Substitution Of Chlorine Atom Research Articles

A covalent modification for graphene by adamantane groups through two-step chlorination-Grignard reactions

Chemical modification of graphene is a promising approach to manipulate its properties for its end applications. Herein we designed a two-step route through chlorination-Grignard reactions to covalently decorate the surface of graphene with adamantane groups. The chemically modified graphene was characterized by Raman spectroscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Chlorination of graphene occurred rapidly, and the substitution of chlorine atoms on chlorinated graphene by adamantane Grignard reagent afforded adamantane graphene in almost quantitative yield. Adamantane groups were found to be covalently bonded to the graphene carbons. The present two-step procedure may provide an effective and facile route for graphene modification with varieties of organic functional groups.

Sulfur-containing polymer and carbon materials based on poly(vinyl chloride)

New sulfur-containing copolymers based on poly(vinyl chloride) have been prepared by the nucleophilic substitution of chlorine atoms by sulfur atoms using sodium tetra- and pentasulfides. It has been shown that these copolymers can be carbonized to produce sulfur-containing carbon materials with residual chlorine content about 2 wt %.

Zunyimycins B and C, New Chloroanthrabenzoxocinones Antibiotics against Methicillin-Resistant Staphylococcus aureus and Enterococci from Streptomyces sp. FJS31-2.

This study performed an optimization of the fermentation conditions to activate the expression of the zunyimycin family biosynthesis genes of the zunyimycin-producing streptomycetes strain Streptomyces sp. FJS31-2. Bioassay-guided isolation and purification by varied chromatographic methods yielded two new compounds of the zunyimycin derivatives, namely, 31-2-7 and 31-2-8, accompanied with three known anthrabenzoxocinones family members of zunyimycin A, BE24566B, and chloroanthrabenzoxocinone. Their structures were elucidated by NMR, HRESIMS, IR, UV, and CD. Results showed that these two compounds were structurally similar to the previously reported compound zunyimycin A but differed in positions and number of chlorine atom substitution. The two novel compounds were called zunyimycins B and C. Antibacterial activity assay indicated that zunyimycin C showed a good inhibitory effect on the methicillin-resistant Staphylococcus aureus and Enterococci.

Synthesis of oligomeric epoxycyclotriphosphazenes and their properties as reactive flame-retardants for epoxy resins

GRAPHICAL ABSTRACT

Phosphorylation of aminomalonates

The reactions of chloroethynylphosphonates with aromatic secondary aminomalonates occur as classic nucleophilic substitution of chlorine atom at the sp-hybridizied carbon atom to form new phosphorylated 2-arylaminomalonates, diethyl esters of 2-(diethoxyphosphorylethynyl)-2-arylaminomalonic acids. Nonobservance of chemo- and regioselectivity was revealed when using cyclohexyl- and benzylaminomalonates.

Molecular modeling studies of 3-acyl-2-phenylamino-1,4-dihydroquinolin-4-one derivatives as phosphatase SerB653 inhibitors

To understand the quantitative structure–activity relationships properties of 3-acyl-2-phenylamino-1,4-dihydroquinolin-4-one derivatives, and to design inhibitors of phosphatase SerB653 were developed. The statistical parameters of two-dimensional quantitative structure–activity relationship model showed it has good reliability and predictive ability (q2 = 0.7180, F test = 62.046, pred_r2 = 0.7519). The best two-dimensional model suggests a chlorine atom substitution at position X4 and Y1 for enhance activity. Three-dimensional quantitative structure–activity relationship was carried out using k-nearest neighbor method and showed cross-validated correlation coefficient (q2) of 0.7484, and a predicted r2 for the external test (pred_r2) of 0.6895 were obtained with best three-dimensional quantitative structure–activity relationship model. The influences of steric and electrostatic field effects generated by the contribution plot are analyzed. Pharmacophore approach for SerB653 inhibitor consists of hydrogen bond acceptor, hydrogen bond donor, and aromatic region. Two-dimensional quantitative structure–activity relationship and three-dimensional quantitative structure–activity relationship, pharmacophore analyses of 3-acyl-2-phenylamino-1,4-dihydroquinolin-4-one derivatives can provide more useful information and important structural insights for designing potent phosphatase SerB653 inhibitors.

The polychlorinated dibenzofuran fingerprint of iron ore sinter plant: Its persistence with suppressant and alternative fuel addition

An earlier demonstration that the relative concentrations of isomers of polychlorinated dibenzofuran do not vary as the flamefront of an iron ore sinter plant progresses through the bed, and profiles are similar for two sinter strands has been widened to include studies of the similarity or otherwise between full scale strand and sinter pot profiles, effect of addition of suppressants and of coke fuel substitution with other combustible materials. For dioxin suppressant addition, a study of the whole of the tetra- penta- and hexaCDF isomer range as separated by the DB5MS chromatography column, indicates no significant change in profile: examination of the ratios of the targeted penta- and hexaCDF isomers suggests the profile is similarly unaffected by coke fuel replacement. Addition of KCl at varied levels has also been shown to have no effect on the ‘fingerprint’ and there is no indication of any effect by the composition of the sinter mix. The recently published full elution sequence for the DB5MS column is applied to the results obtained using this column.It is confirmed that isomers with 1,9-substitution of chlorine atoms are invariably formed in low concentrations. This is consistent with strong interaction between the 1 and 9 substituted chlorine atoms predicted by DFT thermodynamic calculations. Non-1,9-substituted PCDF equilibrium isomer distributions based on DFT-derived thermodynamic data differ considerably from stack gas distributions obtained using SP2331 column separation. A brief preliminary study indicates the same conclusions (apart from the 1,9-interaction effect) hold for the much smaller content of PCDD.

ChemInform Abstract: Williamson Ether Synthesis with Phenols at a Tertiary Stereogenic Carbon: Formal Enantioselective Phenoxylation of β‐Keto Esters.

AbstractFor the first time, the enantioselective synthesis of α‐aryloxy‐β‐keto esters through the sequential enantioselective chlorination of cyclic and non‐cyclic β‐keto esters followed by nucleophilic substitution of chlorine atoms with phenols is described.

Degradation of herbicide 2,4-dichlorophenoxybutanoic acid in the photolysis of [FeOH]2+ and [Fe(Ox)3]3- complexes: A mechanistic study.

In the present work the Fe(III)-assisted photodegradation of the herbicide 2,4-dichlorophenoxybutanoic acid (2,4-DB) has been studied by means of stationary (308 nm) and laser flash (355 nm) photolysis. The initial quantum yield of 2,4-DB photodegradation in [FeOH](2+) and [Fe(Ox)3](3-) systems was evaluated to be 0.11 and 0.17 upon 308 nm exposure, respectively. The prolonged photolysis of [FeOH](2+) and [Fe(Ox)3](3-) systems results in the complete degradation of 2,4-DB with almost complete mineralization of herbicide and its aromatic products in the case of [FeOH](2+) photolysis and the accumulation of some persistent aromatic products in the case of [Fe(Ox)3](3-) photolysis. For both systems the main primary products of 2,4-DB photolysis determined by liquid chromatography - mass spectrometry are products of the hydroxylation, the substitution of chlorine atom to OH group, the loss of aliphatic tail and the opening of benzene ring. The obtained results indicate ROS species (mainly OH radical) to be responsible for the herbicide photodegradation.

Synthesis of New Derivatives of 4‐(4,7,7‐Trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine

Cyclocondensation of 5‐amino‐6‐methyl‐2‐morpholinopyrimidine‐4‐thiol (1) and 2‐bromo‐5,5‐dimethylcyclohexane‐1,3‐dione (2) under mild reaction condition afforded 4,7,7‐trimethyl‐2‐morpholino‐7,8‐dihydro‐5H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐9(6H)‐one (3). The 1H and 13C NMR data of compound (3) are demonstrated that this compound exists primarily in the enamino ketone form. Reaction of compound (3) with phosphorous oxychloride gave 4‐(9‐chloro‐4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine (4). Nucleophilic substitution of chlorine atom of compound (4) with typical secondary amines in DMF and K2CO3 furnished the new substituted derivatives of 4‐(4,7,7‐trimethyl‐7,8‐dihydro‐6H‐benzo[b]pyrimido[5,4‐e][1,4]thiazin‐2‐yl)morpholine (5a, 5b, 5c, 5d, 5e, 5f, 5g, 5h). All the synthesized products were characterized and confirmed by their spectroscopic and microanalytical data.

A poly (vinyl chloride) functionalized by diethylenetriamine, 2,6-bis-(chloromethyl) pyridine and a crowded aromatic amine. Inductively coupled plasma study of the extraction of La(III) and Bi(III) by modified PVC polymers

The aim of this study was to evaluate the efficiency of three new polymers obtained by functionalization of a commercial poly (vinyl chloride) (Mw = 48,000) by grafting diethylenetriamine, 2,6-bis-(chloromethyl) pyridine and 1-chloro-2-phenylaminomethyl-6-phenyl aminomethylene-cyclohex-1-ene groups to extract some metal cations from aqueous solutions. The structural properties of the polymers were systematically investigated by different analytical methods; namely elemental analysis, differential scanning calorimetry and infrared spectroscopy (FT-IR). The percentage of extraction was determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES). One of the obtained polymers gave an extraction ratio of La3+ = 99.57% which highlights the importance of the substitution of chlorine atoms by amino groups.

Synthesis of enantiomers of N-(2-aminopurin-6-yl)amino acids

Nonracemic N-(2-aminopurin-6-yl)-substituted amino acids were synthesized by nucleophilic substitution of chlorine atom in 2-acetamido-6-chloropurine upon treatment with amino acid tert-butyl esters and subsequent removal of protecting groups. Their enantiomeric composition was determined by HPLC on chiral stationary phases.

Synthesis and Antimicrobial Activity of Some 2-Amino-4-(7- Substituted/Unsubstituted Coumarin-3-yl)-6-(Chlorosubstitutedphenyl) Pyrimidines

Purpose: To prepare some 2-amino 4- (7-substituted/unsubstitutedcoumarin-3-yl)-6-(chlorosubstitute dphenyl) pyrimidines as antimicrobial agents.Methods: Some 2-amino-4-(7-substituted/unsubstitutedcoumarin-3-yl)-6-(chlorosubstitutedphenyl) pyrimidines were prepared by reacting 3-chlorosubstitutedphenyl-1-(7-substituted/unsubstituted coumarin 3-yl)prop-2-ene-1-ones with guanidine carbonate. The chemical structures of the synthesized compounds were elucidated by Fourier transform infra-red spectroscopy (FTIR), 1H-nuclear magnetic resonance (1H-NMR), mass spectrometry and elemental analysis. The synthesized compounds were investigated for their antimicrobial activity against four bacteria and five fungi by serial plate dilution method using ofloxacin and ketoconazole as reference antimicrobial drugs, respectively, and their minimum inhibitory concentrations (MICs) were determined.Results: Compounds 1 (p < 0.0001), 2 (p < 0.0001), 6 (p < 0.0001) and 8 (p < 0.0001) were the most active antibacterial agents among the synthesized compounds compared to control and standard agents. Structure-activity relationship revealed that substitution of chlorine atoms at 2- and 6- positions of the phenyl ring are critical for antibacterial activity in the case of dichlorophenyl derivatives, while for monochlorophenyl derivatives, the positions 2 and 4 of the phenyl ring were critical for antibacterial activity. None of the compounds exhibited comparable antifungal activity to the standard antifungal drug, ketoconazole, even at high concentrations.Conclusion: It is evident that the synthesized compounds are relatively very active antibacterial agents but are weak antifungal agents. However, these compounds need further evaluation of their antibacterial activity against other bacterial strains to ascertain their broad spectrum antibacterial activity.Keywords: Pyrimidine, Coumarin, Antibacterial, Antifungal, Structure-activity Relationship

Aerial Oxidation of a V(IV)-Iminopyridine Hydroquinonate Complex: A Trap for the V(IV)-Semiquinonate Radical Intermediate.

The reaction of 2,5-bis[N,N'-bis(2-pyridyl-aminomethyl)aminomethyl]-p-hydroquinone (H2bpymah) with VO(2+) salts in acetonitrile or water at a low pH (2.2-3.5) results in the isolation of [{V(IV)(O)(Cl)}2(μ-bpymah)], the p-semiquinonate complex [{V(IV)(O)(Cl)}2(μ-bpymas)](OH), the cyclic mixed-valent hexanuclear compound [{V(V)(O)(μ-O)V(IV)(O)}(μ-bpymah)]3, and [(V(V)O2)2(μ-bpymah)]. [{V(IV)(O)(Cl)}2(μ-bpymas)](OH) is an intermediate of the radical-mediated oxidation of [{V(IV)(O)(Cl)}2(μ-bpymah)] from O2. At lower pH values (2.2), a reversible intramolecular electron transfer from the metal to the ligand of [{V(IV)(O)(Cl)}2(μ-bpymas)](OH) is induced with the concurrent substitution of chlorine atoms by the oxygen-bridging atoms, resulting in the formation of [{V(V)(O)(μ-O)V(IV)(O)}(μ-bpymah)]3. The metal complexes were fully characterized by X-ray crystallography, infrared (IR) spectroscopy, and magnetic measurements in the solid state, as well as by conductivity measurements, UV-vis spectroscopy, and electrochemical measurements in solution. The oxidation states of the metal ions and ligands were determined by the crystallographic data. The [{V(IV)(O)(Cl)}2(μ-bpymah)]-[{V(IV)(O)(Cl)}2(μ-bpymas)](OH) redox process is electrochemically reversible. The V(IV) ion in the semiquinonate compound exhibits a surprisingly low oxophilicity, resulting in the stabilization of OH(-) counterions at acidic pH values. An investigation of the mechanism of this reaction reveals that these complexes induce the reduction of O2 to H2O2, mimicking the activity of enzymes incorporating two redox-active centers (metal-organic) in the active site.

Iron(II) clathrochelate with an annelated 4,5-dimercapto-[1,3]dithiol-2-thione moiety: Synthesis, structure, and redox reactions

Nucleophilic substitution of chlorine atoms in iron(II) dichloroclathrochelate induced by 4,5-dimercapto-[1,3]dithiol-2-thione dianion gave rise to a cage complex with an annelated sulfur-containing heterocyclic moiety. The composition and structure of this complex were determined by X-ray crystallography and multinuclear NMR spectroscopy in a crystal and in solution, respectively; cyclic voltammetry (CVA) and EPR were used to study the redox reactions of the complex in solution to yield a ligand-centered radical-anionic product.

Common characteristic assessments of transformation mechanism for substituted phenylurea herbicides by reactive oxygen species (ROSs) during photocatalytic process

Substituted phenylurea herbicides, fenuron (fen), isoproturon (iso) and linuron (lin), have been selected as target compounds, and the degradation possibility, kinetics, the contributions of reactive oxidative species (ROSs), and the degradation mechanism have been investigated during photocatalytic process. The results indicate that more than 90% of the three substituted urea herbicides are degraded within 40min. The results from ROSs reveal that surface reactions with photoholes and OH on the surface of TiO2 make major contributions, and BrO3− and S2O82− effectively promote the degradation rates of three substituted phenylurea herbicides. And then the point charges (PCs), frontier election densities (FEDs) and energies have been employed to predict the chemisorption pattern, reaction active sites and direction of reaction, respectively. With the help of calculated data and indentified degradation intermediates, the degradation pathways can be proposed as cleavage of side chain, substitution of chlorine atom and hydroxylated of parent molecules.

In silico analysis of the interaction of avian aryl hydrocarbon receptors and dioxins to decipher isoform-, ligand-, and species-specific activations.

The aryl hydrocarbon receptor (AHR) mediates toxic responses to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and other dioxin-like compounds (DLCs). Avian species possess multiple AHR isoforms (AHR1, AHR1β, and AHR2) that exhibit species- and isoform-specific responses to ligands. To account for the ligand preference in terms of the structural features of avian AHRs, we generated in silico homology models of the ligand-binding domain of avian AHRs based on holo human HIF-2α (PDB entry 3H7W ). Molecular docking simulations of TCDD and other DLCs with avian AHR1s and AHR2s using ASEDock indicated that the interaction energy increased with the number of substituted chlorine atoms in congeners, supporting AHR transactivation potencies and World Health Organization TCDD toxic equivalency factors of congeners. The potential interaction energies of an endogenous AHR ligand, 6-formylindolo [3,2-b] carbazole (FICZ) to avian AHRs were lower than those of TCDD, which was supported by a greater potency of FICZ for in vitro AHR-mediated transactivation than TCDD. The molecular dynamics simulation revealed that mean square displacements in Ile324 and Ser380 of TCDD-bound AHR1 of the chicken, the most sensitive species to TCDD, were smaller than those in other avian AHR1s, suggesting that the dynamic stability of these amino acid residues contribute to TCDD preference. For avian AHR2, the corresponding residues (Val/Ser or Val/Ala type) were not responsible for differential TCDD sensitivity. Application of the three-dimensional reference interaction site model showed that the stabilization of TCDD binding to avian AHRs may be due to the solvation effect depending on the characteristics of two amino acids corresponding to Ile324 and Ser380 in chicken AHR1. This study demonstrates that in silico simulations of AHRs and ligands could be used to predict isoform-, ligand-, and species-specific interactions.

Structure of the product of free-radical substitution of chlorine atoms in iron(II) clathrochelate with two ethanol fragments

The homolytic substitution of chlorine atoms afforded iron(II) clathrochelate bearing two ethanol fragments. The structure of the compound was determined by XRD in the crystalline state and by NMR in solution.

Reactivity of N,C,N-Chelated Antimony(III) and Bismuth(III) Chlorides with Lithium Reagents: Addition vs Substitution

N,C,N-chelated antimony(III) and bismuth(III) chlorides L1,2MCl2 (1–4: for L1, M = Sb (1), Bi (3); for L2, M = Sb (2), Bi (4)) containing ligands L1,2 (where L1 = C6H3-2,6-(CH═N-t-Bu)2, L2 = C6H3-2,6-(CH═N-2′,6′-Me2C6H3)2) were prepared by reactions of lithium precursors with SbCl3 or BiCl3. The identities of 1–4 were established both in solution (1H and 13C NMR spectroscopy) and, in the case of 1–3, in the solid state using single-crystal X-ray diffraction analysis. Treatment of antimony derivatives 1 and 2 with 2 molar equiv of R′Li (R = Me, n-Bu, Ph) yielded the set of substituted 1,3-(R′)2-2-R-7-(CH═NR)-1H-2,1-benzazastiboles 5–10 (where R = t-Bu, 2,6-Me2C6H3 and R′ = Me, n-Bu, Ph) as a result of a nucleophilic attack of one of the lithium compounds across the imino C═N functionality. In contrast, analogous reactions between bismuth congeners 2 and 4 and R′Li (2 equiv, R′ = Me, Ph) gave L1,2BiR′2 (11–13: for L1, R′ = Me (11), Ph (12); for L2, R′ = Me (13)) as products of substitution of chlorine atoms. Compounds 5–13 were characterized by the help of 1H and 13C NMR spectroscopy. The molecular structures of 8, 9, and 13 were unambiguously established using single-crystal X-ray diffraction analysis.

A simple and convenient synthesis of 5-amino-substituted tetrazolo[1,5-a]-1,3,5-triazin-7-one salts

A simple and convenient three-step synthesis of 5-amino-substituted tetrazolo[1,5-a]-1,3,5-triazin-7-one sodium salts based on a fairly simple sequence of nucleophilic substitution of chlorine atoms in cyanuric chloride has been developed. The corresponding tetrabutylammonium salts were synthesized by cation-exchange with tetrabutylammonium chloride. The structures of the products were characterized by IR, 1H NMR and 13C NMR spectroscopy, and by elemental and X-ray analysis.