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Concept: Hydrogen chloride

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Both nitrate and pentachlorophenol (PCP) are familiar pollutants in aqueous environment. This research is focused on the simultaneous removal of nitrate and PCP from simulated contaminated groundwater using a laboratory-scale denitrification reactor packed with corncob as both carbon source and biofilm support. The reactor could be started up readily, and the removal efficiencies of nitrate and PCP reached up to approximately 98 % and 40-45 % when their initial concentrations were 50 mg N/L and 5 mg/L, respectively, after 15-day continuous operation at 10 h of hydraulic retention time (HRT) and 25 °C. Approximately 91 % of PCP removal efficiency was achieved, with 2.47 mg/L of chloride ion release at 24 h of HRT. Eighty-two percent of chlorine in PCP removed was ionized. The productions of 3-chlorophenol and phenol and chloride ion release indicate that the reductive dechlorination reaction is a major degradation pathway of PCP under the experimental conditions.

Concepts: Concentration, Chemistry, Water pollution, Sodium chloride, Ion, Chlorine, Chloride, Hydrogen chloride

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A novel method allowing simultaneous analysis of PhIP, 4'-OH-PhIP, and their precursors (phenylalanine, tyrosine, creatine, creatinine, glucose) has been developed as a robust kinetic study tool by using ultra high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A direct hydrochloric acid (HCl) extraction was applied to achieve the simultaneous extraction of all seven analytes, with the mean recoveries ranging from 60% to 120% at two concentration levels. Then, an Atlantis dC18 column selected from four different chromatographic columns was ultimately used to separate these compounds within 15 min. The limits of detection range of allseven analytes were calculated as 0.14-325.00 μg L(-1). The intra- and interday precision of the proposed method were less than 15.4 and 19.9%, respectively. The proposed method was successfully applied to depict the kinetic profiles of PhIP, 4'-OH-PhIP, and their precursors in pork model, reducing the analysis time and cost in the kinetic study.

Concepts: Hydrogen, Chromatography, Acid dissociation constant, Chlorine, Liquid chromatography-mass spectrometry, Hydrogen chloride, Hydrochloric acid, Leblanc process

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Tetracyclic heterocycles that exhibit high photoluminescence quantum yields were synthesized by anellation reactions of mono-, di-, and trifunctionalized 2,3-dichloroquinoxalines. Thus, treatment of 2,3-dichloroquinoxaline with TMPLi (TMP=2,2,6,6-tetramethylpiperidyl) allows a regioselective lithiation in position 5. Quenching with various electrophiles (iodine, (BrCl2 C)2 , allylic bromide, acid chloride, aryl iodide) leads to 5-functionalized 2,3-dichloroquinoxalines. Further functionalization in positions 6 and 8 can be achieved by using TMPLi or TMPMgCl⋅LiCl furnishing a range of new di- and tri-functionalized 2,3-dichloroquinoxalines. The chlorine atoms are readily substituted by anellation with 1,2-diphenols or 1,2-dithiophenols leading to a series of new tetracyclic compounds. These materials exhibit strong, tunable optical absorption and emission in the blue and green spectral region. The substituted O-heterocyclic compounds exhibit particularly high photoluminescence quantum yields of up to 90 %, which renders them interesting candidates for fluorescence imaging applications.

Concepts: Photon, Light, Absorption, Chlorine, Iodine, Absorption spectroscopy, Hydrogen chloride, Leading

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The synthesis of triblock copolymers based on polysarcosine, poly-N-ε-t-butyloxycarbonyl-l-lysine, and poly-N-ε-t-trifluoroacetyl-l-lysine by ring-opening polymerization of the corresponding α-amino acid N-carboxyanhydrides (NCAs) is described. For the synthesis of N-ε-t-butyloxycarbonyl-l-lysine (lysine(Boc)) NCAs, an acid-free method using trimethylsilylchloride/triethylamine as hydrochloric acid (HCl) scavengers is presented. This approach enables the synthesis of lysine(Boc) NCA of high purity (melting point 138.3 °C) in high yields. For triblock copolypept(o)ides, the degree of polymerization (Xn ) of the polysarcosine block is varied between 200 and 600; poly-N-ε-t-butyloxycarbonyl-l-lysine and poly-N-ε-t-trifluoroacetyl-l-lysine blocks are designed to have a Xn in the range of 10-50. The polypeptide-polypeptoid hybrids (polypept(o)ides) can be synthesized with precise control of molecular weight, high end group integrity, and dispersities indices between 1.1 and 1.2. But more important, the use of tert-butyloxycarbonyl- and trifluoroacetyl-protecting groups allows the selective, orthogonal deprotection of both blocks, which enables further postpolymerization modification reactions in a block-selective manner. Therefore, the presented synthetic approach provides a versatile pathway to triblock copolypept(o)ides, in which functionalities can be separated in specific blocks.

Concepts: Chemical reaction, Hydrogen, Polymer, Polymer chemistry, Chemical synthesis, Chlorine, Hydrogen chloride, Hydrochloric acid

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In order to disclose the reason that the N-doped carbon support can enhance the stability of Au-based catalysts for acetylene hydrochlorination, we established a big graphene cluster model of C110H28 to investigate the effect of different nitrogen-doped carbon supports on three kinds of gold species models of Au dimers, Au2Cl2 and Au2Cl6, through DFT calculations. Comparing the adsorption energy of each Au complex and the transferred charge from the support to the Au complex, it is observed that on the N-doped support GRN-I (the pyridinic N-doped graphene) the adsorption energies of the Au dimer, Au2Cl2 and Au2Cl6, are much higher than those on other three kinds of supports, and the Au complex accepts most of the transferred charges from the support of GRN-I. The effect of different supports on the adsorption of C2H2 and HCl was studied on Au2Cl6/supports, suggesting that the co-adsorption of both reactants occurs on Au2Cl6/GRN-I. The results indicate that the N-doped support of GRN-I can stabilize the gold species Au2Cl6 and enhance the interaction between Au2Cl6 and HCl, which can inhibit the reduction of Au(3+) and then increase the long-term stability of Au-based catalysts.

Concepts: Chemical reaction, Hydrogen, Catalysis, Carbon, Adsorption, Hydrocarbon, Hydrogen chloride, Acetylene

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The cyanosporasides A-F are a collection of monochlorinated benzenoid derivatives isolated from the marine actinomycetes Salinispora and Streptomyces sp. All derivatives feature one of two types of cyanocyclopenta[a]indene frameworks, which are regioisomeric in the position of a single chlorine atom. It is proposed that these chloro-substituted benzenoids are formed biosynthetically through the cycloaromatization of a bicyclic nine-membered enediyne precursor. Herein, we report the synthesis of such a bicyclic precursor, its spontaneous transannulation into a p-benzyne, and its differential 1,4 hydrochlorination reactivity under either organochlorine or chloride-salt conditions. Our bioinspired approach culminated in the first regiodivergent total synthesis of the aglycons A/F and B/C, as well as cyanosporasides D and E. In addition, empirical insights into the site selectivity of a natural-like p-benzyne, calculated to be a ground-state triplet diradical, to hydrogen, chlorine, and chloride sources are revealed.

Concepts: Hydrogen, Atom, Total synthesis, Chlorine, The Marine, Hydrogen chloride, Streptomyces, Hydrochloric acid

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The structure of the gas-phase bimolecular complex formed between vinyl chloride and hydrogen fluoride is determined using Fourier transform microwave spectroscopy from 6.3 to 21.4 GHz. Although all previous examples of complexes formed between protic acids and haloethylenes are observed to have similar modes of binding regardless of the specific identity of the acid, HF, HCl, or HCCH, the planar vinyl chloride-HF complex has HF located at the “top” of the vinyl chloride with the secondary interaction occurring with the cis hydrogen atom as opposed to the “side” binding configuration found for vinyl chloride-HCCH. Nevertheless, the details of the structure, such as hydrogen bond length (2.32 Å) and amount of deviation from linearity (19.8°), do reflect the strength of the interaction and show clear correlations with the gas-phase acidity. Comparison with analogous complexes allows the determination of the relative importance of electrostatic interactions and steric requirements in leading to the observed structures.

Concepts: Oxygen, Acid, Fundamental physics concepts, Water, Hydrogen, Atom, Chlorine, Hydrogen chloride

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2-Arylbenzoyl chlorides undergo annulative coupling with internal alkynes in the presence of a catalyst system of [IrCl(cod)]2/P(t-Bu)3 to selectively afford the corresponding phenanthrene derivatives accompanied by elimination of carbon monoxide and hydrogen chloride. The reaction occurs without addition of any external base. Deuterium labeling experiments using 2-(d5-phenyl)benzoyl chloride suggest that the rate-determining step does not involve the C2'-H bond cleavage. Formation of a [(t-Bu)3PH][(biphenyl-2,2'-diyl)Ir(CO)Cl2] complex dimer, of which structure was determined by single-crystal X-ray analysis, from a stoichiometric reaction at 60 degC without adding alkyne also supports the facile C-H cleavage.

Concepts: Chemical reaction, Hydrogen, Carbon, Alkene, Carbon monoxide, Chlorine, Hydrogen chloride, Hydrochloric acid

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A dually activated ketene enolate, generated from an acid chloride, the unusual chelating nucleophile (1,8-naphthyridine), and a Lewis acid, reacts to afford a host of alpha,alpha-difluorinated products in the presence of a bench top stable fluorinating agent (Selectfluor). The use of this method to synthesize otherwise difficult to make products is highlighted along with computational and spectroscopic support for the proposed chelate.

Concepts: Amine, Gilbert N. Lewis, Carbonyl, Chlorine, Citric acid, Hydrogen chloride

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Internal sample conductivity in scanning electron microscopy can be a valuable alternative to metal coating. Proton conductivity may be used for this purpose. Many solid materials with active hydrogen atoms, such as hydrogen- and ammonium-salts, organic acids, and even ice, are protonic conductors or semiconductors. Here we present a method to generate proton conductivity in dry biological materials. A simple treatment with hydrogen chloride gas or hydrochloric acid vapour for a few minutes provides sufficient conductivity for many samples. After a removal of excess hydrogen chloride vapour with a vacuum desiccator, the objects may be examined in the SEM without metal coating. The use of internally conductive samples extends the range of easy-to-perform SEM preparation techniques. It is advantageous for material contrast imaging of uncoated samples, and it can be used in combination with metal coating to enhance conductivity on difficult samples with complex overlapping surfaces, where simple metal coating does not reliably eliminate charging problems.

Concepts: Electron, Acid, Hydrogen, Proton, Atom, Chlorine, Hydrogen chloride, Hydrochloric acid