4-chlorobenzyl Alcohol Research Articles

Tailoring defects in In2S3/Zn0.3Cd0.7S heterojunctions for efficient photocatalytic CO2 conversion

Defect engineering is a highly effective approach to regulate the electronic structure of the catalyst surface, widely employed in the field of photocatalytic energy conversion. In this study, we have successfully synthesized a novel dual-defective In2S3/Zn0.3Cd0.7S (IS/ZCS) heterojunction structure via a self-assembly method, composed of Zn-vacancy-rich Zn0.3Cd0.7S (ZCS) and S-vacancy-rich In2S3 (IS). Under visible light illumination, 3% IS/ZCS sample exhibits remarkable photocatalytic performance in the synergistic reaction of CO2 reduction and 4-chlorobenzyl alcohol (Cl-PhCH2OH) oxidation with the CO yield significantly improved by a factor of 3.5 and 51 compared to that of ZCS and IS, respectively. The combined experimental data and theoretical calculations demonstrate that the dual-defective structure and Z-scheme transfer mode are the key factors behind the enhanced photocatalytic activity, providing more active sites and effectively improving the utilization of photogenerated charge carriers (PCCs). Moreover, the reaction pathway and catalytic mechanism of photocatalytic CO2 reduction were elucidated by the in-situ FTIR technique combined with DFT calculations, monitoring the intermediate and final products during the reaction period. Our results provide a powerful example of designing novel heterojunction photocatalysts with high activity and accelerating the separation of PCCs, with broad implications for the development of efficient photocatalytic systems.

Hydrothermal Stability and Transport Properties of Optically Detectable Advanced Tracers With Carbonate Rocks in the Presence of Oil

Summary The use of tracer technology to illuminate reservoir characteristics such as well connectivity, volumetric sweep efficiency, and geological heterogeneity for the purpose of improving history-matching fidelity and enriching production optimization algorithms has gained momentum over the last decade. Herein, we report the stringent laboratory qualification of a novel class of fluorescent molecules, optically detectable down to ultratrace levels (<ppb) in produced water, as competent crosswell water tracers for use in highly retentive carbonate reservoirs with harsh salinity and temperature requirements. Tracer molecules, with state-of-the-art fluorobenzoic acids (FBAs) as a benchmark, exhibiting requisite hydrothermal stability and nonretentive behavior in simulated reservoir conditions coreflood tests are scheduled to be field-trialed. Our novel fluorescent tracer material systems, based on dipicolinic acid (DPA) and naphthalene sulfonates, rely on time-resolved luminescence and/or advanced chromatographic separation to eliminate the interfering fluorescent background issue in produced water for near real-time analysis. We systematically evaluated the novel tracer molecules at 95°C in high-salinity injection brine over 4 months, with periodic sampling and analysis by liquid chromatography to ascertain their hydrothermal stability. Coreflood tests at reservoir conditions were conducted to determine their interactions with carbonate rock surfaces with and without residual crude oil. All qualification tests were performed using a reference water tracer 2-FBA and/or a model partitioning tracer 4-chlorobenzyl alcohol as benchmark. Finally, reservoir simulations were performed to study both nonpartitioning and partitioning tracer transports in realistic field conditions. Hydrothermal stability tests indicated that our novel tracers are stable for 132 days in brine under reservoir conditions. Coreflood tests without residual oil revealed that the novel fluorescent tracer materials, such as FBAs, exhibit negligible retention in carbonate rocks (almost 100% recovery of the tracers). Coreflood experiments with residual oil suggested that all tracer materials, including the FBAs, possibly reversibly interact with the rocks, resulting in lower tracer materials recovery. While the overall retention of tracer materials is minimal in the presence of residual oil, these values were found to be relatively higher to that measured without residual oil. We observed no significant change in core permeability due to tracer injection. Field-scale reservoir simulation sensitivity studies in companion with coreflood experiments indicated minimum interferences for consecutive tracer injections in the field trial settings. We believe this is the first time such direct comparative study has been performed in the existing research to evaluate the interaction of both water and partitioning tracers in carbonate rocks at reservoir conditions with and without the presence of residual crude oil. Reducing the burden of analysis is critical in the implementation of this technology to obtain high-fidelity tracer data that can be used to improve waterflood optimization, increasing hydrocarbon recovery by a few percent per well without using additional resources for drilling or production. The ability to use presently commercialized tracer technologies, such as FBA-based molecules, in conjunction with this novel optically detectable fluorescent tracer platform will be a force multiplier to enable large tracer campaigns that provide high-fidelity tracer data for a production optimization algorithm.

Anaerobic degradation of thiobencarb by mixed culture of isolated bacteria.

Thiobencarb is a highly effective thiocarbamate herbicide frequently used in rice fields globally. In this study, three bacterial strains (Dechloromonas sp. Th1, Thauera sp. Th2, and Azoarcus sp. Th3) isolated from immobilized biomass were analyzed for thiobencarb degradation under anaerobic conditions, with nitrate serving as an electron acceptor. The experimental results showed that thiobencarb was transformed by Dechloromonas sp. Th1 and Thauera sp. Th2 to produce high concentrations of metabolites in a mineral medium. Dechloromonas sp. Th1 dechlorinated the herbicide to benzyl mercaptan, which was then degraded by Thauera sp. Th2 and Azoarcus sp. Th3. Azoarcus sp. Th3 effectively degraded intermediates, i.e. 4-chlorobenzyl alcohol, 4-chlorobenzoic acid, and benzoic acid, produced from the degradation by Dechloromonas sp. Th1 and Thauera sp. Th2. The cross-feeding, nutrient sharing, and cooperation of all isolates in the degradation process decreased the concentrations of intermediate products. The determination of the degradation kinetics showed that the utilization in the exponential phase of the mixed bacteria was consistent with the Michaelis-Menten model, with a maximum degradation rate of 1.56±0.16µM day-1. This study showed the degradation mechanisms in bacteria and the synergistic process in the degradation of thiobencarb and its metabolites.

Environmental risk assessment of inter-well partitioning tracer compounds shortlisted for the offshore oil and gas industry

Quantifying residual oil saturation (SOR) in the inter-well region of oil and gas reservoirs is key for successfully implementing EOR solutions. Partitioning inter-well tracer tests (PITTs) has become a common method for quantifying SOR. A new group of seven chemicals – pyridine, 2,3-dimethyl pyrazine, 2,6-dimethyl pyrazine, 4-methoxybenzyl alcohol, 3,4-dimethoxybenzyl alcohol, 4-chlorobenzyl alcohol, and 2,6-dichlorobenzyl alcohol – have been proposed as potential partitioning tracers for quantifying SOR. Using these tracers can lead to their environmental release in the marine environment through produced water discharges, with currently limited knowledge on impacts in the marine ecosystem. The primary objective of the present study is to assess the environmental risk of discharging the tracer compounds in the marine environment. We investigated the fate and effect of these tracers in the marine environment. Biodegradability in seawater was measured to understand the fate of tracers in the marine environment. The acute toxicity of tracers was measured in terms of the percent cell viability of a rainbow trout gill cell line (RTgill-W1) and growth inhibition of the algae Skeletonema costatum. The ecotoxicological information obtained from these experiments was used in the dynamic risk and effects assessment model (DREAM) to calculate the tracers’ contribution to the environmental impact factor (EIF). The results from the DREAM simulations suggest no contribution towards EIF values from any of the tracers at the expected back-produced concentrations. Results from simulations at higher concentrations suggest that both pyrazines have the lowest environmental risk, followed by 3,4-dimethoxybenzyl alcohol, 4-methoxybenzyl alcohol, and pyridine; while both chlorobenzyl alcohols show the highest environmental risk.

Electro organic synthesis as green and sustainable approach for synthesis of chloro substituted benzyl alcohols

▪The rising interest in advances of sustainable and greener synthetic approaches has encouraged chemists to investigate novel methods to stimulate organic compounds. The benzyl alcohol and its derivatives are industrially significant chemicals owing to their huge applications in petrochemical industries. In this context a green and sustainable approach for synthesis of Chloro substituted benzyl alcohols has been established. In present research paper cyclic voltammetry study followed by constant current electrolysis and characterization of synthesized 2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol has been reported. Cyclic voltammetry measurements have been employed to setup optimum conditions for electrolysis and to find out electrochemical nature of various Chloro substituted benzaldehydes. Then these results have been judiciary used to carry out electrochemical reduction of various Chloro substituted benzaldehydes using constant current electrolysis. Influence of scan rate and pH on reduction peaks has also been investigated referring irreversible electron transfer phenomenon in basic medium. The kinetic parameters for reduction reactions have been estimated showing the process under the influence of diffusion control. The characterization of electrochemically synthesized 2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol has been done by using spectroscopic techniques such as IR, 1HNMR and Mass spectral analysis. This has a scientific achievement in terms of the obtained products (2-Chlorobenzyl alcohol, 3-Chlorobenzyl alcohol, 4-Chlorobenzyl alcohol and 2,4-Dichlorobenzyl alcohol) and their derivatives which are industrially and pharmaceutically significant chemicals owing to their huge applications in petrochemical industries and medical sectors. Throat lozenges containing dichlorobenzyl alcohol (DCBA) are used for treatment of respiratory tract infections.

Enhanced anaerobic degradation of thiobencarb using a horizontal-flow anaerobic immobilized biomass bioreactor.

Thiobencarb is a herbicide globally used in the agricultural sector, and its extensive application leads to severe environmental pollution. In this study, the thiobencarb supplementation caused a significant shift in the bacterial community in the sediment slurry. An analysis of the degradation metabolites of microorganisms from the sediment indicated that deschlorothiobencarb, S-4-chlorobenzyl ethylthiocarbamate, 4-chlorobenzyl mercaptan, 4-chlorobenzyl alcohol, 4-chlorobenzoic acid and chlorobenzene were the main intermediates. The degradation rates were significantly enhanced using a horizontal-flow anaerobic reactor with immobilized cells in polyurethane foam. The degradation rates at 2.6, 12.9 and 25.6mg L-1 concentrations by suspended microorganisms from the sediment in the mineral medium supplemented with glucose were 0.085±0.000, 0.383±0.010 and 0.500±0.045mg day-1, respectively. The corresponding data for degradation in the reactor were 2.54±0.03, 11.69±0.72 and 18.58±1.83mg day-1 at the sixth operation period. Moreover, COD removal efficiencies were >90% achieved in the reactor. The proposed method facilitates degradation using a horizontal-flow anaerobic immobilized biomass bioreactor. Moreover, this study reveals the degradation of metabolites of thiobencarb under anaerobic conditions.

Efficient photocatalytic H2 production coupling with selective oxidation of aromatic alcohol under carbon neutrality

To achieve high photocatalytic efficiency, photocatalytic synergistic reaction is a research hotspot in the energy field. A series of ZnxCd1-xS are synthesized, and Zn0.3Cd0.7S performs high photocatalytic activity and stability in the CO2 reduction system coupling with selective oxidation of aromatic alcohol. Taking 4-chlorobenzyl alcohol as an example, H2 (784 μmol g−1 h−1) and CO (67 μmol g−1 h−1) are the main reduction products, and the oxidation product is 4-chlorobenzaldehyde with the rate of 908 μmol g−1 h−1. Moreover, the enhanced reasons of photocatalytic performance are considered from the separation of photogenerated charges, surface defect, band structure, CO2 adsorption and so on. This work improves the utilization rate of the photogenerated electrons and holes, and provides a dual-function photocatalytic system for H2 production and organic synthesis under carbon neutrality.

Variation of the partition coefficient of phase-partitioning compounds between hydrocarbon and aqueous phases: an experimental study

Many non-ionic chemical compounds will form real solutions in equilibrium between two immiscible phases in contact. The partition coefficient (K) is defined as the quotient between the equilibrium concentration of the substance in the hydrocarbon and the aqueous phase. The reversible partition of a compound between hydrocarbon and aqueous phases is the basis of the partitioning inter-well tracer test (PITT). PITTs are of high interest for the characterization of oil reservoirs, in hydrogeology for assessment of the contamination of soils by non-aqueous phase liquids (NAPLs), and in process technology. The K value of substance is influenced by the actual chemical and physical conditions of the system where it will be used as phase-partitioning tracer. Thus, it is important to evaluate the extent of variation that the K value can exhibit under different relevant conditions.In the present document, we report the methodology and findings from the experimental determination of the K values of 4-methoxybenzyl alcohol, 3,4-dimethoxybenzyl alcohol, 4-chlorobenzyl alcohol, 2,6-dichlorobenzyl alcohol, pyridine, 2,3-dimethylpyrazine and 2,6-dimethylpyrazine between different hydrocarbon and aqueous phases. These 7 compounds were previously identified as interesting PITT tracer candidates. Individual K-values were determined under different temperatures, compositions of the hydrocarbon phase (synthetic mixtures of toluene, isooctane, and 1-octanol and 5 real crude oils), and different ionic strengths (I) and ionic compositions of the aqueous phase. The reversibility of the partitioning phenomena was also evaluated. The composition of the hydrocarbon phase and the ionic strength of the water phase were found to influence the K values of all seven compounds. Results suggest that the substitution of monovalent ions with divalent ions in the aqueous phase, keeping the ionic strength constant, does not influence the K values. Temperature effects on the K-values are always visible for 3,4-dimethoxybenzyl alcohol, 2,6-dichlorobenzyl alcohol, pyridine, 2,3-dimethylpyrazine and 2,6-dimethylpyrazine. Dependent on the hydrocarbon phase composition, temperature also influences the K-values for 4-methoxybenzyl alcohol and 4-chlorobenzyl alcohol.

Selective oxidation of alcohols to nitriles with high-efficient Co-[Bmim]Br/C catalyst system

An efficient method for catalyzing the ammoxidation of aromatic alcohols to aromatic nitriles was developed, in which a new heterogeneous catalyst based on transition metal elements was employed, the new catalyst was named Co-[Bmim]Br/C-700 and then characterized by X-ray photo-electronic spectroscopy, transmission electron microscope and X-ray diffraction. The reaction was carried out by two consecutive dehydrogenations under the catalysis of Co-[Bmim]Br/C-700, which catalytically oxidized the alcohol to the aldehyde, and then the aldehyde was subjected to ammoxidation to the nitrile. The catalyst system was suitable for a wide range of substrates and nitriles obtained in high yields, especially, the conversion rate of benzyl alcohol, 4-methoxybenzyl alcohol, 4-chlorobenzyl alcohol and 4-nitrobenzyl alcohol reached 100%. The substitution of ammonia and oxygen for toxic cyanide to participate in the reaction accords with the theory of green chemistry.

Determination of phase-partitioning tracer candidates in production waters from oilfields based on solid-phase microextraction followed by gas chromatography-tandem mass spectrometry.

In the present document, we report the development of an analytical method consisting of a sequential direct-immersion/headspace solid-phase microextraction (DI-HS-SPME) followed by gas-phase chromatography and tandem mass spectrometry (GC-MS/MS) for simultaneous analysis of 4-chlorobenzyl alcohol, 2,6-dichlorobenzyl alcohol, 4-methoxybenzyl alcohol, 3,4-dimethoxybenzyl alcohol, pyridine, and 2,3-dimethylpyrazine in oilfield production waters. These compounds are under evaluation for use as phase-partitioning tracers in oil reservoirs. To the best of our knowledge, this is the first time SPME has been applied to the analysis of these compounds in production waters, or any other type of matrix where the compounds targeted are the base for a technical application. Relevant extraction parameters, such as the adsorbent phase of the fiber, direct immersion or headspace, addition of salt, temperature and time of extraction were investigated. The final optimal operation conditions consist on extracting 5 mL of sample at pH 9.0 with 1.8 g of NaCl with constant stirring during 5 minutes of DI-SPME followed by 15 minutes of HS-SPME at 70 °C using a DVB/CAR/PDMS (50/30 µm) fiber. The limits of quantification (LOQ), linearity, precision and accuracy of the method were evaluated. Analyses of the tracer compounds and recovery studies were also performed on production waters from 8 different oilfields of the Norwegian continental shelf. LOQs between 0.080 and 0.35 µg L-1 were obtained. The recovery yields of the method were consistently higher than 85% and RSDs less than 13%. None of the tracer compounds was found in the real samples processed, which is consistent with one of the requirements for an artificial tracer in an oilfield: absence or constant and low background in the traced fluid. The performance of the method developed, combined with its easiness to automate, introduce a new, accurate and cost-efficient technique to process the hundreds of samples required by an inter-well tracer test.

Hetero-aromatic N-base-promoted oxidation of 4-chlorobenzyl alcohol by Cr(VI) in micellar media

A little attempt has been made to get in touch with the green chemistry studying the successful occurrence of oxidation of 4-chlorobenzyl alcohol to 4-chlorobenzaldehyde in micellar media by Cr(VI), and its kinetics has been recorded spectrophotometrically following pseudo-first-order reaction conditions at λmax = 440 nm. In this purpose, some common hetero-aromatic bases like 2-picolinic acid, 1,10-phenanthroline and 2,2′-bipyridine have been utilized successfully for many fold rate enhancement of the reaction. Necessary spectroscopic evidences have been produced in support of the product formation.

Stability assessment of PITT tracer candidate compounds: The case of benzyl alcohols

The selection of compounds used as inter-well tracers has traditionally been done taking into consideration the goal of the test and the ease in analyzing the chemicals used. This often led to improper selection of the tracers and insufficient knowledge about their behavior under typical reservoir conditions, resulting in several unsuccessful inter-well tracer tests. One of the critical characteristics of any conservative tracer is its stability under various reservoir conditions. In this document we present the study methodology and the findings from stability experiments carried out on 5 benzyl alcohols investigated as oil/water partitioning tracers for partitioning inter-well tracer tests (PITT). This is the first of three documents reporting such studies on 3 families of chemicals.A PITT consists of the simultaneous injection of one or more mass-conservative passive and phase-partitioning (one type of active) tracers. PITT is primarily conceived for mature water-flooded oil fields and measures the residual (or even remaining) oil saturation (SOR) in the swept volumes between wells. Knowledge of SOR may be used to identify EOR targets, assess efficiency of EOR operations, and the efficiency of volumetric sweep between wells. This is important information, in particular for the increasing number of mature oil-fields where EOR projects are under consideration and/or development. A thorough knowledge about the static and dynamic properties of the tracers under reservoir conditions is required both to ensure successful field tests, and also to increase accuracy of the data obtained from them.4-Chlorobenzyl alcohol, 2,6-Dichlorobenzyl alcohol, 4-Methoxybenzyl alcohol, 3,4-Dimethoxybenzyl alcohol, and 4-Hydroxybenzyl alcohol were tested in brine under simulated reservoir conditions with temperatures up to 150 °C during 12 weeks, at different pH values, and in the presence of typical sedimentary basin rock materials, sandstone, carbonate rock (limestone), and clay (kaolinite). 4-Chlorobenzyl alcohol and 2,6-Dichlorobenzyl alcohol were found to be fully stable at all tested conditions. 4-Methoxybenzyl alcohol and 3,4-Dimethoxybenzyl alcohol exhibit thermally induced degradation above 125 °C, but may still be considered for use below this temperature. 4-Hydroxybenzyl alcohol exhibits thermally induced degradation which was found to follow a first order kinetics. The apparent activation energy and pre-exponential constant in the Arrhenius law for the degradation reaction were determined and a kinetic model built. This opens the possibility for use of 4-Hydroxybenzyl alcohol as a non-conservative reservoir tracer to measure temperature or detect thermal fronts.

Manganese (III) salophen supported on nanosilica triazine dendrimer as a selective heterogeneous catalyst for oxidation of alcohols with sodium periodate

In this paper, we present an efficient and practical method for oxidation of alcohols to their corresponding carbonyl compounds catalyzed by [Mn(salophen)@nSTD]. This catalyst was synthesized, and characterized by FT-IR, UV–Vis, TGA, SEM and TEM. The results of experiments proved that this catalyst has excellent selectivity and high activity in the oxidation of different primary and secondary alcohols to their corresponding aldehyde and ketone at room temperature. The effects of important factors in the oxidation of alcohols such as kind of oxidant, solvent and amount of catalyst were investigated in the oxidation of 4-chlorobenzyl alcohol. This catalyst shows high stability and reusability after six catalytic runs.

Synthesis, characterization and applications of highly active and robust sulfated Fe–TiO2 catalyst (ICT-3) with superior redox and acidic properties

A novel multifunctional sulfated Fe–TiO2 catalyst with different Fe loading, leading to the introduction of both redox and superacidic properties (designated as ICaT-3), was developed. Chorosulfonic acid was used to create super acidity in the catalyst matrix. The catalyst was characterized by FT-IR, XRD, TG-DTA, surface area measurements, NH3-TPD, XPS, SEM and EDX analysis with reference to its superior redox and acidic properties. The catalyst was found to be very active and selective as compared to unsulfated catalyst for industrially important oxidation reaction of benzyl alcohol to benzaldehyde and its efficacy was tested in a variety of substrates such as 4-methoxy benzyl alcohol, 4-chlorobenzyl alcohol, styrene, p-bromostyrene, and methyl phenyl sulfide. This induced acidity increases the oxidation activity by twofold as compared to conventional TiO2 catalyst. Its superior acidic properties were also evaluated in the alkylation of toluene with benzyl alcohol. The catalyst was reused repeatedly to find it as stable and reusable.

Toluene and 4-chlorotoluene decomposition in air mixture in electron beam generated non-thermal plasma reactor and their by-products identification

Degradation of toluene and 4-chlorotoluene in air mixture was studied by using electron beam generated plasma reactor. It was found that removal efficiency of toluene and 4-chlorotoluene was influenced by radiation dose, i.e. energy deposited in the gas, and their initial concentration. The by-products formed as a result of degradation of toluene or 4-chlorotoluene under electron beam radiation were identified. The mechanism of their degradation was proposed. •OH radicals play a main role in degradation process of toluene or 4-chlorotoluene. For degradation of 4-chlorotoluene, reaction of •OH radicals with 4-chlorotoluene by hydrogen abstraction from the methyl group, followed by peroxyl radical formation, is a main reaction pathway. 4-chlorobenzaldehyde and 4-chlorobenzyl alcohol are formed according to the Russel-mechanism. For degradation of toluene, reaction pathway of •OH radicals with toluene by hydrogen abstraction from the methyl group plays an important role. Besides it, there are the other two important reaction pathways. One is reaction of •OH radical addition and H atom abstraction from benzene ring; the other is •OH-adduct reaction. Cresol, nitrotoluene and ring cleavage products are formed from these two reaction pathways. Since Cl is more electronegative than H, H atom abstraction from –CH3 by •OH radicals from toluene (HC6H4CH3) is easier than from 4-chlorotoluene (ClC6H4CH3), this may explain why the decomposition efficiency of toluene is slightly higher than that of 4-chlorotoluene in an air mixture under EB radiation.

Osmium-Catalyzed Oxidation of Primary Alcohols with Molecular Oxygen

OsHCl(CO)(PiPr3)2 (1) reacts with O2 to afford the dioxygen derivative OsHCl(CO)(η2-O2)(PiPr3)2 (2), which under atmospheric pressure of oxygen promotes the oxidation of 4-methoxybenzyl alcohol, benzyl alcohol, and 4-chlorobenzyl alcohol to the corresponding aldehydes. Under the same conditions, 1-hexanol and 1-octanol give hexyl hexanoate and octyl octanoate, respectively. On the other hand, cinnamyl alcohol undergoes disproportionation to 3-phenylpropanol and cinnamaldehyde.

A novel metabolic pathway for biodegradation of DDT by the white rot fungi, Phlebia lindtneri and Phlebia brevispora

1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (DDT) was used as the substrate for a degradation experiment with the white rot fungi Phlebia lindtneri GB-1027 and Phlebia brevispora TMIC34596, which are capable of degrading polychlorinated dibenzo-p-dioxin (PCDD) and polychlorinated biphenyls (PCBs). Pure culture of P. lindtneri and P. brevispora with DDT (25μmoll(-1)) showed that 70 and 30% of DDT, respectively, disappeared in a low-nitrogen medium after a 21-day incubation period. The metabolites were analyzed using gas chromatography/mass spectrometry (GC/MS). Both fungi metabolized DDT to 1,1-dichloro-2,2-bis(4-chlorophenyl)ethane (DDD), 2,2-bis(4-chlorophenyl)acetic acid (DDA) and 4,4-dichlorobenzophenone (DBP). Additionally, DDD was converted to DDA and DBP. DDA was converted to DBP and 4,4-dichlorobenzhydrol (DBH). While DBP was treated as substrate, DBH and three hydroxylated metabolites, including one dihydroxylated DBP and two different isomers of monohydroxylated DBH, were produced from fungal cultures, and these hydroxylated metabolites were efficiently inhibited by the addition of a cytochrome P-450 inhibitor, piperonyl butoxide. These results indicate that the white rot fungi P. lindtneri and P. brevispora can degrade DBP/DBH through hydroxylation of the aromatic ring. Moreover, the single-ring aromatic metabolites, such as 4-chlorobenzaldehyde, 4-chlorobenzyl alcohol and 4-chlorobenzoic acid, were found as metabolic products of all substrate, demonstrating that the cleavage reaction of the aliphatic-aryl carbon bond occurs in the biodegradation process of DDT by white rot fungi.

Selective photocatalytic oxidation of benzyl alcohol and its derivatives into corresponding aldehydes by molecular oxygen on titanium dioxide under visible light irradiation

The photocatalytic oxidation of benzyl alcohol and its derivatives, such as 4-methoxybenzyl alcohol, 4-chlorobenzyl alcohol, 4-nitrobenzyl alcohol, 4-methylbenzyl alcohol, 4-(trifluoromethyl)benzyl alcohol, and 4- tertiary-butylbenzyl alcohol, into corresponding aldehydes proceeded at high conversion and selectivity on a TiO 2 photocatalyst under O 2 atmosphere. The reaction was confirmed to proceed under irradiation with both UV-light and visible light. In particular, the visible light response was observed to be attributed to a characteristic surface complex formed by the adsorption of a benzyl alcoholic compound on the TiO 2 surface. Here, the properties of the surface complex as the active center for this selective photocatalytic oxidation and the mechanism behind the reaction have been investigated.

Simultaneous determination of econazole nitrate, main impurities and preservatives in cream formulation by high performance liquid chromatography

A reversed-phase high performance liquid chromatographic (RP-HPLC) method for determination of econazole nitrate, preservatives (methylparaben and propylparaben) and its main impurities (4-chlorobenzyl alcohol and alpha-(2,4-dichlorophenyl)-1 H-imidazole-1-ethanol) in cream formulations, has been developed and validated. Separation was achieved on a column Bondclone ® C18 (300 mm × 3.9 mm i.d., 10 μm) using a gradient method with mobile phase composed of methanol and water. The flow rate was 1.4 mL min −1, temperature of the column was 25 °C and the detection was made at 220 nm. Miconazole nitrate was used as an internal standard. The total run time was less than 15 min. The analytical curves presented coefficient of correlation upper to 0.99 and detection and quantitation limits were calculated for all molecules. Excellent accuracy and precision were obtained for econazole nitrate. Recoveries varied from 97.9 to 102.3% and intra- and inter-day precisions, calculated as relative standard deviation (R.S.D.), were lower than 2.2%. Specificity, robustness and assay for econazole nitrate were also determined. The method allowed the quantitative determination of econazole nitrate, its impurities and preservatives and could be applied as a stability-indicating method for econazole nitrate in cream formulations.

Metabolism of 4,4′-dichlorobiphenyl by white-rot fungi Phanerochaete chrysosporium and Phanerochaete sp. MZ142

Degradation experiment of model polychlorinated biphenyl (PCB) compound 4,4'-dichlorobiphenyl (4,4'-DCB) and its metabolites by the white-rot fungus Phanerochaete chrysosporium and newly isolated 4,4'-DCB-degrading white-rot fungus strain MZ142 was carried out. Although P. chrysosporium showed higher degradation of 4,4'-DCB in low-nitrogen (LN) medium than that in potato dextrose broth (PDB) medium, Phanerochaete sp. MZ142 showed higher degradation of 4,4'-DCB under PDB medium condition than that in LN medium. The metabolic pathway of 4,4'-DCB was elucidated by the identification of metabolites upon addition of 4,4'-DCB and its metabolic intermediates. 4,4'-DCB was initially metabolized to 2-hydroxy-4,4'-DCB and 3-hydroxy-4,4'-DCB by Phanerochaete sp. MZ142. On the other hand, P. chrysosporium transformed 4,4'-DCB to 3-hydroxy-4,4'-DCB and 4-hydroxy-3,4'-DCB produced via a National Institutes of Health shift of 4-chlorine. 3-Hydroxy-4,4'-DCB was transformed to 3-methoxy-4,4'-DCB; 4-chlorobenzoic acid; 4-chlorobenzaldehyde; and 4-chlorobenzyl alcohol in the culture with Phanerochaete sp. MZ142 or P. chrysosporium. LN medium condition was needed to form 4-chlorobenzoic acid, 4-chlorobenzaldehyde, and 4-chlorobenzyl alcohol from 3-hydroxy-4,4'-DCB, indicating the involvement of secondary metabolism. 2-Hydroxy-4,4'-DCB was not methylated. In this paper, we proved for the first time by characterization of intermediate that hydroxylation of PCB was a key step in the PCB degradation process by white-rot fungi.