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Toxics Nov 2019In order to assess the human exposure risks from the release of contaminants from water pipes made of polyvinyl chloride (PVC), experiments were carried out by...
In order to assess the human exposure risks from the release of contaminants from water pipes made of polyvinyl chloride (PVC), experiments were carried out by subjecting the PVC pipe material to burning and leaching conditions followed by analysis of the emission and leachate samples. The emissions of burning pipes were analyzed by both infrared spectrometry and gas chromatography-mass spectrometry (GC-MS). The emission test results indicate the presence of chlorinated components including chlorine dioxide, methyl chloride, methylene chloride, allyl chloride, vinyl chloride, ethyl chloride, 1-chlorobutane, tetrachloroethylene, chlorobenzene, and hydrogen chloride were detected in the emissions of burning PVC pipes. Furthermore, the concentrations of benzene, 1,3-butadiene, methyl methacrylate, carbon monoxide, acrolein, and formaldehyde were found at levels capable of affecting human health adversely. The analysis of PVC pipe leachates using GC-MS shows that there are 40-60 tentatively identified compounds, mostly long-chain hydrocarbons such as tetradecane, hexadecane, octadecane, and docosane, were released when the burned PVC materials were soaked in deionized water for one week. Quantitative analysis shows that 2-butoxyethanol, 2-ethyl-1-hexanol, and diethyl phthalate were found in the burned PVC polymer at the average levels of 2.7, 14.0, and 3.1 micrograms per gram (μg/g) of pipe material. This study has significant implications for understanding the benzene contamination of drinking water in the aftermath of wildfires that burned polymer pipes in California.
PubMed: 31717947
DOI: 10.3390/toxics7040057 -
Physical Chemistry Chemical Physics :... Apr 2018Limitations in current hot gas cleaning methods for chlorine species from biomass gasification may be a challenge for end use such as gas turbines, engines, and fuel...
Limitations in current hot gas cleaning methods for chlorine species from biomass gasification may be a challenge for end use such as gas turbines, engines, and fuel cells, all requiring very low levels of chlorine. During devolatilization of biomass, chlorine is released partly as methyl chloride. In the present work, the thermal conversion of CH3Cl under gasification conditions was investigated. A detailed chemical kinetic model for pyrolysis and oxidation of methyl chloride was developed and validated against selected experimental data from the literature. Key reactions of CH2Cl with O2 and C2H4 for which data are scarce were studied by ab initio methods. The model was used to analyze the fate of methyl chloride in gasification processes. The results indicate that CH3Cl emissions will be negligible for most gasification technologies, but could be a concern for fluidized bed gasifiers, in particular in low-temperature gasification. The present work illustrates how ab initio theory and chemical kinetic modeling can help to resolve emission issues for thermal processes in industrial scale.
PubMed: 29364295
DOI: 10.1039/c7cp07552a -
Acta Crystallographica. Section E,... Jan 2014In the title complex, [ZnCl2(C13H17N3)], the coordination sphere of the zinc cation is distorted square pyramidal. The three N atoms of the N,N',N''-tridentate...
In the title complex, [ZnCl2(C13H17N3)], the coordination sphere of the zinc cation is distorted square pyramidal. The three N atoms of the N,N',N''-tridentate 8-[2-(di-methyl-amino)-ethyl-amino]-quinoline ligand and one chloride ion constitute a considerably distorted square base. The apical site is occupied by another chloride ion. The distortion from the ideal square-pyramidal geometry is manifested by the N-Zn-N angle of 133.25 (11)°. Like most square-pyramidal metal complexes, the zinc cation is displaced towards the apical chloride ion. In the crystal, mol-ecules are linked by N-H⋯Cl inter-actions. This leads to the formation of chains of mol-ecules parallel to the b-axis direction.
PubMed: 24526942
DOI: 10.1107/S1600536813029929 -
Proceedings of the National Academy of... Oct 1998Methyl chloride transferase catalyzes the synthesis of methyl chloride from S-adenosine-L-methionine and chloride ion. This enzyme has been purified 2,700-fold to...
Methyl chloride transferase catalyzes the synthesis of methyl chloride from S-adenosine-L-methionine and chloride ion. This enzyme has been purified 2,700-fold to homogeneity from Batis maritima, a halophytic plant that grows abundantly in salt marshes. The purification of the enzyme was accomplished by a combination of ammonium sulfate fractionation, column chromatography on Sephadex G100 and adenosine-agarose, and TSK-250 size-exclusion HPLC. The purified enzyme exhibits a single band on SDS/PAGE with a molecular mass of approximately 22.5 kDa. The molecular mass of the purified enzyme was 22,474 Da as determined by matrix-associated laser desorption ionization mass spectrometry. The methylase can function in either a monomeric or oligomeric form. A 32-aa sequence of an internal fragment of the methylase was determined (GLVPGCGGGYDVVAMANPER FMVGLDIXENAL, where X represents unknown residue) by Edman degradation, and a full-length cDNA of the enzyme was obtained by rapid amplification of cDNA ends-PCR amplification of cDNA oligonucleotides. The cDNA gene contains an ORF of 690 bp encoding an enzyme of 230 aa residues having a predicted molecular mass of 25,761 Da. The disparity between the observed and calculated molecular mass suggests that the methylase undergoes posttranslational cleavage, possibly during purification. Sequence homologies suggest that the B. maritima methylase defines a new family of plant methyl transferases. A possible function for this novel methylase in halophytic plants is discussed.
Topics: Amino Acid Sequence; Base Sequence; Chromatography, Gel; Cloning, Molecular; DNA, Complementary; Methyltransferases; Molecular Sequence Data; Molecular Weight; Plants; Polymerase Chain Reaction; Recombinant Proteins; Sequence Homology, Amino Acid
PubMed: 9789006
DOI: 10.1073/pnas.95.22.12866 -
Acta Crystallographica. Section E,... Dec 20219-Amino-acridinium chloride ,-di-methyl-formamide monosolvate, CHN Cl·CHNO, crystallizes in the monoclinic space group 2/ The salt was crystallized from...
9-Amino-acridinium chloride ,-di-methyl-formamide monosolvate, CHN Cl·CHNO, crystallizes in the monoclinic space group 2/ The salt was crystallized from ,-di-methyl-formamide. The asymmetric unit consists of two CHN Cl formula units. The 9-amino-acridinium (9-AA) mol-ecules are protonated with the proton on the N atom of the central ring. This N atom is connected to an ,-di-methyl-formamide mol-ecule by a hydrogen bond. The H atoms of the amino groups create short contacts with two chloride ions. The 9-AA cations in adjacent layers are oriented in an anti-parallel manner. The mol-ecules are linked a network of multidirectional π-π inter-actions between the 9-AA rings, and the whole lattice is additionally stabilized by electrostatic inter-actions between ions.
PubMed: 34925903
DOI: 10.1107/S2056989021011816 -
Acta Crystallographica. Section E,... Oct 2022-{[Diphen-yl(vin-yl)sil-yl]meth-yl}-2-methyl-propan-2-amine, CHNSi, is a newly synthesized secondary amino-methyl-silane that can be used, for example, to study...
-{[Diphen-yl(vin-yl)sil-yl]meth-yl}-2-methyl-propan-2-amine, CHNSi, is a newly synthesized secondary amino-methyl-silane that can be used, for example, to study carboli-thia-tion reactions of vinyl-silanes. Because the neutral compound did not crystallize well, the hydro-chloride salt, CHNSi·Cl, was formed, in which the two chloride ions in the asymmetric unit have crystallographic site symmetry. An unusually long Si-C bond of 1.9117 (10) Å is observed in the cation, which may be ascribed to electronic effects due to the β N species. In the crystal, the cations and anions are linked by N-H⋯Cl hydrogen bonds to generate [001] chains. To further investigate the inter-molecular inter-actions, a Hirshfeld surface analysis was performed, which showed that H⋯H, C⋯H/H⋯C and H⋯Cl/Cl⋯H contacts contribute 70.4, 20.0 and 8.3%, respectively.
PubMed: 36250106
DOI: 10.1107/S2056989022009112 -
Proceedings of the National Academy of... Mar 1999Methyl chloride transferase, a novel enzyme found in several fungi, marine algae, and halophytic plants, is a biological catalyst responsible for the production of...
Methyl chloride transferase, a novel enzyme found in several fungi, marine algae, and halophytic plants, is a biological catalyst responsible for the production of atmospheric methyl chloride. A previous paper reports the purification of this methylase from Batis maritima and the isolation of a cDNA clone of the gene for this enzyme. In this paper, we describe the isolation of a genomic clone of the methylase gene and the expression of recombinant methyl chloride transferase in Escherichia coli and compare the kinetic behavior of the wild-type and recombinant enzyme. The recombinant enzyme is active and promotes the production of methyl chloride by E. coli under in vivo conditions. The kinetic data indicate that the recombinant and wild-type enzymes have similar halide (Cl-, Br-, and I-)-binding capacities. Both the recombinant and wild-type enzymes were found to function well in high NaCl concentrations. This high salt tolerance resembles the activity of halobacterial enzymes rather than halophytic plant enzymes. These findings support the hypothesis that this enzyme functions in the control and regulation of the internal concentration of chloride ions in halophytic plant cells.
Topics: Amino Acid Sequence; Base Sequence; Cloning, Molecular; DNA, Complementary; Escherichia coli; Hydrogen-Ion Concentration; Kinetics; Methyltransferases; Molecular Sequence Data; Plants; Recombinant Proteins
PubMed: 10097085
DOI: 10.1073/pnas.96.7.3611 -
Acta Crystallographica. Section E,... Oct 2016The title compounds, [Sn(CH)(OH)(HO)][Sn(CH)(CHO)] () and [Sn(CH)(OH)]Cl·HO (), are partially condensed products of hydrolysed tri-methyl-tin chloride. In the...
Crystal structures of di-aquadi-μ-hydroxido-tris-[tri-methyl-tin(IV)] diformatotri-methyl-stannate(IV) and di-μ-hydroxido-tris-[tri-methyl-tin(IV)] chloride monohydrate.
The title compounds, [Sn(CH)(OH)(HO)][Sn(CH)(CHO)] () and [Sn(CH)(OH)]Cl·HO (), are partially condensed products of hydrolysed tri-methyl-tin chloride. In the structures of and , short cationic tris-tannatoxanes (CHOSn) are bridged by a diformatotri-methyl-tin anion or a chloride anion, respectively. Hydrogen bridges are present and supposedly stabilize these structures against further polymerization to the known polymeric tri-methyl-tin hydroxide. Especially noteworthy is that the formate present in this structure was formed from atmospheric CO.
PubMed: 27746950
DOI: 10.1107/S2056989016014912 -
Acta Crystallographica. Section E,... May 2012The asymmetric unit of the title salt, (C(6)H(14)N)(3)[FeCl(4)]Cl(2), consists of a tetra-hedral tetra-chloro-ferrate anion, three independent 2-methyl-piperidinium...
The asymmetric unit of the title salt, (C(6)H(14)N)(3)[FeCl(4)]Cl(2), consists of a tetra-hedral tetra-chloro-ferrate anion, three independent 2-methyl-piperidinium cations and two chloride ions. All the piperidine rings adopt chair conformations. In the crystal, the organic cations and the free chloride anions are linked into chains parallel to the a axis by N-H⋯Cl hydrogen bonds.
PubMed: 22590144
DOI: 10.1107/S1600536812017151