Chlorinated Phenols Research Articles

Corrole–chelated phosphorus complex: enabling dual C–H chlorination and H₂O₂ generation

Corroles, despite their highly tunable and excellent photophysical and electrochemical properties, have rarely been explored as mainstream photocatalytic photosensitizers. Our study introduces a novel application of the highly oxidizing penta–CF3 substituted phosphorus corrole, P–(CF3)5, which has shown remarkable efficacy in the chlorination of phenol and related natural compounds (the beta 2, 3, 8, 17, 18-substituted isomer: 2,3,8,17,18–pentatrifluoromethyl–(5,10,15–tris(pentafluorophenyl) corrole phosphorus (V) difluoride). Here, we report the first case of the simultaneous photocatalytic chlorination of phenol or toluene and H2O2 formation, with the latter achieving a notable rate of > 7 mM/g/h under ambient conditions. Notably, the oxidation of toluene predominantly yields benzaldehyde over benzyl chloride. The H2O2 formation can be finely tuned by adjusting the water/acetonitrile ratio and acid concentration. Comprehensive experimental and theoretical (DFT) investigations were conducted to elucidate the underlying mechanisms of both chlorination and oxidation. This dual–function catalytic process not only enhances reaction efficiency but also underscores the potential of corrole–based catalysts in advancing sustainable and green chemical methodologies.

Amplifying chlorinated phenol decomposition via Dual-Pathway O2 Activation: The impact of zirconium loading on BiOCl

The effectiveness of photocatalytic molecular oxygen (O2) activation in pollutant removal relies on the targeted production of reactive oxygen species (ROS). Herein, we demonstrate the dual-pathway activation of O2 on BiOCl through zirconium (Zr) loading. The incorporation of Zr onto the surface of BiOCl not only leads to an increased generation of oxygen vacancies (OV) but also fosters a coupling between the d electrons of Zr and OV, forming dual-active sites known as Zr-oxygen vacancies (Zr-OV). Generally, OV adsorbs O2 and transfers one electron directly to form superoxide radicals (•O2–). Contrary to the conventional single-electron direct activation of O2 to form •O2–, Zr-OV exhibits more flexible coordination and superior electron-donating capabilities. It facilitates O2 conversion to peroxide radicals (O22–) and enables the subsequent generation of •O2– from O22–, significantly promotes the dechlorination and mineralization efficiency of chlorophenol under visible light. This study presents a straightforward strategy to precisely regulate ROS production by expanding pathways, shedding light on the critical role of managing ROS generation for effective pollutant purification.

Experimental and theoretical unraveling of the electrocatalytic hydrodechlorination of chlorinated phenol using Pd promoted by oxygen vacancies in TiO2 array

The electrocatalytic dichlorination (EHDC) shows a promising potential to degrade chlorinated phenols (CPs). It is also a green technology in reducing the corresponding hazardous impact on the environment. In this study, we constructed a catalytic structure which was Pd on a TiO2 array with oxygen vacancies on carbon fibre paper substrate (Pd/TiO2/CFP) by a relatively mild route. Due to the presence of the oxygen vacancies, the resulting strong metal-support interaction (SMSI) effect has been identified which featured a redistribution of spatial charge in Pd/TiO2. The electron flow from the oxygen vacancies in the TiO2 to Pd facilitated the adsorption of Pd with 4-chlorophenol (4-CP) and endowed the Pd metal with an improved chemical reaction kinetics even at a low Pd loading. Experimentally, we studied the dependence of pH, concentration of 4-CP, and working potential on the reaction conditions of EHDC. The results showed that the conversion of 4-CP reached 100 % within 180 min with an apparent rate constant of 2.9 × 10-2 min−1 and the dominant product was phenol (P). The multi-cycle test illustrated that the Pd/TiO2/CFP electrode showed superior stability. The results also revealed that the comprehensive catalytic behavior was much better than those of the Pd/CFP and the TiO2/CFP electrodes. The density function theory (DFT) calculations indicated that 4-CP was more preferably absorbed on Pd/TiO2/CFP than Pd/CFP due to the SMSI assistance. This study provides a valuable guide in the preparation of precious metal-based electrodes for EHDC with a reduced loading and cost but without performance compromise.

Formation and toxicity contribution of chlorinated and dechlorinated halobenzoquinones from dichlorophenols after ozonation

Halobenzoquinones (HBQs) are a class of disinfection byproducts with high cytotoxicity and potential carcinogenicity, which have been widely detected in chlorination of drinking water and swimming pool water. However, to date, the formation of HBQs upon ozonation and the HBQ precursors have been overlooked. This study investigated the formation of chlorinated and dechlorinated HBQs from six dichlorophenol (DCP) isomers. The monomeric and dimeric HBQs were identified in all the ozonation effluents, exhibiting 1–100 times higher toxicity levels than their precursors. The sum of detected HBQs intensity had a satisfactory linear relation with the maximum toxic unit (R2 = 0.9657), indicating the primary toxicity contribution to the increased overall toxicity of effluents. Based on density functional theory calculations, when ozone attacks the para carbon to the hydroxyl group of 2,3-DCP, the probability of producing chlorinated HBQs is 80.41 %, indicating that the para carbon attack mainly resulted in the formation of monomeric HBQs. 2,3-dichlorophenoxy radicals were successfully detected in ozonated 2,3-DCP effluent through electron paramagnetic resonance and further validated using theoretical calculation, revealing the formation pathway of dimeric HBQs. The results indicate that chlorinated phenols, regardless of the positions of chlorine substitution, can potentially serve as precursors for both chlorinated and dechlorinated HBQs formation during ozonation.

Transformation of hydroxylated polychlorinated biphenyls by bacterial 2-hydroxybiphenyl 3-monooxygenase

Monohydroxylated PCBs (OH-PCBs) are an (eco)toxicologically significant group of compounds, as they arise from the oxidation of polychlorinated biphenyls (PCBs) and, at the same time, may exert even more severe toxic effects than their parent PCB molecules. Despite having been widely detected in environmental samples, plants, and animals, information on the fate of OH-PCBs in the environment is scarce, including on the enzymatic machinery behind their degradation. To date, only a few bacterial taxa capable of OH-PCB transformation have been reported. In this study, we aimed to obtain a deeper insight into the transformation of OH-PCBs in soil bacteria and isolated a Pseudomonas sp. strain P1B16 based on its ability to use o-phenylphenol (2-PP) which, when exposed to the Delor 103-derived OH-PCB mixture, depleted a wide spectrum of mono-, di, and trichlorinated OH-PCBs. In the P1B16 genome, a region designated as hbp was identified, which bears a set of putative genes involved in the transformation of OH-PCBs, namely hbpA encoding for a putative flavin-dependent 2-hydroxybiphenyl monooxygenase, hbpC (2,3-dihydroxybiphenyl-1,2-dioxygenase), hbpD (2-hydroxy-6-oxo-6-phenylhexa-2,4-dienoate hydrolase), and the transcriptional activator-encoding gene hbpR. The hbpA coding sequence was heterologously expressed, purified, and its substrate specificity was investigated towards the Delor 103-derived OH-PCB mixture, individual OH-PCBs, and multiple (chlorinated) phenolics. Apart from 2-PP and 2-chlorophenol, HbpA was also demonstrated to transform a range of OH-PCBs, including a 3-hydroxy-2,2′,4′,5,5′-pentachlorobiphenyl. Importantly, this is the first direct evidence of HbpA homologs being involved in the degradation of OH-PCBs. Moreover, using a P1B16-based biosensor strain, the specific induction of hbp genes by 2-PP, 3-phenylphenol, 4-phenylphenol, and the OH-PCB mixture was demonstrated. This study provides direct evidence on the specific enzymatic machinery responsible for the transformation of OH-PCBs in bacteria, with many implications in ecotoxicology, environmental restoration, and microbial ecology in habitats burdened with PCB contamination.

Sorption Behavior of Organic Pollutants on Biodegradable and Nondegradable Microplastics: pH Effects

Microplastics (MPs), chlorinated phenols (CPs), polycyclic aromatic hydrocarbons (PAHs) and halogenated benzenes (HBs) are pollutants that are widely present in freshwater systems. As alternatives to conventional plastics, bioplastics are receiving a lot of attention, but there are limited data on their impact on pollutant behavior. This work therefore investigated the impact of pH on the sorption of CPs, PAHs and HBs, as some of the toxic and highly persistent pollutants, on seven different plastics using kinetic and isotherm studies. The pH of the water matrix impacted the adsorption behavior of CPs on all selected MPs, with the highest degree of adsorption occurring at pH 7 for the majority of the selected CPs. The highest adsorption affinity of CPs on the MPs, at pH 7, was obtained for 4-chlorophenol and 2,4-dichlorophenol on powdered polyethylene standard (qt = 221 μg/g), while the lowest was obtained for the adsorption of pentachlorophenol on polyethylene terephthalate (qt = 25 μg/g). On the other hand, the pH value of the water matrix did not affect the adsorption of halogenated benzenes and PAHs on MPs. The pseudo-second-order rate model fit the adsorption kinetics data of all experiments. The results obtained for the adsorption of CPs on MPs indicated a lower sorption affinity of CPs with MPs at pH 4 and pH 10 compared to pH 7. The Langmuir isotherm, at pH 7, implied that 4-chlorophenol’s adsorption affinity was not significantly influenced by the type of MPs. On the other hand, at pH 7, the adsorption of 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol varied greatly, with powdered MP types showing the highest affinity for CP adsorption. Furthermore, the obtained adsorption isotherm results imply that electrostatic attraction, hydrogen bonds, π-π interactions and van der Waals interactions, are an integral part of adsorption mechanisms of the CPs on the MPs.

Influence of Application Method on Disinfectant Byproduct Formation during Indoor Bleach Cleaning: A Case Study on Phenol Chlorination

Influence of Application Method on Disinfectant Byproduct Formation during Indoor Bleach Cleaning: A Case Study on Phenol Chlorination

Chlorination of phenol, bisphenol A, and methylparaben in the presence of bromide: Kinetic simulation and formation of brominated aromatic byproducts

The seawater intrusion caused by the rising sea level increased the bromide (Br−) levels in the source waters of coastal cities. Adding bromide could significantly improve the degradation of phenol, bisphenol A, and methylparaben by chlorine. Bromide in water was first oxidized to active bromine species, which further reacted with phenols to generate brominated aromatic byproducts. A kinetic model including the reactions of chlorine oxidizing bromide, chlorine with phenol, and active bromine with phenol was established. The reaction rate constants of active bromine with phenols were calculated by fitting the degradation of phenols by chlorine in the presence of different bromide concentrations via the kinetic model. The rate constants of active bromine with phenols (1.5 × 104 to 2.9 × 104 M−1s−1 at pH 7.0) were higher than those of chlorine with phenols (4.0 × 101 to 8.9 × 101 M−1s−1 at pH 7.0), resulting in a bromide enhancement effect. The kinetic model could accurately simulate the evolution of total oxidant concentration with time (R2 > 0.96). Various brominated aromatic byproducts were identified in the chlorine/phenols/bromide systems, and they were first produced and then further degraded by chlorine. The technology of removing bromide and phenolic components from source water should be developed to control the formation of toxic brominated aromatic byproducts.

Chlorination of amides: Kinetics and mechanisms of formation of N-chloramides and their reactions with phenolic compounds

Amides are common constituents in natural organic matter and synthetic chemicals. In this study, we investigated kinetics and mechanisms of the reactions of chlorine with seven amides, including acetamide, N-methylformamide, N-methylacetamide, benzamide, N-methylbenzamide, N-propylbenzamide, and N-(benzoylglycyl)glycine amide. Apparent second-order rate constants for the reactions of the amides with chlorine at pH 8 are in the range of 5.8 × 10−3 – 1.8 M−1s−1 and activation energies in the range of 62-88 kJ/mol. The second-order rate constants for the reactions of chlorine with different amides decrease with increasing electron donor character of the substituents on the amide-N and N-carbonyl-C in the amide structures. Hypochlorite (‒OCl) dominates the reactions of chlorine with amides yielding N-chloramides with species-specific second-order rate constants in the range of 7.3 × 10−3 – 2.3 M−1s−1. Kinetic model simulations suggest that N-chlorinated primary amides further react with HOCl with second-order rate constants in the order of 10 M−1s−1. The chlorination products of amides, N-chloramides are reactive towards phenolic compounds, forming chlorinated phenols via electrophilic aromatic substitution (phenol and resorcinol) and quinone via electron transfer (hydroquinone). Meanwhile, N-chloramides were recycled to the parent amides. At neutral pH, apparent second-order rate constants for the reactions between phenols and N-chloramides are in the order of 10−4-0.1 M−1s−1, comparable to those with chloramine. The findings of this study improve the understanding of the fate of amides and chlorine during chlorination processes.

Polypyrrole-induced active-edge-S and high-valence-Mo reinforced composites with boosted electrochemical performance for the determination of 2,4,6-trichlorophenol in the aquatic environment

With the extensive application of halogenated aromatic compounds, including 2,4,6-Trichlorophenol (2,4,6-TCP), improper treatment or discharge contribute to persistently harmful effects on humans and the ecosystem, rendering the identification and monitoring of 2,4,6-TCP in the aquatic environment urgently required. In this study, a highly sensitive electrochemical platform was developed using active-edge-S and high-valence-Mo rich MoS2/polypyrrole composites. MoS2/PPy illustrates superior electrochemical performance and catalytic activity and has not been explored for detecting chlorinated phenols previously. The local environment of polypyrrole induces the richness of active edge S and a high oxidation state of Mo species in the composites, both of which endorse a sensitive anodic current response due to the favored oxidation of 2,4,6-TCP through nucleophilic substitution. Also, the higher complementarity between pyrrole and 2,4,6-TCP with respective electron-rich and electron-poor features through π-π stacking interactions enhances the specific detection capability of 2,4,6-TCP by the MoS2/polypyrrole-modified electrode. The MoS2/polypyrrole-modified electrode achieved a linear range of 0.1–260 μM with an ultralow limit of detection of 0.009 μM. Additionally, the structural stability boosted by the linkage of polypyrrole and MoS2 results in good resistance and satisfactory recovery in real water samples. The compiled results demonstrate that the proposed MoS2/polypyrrole composite opens up a new potential to advance a sensitive, selective, facile fabrication, and low-cost platform for the on-site determination of 2,4,6-TCP in aquatic systems. The sensing of 2,4,6-TCP is important to monitor its occurrence and transport, and can also serve to track the effectiveness and adjust subsequent remediation treatments applied to contaminated sites.

Biochar–supported sulfurized nanoscale zero–valent iron facilitates extensive dechlorination and rapid removal of 2,4,6–trichlorophenol in aqueous solution

Nanoscale zero–valent iron (NZVI) has been widely used in rapid remediation of contaminants. However, several obstacles such as aggregation and surface passivation hampered NZVI from further application. In this study, sulfurized nanoscale–zero valent iron supported by biochar (BC–SNZVI) was successfully synthesized and utilized for highly efficient 2,4,6–trichlorophenol (2,4,6–TCP) dechlorination in aqueous solution. SEM-EDS analysis revealed the even distribution of SNZVI on the surface of BC. FTIR, XRD, XPS and N2 Brunauer–Emmett–Teller (BET) adsorption analyses were carried out to characterize the materials. Results showed that BC–SNZVI with S/Fe molar ratio of 0.088, Na2S2O3 as sulfurization agent, and pre–sulfurization as the sulfurization strategy exhibited the superior performance for 2,4,6–TCP removal. The overall removal of 2,4,6–TCP was well described with the pseudo–first–order kinetics (R2 > 0.9), and the observed kinetics constant Kobs was 0.083 min−1 with BC–SNZVI, which was one order of magnitude higher than that of BC–NZVI (0.0092 min−1) and SNZVI (0.0042 min−1), and two orders of magnitude higher than that of NZVI (0.00092 min−1). Moreover, the removal efficiency of 2,4,6–TCP reached 99.5% by BC–SNZVI with dosage of 0.5 g L−1, initial 2,4,6–TCP concentration of 30 mg L−1 and initial solution pH of 3.0 within 180 min. The removal of 2,4,6–TCP by BC–SNZVI was acid–promoted and the removal efficiencies of 2,4,6–TCP decreased with the increase of initial 2,4,6–TCP concentrations. Furthermore, more extensive dechlorination of 2,4,6–TCP was achieved with BC–SNZVI and complete dechlorination product phenol became predominant. The facilitation of sulfur for Fe0 utilization and electron distribution in the presence of biochar remarkably enhanced the dechlorination performance of BC–SNZVI for 2,4,6–TCP. These findings provide insights into BC–SNZVI as an alternative engineering carbon based NZVI material for treating chlorinated phenols.

Peroxymonosulfate Activation by Fe(III)-Picolinate Complexes for Efficient Water Treatment at Circumneutral pH: Fe(III)/Fe(IV) Cycle and Generation of Oxyl Radicals.

Improving the reactivity of Fe(III) for activating peroxymonosulfate (PMS) at circumneutral pH is critical to propel the iron-activated PMS processes toward practical wastewater treatment but is yet challenging. Here we employed the complexes of Fe(III) with the biodegradable picolinic acid (PICA) to activate PMS for degradation of selected chlorinated phenols, antibiotics, pharmaceuticals, herbicides, and industrial compounds at pH 4.0-6.0. The FeIII-PICA complexes greatly outperformed the ligand-free Fe(III) and other Fe(III) complexes of common aminopolycarboxylate ligands. In the main activation pathway, the key intermediate is a peroxymonosulfate complex, tentatively identified as PICA-FeIII-OOSO3-, which undergoes O-O homolysis or reacts with FeIII-PICA and PMS to yield FeIV=O and SO4•- without the involvement of commonly invoked Fe(II). PICA-FeIII-OOSO3- can also react directly with certain compounds (chlorophenols and sulfamethoxazole). The relative contributions of PICA-FeIII-OOSO3-, FeIV=O, and SO4•- depend on the structure of target compounds. This work sets an eligible example to enhance the reactivity of Fe(III) toward PMS activation by ligands and sheds light on the previously unrecognized role of the metal-PMS complexes in directing the catalytic cycle and decontamination as well.

Catalyst-Tuned Electrophilic Chlorination of Diverse Aromatic Compounds with Sulfuryl Chloride and Regioselective Chlorination of Phenols with Organocatalysts.

In this work, we demonstrate that diverse aromatic compounds can be selectively chlorinated through the fine-tuning of the reactivity of sulfuryl chloride (SO2Cl2) by organocatalysts. Acetonitrile has been identified to activate SO2Cl2 most strongly, thus enabling even chlorination of p-xylene with high yields. 1,4-Dioxane effects chlorination of oxidation-labile aromatic compounds such as p-cresol and 2-naphthol with high yields, 95% and 85%, respectively. An array of potential catalysts has been screened for ortho- and para-selective chlorination of phenols. Thus, we found that acetonitrile, (S)-BINAPO (5 mol %), and diisopropyl ether (4.00 equiv) can catalyze the chlorination of phenols in a para-selective manner (with ≤4:96 o:p ratio), whereas Nagasawa's bis-thiourea (1 mol %), phenyl boronic acid (5 mol %), and (S)-diphenylprolinol (1 mol %) exhibit high ortho selectivity [with ≤99:1 o:p ratio by (S)-diphenylprolinol].

Efficient Electroenzymatic Cascade Catalysis for Ortho-Selective Chlorination of Phenol

Efficient Electroenzymatic Cascade Catalysis for Ortho-Selective Chlorination of Phenol

Degradation efficiencies of 2,4,6-TCP by Fe0-based advanced oxidation processes (AOPs) with common peroxides.

Degradation of 2,4,6-trichlorophenol (2,4,6-TCP) by zero-valent iron (ZVI) activating three common peroxides (peroxymonosulfate (PMS), hydrogen peroxide (H2O2), and peroxydisulfate (PS)) was investigated. The effects of ZVI dosage, peroxides concentration, initial pH, and Cl- concentration were examined. The 2,4,6-TCP degradation efficiencies by Fe0/peroxides (PMS, H2O2, PS) were compared. Results showed that the order for degradation efficiency was H2O2≥PMS>PS. The degradation efficiency of 2,4,6-TCP in ZVI/peroxides systems were optimal at c(Ox) = 1 mmol•L-1; c(Fe0) = 0.1 g/L; initial pH = 3.2. Additionally, pH had a vital effect on 2,4,6-TCP degradation. At pH<3.2, ferrous play a vital role in all reaction, and accelerate the reaction rate rapidly. The existence of NaCl showed different results in the four systems. Chloride had little effect on 2,4,6-TCP degradation when chloride concentration at 5 mM, whereas the presence of 300 mM chloride significantly accelerated the degradation of 2,4,6-TCP from 72.7% to 95.2% in ZVI-PMS system. Notably, the other three systems showed opposite results. In contrast, the AOX (Absorbable Organic Halogen) values were highest in ZVI-PMS-Cl- system, due to the formation of lots of refractory chlorinated phenols as identified by GC-MS. These findings are good for choosing the most suitable technology for chlorophenol wastewater treatment.

Development of Efficient and Selective Processes for the Synthesis of Commercially Important Chlorinated Phenols

para-Selective processes for the chlorination of phenols using sulphuryl chloride in the presence of various sulphur-containing catalysts have been successfully developed. Several chlorinated phenols, especially those derived by para-chlorination of phenol, ortho-cresol, meta-cresol, and meta-xylenol, are of significant commercial importance, but chlorination reactions of such phenols are not always as regioselective as would be desirable. We, therefore, undertook the challenge of developing suitable catalysts that might promote greater regioselectivity under conditions that might still be applicable for the commercial manufacture of products on a large scale. In this review, we chart our progress in this endeavour from early studies involving inorganic solids as potential catalysts, through the use of simple dialkyl sulphides, which were effective but unsuitable for commercial application, and through a variety of other types of sulphur compounds, to the eventual identification of particular poly(alkylene sulphide)s as very useful catalysts. When used in conjunction with a Lewis acid such as aluminium or ferric chloride as an activator, and with sulphuryl chloride as the reagent, quantitative yields of chlorophenols can be obtained with very high regioselectivity in the presence of tiny amounts of the polymeric sulphides, usually in solvent-free conditions (unless the phenol starting material is solid at temperatures even above about 50 °C). Notably, poly(alkylene sulphide)s containing longer spacer groups are particularly para-selective in the chlorination of m-cresol and m-xylenol, while, ones with shorter spacers are particularly para-selective in the chlorination of phenol, 2-chlorophenol, and o-cresol. Such chlorination processes result in some of the highest para/ortho ratios reported for the chlorination of phenols.

Bioremediation of lignin derivatives and phenolics in wastewater with lignin modifying enzymes: Status, opportunities and challenges.

Lignin modifying enzymes from fungi and bacteria are potential biocatalysts for sustainable mitigation of different potentially toxic pollutants in wastewater. Notably, the paper and pulp industry generates enormous amounts of wastewater containing high amounts of complex lignin-derived chlorinated phenolics and sulfonated pollutants. The presence of these compounds in wastewater is a critical issue from environmental and toxicological perspectives. Some chloro-phenols are harmful to the environment and human health, as they exert carcinogenic, mutagenic, cytotoxic, and endocrine-disrupting effects. In order to address these most urgent concerns, the use of oxidative lignin modifying enzymes for bioremediation has come into focus. These enzymes catalyze modification of phenolic and non-phenolic lignin-derived substances, and include laccase and a range of peroxidases, specifically lignin peroxidase (LiP), manganese peroxidase (MnP), versatile peroxidase (VP), and dye-decolorizing peroxidase (DyP). In this review, we explore the key pollutant-generating steps in paper and pulp processing, summarize the most recently reported toxicological effects of industrial lignin-derived phenolic compounds, especially chlorinated phenolic pollutants, and outline bioremediation approaches for pollutant mitigation in wastewater from this industry, emphasizing the oxidative catalytic potential of oxidative lignin modifying enzymes in this regard. We highlight other emerging biotechnical approaches, including phytobioremediation, bioaugmentation, Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-based technology, protein engineering, and degradation pathways prediction, that are currently gathering momentum for the mitigation of wastewater pollutants. Finally, we address current research needs and options for maximizing sustainable biobased and biocatalytic degradation of toxic industrial wastewater pollutants.

Effective removal of methylated phenol and chlorinated phenol from aqueous solutions using a new activated carbon derived from Halodule uninervis waste

Due to the toxicity of methylated and chlorinated phenols, it is necessary to remove them from aqueous solutions. Therefore, a highly efficient adsorbent was developed from the dead leaves of Halodule uninervis seagrass (SG) through a chemical and thermal activation process. The prepared activated carbon (SGAC) was characterized and investigated for removal of 2,4-Dimethylphenol (DMP) and 2,4-Dichlorophenol (DCP) from aqueous solutions. The batch adsorption mode was used and the effects of adsorption conditions were studied. SGAC adsorbent showed high adsorption capacities which were 364 mg DMP/g and 333 mg DCP/g. The adsorption experimental results fitted Freundlich and Langmuir models and followed pseudo-second-order kinetics. The adsorption of both adsorbates was spontaneous. The prepared adsorbent was able to remove 90% of DMP and 97% of DCP from the synthetic wastewater. This study indicated that SGAC adsorbent is efficient and reusable in the synthetic wastewater for at least four times.

A Bifunctional Thiourea–Selenoether-Mediated ortho-Selective Chlorination of Phenols and Anilines

Key words electrophilic aromatic substitution - chlorination - chlorophenols - chloroanilines - thiourea–selenoether - hydrogen bonding

Catalyst-Controlled Regioselective Chlorination of Phenols and Anilines through a Lewis Basic Selenoether Catalyst.

We report a highly efficient ortho-selective electrophilic chlorination of phenols utilizing a Lewis basic selenoether catalyst. The selenoether catalyst resulted in comparable selectivities to our previously reported bis-thiourea ortho-selective catalyst, with a catalyst loading as low as 1%. The new catalytic system also allowed us to extend this chemistry to obtain excellent ortho-selectivities for unprotected anilines. The selectivities of this reaction are up to >20:1 ortho/para, while the innate selectivities for phenols and anilines are approximately 1:4 ortho/para. A series of preliminary studies revealed that the substrates require a hydrogen-bonding moiety for selectivity.