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PubMed1997

Fractal Dimensionality of Vinyl Chloride Monomer Adsorption on Polyvinyl Chloride Particles

The extent of adsorption of vinyl chloride monomer (VCM) on polyvinyl chloride (PVC) beads of various size was examined using the inverse gas chromatography technique at 288, 295, 303, and 313 K. The sizes of the PVC beads were 60-80, 100-120, and 150-200 mesh. On them the specific retention volume Vg (ml/g) of the injected gaseous monomer was determined. Vg depends on the mean particle size &dmacr; of PVC beads according to the relationship log Vg = (D - 3)log &dmacr;, from which the mass fractal D values were determined between 2.95 and 2.63 depending on the temperature and the dilution of monomer. Higher temperatures (313 K) are associated with lower D values (2.63-2.67), whereas lower temperatures (288 K) are associated with higher D values (2.87-2.95). These results suggest that the PVC behaves more as a two-dimensional material in relation to VCM adsorption at higher temperatures, whereas at lower temperatures it looks more like a three-dimensional Euclidean solid.

Journal Article↗
PubMed2001

Shape Transition in Micelles of Undecylammonium Chloride in the Presence of Sodium Chloride and n-Butanol: A Study by Dynamic Light Scattering.

Dynamic light scattering measurements have been performed on micellar solutions of undecylammonium chloride in the presence of 0 to 0.5 mol dm(-3) n-butanol and 0 to 0.2 mol dm(-3) sodium chloride. The results support opposing effects of these additives on micellar growth, with the n-butanol causing a reduction of micelle size. The dependence of the aggregation number on the hydrodynamic radius suggests a transition from sphere to prolate ellipsoid when the aggregation number approximates that predicted for the maximum aggregation number of a spherical micelle. Micelle dimensions calculated from the aggregation number, conformational considerations, and packing criteria of the monomers in the micelle are compared with those from dynamic light scattering data. Copyright 2001 Academic Press.

Journal Article↗
PubMed2005

Theoretical mechanism of the formation of cholesteryl chloride from cholesterol and thionyl chloride.

This work describes a theoretical approach to the substitution reaction mechanism involving the conversion of cholesterol to cholesteryl chloride. Two chlorosulfite ester molecules were formed as intermediates. An iso-steroid was found as the transition state. The final product was cholesteryl chloride and the side products were HCl and SO2. Calculations were carried out at high level Hartree-Fock theory, using the 6-31G* basis set. From the electronic structure of the reactants, the most important physicochemical properties involved in the reaction pathway were used. Thus, to determine the participation of each molecule and to explain the mechanism of reaction; the total energy, HOMO and LUMO, atomic orbital contribution to frontier orbitals formation, electrostatic potentials, atomic charges, hardness and dipole moment were used. Characterization of intermediates and transition state was supported by their respective energy minima, fundamental frequencies and equilibrium geometry.

Cholestenes↗
PubMed1982

Formation of 6-dimethylcarbamyloxy-dGuo, 6-dimethylamino-dGuo and 4-dimethylamino-dThd following in vitro reaction of dimethylcarbamyl chloride with calf thymus DNA and 6-diethylcarbamyloxy-dGuo following in vitro reaction of diethylcarbamyl chloride with calf thymus DNA.

The rodent carcinogens dimethylcarbamyl chloride (DMCC) and diethylcarbamyl chloride (DECC) react with dGuo (pH 7.0-7.5, 37 degrees C, 4 h) to form the O6-acyl derivatives 6-dimethylcarbamyloxy-2'-deoxyguanosine (6-DMC-dGuo) and 6-diethylcarbamyloxy-2'-deoxyguanosine (6-DEC-dGuo), respectively. Reaction of DMCC with dThd under identical conditions yielded 4-dimethylamino-thymidine (4-DMA-dThd). Compounds 6-DMC-dGuo and 6-DEC-dGuo undergo a nucleophilic aromatic substitution reaction with dimethylamine (DMA) to form 6-dimethylamino-2'-deoxyguanosine (6-DMA-dGuo) via displacement of the C-6 dialkylcarbamyloxy moiety. The substitution reaction did not take place when diethylamine or NH3 were substituted for DMA. The structures of the new compounds 6-DMC-dGuo, 6-DEC-dGuo, 4-DMA-dThd and 6-DMA-dGuo were deduced from chemical analyses and syntheses, UV and nuclear magnetic resonance (NMR) spectra and electron impact, isobutane chemical ionization and source insertion isobutane chemical ionization mass spectra. It was postulated that 4-DMA-dThd was formed following reaction of the transient intermediate 4-DMC-dThd with DMA formed by hydrolysis of DMCC. Calf thymus DNA was reacted in vitro with DMCC (pH 7.0-7.5, 37 degrees C, 4 h) and the modified DNA hydrolyzed enzymatically to 2'-deoxynucleosides. Compounds 6-DMC-dGuo, 4-DMA-dThd and 6-DMA-dGuo were identified in the hydrolysate by high-pressure liquid chromatography (HPLC). In an identical manner 6-DEC-dGuo was identified following in vitro reaction of DECC with calf thymus DNA. Compounds 6-DEC-dGuo and 6-DMC-dGuo possess novel structures with respect to the types of adducts known to be formed between carcinogens and bases in DNA. The implications of these findings with respect to chemical mutagenesis and carcinogenesis is discussed. The structural relationship between N4-dimethyl-5-methylcytosine (4-dimethylamino-Thy) formed in DNA following in vitro reaction with DMCC and 5-methylcytosine, the only modified base found in vertebrate DNA is noted.

Animals↗
PubMed1980

Biochemical changes resulting from the intraperitoneal administration of mercuric chloride and methylmercuric chloride to mice.

I.p. administration of mercuric chloride (HgCl2) and methylmercuric chloride (MeHgCl) at 1 mg/kg body wt./day for 10 consecutive days markedly influenced the phospholipid, DNA, RNA and protein of various tissues of mice. HgCl2 led to a significant increase (42%) in the liver phospholipid content but to a similar decrease in kidney phospholipid. MeHgCl reduced the phospholipid content of the brain and kidney. Kidney DNA decreased following administration of both HgCl2 and MeHgCl. MeHgCl resulted in the depleted rates of 32P uptake in the DNA fraction of all tissues studied. Both compounds increased liver and testis RNA and reduced the protein content and the 32P uptake from the protein fraction in all tissues studied.

Animals↗
PubMed2003

Acute toxicity effects of tributyltin chloride and triphenyltin chloride on gilthead seabream, Sparus aurata L., embryos.

Acute toxicity studies, using two organotin compounds, tributyltin chloride (TBTCl) and triphenyltin chloride (TPhTCl), were performed on gilthead seabream, Sparus aurata, fertilized eggs. The tests were static and run for 24 h (temperature = 19 +/- 1 degrees C, salinity = 39.5 g/L). Three replicate egg groups were incubated in solutions containing different concentrations of the toxicants. The (24h)LC(50) value for TBTCl was 28.3 microg/L and for TPhTCl was 34.2 microg/L, when the embryos were at the morula and late blastula stage at the start of the experiment. The value for TBTCl was 38.6 microg/L, when the embryos were at the gastrula stage at the start of the experiment. The results reconfirm the expected toxicity of TBT to this euryhaline fish species and introduce TPhT as a toxicant of potentially similar impact on teleosts.

Animals↗
PubMed1990

Determination of the oximes 2-hydroxyiminomethyl-3-methyl-1-[2-(3-methyl- 3-nitrobutyloxymethyl)]imidazolium chloride and 1-[1-(3-butynyloxymethyl)]-2-hydroxyiminomethyl-3-methylimida zolium chloride in plasma by high-performance liquid chromatography.

An assay is presented for the extraction and quantitation of two oximes, 2-hydroxyimino-methyl-3-methyl-1-[2-(3-methyl-3-nitrobutyloxyme thyl)] imidazolium chloride (oxime A) and 1-[1-(3-butynyloxymethyl)]-2-hydroxyiminomethyl-3-methylimidazo lium chloride (oxime B), in human plasma and is demonstrated to be linear over two overlapping concentration ranges: 10-500 and 100-1000 ng/ml. The assay utilizes a liquid-liquid, ion-pair extraction and a normal-phase chromatographic separation on a silica column with ultraviolet detection at 270 nm. The method is sensitive, rapid and accurate. The limit of detection is 10 ng/ml (signal-to-noise ratio S/N greater than 10). The mean extraction recoveries of the oximes were greater than 86% at all concentration levels. The intra-assay variability was less than 3.3%, the inter-assay variability less than 7.2%. The compound is stable in plasma for 23 weeks when stored at -15 degrees C or -80 degrees C.

Chromatography, High Pressure Liquid↗
PubMed2002

Layered zirconium phosphate chloride dimethyl sulfoxide as a two-dimensional exchanger of anionic ligands. Part I. Substitution of chloride with inorganic monodentate ligands.

Crystalline ZrPO(4)Cl(CH(3))(2)SO was prepared by direct precipitation in the presence of oxalic acid as a zirconium complexing agent. The structure of ZrPO(4)Cl(CH(3))(2)SO, refined with the Rietveld method using X-ray powder diffraction data, was confirmed to be close to that of the compound prepared using gamma-zirconium phosphate as a precursor. Chloride anions directly bonded to zirconium were found to act as weak ligands; this made possible their replacement with other monodentate anionic ligands. The preparation and a preliminary characterization of a series of inorganic derivatives obtained by topotactic replacement of Cl with OH, Br, MSO(4) (M = H, NH(4), Na), NaMoO(4), and HCrO(4) anions is reported. The possibility of replacement of chloride also with organic anions, such as alkoxides and carboxylates, and the possibility of substituting also dimethyl sulfoxide with other neutral ligands, as shown by preliminary study, makes ZrPO(4)Cl(CH(3))(2)SO a useful and very flexible precursor for materials chemistry.

Journal Article↗
PubMed2006

Dimethylammonium trichlorocuprate(II): structural transition, low-temperature crystal structure, and unusual two-magnetic chain structure dictated by nonbonding chloride-chloride contacts.

Catena(dimethylammonium-bis(mu2-chloro)-chlorocuprate), (CH3)2NH2CuCl3, forms chains of Cu2Cl6(2-) bifold dimers linked along the structural chain axis by terminal chlorides forming long semicoordinate bonds to adjacent dimers. The structural chains are separated by dimethylammonium ions that hydrogen bond to chloride ions of the dimers. A structural phase transition below room temperature removes disorder in the hydrogen bonding, leaving adjacent dimers along the chain structurally and magnetically inequivalent, with alternating ferromagnetic and antiferromagnetic pairs. The coupled dimers are magnetically isolated from each other along the structural chain axis by the long semicoordinate Cu-Cl bond. However, the dimers couple to like counterparts on adjacent chains via nonbonding Cl...Cl contacts. The result is two independent magnetic chains, one an alternating antiferromagnetic chain and the other an antiferromagnetic chain of ferromagnetically coupled copper dimers, which run perpendicular to the structural chains. This magnetostructural analysis is used to fit unusual low-temperature (1.6 K) magnetization vs field data that display a two-step saturation. The structural phase transition is identified with neutron scattering and capacitance measurements, and the X-ray crystal structures are determined at room temperature and 84 K. The results appear to resolve long-standing confusion about the origins of the magnetic behavior of this compound and provide a compelling example of the importance of two-halide magnetic exchange.

Journal Article↗
PubMed1997

Electrophilic Aromatic Substitution. 13.(1) Kinetics and Spectroscopy of the Chloromethylation of Benzene and Toluene with Methoxyacetyl Chloride or Chloromethyl Methyl Ether and Aluminum Chloride in Nitromethane or Tin Tetrachloride in Dichloromethane. The Methoxymethyl Cation as a Remarkably Selective Common Electrophile.

Vacuum line kinetics studies have been made of the reaction in nitromethane between benzene and/or toluene, methoxyacetyl chloride (MAC), and AlCl(3) to produce benzyl or xylyl chlorides, CO, and a CH(3)OH(-)AlCl(3) complex. For both arenes, the rate law appears to be R = (k(3)/[AlCl(3)](0)) [AlCl(3)](2)[MAC]. When chloromethyl methyl ether (CMME) is substituted for MAC, a similar rate law is obtained. Both chloromethylation reactions yielded similar, large k(T)()/k(B)() ratios (500-600) and similar product isomer distributions with low meta percentages ( approximately 0.4) which suggest CH(3)OCH(2)(+) or the CH(3)OCH(2)(+)Al(2)Cl(7)(-) ion pair as a common, remarkably selective, electrophile. The kinetics of MAC decomposition to CMME and CO in the presence of AlCl(3) yielded the rate law R = k(2)[AlCl(3)](0)[MAC]. Here AlCl(3) is a catalyst (no CH(3)OH is formed), and thus the rate law is equivalent to the chloromethylation rate law. All three reactions have comparable reactivities, which is consistent with rate-determining production of the electrophile. Kinetics studies of benzene or toluene with SnCl(4) and MAC or CMME in dichloromethane were also completed. With MAC and benzene the rate law is R = k(3)[SnCl(4)](0)[MAC][benzene] and with toluene R = k(2)[SnCl(4)](0)[MAC]. MAC decomposition, again followed by CO production, was unaffected by the presence of either aromatic and obeyed the rate law R = k(2)' [SnCl(4)](0)[MAC] where k(2) approximately k(2)'. Chloromethylation with CMME followed the rate law R = k(3)[SnCl(4)](0)[CMME][arene] for benzene and toluene and produced a k(T)()/k(B)() ratio and product isomer distributions very similar to those determined with AlCl(3) in nitromethane, further supporting a common electrophile. Low-temperature (13)C and (119)Sn FT-NMR and Raman spectroscopic studies suggest the existence of a weak 1:1 adduct between MAC and SnCl(4) of the type RCXO --> SnCl(4), with electron donation to the metal through carboxy oxygen. Finally, an explanation is provided for the range of chloromethylation k(T)()/k(B)() values and product isomer percentages published in the literature.

Journal Article↗
PubMed2000

An unexpected carbon dioxide insertion in the reaction of trans-2, 4-disubstituted azetidine, trans-2,5-disubstituted pyrrolidine, or trans-2,6-disubstituted piperidine with diphenylthiophosphinic chloride and diphenylselenophosphinic chloride

In the reaction of trans-2,4-disubstituted azetidine, trans-2, 5-disubstituted pyrrolidine, or trans-2,6-disubstituted piperidine with diphenylthiophosphinic chloride or diphenylselenophosphinic chloride in acetonitrile in the presence of potassium carbonate at room temperature, an unexpected carbon dioxide insertion produced carbamic diphenylthiophosphinic or diphenylselenophosphinic anhydride in good yield. The same product could be also obtained when the reaction was carried out under carbon dioxide atmosphere using potassium hydroxide or triethylamine as a base. This is a very simple reaction process related to the fixation of carbon dioxide without a metal catalyst.

Journal Article↗
PubMed2006

Formation of porous silver by electrochemical alloying/dealloying in a water-insensitive zinc chloride-1-ethyl-3-methyl imidazolium chloride ionic liquid.

This paper describes the formation of a porous silver surface by a convenient two-step process involving electrochemical formation of a binary silver-zinc alloy film on a silver surface followed by electrochemical etching of the zinc from the alloy. Both the deposition and the dealloying steps were performed in a single bath of low-temperature zinc chloride-1-ethyl-3-methylimidazolium chloride ionic liquid at temperatures below 150 degrees C without using any other corrosive acids or bases. The effects of the deposited zinc quantity, deposition potential, current, and temperature on the structures and morphologies of the porous silver film were examined. In comparison with conventional molecular electrolyte solutions, ionic liquids provide a more versatile environment for fabricating porous metals. Because the zinc(II) species consumed during the deposition step was recovered during the dealloying step, the ionic liquid is reusable.

Journal Article↗
PubMed2004

Oxidation of thioanisole by peroxomolybdate in assemblies of cetylpyridinium chloride and methyltri-n-octylammonium chloride.

Methyltri-n-octylammonium chloride (Aliquat 336) is sparingly soluble in water but is readily soluble with a 2-fold excess of micellized cetylpyridinium chloride (CPyCl), and the mixtures show breaks in plots of surface tension or electrolytic conductance against concentration indicative of a critical micelle concentration slightly lower than that of CPyCl. Micellization markedly increases 35Cl and 14N NMR line widths of CPyCl, but addition of NaCl reduces the 35Cl line width and addition of Aliquat increases it. Mixing Aliquat and CPyCl has little effect on their 14N line widths. Ion pairing in alcohol mixtures also increases 35Cl line widths. In water these mixed assemblies behave similarly to micelles of CPyCl as regards effects on rates and equilibria of interconversion of tri- and tetraperoxomolybdate ions, and oxidation of thioanisole by the latter, although it is slightly slower than in micelles of CPyCl. Despite differences in the hydrophobic regions, and relationships between amphiphilic structures and morphologies of association colloids, assemblies of CPyCl and Aliquat behave very much like CPyCl micelles in their physical properties and effects upon reactivity. Geometrical optimization indicates that Aliquat can adopt conformations that allow intercalation with CPyCl micelles.

Journal Article↗
PubMed1994

Tumour affinity of 203Pb-chloride: comparison with 67Ga-citrate and 201Tl-chloride.

The radionuclide 203Pb decays completely by electron capture to stable 203Tl with a half-life of 52 h. The primary radiation from the decay is gamma-ray radiation 280 keV (80%). 203Pb is produced easily from the natural metal thallium by the method described below. 203Pb-chloride is a promising imaging agent for tumour scanning because of the large retention value for tumour tissue and the small value for normal organs, but the large value for the kidney and bone is a shortcoming when considering it as an imaging agent. The retention value of 203Pb in tumour tissue is larger than that of 201Tl and smaller than that of 67Ga. The tumour/inflammatory lesion retention ratio for 203Pb is very large in comparison with those for 67Ga and 201Tl. 203Pb accumulates to a large extent in viable tumour tissue, and less in necrotic tumour tissue and in inflammatory lesion. Therefore, 203Pb-chloride is far better for visualization of viable tumour tissue than 67Ga and 201Tl if the large retention values for the kidney and bone were reduced.

Animals↗
PubMed2001

Tetrakis(2-amino-5-methyl-1,3,4-thiadiazole-N3)chlorocopper(II) chloride monohydrate and tetrakis(2-amino-5-ethyl-1,3,4-thiadiazole-N3)chlorocopper(II) chloride.

The structures of the title compounds, [CuCl(C(3)H(5)N(3)S)(4)]Cl.H(2)O, (I), and [CuCl(C(4)H(7)N(3)S)(4)]Cl, (II), comprise square-pyramidal Cu centres with four N-bound organic ligands filling the base positions, a Cl atom in the apical position and a Cl(-) as a free counter-ion. The cation and free chloride ion in (II) have fourfold crystallographic symmetry. Hydrogen-bonding associations from the 2-amino H atoms dominate both structures, with the principal acceptors being the chlorides, although in (I), the N4 atoms are also involved. Furthermore, (I) is a hydrate, with the water molecule participating in the hydrogen-bonding network.

Copper↗
PubMed2004

L-Methioninium chloride and L-selenomethioninium chloride at 103 K.

The crystal structures of the title compounds, (S)-1-carboxy-3-(methylsulfanyl)propanaminium chloride, C(5)H(12)NO(2)S(+).Cl(-), and (S)-1-carboxy-3-(methylselanyl)propanaminium chloride, C(5)H(12)NO(2)Se(+).Cl(-), are isomorphous. The protonated L-methionine and L-selenomethionine molecules have almost identical conformations and create very similar contacts with the Cl(-) anions in the crystal structures of both compounds. The amino acid cations and the Cl(-) anions are linked viaN-H...Cl(-) and O-H...Cl(-) hydrogen bonds.

Crystallography, X-Ray↗
PubMed1978

Plasmid conferring increased sensitivity to mercuric chloride and cobalt chloride found in some laboratory strains of Escherichia coli K-12.

Some lines of the widely used strain CR34 of Escherichia coli K-12 carry a plasmid. The plasmid has a mass of 12 +/- 2 X 10(6) megadaltons and is maintained at a low copy number per cell (1 to 2), and this number is not amplified by growth of cells in the presence of chloramphenicol. The plasmid is designated as pCU3. The presence of pCU3 confers on the strain increased sensitivity to mercuric chloride and cobalt chloride. The plasmid has also been observed to fuse or recombine with the plasmid R64-11.

Cobalt↗