Substitution Of Chlorine Atom Research Articles

New triazinephosphonate dopants for Nafion proton exchange membranes (PEM).

A new paradigm for energy is underway demanding decarbonized energy systems. Some of them rely on emerging electrochemical devices, crucial in hydrogen technologies, including fuel cells, CO2 and water electrolysers, whose applications and performances depend on key components such as their separators/ion-exchange membranes. The most studied and already commercialized Nafion membrane shows great chemical stability, but its water content limits its high proton conduction to a limited range of operating temperatures. Here, we report the synthesis of a new series of triazinephosphonate derivatives and their use as dopants in the preparation of new modified Nafion membranes. The triazinephosphonate derivatives were prepared by substitution of chlorine atoms in cyanuric chloride. Diverse conditions were used to obtain the trisubstituted (4-hydroxyphenyl)triazinephosphonate derivatives and the (4-aminophenyl)triazinephosphonate derivatives, but with these amino counterparts, only the disubstituted compounds were obtained. The new modified Nafion membranes were prepared by casting incorporation of the synthesized 1,3,5-triazinephosphonate (TPs) derivatives. The evaluation of the proton conduction properties of the new membranes and relative humidity (RH) conditions and at 60 °C, showed that they present higher proton conductivities than the prepared Nafion membrane and similar or better proton conductivities than commercial Nafion N115, in the same experimental conditions. The Nafion-doped membrane with compound TP2 with a 1.0 wt % loading showed the highest proton conductivity with 84 mS·cm-1.

Chlorinated Oligomers with Regulate Planarity Achieving Superior Photovoltaic Performance.

Chlorine substitution, as an effective and low-cost modification strategy, has been applied in the design of donor and acceptor structures in organic solar cells. We synthesized a series of chlorinated dimerized acceptors to investigate the effect of chlorine numbers and locations on the photovoltaic properties. The results show that the planarity and morphology of DYV-γ-2Cl are greatly improved due to the appropriate numbers and positions of the substituted chlorine atoms. Therefore, the device based on PM6:DYV-γ-2Cl achieves a superior power conversion efficiency (PCE) of 15.54% among the three oligomeric acceptors with optimized molecular planarity and film morphology. This work demonstrated the positive effect of suitable numbers and the substitution positions of chlorines on the molecular arrangement and photovoltaic properties of the corresponding dimerized acceptors.

Microflow Synthesis of Unsymmetrical H-Phosphonates via Sequential and Direct Substitution of Chlorine Atoms in Phosphorus Trichloride with Alkoxy Groups.

Unsymmetrical H-phosphonates were synthesized by a rapid (<15 s) and mild (20 °C) process in a microflow reactor as the first example of the sequential direct substitution of the chlorine atoms in PCl3 with alkoxyl/aryloxy groups using equivalent amounts of PCl3 and alcohols. The optimal base concentration differed in each step, presumably attributed to differences in the Brønsted basicity of the electrophilic intermediates. Phosphite hydrolysis was observed, and the structure-hydrolysis relationship was quantitatively evaluated.

ZIRCONIUM AND HAFNIUM DIHYDROXY­PHTHALO­CYANINATES: METHODS OF SYNTHESIS AND REACTIVITY

Usually in order to obtain out-of-plane sub­stituted phthalocyanine complexes of zirconium and hafnium (PcML2), the reaction of substitution of chlorine atoms in dichloridophthalocyaninates PcMCl2 is used. How­ever, this method has some limitations because during this reaction, hydrogen chloride is released, which can initiate the hydrolysis of starting compounds sensitive to an acidic environment, in particular, β-ketoesters, which, in turn, can lead to the formation of by-pro­ducts and, accordingly, to a decrease purity and yield of target complexes. At the same time, in similar reactions in which the initial phthalocyanine compounds are dihydroxyphthalocyaninates of zirconium and hafnium (PcM(OH)2), as a result of interaction with dicarbonyl compounds or carboxylic acids, water is formed, which does not have a negative effect on the starting substances or on the course of the reaction as a whole. Methods of obtaining zirconium and hafnium dihydroxyphthalocyaninates based on metal alkoxides and by hydrolysis of the corresponding PcMCl2 were investigated in the work. It was established that the synthesis of PcM(OH)2 based on the corresponding alkoxides occurs with low yields (25–40%), increasing the reaction temperature from 140 to 220oC does not lead to their significant increase. It was found that the hydrolysis of PcMCl2 should be carried out under more stringent conditions than previously described, which makes it possible to obtain PcM(OH)2 with high yields.&#x0D; The reactivity of PcM(OH)2 was investigated when interacting with β-diketones and aliphatic carboxylic acids and compared with the reactivity of PcMCl2. It was established that the reactivity of PcM(OH)2 is similar to PcMCl2. However, it should be noted that in the case of the synthesis of β-ketoesterphthalocyanine complexes, the use of the corresponding PcM(OH)2 leads to a significant increase in the yield of the final products of the reaction compared to PcMCl2. This effect can be explained by the fact that hydrogen chloride is not released during the reaction with PcM(OH)2 and, accordingly, hydrolysis of the ester group does not occur.

Structure of oxidized hydrolysis lignin

The main goal of this study was the elucidation of structures of products of oxidation of industrial hydrolysis lignin (HL) obtained in the system H2O2-H2SO4-H2O. It was found that the obtained oxidized hydrolysis lignin (OHL) contained structural fragments of muconic acid dilactone. The latter appeared as a result of the oxidation of aromatic ring of HL into unstable structures of 3,4-dihydroxyadipic acid, which are spontaneously cyclized into the corresponding fragments of muconic acid dilactone in acidic oxidative medium. Consequent reaction of OHL with aqueous sodium hydroxide (NaOH) led to the formation of sodium salt of OHL (Na-OHL), in which the muconic acid dilactone units of OHL opened into fragments of disodium salts of 3,4-dihydroxyadipic acid. The Na-OHL was transformed into the series of novel derivatives of lignins. Thus, the reaction of Na-OHL with thionyl chloride proceeded as a substitution of hydroxyl groups into chlorine atoms in the structure of OHL, that afforded chloro-derivative of OHL. The latter was transformed into amino-amide and ester-ether derivatives of OHL by nucleophilic substitution of chlorine atoms with amines and alcohols correspondingly.

How are polychlorinated biphenyls currently being produced, despite the production ban, and do they pose a risk to the environment?

Abstract Polychlorinated biphenyls (PCBs) are a group consisting of 209 congeners, differing in the number and site of substitution of chlorine atoms to the biphenyl molecule. Due to their physicochemical properties, they have found wide industry use. As a result of many years of large-scale use of PCBs, their toxic properties began to be noticed as they manifested in poisoning among humans. After thorough testing of PCBs, they were classified in the group of persistent organic pollutants (POPs), and their production was banned and they were withdrawn from use. Although PCBs are no longer produced in factories, they can still be formed. In this article, will be presented and explained methods of accidental formation of PCBs. Based on data from the literature, we performed an environmental risk assessment for PCB-contaminated soils.

New Cycloadditon Reaction of 2-Chloroprop-2-enethioamides with Dialkyl Acetylenedicarboxylates: Synthesis of Dialkyl 2-[4,5-bis(alkoxycarbonyl)-2-(aryl{alkyl}imino)-3(2H)-thienylidene]-1,3-dithiole-4,5-dicarboxylates.

The 1,3-dipolar cycloaddition of 1,2-dithiole-3-thiones with alkynes to form 1,3-dithioles is one of the most studied reactions in this class of polysulfur-containing heterocycles. Nucleophilic substitution of chlorine atoms in dimethyl 2-(1,2-dichloro-2-thioxoethylidene)-1,3-dithiole-4,5-dicarboxylate, which was obtained by addition one molecules of DMAD to 4,5-dichloro-3H-1,2-dithiole-3-thione, led to a series of 2-chloro-2-(1,3-dithiol-2-ylidene)ethanethioamides. Cycloaddition reaction of 2-chloro-2-(1,3-dithiol-2-ylidene)ethanethioamides with activated alkynes led to the unexpected formation of 2-(thiophen-3(2H)-ylidene)-1,3-dithioles via new intermediate, 1-(1,3-dithiol-2-ylidene)-N-phenylethan-1-yliumimidothioate. Structure of dimethyl 2-(4,5-bis(methoxycarbonyl)-2-(phenylimino)thiophen-3(2H)-ylidene)-1,3-dithiole-4,5-dicarboxylate was finally proven by single crystal X-ray diffraction study. Optimized reaction conditions and a mechanistic rationale for the 1,3-dipolar cycloaddition of novel intermediate are presented.

Deposition of Iodine-125 on Silver Supports of Microsources for Prostate Cancer Brachytherapy

A method of iodine-125 deposition on a surface of microsource silver supports for brachytherapy of prostate cancer was reported, which includes preparing the support surface by sequentially treating them with nitric acid and thiourea solutions, followed by chlorination of the support surface with a chlorinating agent to form silver chloride on the support surface, and substitution of chlorine atoms for 125I atoms by placing supports containin silver chloride on the surface in a solution with 125I ions to create a 125I layer on the support surface. The method described allows fixing 125I on supports with a low activity distribution on each activity-carrying support.

The halogen effect of perylene diimide-based non-fullerene acceptors on photovoltaic properties

To develop photovoltaic materials based on perylene diimide, two non-fullerene acceptors namely PCPD-F and PCPD-Cl are rationally designed and readily synthesized. By introducing the cyclopentadithiophene unit with the strong electron-donating ability, PCPD-F and PCPD-Cl exhibit strong and bathochromic absorption compared to other perylene diimide derivatives. Meanwhile, different halogens in PCPD-F and PCPD-Cl significantly affect the physicochemical properties and device performance. With the substitution of chlorine atom, PCPD-Cl shows relatively broad absorption and strong crystallinity. However, the chlorination makes PCPD-Cl less miscible with polymer donors, leading to the unfavorable morphology with large-scale phase separation in organic solar cells. Consequently, the device based on PCPD-F achieves the best power conversion efficiency of 9.03% by blending with the polymer donor PM6, which is among the high-performance organic solar cells based on perylene diimide. This work demonstrates it is crucial to meticulously select the substituted atom and position in the design of non-fullerene acceptors.

Effect of Bulky Atom Substitution on Backbone Coplanarity and Electrical Properties of Cyclopentadithiophene‐Based Semiconducting Polymers

Front Cover: In article number 2100709 by Byoung Hoon Lee and co-workers, the effect of chlorine atom substitution on the optoelectronic properties of cyclopentadithiophene-based donor–acceptor π-conjugated polymers is investigated. The chlorine atom substitution leads to deteriorated optical and electrical properties of the polymer due to chain distortion as a consequence of steric hindrance adjacent to the chlorine atoms.

Direct UV photodegradation of herbicide triclopyr in aqueous solutions: A mechanistic study

Mechanism of direct UV photolysis of pyridine herbicide triclopyr (TRI) was revealed by the combination of nanosecond laser flash photolysis, steady-state photolysis coupled with high resolution LC-MS and DFT quantum-chemical calculations. Both the detection of short-lived intermediates and the detailed identification of final products were done for the first time. The quantum yield of TRI photodegradation is about 4% at both UVC (254 nm) and UVB (308 nm) excitation. The primary stage is the heterolytic cleavage of C–Cl bond in dissociative triplet state of TRI with the formation of phenyl cation followed by a fast nucleophilic attack by a solvent molecule. The minor channel is the photohydrolysis leading to the formation of 3,5,6-trichloropyridin-2-ol. Primary photoproducts undergo secondary photolysis by the mechanism similar to initial TRI with the formation of products of acetic group elimination, sequential substitution of chlorine atoms to hydroxyl groups and, finally, oxidation and opening of the pyridine ring. Obtained results can be important for understanding the fate of pyridine herbicides in the processes of UVC disinfection and in natural waters under action of the sunlight.

Synthesis of Cyanuric Chloride based Chiral Reagent for RP-HPLC Enantioseparation of (RS)-Propranolol

In this work, four cyanuric chloride based chiral reagents were prepared via nucleophile substitution of chlorine atom by L-proline derivatives and characterized by UV, FT-IR, HRMS, NMR and elemental analysis. Racemic propranolol was chosen for the chiral recognition study. The prepared chiral reagents were used in the synthesis of diastereomeric derivatives of (RS)-propranolol, under microwave heating conditions. RP-HPLC was used to separate the prepared diastereomeric derivatives. The effect of varying eluting phase concentrations and sample concentrations was optimized. The DFT calculations were performed using Gaussian 09 Rev A.02 to create the lowest energy optimised structures of diastereomeric derivatives. LOD (0.324 ng mL-1), LOQ (0.972 ng mL-1), calibration range (0.02-2.0 mg mL-1), correlation-coefficient (0.999), and recovery were the validation parameters for the present method (99.09 and 99.81 % for inter-day assay and 98.47 and 99.72 % for intra-day assay).

Effect of chlorine atoms in choline chloride-monocarboxylic acid for the pretreatment of oil palm fronds and enzymatic hydrolysis

Choline chloride (ChCl) and various monocarboxylic acids (monochloroacetic acid, MCA; dichloroacetic acid, DCA; trichloroacetic acid, TCA) with increasing numbers of substituted chlorine atoms were utilized for the pretreatment of oil palm fronds (OPFs). To the best of our knowledge, this study was the first attempt to utilize these three novel solvents in biomass pretreatment. The result of ChCl:TCA was excluded due to instability in conducting the pretreatment. Under the recommended conditions of 120 °C and 60 min, similar delignification percentages of 75.96% and 74.89% were obtained for ChCl:MCA and ChCl:DCA, respectively. Enzymatic hydrolysis of the pretreated OPFs was demonstrated after pretreatment. By using ChCl:DCA, a shorter duration of enzymatic hydrolysis (24 h) enabled glucan conversion of pretreated OPFs up to 89%. Although a longer duration of 72 h was imposed, glucan conversion of only 82% could be obtained by using ChCl:MCA. Thus, a solvent with a higher number of chlorine atoms (ChCl:DCA) could lead to more effective enzymatic hydrolysis. The results were compared to the literature findings, and ChCl:DCA was determined to be one of the most effective solvents for biomass pretreatment under relatively mild conditions.

The Antifungal Action Mode of N-Phenacyldibromobenzimidazoles

Our study aimed to characterise the action mode of N-phenacyldibromobenzimidazoles against C. albicans and C. neoformans. Firstly, we selected the non-cytotoxic most active benzimidazoles based on the structure–activity relationships showing that the group of 5,6-dibromobenzimidazole derivatives are less active against C. albicans vs. 4,6-dibromobenzimidazole analogues (5e–f and 5h). The substitution of chlorine atoms to the benzene ring of the N-phenacyl substituent extended the anti-C. albicans action (5e with 2,4-Cl2 or 5f with 3,4-Cl2). The excellent results for N-phenacyldibromobenzimidazole 5h against the C. albicans reference and clinical isolate showed IC50 = 8 µg/mL and %I = 100 ± 3, respectively. Compound 5h was fungicidal against the C. neoformans isolate. Compound 5h at 160–4 µg/mL caused irreversible damage of the fungal cell membrane and accidental cell death (ACD). We reported on chitinolytic activity of 5h, in accordance with the patterns observed for the following substrates: 4-nitrophenyl-N-acetyl-β-d-glucosaminide and 4-nitrophenyl-β-d-N,N′,N″-triacetylchitothiose. Derivative 5h at 16 µg/mL: (1) it affected cell wall by inducing β-d-glucanase, (2) it caused morphological distortions and (3) osmotic instability in the C. albicans biofilm-treated. Compound 5h exerted Candida-dependent inhibition of virulence factors.

Modification of poly(vinyl chloride) by aromatic amines: application to the extraction of some metal cation

The reaction of poly(vinyl chloride) (PVC) with various aliphatic amines in 1,4-dioxane has been studied. These reactions led to the formation of new polymers (PVC-L), which were characterized by different spectroscopic methods: differential thermal analysis (DTA) and infrared. The extraction percentages were determined by comparing the initial conductivity of the aqueous solution containing the studied metal with the final conductivity of the aqueous solution at extraction equilibrium. One of the obtained polymers gave an extraction rate of 82.05% for Li+, which underlines the importance of the substitution of chlorine atoms by diethylenetriamine groups. A kinetic study of the extraction shows that the optimal duration of extraction was obtained with the polymer most substituted by diethylenetriamine groups.

Kinetics and mechanisms of phenolic compounds by Ferrate(VI) assisted with density functional theory

In this paper, Phenol, 4-Chlorophenol (4-CP), 2,4-Dichlorophenol (2,4-DCP) and 2,4,6-Trichlorophenol (2,4,6-TCP) were selected as model pollutants to explore the oxidant mechanism by ferrate (Fe(VI)). The reactions between ferrate (1000 μM) and four phenolic compounds (100 μM) were conformed to the second-order reaction kinetics at pH 9.2, and the order of kobs followed as: k4-CP (129 M−1 s−1) > k2,4-DCP (96 M−1 s−1) > k2,4,6-TCP (44 M−1 s−1) > kPhenol (12 M−1 s−1). Meanwhile, the degradation rates of all four compounds by Fe(VI) increased with increased pH (3.1–9.2). A total of 14 degradation products were identified by Liquid chromatography-Time-of-Flight-Mass Spectrometry (LC-TOF-MS), and two pathways including hydroxylation of benzene ring and substitution of chlorine atom were proposed. Hydroxyl radicals, played a vital role during the degradation of phenolic compounds. Moreover, density functional theory calculations were used to explore the degradation mechanisms. The results showed that the hydroxyl radical was more favorable to substitute chlorine atom than hydrogen atom, and the substitution on ortho-position was more favorable than para-position for all four compounds. The findings of this study could greatly improve our understanding on the degradation mechanism of chlorophenol-like compounds by Fe(VI) for environmental remediation.

Synthesis and Application of Arylaminophosphazene as a Flame Retardant and Catalyst for the Polymerization of Benzoxazines.

A novel type of phosphazene containing an additive that acts both as a catalyst and as a flame retardant for benzoxazine binders is presented in this study. The synthesis of a derivative of hexachlorocyclotriphosphazene (HCP) and meta-toluidine was carried out in the medium of the latter, which made it possible to achieve the complete substitution of chlorine atoms in the initial HCP. Thermal and flammability characteristics of modified compositions were investigated. The modifier catalyzes the process of curing and shifts the beginning of reaction from 222.0 °C for pure benzoxazine to 205.9 °C for composition with 10 phr of modifier. The additive decreases the glass transition temperature of compositions. Achievement of the highest category of flame resistance (V-0 in accordance with UL-94) is ensured both by increasing the content of phenyl residues in the composition and by the synergistic effect of phosphorus and nitrogen. A brief study of the curing kinetics disclosed the complex nature of the reaction. An accurate two-step model is obtained using the extended Prout–Tompkins equation for both steps.

Structural Modification of Pyridoxal. Synthesis and Evaluation of Anti-Infective Activity of New 4-Chloro- and 4-Alkyl(dialkyl)aminomethyl-2-hetaryl(hetaroyl)furo[2,3-c]pyridines

4-Hydroxymethyl-2-hetaryl(hetaroyl)furo[2,3-c]pyridines, the products of furan cyclization of pyridoxal with acylmethyl- and heteroarylmethyl halides, easily react with thionyl chloride in DMF to form new series of 4-chloromethyl-2-heteroaryl[2,3-c]pyridines. Further action of primary or secondary amines on these chloromethyl derivatives leads to the nucleophilic substitution of chlorine atoms with the formation of 4-aminomethyl-2-heteroaryl[2,3-c]pyridines. The study of anti-infective activity of the 4-RCH2-furo[2,3-c]pyridines (R = OH, Cl, NR1R2) showed significant protistocidal and moderate antibacterial activity of some of representatives of these compounds.

Theoretical chemistry study on the toxicity of some polychlorobiphenyl (PCB) compounds using molecular descriptors

This study was carried out to establish, validate and apply a model that relates the toxicity of some PCBs (2,4-dichlorobiphenyl, 2,4’5-trichlorobiphenyl, 2,2’3,4,4’,5’,6-heptachlorobiphenyl, 2,2’,5,5’-tetrachlorobiphenyl and 2,3,3’4,4’-pentachlorobiphenyl) to molecular descriptors (quantum chemical, physicochemical and topological descriptors) through quantitative structure toxicity relationship. The established model reveal that the total molecular energy, electronic energy, core repulsion energy, energy of the highest occupied molecular orbital, energy of the lowest unoccupied molecular orbital, cosmo area, cosmo volume and dipole moment displayed excellent correlation with LD50 values of the PCBs. Some topological parameters (namely molecular topological index, Weiner index, total connectivity and Balaban index) also exhibited excellent correlation with experimentally determined LD50 data. Two equations suitable for estimating theoretical LD50 values of the studied PCBs were derived using quantum chemical and topological descriptors. These equations gave perfect fitness when experiment and theoretical LD50 values were plotted (i.e. R2 value approximated unity) against each other. Perfect correlation was also obtained between theoretical and experimentally derived LD50 values for 2,2’,3,4’,5’,6-hexaxhlorobiphenyl, 2,2’,4,5,5’-pentachlorobiphenyl, 2,3’,4,4’-tetrachlorobiphenyl and 2,2’,4,4’,5,5’-hexachlorobiphenyl, where were PCBs used for model validation. The model was also used to predict the toxicity of other PCBs that lacks accurate experimental data. The study revealed that the reactivity of PCBs can be influence by the number of substituted chlorine atom and by the position of the reactive aromatic carbon. From the results and findings of the study, it was concluded that the applications of quantitative structure-toxicity relation principles to quantum and topological parameters provide excellent avenue for estimating the degree of toxicity of PCBs.

Synthesis and Evaluation on Anticonvulsant and Antidepressant Activities of Naphthoquinone Derivatives Containing Pyrazole and Pyrimidine Fragments

Novel heterocyclic dichloronaphthoquinone derivatives have been synthesized by chlorine atom substitution in 2,3-dichloro-1,4-naphthoquinone to pyrazole or pyrimidine fragments. The structures of these compounds have been confirmed by FT-IR, ESI-MS, 1H?NMR, 13C-NMR and elementary analysis. Synthesized compounds were evaluated for their anticonvulsant action in a pentylenetetrazole (PTZ)-convulsion model and antidepressant activity in the forced swimming test (FST). All naphthoquinone derivatives at a dose 100 mg/kg indicated anticonvulsant effect in PTZ-induced test at 3 h and 24 h after oral administration. In addition, these compounds possessed prolonged antidepressant properties significantly reducing the duration of immobility time when compared to the reference drug amitriptyline.