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Lithium Bromide (lithium + bromide)
Selected AbstractsOne-Pot Synthesis of Dihydropyrimidinones Catalyzed by Lithium Bromide: An Improved Procedure for the Biginelli Reaction.CHEMINFORM, Issue 26 2003Gourhari Maiti Abstract For Abstract see ChemInform Abstract in Full Text. [source] The Biginelli Condensation: A Novel and Efficient Regioselective Synthesis of Dihydropyrimidin-2(1H)-ones Using Lithium Bromide.CHEMINFORM, Issue 10 2003Partha P. Baruah Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: An Efficient Chemo- and Regioselective Oxidative Nuclear Bromination of Activated Aromatic Compounds Using Lithium Bromide and Ceric Ammonium Nitrate.CHEMINFORM, Issue 52 2001Subhas Chandra Roy Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Experimental study of the use of additives in the performance of a single-stage heat transformer operating with water,lithium bromideINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2005W. Rivera Abstract In the present paper, the additives 1-octanol and 2-ethyl-1-hexanol, have been used for the first time in a 2 kW single-stage heat transformer installed in the Energy Research Centre of the National University of Mexico utilizing H2O/LiBr, operating at absorber temperatures in a range between 70 and 110°C. The results showed that at the same conditions, absorber temperatures increased about 5°C by adding 400 ppm of 2-ethyl-1-hexanol to the lithium bromide mixture. Also it was shown that the coefficient of performance increases up to 40% with the same additive. Copyright © 2005 John Wiley & Sons, Ltd. [source] Theoretical and experimental comparison of the performance of a single-stage heat transformer operating with water/lithium bromide and water/CarrolÔINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2002W. Rivera This paper compares under the same operating conditions, the theoretical and experimental performance of a single-stage heat transformer operating with the water/lithium bromide and the water/CarrolÔ mixtures, where CarrolÔ is a mixture of lithium bromide and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight patented by Carrier Corp. Flow ratios, gross temperature lifts, useful heat, and coefficients of performance are plotted for the heat transformer against temperatures and solution concentrations. Because the water/CarrolÔ mixture has higher solubility than water/lithium bromide and high experimental values were obtained for the gross temperature lift, it seems to be a better alternative mixture to be used in absorption heat transformers. Copyright © 2002 John Wiley & Sons, Ltd. [source] Pentacyclic Compounds by Samarium Diiodide-Induced Cascade Cyclizations of Naphthyl-Substituted 1,3-DionesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 1 2008Ulrike Abstract Treatment of naphthyl-substituted cyclopentane-1,3-diones with the samarium diiodide- hexamethylphosphoramide (HMPA) complex in the presence of tert -butyl alcohol provided the expected tetracyclic diols with steroid-like structures. Surprisingly, reactions without the proton source led to the efficient formation of a new pentacyclic diol. In this case the toxic additive HMPA could be substituted by a combination of lithium bromide (in situ generation of samarium dibromide) and N,N -dimethylimidazolidone. The styrene-like alkene moiety of this product was used to prepare an ensemble of highly substituted pentacyclic steroid-like compounds. [source] Viscosity behavior of microwave-heated and conventionally heated poly(ether sulfone)/dimethylformamide/lithium bromide polymer solutionsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Ani Idris Abstract This article investigates the viscosity behavior of new membrane dope solutions of poly(ether sulfone) (PES) and dimethylformamide with low-molecular-weight halogenated lithium bromide (LiBr) additives prepared with two different techniques: (1) a microwave (MW) technique and (2) a conventional heating (CH) technique. In addition, the influence of different concentrations of anhydrous halogenated LiBr additives (0,5 wt %) on the viscosity behavior is analyzed. The viscosity of the dope solutions was assessed with a conical rheometer equipped with a high-viscosity adapter. The results revealed that the pure PES solutions prepared by the MW and CH techniques exhibited pseudoplastic and Newtonian behavior, respectively. Both the MW and CH PES solutions containing the LiBr additives exhibited dilatant behavior, which obeyed the power law. The apparent viscosity of all the dope solutions prepared with the MW technique was lower than that of those prepared with the CH technique. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] An efficient O -dealkylation procedure for the synthesis of (3as,cis)-1,2,3,3a,8,8a-hexahydro-1,3a,8-trimethylpyrrolo[2,3- b]indol-5-yl-3,4-dihydro-2(1H)-isoquinolinecarboxylateJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2000Zhongli Gao The title compound is synthesized in high yields and purity from (-)-eserethole (2a) via a lithium bromide catalyzed hydrobromic acid O -dealkylation procedure as the key step. [source] Synthesis of a norbornene monomer having cyclic carbonate moiety based on CO2 fixation and its transition metal-catalyzed polymerizationsJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2010Atsushi Sudo Abstract A norbornene monomer bearing cyclic carbonate moiety (NB-CC) was successfully synthesized from the corresponding precursor having epoxy moiety by its reaction with carbon dioxide under atmospheric pressure, which was efficiently catalyzed by lithium bromide. NB-CC underwent the ring-opening metathesis polymerization (ROMP) catalyzed by a ruthenium carbene complex to give the corresponding poly(norbornene), of which side chain inherited the cyclic carbonate moiety from the monomer without any deterioration. The same ROMP system was applicable to the copolymerization of NB-CC and 5-butyl-2-norbornene (BNB), which afforded the corresponding copolymer with a composition ratio same as a feed ratio. In addition, by using a catalytic system consisted of palladium (II) acetate/tricyclohexylphosphine/triphenylcarbenium tetrakis(pentafluorophenyl)borate, the copolymerization of NB-CC and BNC proceeded successfully in a vinyl addition polymerization mode to give the corresponding poly(norbornene) having CC moiety in the side chain. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3896,3902, 2010 [source] Preparation of carbonated natural rubberJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 4 2006Seiichi Kawahara Carbonated natural rubber was prepared from deproteinized natural rubber with supercritical carbon dioxide, in which the deproteinization of natural rubber was performed in the latex stage with urea in the presence of a surfactant. The deproteinized natural rubber was epoxidized with peracetic acid in the latex stage, and this was followed by depolymerization with peroxide to prepare liquid epoxidized natural rubber. The liquid epoxidized rubber was incubated with supercritical carbon dioxide with lithium bromide as a catalyst at various temperatures and pressures. The product was proved to be carbonated natural rubber by means of Fourier transform infrared, 1H NMR, 13C NMR, two-dimensional 1H,1H correlation, two-dimensional 1H,13C correlation, and two-dimensional heteronuclear multiple bond correlation. [source] NMR spectroscopy of organolithium compounds.MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2004LiI in diethyl ether, The aggregation behaviour of methyllithium in the presence of LiBr, tetrahydrofuran Abstract 1H, 6Li and 13C NMR spectroscopy were used to determine the structure of aggregates formed in mixtures of methyllithium, H3CLi, and lithium bromide and iodide in diethyl ether and tetrahydrofuran. From the chemical shifts, the signal intensity distribution and the isotope shifts observed for partially deuterated systems, it was shown that generally tetrameric structures with different halogen contents dominate. For methyllithium,lithium bromide (1:1) in THF a considerable concentration of an H3CLiLiBr dimer was found. For the first time, deuterium-induced 6Li isotope shifts over four bonds were observed. Copyright © 2004 John Wiley & Sons, Ltd. [source] Energy and exergy analysis of a double absorption heat transformer operating with water/lithium bromideINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2009H. Martínez Abstract In the present study, the first and second law of thermodynamics have been used to analyze in detail the performance of a double absorption (lift) heat transformer operating with the water,lithium bromide mixture. A mathematical model was developed to estimate the coefficient of performance (COP), the exergy coefficient of performance (ECOP), the total exergy destruction in the system (,TD) and the exergy destruction (,D) in each one of the main components, as a function of the system temperatures, the efficiency of the economizer (EFEC), the gross temperature lift and flow ratio (FR). The results showed that the generator is the component with the highest irreversibilities or exergy destruction contributing to about 40% of the total exergy destruction in the whole system, reason why this component should be carefully designed and optimized. The results also showed that the COP and ECOP increase with increase in the generator, the evaporator and the absorber,evaporator temperatures and decrease with the absorber and condenser temperatures. Finally, it was observed that the COP and ECOP are very dependent of the FR and the economizer efficiency (EFEC) values. Also the optimum operating region of the analyzed system is shown in the present study. Copyright © 2009 John Wiley & Sons, Ltd. [source] Theoretical and experimental comparison of the performance of a single-stage heat transformer operating with water/lithium bromide and water/CarrolÔINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 8 2002W. Rivera This paper compares under the same operating conditions, the theoretical and experimental performance of a single-stage heat transformer operating with the water/lithium bromide and the water/CarrolÔ mixtures, where CarrolÔ is a mixture of lithium bromide and ethylene glycol [(CH2OH)2] in the ratio 1:4.5 by weight patented by Carrier Corp. Flow ratios, gross temperature lifts, useful heat, and coefficients of performance are plotted for the heat transformer against temperatures and solution concentrations. Because the water/CarrolÔ mixture has higher solubility than water/lithium bromide and high experimental values were obtained for the gross temperature lift, it seems to be a better alternative mixture to be used in absorption heat transformers. Copyright © 2002 John Wiley & Sons, Ltd. [source] | |||||||||||||