Home About us Contact
|
Home About us Contact | ||
|
|
||
Product Mixture (product + mixture)
Selected AbstractsBank Security Dye Packs: Synthesis, Isolation, and Characterization of Chlorinated Products of Bleached 1-(methylamino)anthraquinoneJOURNAL OF FORENSIC SCIENCES, Issue 6 2006James M. Egan Ph.D. ABSTRACT: Banknote evidence is often submitted after a suspect has attempted to disguise or remove red dye stain that has been released because of an anti-theft device that activates after banknotes have been unlawfully removed from bank premises. Three chlorinated compounds have been synthesized as forensic chemical standards to indicate bank security dye bleaching as a suspect's intentional method for masking a robbery involving dye pack release on banknotes. A novel, facile synthetic method to provide three chlorinated derivatives of 1-(methylamino)anthraquinone (MAAQ) is presented. The synthetic route involved Ultra CloroxÔ bleach as the chlorine source, iron chloride as the catalyst, and MAAQ as the starting material and resulted in a three-component product mixture. Two mono-chlorinated isomers (2-chloro-1-(methylamino)anthraquinone and 4-chloro-1-(methylamino)anthraquinone) and one di-chlorinated compound (2,4-dichloro-1-(methylamino)anthraquinone) of the MAAQ parent molecule were detected by gas chromatography mass spectrometry (GC-MS), and subsequently isolated by liquid chromatography (LC) with postcolumn fraction collection. Although GC-MS is sensitive enough to detect all of the chlorinated products, it is not definitive enough to identify the structural isomers. Liquid-state nuclear magnetic resonance (NMR) spectroscopy was utilized to elucidate structurally the ortho- and para-mono-chlorinated isomers once enough material was properly isolated. A reaction mechanism involving iron is proposed to explain the presence of chlorinated MAAQ species on stolen banknotes after attempted bleaching. [source] Synthesis of multiwalled carbon nanotubes on Al2O3 supported Ni catalysts in a fluidized-bedAICHE JOURNAL, Issue 1 2010Jun Liu Abstract Multiwalled carbon nanotubes (MWNTs) were synthesized on Al2O3 supported Ni catalysts from C2H2 and C2H4 feedstocks in a fluidized bed. The influence of the ratio of superficial gas velocity to the minimum fluidization velocity (U/Umf), feedstock type, the ratio of carbon in the total quantity of gas fed to the reactor, reaction temperature, the ratio of hydrogen to carbon in the feed gas, and nickel loading were all investigated. Significantly, the pressure drop across the fluidized-bed increased as the reaction time increased for all experiments, due to the deposition of MWNTs on the catalyst particles. This resulted in substantial changes to the depth and structure of the fluidized bed as the reaction proceeded, significantly altering the bed hydrodynamics. TEM images of the bed materials showed that MWNTs, metal catalysts, and alumina supports were predominant in the product mixture, with some coiled carbon nanotubes as a by-product. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Xanthene dye functionalized norbornenes for the use in ring opening metathesis polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 7 2007Martina Sandholzer Abstract A convenient synthetic route towards polymerizable fluorescein, dicholorofluorescein, and eosin dyes is presented. Polymerizability was provided by linking 2-norbornene carboxylic acid, 11-bromo-undecyl ester to the dye's carboxylate functionality. Although the monomers bearing dichlorofluorescein and eosin were obtained in high yield, the related fluorescein bearing monomer could only be obtained in low yield. In the latter case, concurring etherification and esterification led to a product mixture of the desired carboxy modified monomer and a double substituted by-product. The dye-monomers were used successfully for the preparation of statistical copolymers with endo,exo -2,3-norbornene dicarboxylic acid dimethylester by ROMP. Absorption and luminescence characteristics and, in particular, the acid/base sensitive behavior of the parent dyes were preserved in the monomers and copolymers. The absorption and emission maxima in THF solution and in the solid state were red shifted in comparison to the aqueous samples of the parent dyes. Dye-copolymers exhibited good film forming properties. Solid state luminescence studies of the copolymers revealed an increasing sensitivity towards NEt3 vapor in the order fluorescein < dichlorofluorescein < eosin bearing copolymer. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1336,1348, 2007 [source] Use of 19F NMR spectroscopy to probe enzymatic oxidation of fluorine-tagged sulfidesMAGNETIC RESONANCE IN CHEMISTRY, Issue 8 2002Behnaz Behrouzian Abstract A novel 19F NMR-based method for monitoring the enzymatic oxidation of thia fatty acid analogues is presented. Our approach is based on the observation that methyl ,-monofluorinated 9-thia- and 10-thiaoctadecanoates and their S -oxide and S -dioxide derivatives are easily distinguishable via their 1H-decoupled 19F spectra. These long-range substituent effects were used to probe the regio- and chemoselectivity of stearoyl ACP (acyl carrier protein) ,9 desaturase-mediated sulfoxidation. The results clearly demonstrate that mono-oxygenation of a 10-thia analogue ACP ,9 desaturase was more efficient than that of a 9-thia substrate. A product previously undetected by TLC was observed for the first time in the product mixture obtained from 18-fluoro-9-thiaoctadecanoyl-ACP. Copyright © 2002 John Wiley & Sons, Ltd. [source] Recovery of Homogeneous Polyoxometallate Catalysts from Aqueous and Organic Media by a Mesoporous Ceramic Membrane without Loss of Catalytic ActivityCHEMISTRY - A EUROPEAN JOURNAL, Issue 11 2006Sankhanilay Roy Chowdhury Dr. Abstract The recovery of homogeneous polyoxometallate (POM) oxidation catalysts from aqueous and non-aqueous media by a nanofiltration process using mesoporous ,-alumina membranes is reported. The recovery of Q12[WZn3(ZnW9O34)2] (Q=[MeN(n -C8H17)3]+) from toluene-based media was quantitative within experimental error, while up to 97,% of Na12[WZn3(ZnW9O34)2] could be recovered from water. The toluene-soluble POM catalyst was used repeatedly in the conversion of cyclooctene to cyclooctene oxide and separated from the product mixture after each reaction. The catalytic activity increased steadily with the number of times that the catalyst had been recycled, which was attributed to partial removal of the excess QCl that is known to have a negative influence on the catalytic activity. Differences in the permeability of the membrane for different liquid media can be attributed to viscosity differences and/or capillary condensation effects. The influence of membrane pore radius on permeability and recovery is discussed. [source] Biological activity associated with noncoplanar polychlorinated biphenyls after microbial dechlorination of aroclor 1242® and aroclor 1254®ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 5 2000Patricia E. Ganey Abstract Bioremediation of polychlorinated biphenyls (PCBs) byanaerobic microbial dechlorination occurring naturally in the subsurface and in engineered systems results in mixtures of lower-chlorinated, primarily ortho-substituted biphenyls. The purpose of this study was to determine whether this process of bacterial dechlorination results in a mixture that differs in biological activity from that of the parent PCB mixture. Two biological assays sensitive to the action of ortho-substituted PCBs were employed: insulin release by RINm5F cells, and superoxide anion (O2) production by rat neutrophils. The PCB mixtures Aroclor 1242® and Aroclor 1254® were incubated for nine months with microbes from PCB-contaminated sites (Silver Lake, MA, USA, or River Raisin, MI, USA), and the products of dechlorination were then extracted. Exposure of RINm5F cells to dechlorinated Aroclor 1242 or 1254 product mixtures caused an increase in insulin release similar to the hormone release from cells exposed to non-dechlorinated Aroclors. When tested alone, several of the major products identified in the dechlorination mixture (i.e., 2,2,,4,4,-tetrachlorobiphenyl, 2,2,,4-trichlorobiphenyl [TCB], 2,3,,4-TCB, 2,3,,5-TCB, and 2,2,-dichlorobiphenyl) caused an increase in insulin release. In studies using neutrophils isolated from rat peritoneum, the amount of O2 produced on exposure to product mixtures resulting from dechlorination of Aroclor 1242 was not different from the amount produced in nondechlorinated controls. The product mixture resulting from Aroclor 1254 dechlorination by organisms from River Raisin increased generation of O2, relative to the parent Aroclor. Taken together, these results suggest that anaerobic dechlorination of Aroclor mixtures of PCBs does not reduce the biological activities associated with lightly chlorinated and ortho -substituted PCBs. This observation has implications for the usefulness of PCB bioremediation efforts that involve only anaerobic dechlorination. [source] A general method to prepare monodentate phosphane ligands with mixed substituentsHETEROATOM CHEMISTRY, Issue 7 2009Jennifer E. Phelps Treatment of (2,2,-biphenylylene)- phosphorchloridite ester [(C12H8O2)PCl] (1) with C2F5Li yields (C12H8O2)PC2F52; treatment of 1 with Grignard reagents yields compounds of the type (C12H8O2)PR (R = iPr, 5; Et 6). In both cases, the 1,3-dioxepine ring formed when 2,2,-biphenol reacts with PCl3 to form 1 serves as a protecting group at the phosphorus atom; the ring allows the stepwise introduction of one substituent and prevents undesirable product mixtures associated with multiple substitutions at the phosphorus. Additional treatment of compounds 2, 5, and 6 with Grignard, alkyl-, or aryllithium reagents results in the formation of unsymmetrically substituted phosphanes. The use of (2,2,-biphenylylene)phosphorchloridite ester as a starting material for the preparation of electroneutral phosphanes of the type (Rf)PR2 and electron-poor phosphanes of the type (Rf)2PR is described. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 20:393,397, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20563 [source] | ||||||||||