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1-hexene/toluene Mixtures (toluene + mixture)

Distribution by Scientific Domains
Polymers and Materials Science40%

Selected Abstracts

Ignition and oxidation of 1-hexene/toluene mixtures in a shock tube and a jet-stirred reactor: Experimental and kinetic modeling study

INTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 9 2007
M. Yahyaoui
The oxidation of several binary mixtures 1-hexene/toluene has been investigated both in a shock tube and in a jet-stirred reactor (JSR). The self-ignition behavior of binary mixtures was compared to that of neat hydrocarbons studied under the same conditions. Furthermore, molecular species concentration profiles were measured by probe-sampling and GC/MS, FID, TCD analyses for the oxidation of the mixtures in a JSR. Experiments were carried out over the temperature range 750,1860 K. Mixtures were examined under two pressures 0.2 and 1 MPa, with 0.1% initial concentration of fuel. The equivalence ratio was varied from 0.5 to 1.5. The experiments were modeled using a detailed chemical kinetic reaction mechanism. The modeling study showed that interactions between hydrocarbons submechanisms were not limited to small reactive radicals. Other types of interactions involving hydrocarbon fragments derived from the oxidation of the fuel components must be considered. These interactions mainly consist of hydrogen abstraction reactions. For example, benzyl radical that is the major radical produced from the oxidation of toluene at high temperature can abstract hydrogen from 1-hexene and their products such as hexenyl radicals. Similarly, propyl, allyl, and hexenyl radicals that are the major radicals produced during 1-hexene oxidation at high temperature can abstract hydrogen from toluene. Improved modeling was achieved when such interaction reactions were included in the model. Good agreement between experimental and calculated data was obtained using the proposed detailed chemical kinetic scheme. © 2007 Wiley Periodicals, Inc. Int J Chem Kinet 39: 518,538, 2007 [source]

Dynamic Study of Excited State Hydrogen-bonded Complexes of Harmane in Cyclohexane,Toluene Mixtures,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2002
Carmen Carmona
ABSTRACT Photoinduced proton transfer reactions of harmane or 1-methyl-9H -pyrido[3,4- b]indole (HN) in the presence of the proton donor hexafluoroisopropanol (HFIP) in cyclohexane,toluene mixtures (CY,TL; 10% vol/vol of TL) have been studied. Three excited state species have been identified: a 1:2 hydrogen-bonded proton transfer complex (PTC), between the pyridinic nitrogen of the substrate and the proton donor, a hydrogen-bonded cationlike exciplex (CL*) with a stoichiometry of at least 1:3 and a zwitterionic exciplex (Z*). Time-resolved fluorescence measurements evidence that upon excitation of ground state PTC, an excited state equilibrium is established between PTC* and the cationlike exciplex, CL*, ,em, 390 nm. This excited state reaction is assisted by another proton donor molecule. Further reaction of CL* with an additional HFIP molecule produces the zwitterionic species, Z*, ,em, 500 nm. From the analysis of the multiexponential decays, measured at different emission wavelengths and as a function of HFIP concentration, the mechanism of these excited state reactions has been established. Thus, three rate constants and three reciprocal lifetimes have been determined. The simultaneous study of 1,9-dimethyl-9H -pyrido[3,4- b]indole (MHN) under the same experimental conditions has helped to understand the excited state kinetics of these processes. [source]

Stimuli-responsive properties of aminophenylboronic acid-carrying thermosensitive copolymers

POLYMER INTERNATIONAL, Issue 5 2003

Abstract Thermosensitive copolymers of N -isopropylacrylamide (NIPA) and N -acryloxysuccinimide (NASI) were obtained by solution polymerization using azobisisobutyronitrile as the initiator in a tetrahydrofuran,toluene mixture at 65,°C. A boronic acid-carrying ligand, m -aminophenylboronic acid (APBA) was covalently attached to the thermosensitive copolymer via the reaction between amino and succinimide groups. APBA-coupled thermosensitive copolymer exhibited both temperature and pH sensitivity. Thermally reversible phase transitions were observed both in the acidic and alkaline pH region for the APBA-modified copolymers obtained with different NASI feed concentrations. In our study, ribonucleic acid (RNA) was selected as a biomolecule having reactive groups which could potentially interact with the boronic acid functionality. The response of boronic acid-carrying thermosensitive copolymer against RNA was investigated in aqueous media in the pH range 4,9. In the acidic pH region, an increase was observed in the lower critical solution temperature (LCST) of the APBA-coupled thermosensitive copolymer with increasing RNA concentration. However, LCST decreased with increasing RNA concentration at both neutral and alkaline pH values. The LCST of the APBA-attached copolymer varied linearly with the RNA concentration at pH of 3, 4 and 7. © 2003 Society of Chemical Industry [source]

Dynamic Study of Excited State Hydrogen-bonded Complexes of Harmane in Cyclohexane,Toluene Mixtures,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 3 2002
Carmen Carmona
ABSTRACT Photoinduced proton transfer reactions of harmane or 1-methyl-9H -pyrido[3,4- b]indole (HN) in the presence of the proton donor hexafluoroisopropanol (HFIP) in cyclohexane,toluene mixtures (CY,TL; 10% vol/vol of TL) have been studied. Three excited state species have been identified: a 1:2 hydrogen-bonded proton transfer complex (PTC), between the pyridinic nitrogen of the substrate and the proton donor, a hydrogen-bonded cationlike exciplex (CL*) with a stoichiometry of at least 1:3 and a zwitterionic exciplex (Z*). Time-resolved fluorescence measurements evidence that upon excitation of ground state PTC, an excited state equilibrium is established between PTC* and the cationlike exciplex, CL*, ,em, 390 nm. This excited state reaction is assisted by another proton donor molecule. Further reaction of CL* with an additional HFIP molecule produces the zwitterionic species, Z*, ,em, 500 nm. From the analysis of the multiexponential decays, measured at different emission wavelengths and as a function of HFIP concentration, the mechanism of these excited state reactions has been established. Thus, three rate constants and three reciprocal lifetimes have been determined. The simultaneous study of 1,9-dimethyl-9H -pyrido[3,4- b]indole (MHN) under the same experimental conditions has helped to understand the excited state kinetics of these processes. [source]

Cobalt(II) octanoate and cobalt(II) perfluorooctanoate catalyzed atom transfer radical polymerization of styrene in toluene and fluorous media,A versatile route to catalyst recycling and oligomer formation

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2005
Marc-Stephan Weiser
Abstract Cobalt(II) perfluorooctanoate-catalyzed atom transfer radical polymerization (ATRP) and reverse ATRP were developed to prepare oligostyrenes (Mn < 2500) with low polydispersities Mw/Mn < 1.5. Fluorous biphase catalysis was applied for effective recycling of catalyst and fluorous solvent. The homogeneous polymerization reaction was performed at 90 °C in toluene/cyclohexane/perfluorodecalin mixture (1:1:1) and fluorine-free solvents. Temperature-induced phase separation of this fluorous solvent mixture occurred at room temperature and proved to be the key for the very effective separation of the cobalt(II) perfluorooctanoate from the oligostyrene and fluorine-free solvents. Both the fluorine-tagged cobalt catalysts and the fluorous media were recycled and reused up to three times without encountering catalyst activity losses. The roles of cobalt catalysts, fluorous media, and monomer/initiator ratio were examined with respect to the polymerization kinetics. Fluorine-containing and fluorine-free cobalt(II) octanoate catalyzed controlled styrene oligomerization according to the ATRP mechanism. The molar mass control range was limited in fluorous biphase catalysis most likely because of precipitation of high molar mass polystyrenes in the fluorous reaction medium. To the best of our knowledge, this is the first time temperature-induced phase separation of fluorous and fluorine-free solvents has been successfully applied to polymerization processing. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3804,3813, 2005 [source]