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Allyl Bromide (allyl + bromide)
Selected AbstractsNovel Indium-Mediated Ternary Reactions Between Indole-3-carboxaldehydes,Allyl Bromide,Enamines: Facile Synthesis of Bisindolyl- and Indolyl-Heterocyclic Alkanes.CHEMINFORM, Issue 22 2003Subodh Kumar Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Rapid and Efficient Stereoselective Synthesis of (Z)- and (E)-Allyl Bromides from Baylis,Hillman Adducts Using Bromo(dimethyl)sulfonium Bromide,HELVETICA CHIMICA ACTA, Issue 7 2006Biswanath Das Abstract Treatment of Baylis,Hillman adducts 1 with bromo(dimethyl)sulfonium bromide, Br(Me2)S+Br,, in MeCN was found to stereoselectively afford (Z)- and (E)-allyl bromides 2. The reaction is rapid at room temperature, high-yielding, and highly stereoselective. [source] Molybdenum Carbonyl Complexes Bearing PN Ligands Based on 2-Aminopyridine,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 27 2009Christina Maria Standfest-Hauser Abstract Molybdenum complexes of the general formula Mo(PN)(CO)4 containing both achiral and chiral phosphorus-nitrogen donor bidentate ligands based on 2-aminopyridine were prepared and characterized by their NMR and IR spectra. The oxidative addition of allyl bromide to Mo(PN)(CO)4 was studied with PN = N -(diisopropylphosphanyl)-2-aminopyridine (PN- iPr). X-ray structures of representative compounds were determined. The mechanism of the oxidative addition of allyl bromide to Mo(PN- iPr)(CO)4 was analyzed by DFT/B3LYP calculations. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A Spirocyclic Chiral Borate for Catalytic Enantioselective Nozaki-Hiyama Allylation of KetonesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 18 2009Xin-Ren Huang Abstract A new class of chiral spirocyclic borate ligands 5a,d with a rigid borocycle has been developed. The catalyst formed from chromium(II)- 5a promotes the highly efficient enantioselective Nozaki,Hiyama allylation of alkyl and aryl ketones using allyl bromide. The scope of the present method is shown to be wide, and it affords an efficient access to chiral tertiary homoallylic alcohols. [source] Preparation and adsorption behavior of a cellulose-based, mixed-mode adsorbent with a benzylamine ligand for expanded bed applicationsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008Dong Gao Abstract A novel mixed-mode expanded bed adsorbent with anion-exchange properties was explored with benzylamine as the functional ligand. The cellulose composite matrix, densified with stainless steel powder, was prepared with the method of water-in-oil suspension thermal regeneration. High activation levels of the cellulose matrix were obtained with allyl bromide because of the relative inertness of the allyl group under the conditions of the activation reaction. After the formation of the bromohydrin with N -bromosuccinimide and coupling with benzylamine, the activated matrix was derived to function as a mixed-mode adsorbent containing both hydrophobic and ionic groups. The protein adsorption capacity was investigated with bovine serum albumin as a model protein. The results indicated that the prepared adsorbent could bind bovine serum albumin with a high adsorption capacity, and it showed salt tolerance. Effective desorption was achieved by a pH adjustment across the isoelectric point of the protein. The interactions between the cell and adsorbent were studied, and the bioadhesion was shielded by the adjustment of the salt concentration above 0.1M. Stable fluidization in the expanded bed was obtained even in a 2% (dry weight) yeast suspension. The direct capture of target proteins from a biomass-containing feedstock without extra dilution steps could be expected with the mixed-mode adsorbent prepared in this work, and this would be especially appropriate for expanded bed adsorption applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Synthesis and alkylation of 5-(3-chlorobenzo[b]thien-2-yl)-4H -1,2,4-triazole-3-thiol under classical and microwave conditions.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2006AM1 semiemperical calculations for investigating the regioselectivity of alkylation Under microwave irradiation (MWI), 5-(3-chlorobenzo[b]thien-2-yl)-4H -1,2,4-triazole-3-thiol (3) was synthesized in a good yield by intramolecular cyclization of the carbonyl thiosemicarbazide 2. A regioselective S-alkylation of 3 with benzyl chloride or allyl bromide has been achieved by using triethylamine as a base, while other different basic conditions led to a mixture of bis(alkylated) derivatives N4, S- and S, N2 -, under both of classical and MWI conditions. The relative stabilities, charge densities, dipole moments and electronic energies of reactants, transition states and intermediates were calculated by the AM1 method and used for investigating the regioselectivity. [source] The mechanisms of the homogeneous, unimolecular, elimination kinetics of several , -substituted diethyl acetals in the gas-phaseJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 9 2010José R. Mora Abstract The rates of gas-phase elimination of several , -substituted diethyl acetals have been determined in a static system and seasoned with allyl bromide. The reactions, inhibited with toluene, are homogeneous, unimolecular, and follow first-order law kinetics. These elimination processes involve two parallel reactions. The first parallel reaction yields ethanol and the corresponding ethyl vinyl ether. The latter product is an unstable intermediate and further decomposes to ethylene and the corresponding substituted aldehyde. The second parallel reaction gives ethane and the corresponding ethyl ester. The kinetics has been measured over the temperature range of 370,441,°C and pressure range of 23,160,torr. The rate coefficients are given by the following Arrhenius equations: The differences in the rates of ethanol formation may be attributed to electronic transmission of the , -substituent. The comparative kinetic and thermodynamic parameters of the parallel reactions suggest two different concerted polar four-membered cyclic transition state types of mechanisms. Copyright © 2010 John Wiley & Sons, Ltd. [source] Joint theoretical and experimental study of the gas-phase elimination kinetics of tert -butyl ester of carbamic, N, N -dimethylcarbamic, N -hydroxycarbamic acids and 1-(tert -butoxycarbonyl)-imidazoleJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 12 2007Jose R Mora Abstract The gas-phase elimination kinetics of the title compounds were carried out in a static reaction system and seasoned with allyl bromide. The working temperature and pressure ranges were 200,280,°C and 22,201.5,Torr, respectively. The reactions are homogeneous, unimolecular, and follow a first-order rate law. These substrates produce isobutene and corresponding carbamic acid in the rate-determining step. The unstable carbamic acid intermediate rapidly decarboxylates through a four-membered cyclic transition state (TS) to give the corresponding organic nitrogen compound. The temperature dependence of the rate coefficients is expressed by the following Arrhenius equations: for tert -butyl carbamate logk1 (s,1),=,(13.02,±,0.46),,,(161.6,±,4.7) kJ/mol(2.303,RT),1, for tert -butyl N -hydroxycarbamate logk1 (s,1),=,(12.52,±,0.11),,,(147.8,±,1.1) kJ/mol(2.303,RT),1, and for 1-(tert -butoxycarbonyl)-imidazole logk1 (s,1),= (11.63,±,0.21),(134.9,±,2.0) kJ/mol(2.303,RT),1. Theoretical studies of these elimination were performed at Møller,Plesset MP2/6-31G and DFT B3LYP/6-31G(d), B3LYP/6-31G(d,p) levels of theory. The calculated bond orders, NBO charges, and synchronicity (Sy) indicate that these reactions are concerted, slightly asynchronous, and proceed through a six-membered cyclic TS type. Results for estimated kinetic and thermodynamic parameters are discussed in terms of the proposed reaction mechanism and TS structure. Copyright © 2007 John Wiley & Sons, Ltd. [source] Experimental and theoretical studies of the elimination kinetics of 3-hydroxy-3-methyl-2-butanone in the gas phaseJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7 2005Mariana Graterol Abstract The kinetics of the gas-phase elimination of 3-hydroxy-3-methyl-2-butanone was investigated in a static system, seasoned with allyl bromide, and in the presence of the free chain radical inhibitor toluene. The working temperature and pressure range were 439.6,489.3°C and 81,201.5,Torr (1,Torr,=,133.3,Pa), respectively. The reaction was found to be homogeneous, unimolecular and to follow a first-order rate law. The products of elimination are acetone and acetaldehyde. The temperature dependence of the rate coefficients is expressed by the following equation: log[k1(s,1)],=,(13.05±0.53),(229.7±5.3),kJ,mol,1 (2.303RT),1. Theoretical estimations of the mechanism of this elimination suggest a molecular mechanism of a concerted non-synchronous four-membered cyclic transition-state process. An analysis of bond order and natural bond orbital charges suggests that the bond polarization of C(OH),C(O),, in the sense of C(OH),+&·C(O),,, is rate limiting in the elimination reaction. The rate coefficients obtained experimentally are in reasonably good agreement with the theoretical calculations. The mechanism of 3-hydroxy-3-methyl-2-butanone elimination is described. Copyright © 2005 John Wiley & Sons, Ltd. [source] Plasmabromination , the Selective Way to Monotype Functionalized Polymer SurfacesPLASMA PROCESSES AND POLYMERS, Issue 9 2007Sascha Wettmarshausen Abstract In contrast to other plasma modification processes of polymer surfaces, the bromination is very selective and shows a high yield in CBr groups. The most convenient bromination process was found using bromoform, which was thus preferred to elemental bromine, allyl bromide, vinyl bromide or tert -butylbromide. The bromoform process give yields in CBr up to 40 CBr or more, with only 2,3% co-introduction of O-functionalities whereas allyl bromide results in yields of about 20 CBr and more, but in more than 10% oxygen-containing by-products. CBr groups serve as anchoring points for grafting of molecules, oligomers and pre-polymers of diole or diamine character. [source] Phenol recovery from simulated wastewater using a vertical membrane reactorASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 3 2010Manoj Jhanwar Abstract Phenol was recovered from the simulated wastewater in the form of a useful product, allyl phenyl ether, using A-172 membrane as phase-transfer catalyst in a batch and a continuous membrane reactor. The effects of temperature, agitation rates and flow rates of aqueous and organic phases, and concentrations of phenol and allyl bromide on the yield of allyl phenyl ether in the organic phase and phenol removal in the aqueous phase after the reaction were studied. Activation energy and turnover number of the reaction were calculated as well. In the batch mode, the phenol concentration in the treated aqueous phase was found to be < 2 ppm, reduced from 5000 ppm, and more than 99% of the phenol was recovered in the form of allyl phenyl ether after reacting for 180 min. In a continuous mode, the phenol concentration can be reduced from 5000 to 100 ppm in the steady state operation of the reactor. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Metal-Catalyzed Cyclization of ,- and ,-Allenols Derived from D -Glyceraldehyde,Synthesis of Enantiopure Dihydropyrans and Tetrahydrooxepines: An Experimental and Theoretical StudyCHEMISTRY - A EUROPEAN JOURNAL, Issue 36 2009Benito Alcaide Prof. Abstract Regiocontrolled metal-catalyzed preparations of enantiopure dihydropyrans and tetrahydrooxepines have been synthesized starting from ,- and ,-allenols derived from D -glyceraldehyde. The PdII -catalyzed cyclizative coupling reactions of ,-allenols 1,a and 1,b with allyl bromide effectively afforded enantiopure tetrafunctionalized dihydropyrans through a 6- endo oxycyclization protocol, whereas the gold-, platinum-, and palladium-mediated heterocyclization of ,-allenol 2 furnished tetrahydrooxepines 13,16 through regioselective 7- endo- trig oxycyclization reactions. Moreover, density functional calculations were performed to predict the regioselectivity of the ,-allenol cycloetherification to tetrahydrooxepines on the basis of both the tether nature and characteristics of the metals, and to gain an insight into the mechanism of the oxycyclization reactions. La reacción de heterociclación de ,- y ,-alenoles derivados de D -gliceraldehíido catalizada por metales es un proceso regiocontrolado que da lugar a dihidropiranos y tetrahidrooxepinas enantiopuros. La reacción de ciclación/acoplamiento cruzado entre los ,-alenoles 1,a y 1,b con bromuro de alilo fue eficaz como protocolo de oxiciclación 6-endo para dar lugar a dihidropiranos tetrafuncionalizados, mientras que las heterociclaciones del ,-alenol 2 catalizadas por oro, platino y paladio generan las tetrahidrooxepinas 13,16 via una oxiciclación 7-endo-trig regioespecífica. Además, los mecanismos de estas heterociclaciones de ,-alenoles catalizadas por metales han sido investigados teóricamente. [source] Reductive-Cyclization-Mediated Synthesis of Fused Polycyclic Quinolines from Baylis,Hillman Adducts of Acrylonitrile: Scope and Limitations,,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2009Virender Singh Abstract The synthesis of a variety of polycyclic quinolines is described. The target molecules were obtained in two steps by an initial reductive cyclization followed by another intramolecular cyclization in the allylamines afforded from either the acetates or allyl bromides of Baylis,Hillman adducts of 2-nitrobenzaldehydes and acrylonitrile. The two steps proceeded in one-pot for those substrates in which a formyl or hydroxy group reacted with the amino group of the 2-aminoquinoline in the second intramolecular cyclization. In contrast, a basic medium was necessary for the second intramolecular cyclization reaction in substrates in which an alkoxycarbonyl group and the amino group participated. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] A Rapid and Efficient Stereoselective Synthesis of (Z)- and (E)-Allyl Bromides from Baylis,Hillman Adducts Using Bromo(dimethyl)sulfonium Bromide,HELVETICA CHIMICA ACTA, Issue 7 2006Biswanath Das Abstract Treatment of Baylis,Hillman adducts 1 with bromo(dimethyl)sulfonium bromide, Br(Me2)S+Br,, in MeCN was found to stereoselectively afford (Z)- and (E)-allyl bromides 2. The reaction is rapid at room temperature, high-yielding, and highly stereoselective. [source] | |||||||||||||||||||||||||