaCl, have no significant effect on the rate. The reaction was studied at different temperatures and activation parameters have been deduced. Ranitidine-S'-oxide was identified as the oxidation product of RNH by GC-MS in both media. The conjugate free acid CH3C6H4S02NHC1 of CAT is postulated as the reactive oxidizing species in both cases. The observed results have been explained by plausible mechanisms and related rate laws have been deduced.

A series of tetrahydroisoquinolin-pyrrolopyridinones were prepared from an easily accessible aldehyde, a commercially available amine, a readily isolable isonitrile, and maleic anhydride via a triple process: Ugi-3CR–aza Diels–Alder/S-oxidation/Pummerer. The combination of a multicomponent Ugi-type reaction with other post-functionalization processes provides a powerful tool for the preparation of fused polyheterocyclic compounds.

We have investigated room temperature sensing characteristics of CuO films to various gases i.e. Cl 2 , H 2 S, NH 3 , CH 4 , CO and NO. CuO films were prepared by oxidation of Cu films, which were deposited on polycrystalline alumina substrates by thermal evaporation technique. CuO films have been found to be highly selective towards H 2 S. We demonstrate that the H 2 S response of CuO films can be divided in to three regions: (a) low concentrations (100–400 ppb), (b) intermediate concentrations (500 ppb to 50 ppm), and (c) high concentrations (>50 ppm). For low concentrations (100–400 ppb), the response curves have been found to be highly reversible with very small response (∼60 s) and recovery (∼90 s) times, indicating suitability of CuO films for sub-ppm sensing of H 2 S. Oxidation of H 2 S by adsorbed oxygen is found to be the responsible sensing mechanism. However, at very high H 2 S concentrations (>50 ppm), surface of CuO grains is found to convert into CuS, resulting in an irreversible response curve. For intermediate concentrations (500 ppb to 50 ppm), the response curve is governed by both H 2 S oxidation and CuS formation mechanisms.

Most organophosphate (OP) pesticides require metabolic activation before attacking the target site, as opposed to chemical nerve agents, such as VX and sarin, which inhibit the enzyme directly. The majority of OP pesticides exhibit weak anticholinesterase activity in vitro compared to their In Vivo activity. Biooxidation is probably the principal route by which these pesticides are activated or detoxified. The oxidized product, usually a short-lived intermediate, may either hit the target directly or hydrolyze rapidly or, following a rearrangement reaction, convert to another species with enhanced reactivity (metaphosphate) or lose its phosphorylation or carbamoylation properties. Biomimetic studies of these processes, using various model systems, have important advantages: in some cases they allow for identifying short-lived intermediates, formed metabolically, and direct monitoring of the systems' properties by NMR. Once identified, they may be synthesized in large amount to investigate their adverse effects, if any. Biomimetic studies allow for monitoring reactions at low temperature seeking transient intermediates and evaluation of activation and detoxification mechanisms as well as mode of action based on chiral isomers. This, in turn, allows for determination of whether certain compounds act directly, on preactivation, or both, and the possible design of safer pesticides. This paper covers over three decades of extensive fundamental and applied research that has been carried out at the Environmental Chemistry and Toxicology Laboratory (ECTL) at the University of California at Berkeley under the supervision of Prof. John E. Casida.

This article first presented direct applicability of Fenton's oxidation to high-strength wastewater, especially when efficiency of biological treatment for high-strength wastewater is insufficient. Fenton's oxidation was applied both to biologically pretreated molasses wastewater (BMW) and untreated molasses wastewater (MW), and the removal of color and chemical oxygen demand using chromate (CODcr) were compared between the two wastewaters. The optimum reaction time was 20 min for both BMW and MW. Neither the different dosages of Fenton's reagents nor the initial pH affected the removal ratios of CODcr and color from either BMW or MW. The maximum removal ratios of CODcr and color were approximately 90 and 97% for BMW and 88 and 98% for MW, respectively. Although these ratios are similar, the optimum H2O2 dose (g L−1)/initial CODcr (g L−1) ratio and the optimum H2O2/Fe2+ molar ratio for BMW treatment were larger than those for MW treatment. This indicates that direct Fenton treatment of MW uses le...

The performance of vanadia-doped titania-pillared clay (V/Ti-PILC) in the selective catalytic oxidation of H 2 S was investigated in this study. A series of V/Ti-PILC with various amounts of vanadia were prepared and characterized. XRD analysis revealed the presence of titania anatase peak without any evidence of crystalline vanadia. V/Ti-PILC showed a very good catalytic performance towards H 2 S oxidation at temperatures ranging from 220–300 °C without the considerable emission of SO 2 . At 300 °C, all the catalysts showed high H 2 S conversion of about 85%. The H 2 S conversions over V/Ti-PILC increased with increasing vanadia content and temperature.

A comprehensive study of the chemical oxidation degradation of diethyl phthalate (DEP) was conducted through Fenton processes. Effects of various operating parameters that considerably affect DEP decomposition were investigated, including solution pH, H

This study was performed in order to explain different orientation in the reaction of quinolinyl sulfides with nitrating mixture, which converted on one hand quinolinyl sulfides 1, 3 and 5 to sulfoxides 2, 4 and 8, respectively, on the other hand, sulfides 6, 7 to the respective nitroderivatives 9 and 10. Competitive experiments showed following reactivity order: thianthrene 11 ≥ thianthrene 5-oxide 12 ≥ isothioquinanthrene 3 ≥ thioquinanthrene 1 ≥ 3,3′-diquinolinyl sulfide 5 ≥ 3,4′-diquinolinyl sulfide 6 ≥ 4,4′-diquinolinyl sulfide 7. Considering that NO2+ (as reactive form of nitrating mixture) attacks the most electronodonating (sulfur or carbon) center the reactivity order well correlates with the results of HOMO as well as MEP calculations.

High strength refractory organic stream is produced during the production of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran (One Dye Black 2, abbr. ODB 2), a novel heat-sensitive material with a promising market. In this study, a combination of acidification-precipitation, primary biological treatment, Fenton's oxidation and another biological treatment was successfully used for the removal of COD from 18000-25000 mg/L to below 200 mg/L from the ODB 2 production wastewater in a pilot experiment. A COD removal of 70%-80% was achieved by acidification-precipitation under a pH of 2.5-3.0. The first step biodegradation permitted an average COD removal of 70% under an hydraulic residence time (HRT) of 30 h. By batch tests, the optimum conditions of Fenton's oxidation were acquired as: Fe2+ dose 6.0 mmol/L; H202 dose 3000 mg/L; and reaction time 6 h. The second step biological treatment could ensure an effluent COD below 200 mg/L under an HRT of 10 h following the Fenton's treatment.

The rate of S oxidation in elemental S fertilizers to plant-available sulphate-S depends on factors that affect microbial activity, such as soil moisture, temperature, aeration and size of fertilizer granules. Three field experiments were conducted on S-deficient Gray and Dark Gray Luvisol soils (Typic Cryoboralf) during 2000 and 2001 in Saskatchewan (exp. 1 at Porcupine Plain and exp. 3 at Canwood) and Alberta (exp. 2 at Legal) to determine the effects of formulation of elemental S fertilizers on yield, oil, protein and S concentration, S uptake, percent recovery of applied S and N uptake in seed of canola (Brassica napus L. ‘A4573’ at Porcupine Plain and ‘Invigor 2663’ at Legal and Canwood). In exp. 1 (2000 and 2001) and exp. 2 (2000), treatments included five elemental S fertilizers (granular ES-99, ES-95, ES-90 and Biosul-90; and Biosul-50 suspension), granular potassium sulphate and zero-S control. In exp. 3, treatments included eight elemental S fertilizers (granular ES-99, ES-95, ES-90 and Biosul-90; powder Lab fine ES-99.5, ES Settle-47 and ES SPB571-85.8; and Biosul-50 suspension), 21.7% elemental S plus 18.7% sulphate-S (Agrium Plus), blend of granular ES-90 and ammonium sulphate (1:1), granular ammonium sulphate and zero-S control. The S fertilizers were surface-broadcast or sprayed at 15 and 30 kg S ha-1 rates within 2–3 d after sowing in spring. Canola plants in the zero-S treatment showed S deficiency in the growing season, and seed yield increased with sulphate-S fertilizer by 21.8, 1.4, and 3.6 times in exps. 1, 2, and 3, respectively. There was little effect of S fertilizer on protein concentration in seed. Biosul-50 suspension in all experiments and powder forms of elemental S fertilizers, used only in exp. 3, were almost as effective as sulphate-S fertilizers. In all experiments, granular elemental S fertilizers had no or only a very small effect on yield, S uptake, percent recovery of applied S, N uptake, oil concentration, S concentration and protein concentration of canola seed in the first year of application. In the second year of exp. 1, granular elemental S fertilizers tended to increase yield, S uptake, N uptake, oil concentration, and S concentration of canola seed, but none of them produced seed yield or improved other parameters of canola seed comparable with the sulphate-S and elemental S powder or suspension fertilizers. In summary, granular elemental S fertilizers were not effective in increasing canola seed yield and S uptake on S-deficient soils in the first year of application. After the second annual application, most granular elemental S fertilizers tended to correct deficiency of S in canola plants, but improvements in yield and other parameters of seed were still less than the sulphate-S and suspension or powder forms of elemental S fertilizers. Key words: Canola, elemental and sulphate S fertilizers, granular, suspension, oil and protein content, seed yield, S uptake

The Fenton's oxidation kinetics of herbicide 2,4-D at various [Fe(II)] and [H(2)O(2)] combinations was investigated and modelled through an unconventional approach. The reaction kinetics of 2,4-D degradation demonstrated a two-stage pattern of decay, where a very fast reactive stage was followed by a retardation stage due to the depletion of oxidants and to the competitive side-reactions of the intermediates (including 2,4-dichlorophenol, chlorohydroquinone and 2,6-dichlororesorcinol). A model characterized by two newly established constants, the initial decay rate and the maximum oxidative capacity, was proposed and proven capable of describing the two-stage process, which cannot easily be described by conventional first- or second-order kinetics approaches.

Sanitary Landfill leachate treatment by a combined anaerobic fluidized bed reactor and Fenton's oxidation was investigated. Anaerobic treatability studies were performed in a pilot-scale fluidized ...

The identity of the enzyme(s) responsible for the S-oxidation of the mucoactive drug S-carboxy-methyl-l-cysteine (SCMC) is unknown but the protein(s) are a susceptibility factor for a number of chronic degenerative diseases. The structural similarities between the amino acid l-cysteine and SCMC have raised the possibility that cysteine dioxygenase (CDO) may be responsible for this biotransformation reaction. Both CDO and SCMC S-oxygenase were found to require Fe2+ for enzymatic activity, and both enzyme activities were inhibited by Fe2+ and Fe3+ chelators. However, sulphydryl group modification of the enzymes resulted in the activation of the S-oxidation of SCMC but inhibition of the S-oxidation of l-cysteine. When the two enzyme activities were quantified in 20 female hepatic cytosolic fractions no linear correlation in the production of their respective metabolites was seen. The results of this investigation indicate that CDO is not responsible for the S-oxidation of SCMC in the rat.

The removal of the herbicide simazine (2-chloro-4,6-bis(ethylamino)-s-triazine) in aqueous phase has been carried out continuously by means of Fenton’s reagent (Fe(II)+H2O2). The influence of the main operating parameters, Fe(II) concentration (5.0×10−5 to 4.0×10 −4 M ), pH (2–6) and temperature (10–30 °C) has been studied. Based on HPLC analysis, the main route of simazine removal has been proposed to be the dechlorination reaction to generate 2-hydroxy-4,6-bis(ethylamino)-s-triazine. Nevertheless the dealkylated first intermediate of the herbicide was also identified by chromatography techniques. By means of a pseudoempirical model based on the classic Fenton’s chemistry and the mass balances for a continuos perfectly mixed reactor, the theoretical evolution profiles of the species involved in the process have been calculated.

A variety of activated and non-activated secondary alcohols were selectively oxidized to the ketones with N-bromosuccinimide using cobalt (II) acetylacetonate as catalyst.