a b s t r a c t PEDOT layers are synthesized in aqueous solutions in the presence of one of the t... more a b s t r a c t PEDOT layers are synthesized in aqueous solutions in the presence of one of the three different anionic species -polysterenesulfonate (PSS), poly(2-acrylamido-2-methyl-1-propane-sulfonate) (PAMPS) and dodecylsulfate without any addition of further inorganic anions. Simultaneous electrochemical and acoustic admittance measurements are carried out in the course of polymerization. The data from the admittance spectra are used to extract information on the mechanical shear storage and loss moduli of the three types of PEDOT layers. The anionic species are found to affect the polymerization kinetics, the surface morphology and most markedly the viscoelastic properties of the three types of layers. The latter depend primarily on the innate structure arising in the course of polymerization whereas the solution specifics play a secondary role. Dodecylsulfate imparts significant stiffness to the PEDOT layers with high rigidity preserved for relatively large polymerization charges. The G moduli in this case exceed 10 9 dyn/cm 2 . Both polyanion-doped PEDOT layers are found to be softer but there is nevertheless a clear difference between them with PEDOT/PAMPS having a strong predisposition for swelling.
Direct anodic oxidation of (S)-(−)-1,1 -bi-2-naphthol dimethyl ether (BNME) in CH 2 Cl 2 /CHCl 3 ... more Direct anodic oxidation of (S)-(−)-1,1 -bi-2-naphthol dimethyl ether (BNME) in CH 2 Cl 2 /CHCl 3 containing boron trifluoride diethyl etherate (BFEE) as the supporting electrolyte led to facile electrodeposition of high-quality free-standing poly((S)-(−)-1,1 -bi-2-naphthol dimethyl ether) (PBNME) film on stainless steel (SS)/indium tin oxide (ITO) electrodes. As-formed PBNME films showed good electroactivity and redox stability in CH 2 Cl 2 -BFEE, BFEE, and even in concentrated sulfuric acid. Both doped and dedoped PBNME films were partly soluble in strong polar solvents, such as dimethyl sulfoxide (DMSO). Quantum chemistry calculations of BNME and FT-IR spectrum of dedoped PBNME films demonstrated that the polymerization probably occurred at 4-and 4 -positions. Optical rotation determination showed that the conformation of the monomer was maintained during the electrochemical polymerization process and the polymer exhibited greatly enhanced optical rotation value with main chain axial chirality compared with that of the monomer. Fluorescent spectral studies indicated that soluble PBNME was a good blue-light emitter with maximum emission at 415 nm and fluorescence quantum yield of 0.15, while solid-state PBNME film showed its emission centered at 380 nm. Furthermore, as-formed PBNME manifested favorable thermal stability and relatively high electrical conductivity of about 10 −1 S cm −1 at room temperature.
Polynaphthalene films with electrical conductivity of 10 −3 S cm −1 were successfully electrosynt... more Polynaphthalene films with electrical conductivity of 10 −3 S cm −1 were successfully electrosynthesized by direct anodic oxidation of 1,1 -binaphthyl (BN) and 1,1 -bi-2-naphthol (BNO) in CH 2 Cl 2 containing additional boron trifluoride diethyl etherate (BFEE). The introduction of BFEE greatly lowered the onset oxidation potentials of the monomers compared with other supporting electrolytes. The resulting poly(1,1 -binaphthyl) (PBN) films exhibited good redox activity and stability in different monomer-free electrolytes. Moreover, FT-IR spectra and quantum chemistry calculation results proved that PBN and poly(1,1 -bi-2-naphthol) (PBNO) were both synthesized mainly through the coupling of the monomers at ␣-positions of the naphthalene ring. Fluorescence spectral determination showed that the polymers were typical blue light-emitters with solution quantum yields of 0.17 and 0.13, respectively. The substitution of hydroxyl and naphthyl groups did not change the emission wavelength of polynaphthalene (about 417 nm). Surface morphology determination revealed that regular particles with different sizes were orderly assembled on ITO electrode after electrochemical growth.
Poly(3-methylthiophene-co-benzanthrone), a novel copolymer, was successfully achieved by electroc... more Poly(3-methylthiophene-co-benzanthrone), a novel copolymer, was successfully achieved by electrochemical oxidation of the monomer mixtures of 3-methylthiophene (3MeT) and benzanthrone in the binary solvent system containing boron trifluoride diethyl etherate and acetonitrile. A series of experiments with different monomer feed ratios were carried out to investigate the influence of monomer feed ratio on the electrochemical copolymerization and the overall properties of the copolymer films. The resulting copolymer possesses the advantages of both polybenzanthrone and poly(3-methylthiophene), such as considerable fluorescence property, good redox activity, high thermal stability, and relatively high electrical conductivity. Ultraviolet–visible, FT-IR, and thermal analysis were used to characterize and investigate the structure and thermal stability of the copolymers. Fluorescence spectroscopic studies revealed that the copolymer dissolved in common organic solvents was a good green or yellow-green light emitter, with a strong emission at 499 nm in doped state and 529 nm in dedoped state.
The electrochemical polymerization study of a set of monomers, dibenzothiophene (DBT), benzothiop... more The electrochemical polymerization study of a set of monomers, dibenzothiophene (DBT), benzothiophene-S,S-dioxide (BTO), and dibenzothiophene-S,S-dioxide (DBTO) was reported and novel conducting poly(dibenzothiophene-S,S-dioxide) (PDBTO) was successfully electrosynthesized in boron trifluoride diethyl etherate (BFEE) and in the binary solvent system of BFEE and trifluoroacetic acid (TFA) for the first time. The strong electron-withdrawing sulphonyl group substitution on BTO partly damaged the aromatic system of BT and significantly inhibited electrochemical polymerization. The electronic clouds of DBT and the electron spin density of its radical cation centralized dominantly on the sulfur atom, thus making it impossible to get the corresponding polymer electrochemically. Furthermore, structural characterization, molecular weight, ionization potentials and electron affinities, fluorescence properties, thermal stability, electrical conductivity, and morphology of PDBTO were minutely investigated. From FT-IR spectra and computational results, DBTO was probably polymerized through the coupling at C(3) and C(7) positions, with the same structure to electrosynthesized polyfluorenes. The substitution of sulphonyl group in the fluorene ring increases its electron affinity considerably for improving electron injection/ transport. Additionally, as-formed PDBTO was found to be a typical blue-light-emitter with maximum emission at 458 nm and concurrently exhibited good electroactivity and thermal stability. The successful electrosynthesis of PDBTO should represent a unique approach to DBTO-based donor-acceptor co-oligomers/polymers, which hold promise for the design of a new generation of optoelectronic materials and are hotly researched in the field of electronic devices currently.
Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene was successful... more Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene was successfully achieved in boron trifluoride diethyl etherate by direct anodic oxidation of the monomer mixtures. The structure and properties of the copolymers were investigated with ultraviolet–visible, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, fluorescence spectra, and thermal analysis. The novel copolymers had the advantages of both poly(9,10-dihydrophenanthrene) and poly(3-methylthiophene), such as good electrochemical behavior, good mechanical properties, and high electrical conductivity. Fluorescence spectroscopy studies revealed that the copolymers had good fluorescence properties, and the emitting properties of the copolymer could be parameters by changing the feed ratio of the monomer mixtures during the electrochemical polymerization.
Potential-energy surface of the CH3CO + O2 reaction has been calculated by ab initio quantum chem... more Potential-energy surface of the CH3CO + O2 reaction has been calculated by ab initio quantum chemistry methods. The geometries were optimized using the second-order Moller-Plesset theory (MP2) with the 6-311G(d,p) basis set and the coupled-cluster theory with single and double excitations (CCSD) with the correlation consistent polarized valence double zeta (cc-pVDZ) basis set. The relative energies were calculated using the Gaussian-3 second-order Moller-Plesset theory with the CCSD/cc-pVDZ geometries. Multireference self-consistent-field and MP2 methods were also employed using the 6-311G(d,p) and 6-311++G(3df,2p) basis sets. Both addition/elimination and direct abstraction mechanisms have been investigated. It was revealed that acetylperoxy radical [CH3C(O)OO] is the initial adduct and the formation of OH and alpha-lactone [CH2CO2(1A')] is the only energetically accessible decomposition channel. The other channels, e.g., abstraction, HO2 + CH2CO, O + CH3CO2, CO + CH3O2, and CO2 + CH3O, are negligible. Multichannel Rice-Ramsperger-Kassel-Marcus theory and transition state theory (E-resolved) were employed to calculate the overall and individual rate coefficients and the temperature and pressure dependences. Fairly good agreement between theory and experiments has been obtained without any adjustable parameters. It was concluded that at pressures below 3 Torr, OH and CH2CO2(1A') are the major nascent products of the oxidation of acetyl radicals, although CH2CO2(1A') might either undergo unimolecular decomposition to form the final products of CH2O + CO or react with OH and Cl to generate H2O and HCl. The acetylperoxy radicals formed by collisional stabilization are the major products at the elevated pressures. In atmosphere, the yield of acetylperoxy is nearly unity and the contribution of OH is only marginal.
Direct anodic oxidation of 1,2-methylenedioxybenzene (MDOB) and 1,2-ethylenedioxybenzene (EDOB), ... more Direct anodic oxidation of 1,2-methylenedioxybenzene (MDOB) and 1,2-ethylenedioxybenzene (EDOB), analogues of 3,4-alkylenedioxythiophene and 3,4-alkylenedioxypyrrole, led to the formation of polyacetylene derivatives, poly(1,2-methylenedioxybenzene) (PMDOB) and poly(1,2-ethylenedioxybenzene) (PEDOB), on a platinum sheet in pure boron trifluoride diethyl etherate (BFEE). IR, 1H NMR, 13C NMR and quantum chemistry calculations confirmed that the polymerization occurred at C(4) and C(5) position on the benzene ring
The reaction of F(2P) with acetone has been studied theoretically using ab initio quantum chemist... more The reaction of F(2P) with acetone has been studied theoretically using ab initio quantum chemistry methods and transition state theory. The potential energy surface was calculated at the G3MP2 level using the MP2/6-311G(d,p) optimized structures. Additionally, to ensure the accuracy of the calculations, optimizations with either larger basis set (e.g., MP2/G3MP2Large) or higher level electron correlation [e.g., CCSD/ 6-311G(d,p)] were also performed. It has been revealed that the F + CH3C(O)CH3 reaction proceeds via two pathways: (1) the direct hydrogen abstraction of acetone by F gives the major products HF + CH3C(O)CH2; (2) the addition of F atom to the >C=O double bond of acetone and the subsequent C-C bond cleavage gives the minor products CH3 + CH3C(O)F. All other product channels are of no importance due to the occurrence of significant barriers. Both abstraction and addition appear to be barrierless processes. Variational transition state model and multichannel RRKM theory were employed to calculate the temperature- and pressure-dependent rate constants and branching ratios. The predicted rate constants for the abstraction channel and the yields of HF + CH3C(O)CH3 and CH3 + CH3C(O)F are both in good agreement with the experimental data at 295 K and 700 Torr. A negative temperature dependence of the overall rate constants was predicted at temperatures below 500 K.
Eight exothermic product channels of the reaction of chlorinated vinyl radical (C 2 Cl 3 ) with m... more Eight exothermic product channels of the reaction of chlorinated vinyl radical (C 2 Cl 3 ) with molecular oxygen (O 2 ) have been investigated using ab initio quantum chemistry methods. The energetics of the reaction pathways were calculated at the second-order Moller-Plesset Gaussian-3 level of theory (G3MP2) using the B3LYP/ 6-311G(d) optimized geometries. It has been shown that the C 2 Cl 3 + O 2 reaction takes place via a barrierless addition to form the chlorinated vinylperoxy radical complex, which can decompose or isomerize to various products via the complicated mechanisms. Two major reaction routes were revealed, i.e., the three-memberring reaction mechanism leading to ClCO + CCl 2 O, CO + CCl 3 O, CO 2 + CCl 3 , Cl + (ClCO) 2 , etc., and the OO bond cleavage mechanism leading to O( 3 P) + C 2 Cl 3 O. The other mechanisms are shown to be unimportant. The results are validated by the calculations using the restricted coupled cluster theory [RCCSD(T)] with the complete basis set extrapolation. Variational transition state theory was employed to calculate the individual and total rate coefficients as a function of temperature and pressure (helium). The theoretical rate coefficients are in good agreement with the available experimental data. It was found that the total rate coefficients show strong negative temperature dependence in the range 200-2000 K. At room temperature (297 K), the total rate coefficients are shown to be nearly pressure independent over a wide range of helium pressures (1-10 9 Torr). The deactivation of the initial adduct, C 2 Cl 3 O 2 , is only significant at pressures higher than 1000 Torr. The three-member-ring reaction mechanism is always predominant over the OO bond cleavage.
Mechanisms and kinetics of the reaction of atomic oxygen with acetone have been investigated usin... more Mechanisms and kinetics of the reaction of atomic oxygen with acetone have been investigated using ab initio quantum chemistry methods and transition state theory. The structures of the stationary points along the possible reaction pathways were obtained using the second-order Møller-Plesset theory and the coupled-cluster theory with single and double excitations with the triple-zeta quality basis sets. The energetics of the reaction pathways were calculated at the reduced second-order Gaussian-3 level and the extrapolated full coupled-cluster/complete basis set limit. The rate coefficients were calculated in the temperature range 200-3000 K, with the detailed consideration of the hindered internal rotation and the tunneling effect using Eckart and the semiclassical WKB approximations. It is shown that the predominant mechanism is the direct hydrogen abstraction producing hydroxyl and acetonyl radicals. Although the nucleophilic OC addition/elimination channel leading to CH3 and CO2 involves comparable barrier with the direct hydrogen abstraction channel, kinetically it cannot play any role in the overall reaction. It is predicted that the rate coefficients show positive temperature dependence in the range 200-3000 K and strong non-Arrhenius behavior. The tunneling effect plays a significant role. Moreover, the reaction has strong kinetic isotope effect. The calculated results are in good agreement with the available experimental data. The present rigorous theoretical work is helpful for the understanding of the characteristics of the reaction of atomic oxygen with acetone.
a b s t r a c t PEDOT layers are synthesized in aqueous solutions in the presence of one of the t... more a b s t r a c t PEDOT layers are synthesized in aqueous solutions in the presence of one of the three different anionic species -polysterenesulfonate (PSS), poly(2-acrylamido-2-methyl-1-propane-sulfonate) (PAMPS) and dodecylsulfate without any addition of further inorganic anions. Simultaneous electrochemical and acoustic admittance measurements are carried out in the course of polymerization. The data from the admittance spectra are used to extract information on the mechanical shear storage and loss moduli of the three types of PEDOT layers. The anionic species are found to affect the polymerization kinetics, the surface morphology and most markedly the viscoelastic properties of the three types of layers. The latter depend primarily on the innate structure arising in the course of polymerization whereas the solution specifics play a secondary role. Dodecylsulfate imparts significant stiffness to the PEDOT layers with high rigidity preserved for relatively large polymerization charges. The G moduli in this case exceed 10 9 dyn/cm 2 . Both polyanion-doped PEDOT layers are found to be softer but there is nevertheless a clear difference between them with PEDOT/PAMPS having a strong predisposition for swelling.
Direct anodic oxidation of (S)-(−)-1,1 -bi-2-naphthol dimethyl ether (BNME) in CH 2 Cl 2 /CHCl 3 ... more Direct anodic oxidation of (S)-(−)-1,1 -bi-2-naphthol dimethyl ether (BNME) in CH 2 Cl 2 /CHCl 3 containing boron trifluoride diethyl etherate (BFEE) as the supporting electrolyte led to facile electrodeposition of high-quality free-standing poly((S)-(−)-1,1 -bi-2-naphthol dimethyl ether) (PBNME) film on stainless steel (SS)/indium tin oxide (ITO) electrodes. As-formed PBNME films showed good electroactivity and redox stability in CH 2 Cl 2 -BFEE, BFEE, and even in concentrated sulfuric acid. Both doped and dedoped PBNME films were partly soluble in strong polar solvents, such as dimethyl sulfoxide (DMSO). Quantum chemistry calculations of BNME and FT-IR spectrum of dedoped PBNME films demonstrated that the polymerization probably occurred at 4-and 4 -positions. Optical rotation determination showed that the conformation of the monomer was maintained during the electrochemical polymerization process and the polymer exhibited greatly enhanced optical rotation value with main chain axial chirality compared with that of the monomer. Fluorescent spectral studies indicated that soluble PBNME was a good blue-light emitter with maximum emission at 415 nm and fluorescence quantum yield of 0.15, while solid-state PBNME film showed its emission centered at 380 nm. Furthermore, as-formed PBNME manifested favorable thermal stability and relatively high electrical conductivity of about 10 −1 S cm −1 at room temperature.
Polynaphthalene films with electrical conductivity of 10 −3 S cm −1 were successfully electrosynt... more Polynaphthalene films with electrical conductivity of 10 −3 S cm −1 were successfully electrosynthesized by direct anodic oxidation of 1,1 -binaphthyl (BN) and 1,1 -bi-2-naphthol (BNO) in CH 2 Cl 2 containing additional boron trifluoride diethyl etherate (BFEE). The introduction of BFEE greatly lowered the onset oxidation potentials of the monomers compared with other supporting electrolytes. The resulting poly(1,1 -binaphthyl) (PBN) films exhibited good redox activity and stability in different monomer-free electrolytes. Moreover, FT-IR spectra and quantum chemistry calculation results proved that PBN and poly(1,1 -bi-2-naphthol) (PBNO) were both synthesized mainly through the coupling of the monomers at ␣-positions of the naphthalene ring. Fluorescence spectral determination showed that the polymers were typical blue light-emitters with solution quantum yields of 0.17 and 0.13, respectively. The substitution of hydroxyl and naphthyl groups did not change the emission wavelength of polynaphthalene (about 417 nm). Surface morphology determination revealed that regular particles with different sizes were orderly assembled on ITO electrode after electrochemical growth.
Poly(3-methylthiophene-co-benzanthrone), a novel copolymer, was successfully achieved by electroc... more Poly(3-methylthiophene-co-benzanthrone), a novel copolymer, was successfully achieved by electrochemical oxidation of the monomer mixtures of 3-methylthiophene (3MeT) and benzanthrone in the binary solvent system containing boron trifluoride diethyl etherate and acetonitrile. A series of experiments with different monomer feed ratios were carried out to investigate the influence of monomer feed ratio on the electrochemical copolymerization and the overall properties of the copolymer films. The resulting copolymer possesses the advantages of both polybenzanthrone and poly(3-methylthiophene), such as considerable fluorescence property, good redox activity, high thermal stability, and relatively high electrical conductivity. Ultraviolet–visible, FT-IR, and thermal analysis were used to characterize and investigate the structure and thermal stability of the copolymers. Fluorescence spectroscopic studies revealed that the copolymer dissolved in common organic solvents was a good green or yellow-green light emitter, with a strong emission at 499 nm in doped state and 529 nm in dedoped state.
The electrochemical polymerization study of a set of monomers, dibenzothiophene (DBT), benzothiop... more The electrochemical polymerization study of a set of monomers, dibenzothiophene (DBT), benzothiophene-S,S-dioxide (BTO), and dibenzothiophene-S,S-dioxide (DBTO) was reported and novel conducting poly(dibenzothiophene-S,S-dioxide) (PDBTO) was successfully electrosynthesized in boron trifluoride diethyl etherate (BFEE) and in the binary solvent system of BFEE and trifluoroacetic acid (TFA) for the first time. The strong electron-withdrawing sulphonyl group substitution on BTO partly damaged the aromatic system of BT and significantly inhibited electrochemical polymerization. The electronic clouds of DBT and the electron spin density of its radical cation centralized dominantly on the sulfur atom, thus making it impossible to get the corresponding polymer electrochemically. Furthermore, structural characterization, molecular weight, ionization potentials and electron affinities, fluorescence properties, thermal stability, electrical conductivity, and morphology of PDBTO were minutely investigated. From FT-IR spectra and computational results, DBTO was probably polymerized through the coupling at C(3) and C(7) positions, with the same structure to electrosynthesized polyfluorenes. The substitution of sulphonyl group in the fluorene ring increases its electron affinity considerably for improving electron injection/ transport. Additionally, as-formed PDBTO was found to be a typical blue-light-emitter with maximum emission at 458 nm and concurrently exhibited good electroactivity and thermal stability. The successful electrosynthesis of PDBTO should represent a unique approach to DBTO-based donor-acceptor co-oligomers/polymers, which hold promise for the design of a new generation of optoelectronic materials and are hotly researched in the field of electronic devices currently.
Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene was successful... more Electrochemical copolymerization of 9,10-dihydrophenanthrene and 3-methylthiophene was successfully achieved in boron trifluoride diethyl etherate by direct anodic oxidation of the monomer mixtures. The structure and properties of the copolymers were investigated with ultraviolet–visible, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, fluorescence spectra, and thermal analysis. The novel copolymers had the advantages of both poly(9,10-dihydrophenanthrene) and poly(3-methylthiophene), such as good electrochemical behavior, good mechanical properties, and high electrical conductivity. Fluorescence spectroscopy studies revealed that the copolymers had good fluorescence properties, and the emitting properties of the copolymer could be parameters by changing the feed ratio of the monomer mixtures during the electrochemical polymerization.
Potential-energy surface of the CH3CO + O2 reaction has been calculated by ab initio quantum chem... more Potential-energy surface of the CH3CO + O2 reaction has been calculated by ab initio quantum chemistry methods. The geometries were optimized using the second-order Moller-Plesset theory (MP2) with the 6-311G(d,p) basis set and the coupled-cluster theory with single and double excitations (CCSD) with the correlation consistent polarized valence double zeta (cc-pVDZ) basis set. The relative energies were calculated using the Gaussian-3 second-order Moller-Plesset theory with the CCSD/cc-pVDZ geometries. Multireference self-consistent-field and MP2 methods were also employed using the 6-311G(d,p) and 6-311++G(3df,2p) basis sets. Both addition/elimination and direct abstraction mechanisms have been investigated. It was revealed that acetylperoxy radical [CH3C(O)OO] is the initial adduct and the formation of OH and alpha-lactone [CH2CO2(1A')] is the only energetically accessible decomposition channel. The other channels, e.g., abstraction, HO2 + CH2CO, O + CH3CO2, CO + CH3O2, and CO2 + CH3O, are negligible. Multichannel Rice-Ramsperger-Kassel-Marcus theory and transition state theory (E-resolved) were employed to calculate the overall and individual rate coefficients and the temperature and pressure dependences. Fairly good agreement between theory and experiments has been obtained without any adjustable parameters. It was concluded that at pressures below 3 Torr, OH and CH2CO2(1A') are the major nascent products of the oxidation of acetyl radicals, although CH2CO2(1A') might either undergo unimolecular decomposition to form the final products of CH2O + CO or react with OH and Cl to generate H2O and HCl. The acetylperoxy radicals formed by collisional stabilization are the major products at the elevated pressures. In atmosphere, the yield of acetylperoxy is nearly unity and the contribution of OH is only marginal.
Direct anodic oxidation of 1,2-methylenedioxybenzene (MDOB) and 1,2-ethylenedioxybenzene (EDOB), ... more Direct anodic oxidation of 1,2-methylenedioxybenzene (MDOB) and 1,2-ethylenedioxybenzene (EDOB), analogues of 3,4-alkylenedioxythiophene and 3,4-alkylenedioxypyrrole, led to the formation of polyacetylene derivatives, poly(1,2-methylenedioxybenzene) (PMDOB) and poly(1,2-ethylenedioxybenzene) (PEDOB), on a platinum sheet in pure boron trifluoride diethyl etherate (BFEE). IR, 1H NMR, 13C NMR and quantum chemistry calculations confirmed that the polymerization occurred at C(4) and C(5) position on the benzene ring
The reaction of F(2P) with acetone has been studied theoretically using ab initio quantum chemist... more The reaction of F(2P) with acetone has been studied theoretically using ab initio quantum chemistry methods and transition state theory. The potential energy surface was calculated at the G3MP2 level using the MP2/6-311G(d,p) optimized structures. Additionally, to ensure the accuracy of the calculations, optimizations with either larger basis set (e.g., MP2/G3MP2Large) or higher level electron correlation [e.g., CCSD/ 6-311G(d,p)] were also performed. It has been revealed that the F + CH3C(O)CH3 reaction proceeds via two pathways: (1) the direct hydrogen abstraction of acetone by F gives the major products HF + CH3C(O)CH2; (2) the addition of F atom to the >C=O double bond of acetone and the subsequent C-C bond cleavage gives the minor products CH3 + CH3C(O)F. All other product channels are of no importance due to the occurrence of significant barriers. Both abstraction and addition appear to be barrierless processes. Variational transition state model and multichannel RRKM theory were employed to calculate the temperature- and pressure-dependent rate constants and branching ratios. The predicted rate constants for the abstraction channel and the yields of HF + CH3C(O)CH3 and CH3 + CH3C(O)F are both in good agreement with the experimental data at 295 K and 700 Torr. A negative temperature dependence of the overall rate constants was predicted at temperatures below 500 K.
Eight exothermic product channels of the reaction of chlorinated vinyl radical (C 2 Cl 3 ) with m... more Eight exothermic product channels of the reaction of chlorinated vinyl radical (C 2 Cl 3 ) with molecular oxygen (O 2 ) have been investigated using ab initio quantum chemistry methods. The energetics of the reaction pathways were calculated at the second-order Moller-Plesset Gaussian-3 level of theory (G3MP2) using the B3LYP/ 6-311G(d) optimized geometries. It has been shown that the C 2 Cl 3 + O 2 reaction takes place via a barrierless addition to form the chlorinated vinylperoxy radical complex, which can decompose or isomerize to various products via the complicated mechanisms. Two major reaction routes were revealed, i.e., the three-memberring reaction mechanism leading to ClCO + CCl 2 O, CO + CCl 3 O, CO 2 + CCl 3 , Cl + (ClCO) 2 , etc., and the OO bond cleavage mechanism leading to O( 3 P) + C 2 Cl 3 O. The other mechanisms are shown to be unimportant. The results are validated by the calculations using the restricted coupled cluster theory [RCCSD(T)] with the complete basis set extrapolation. Variational transition state theory was employed to calculate the individual and total rate coefficients as a function of temperature and pressure (helium). The theoretical rate coefficients are in good agreement with the available experimental data. It was found that the total rate coefficients show strong negative temperature dependence in the range 200-2000 K. At room temperature (297 K), the total rate coefficients are shown to be nearly pressure independent over a wide range of helium pressures (1-10 9 Torr). The deactivation of the initial adduct, C 2 Cl 3 O 2 , is only significant at pressures higher than 1000 Torr. The three-member-ring reaction mechanism is always predominant over the OO bond cleavage.
Mechanisms and kinetics of the reaction of atomic oxygen with acetone have been investigated usin... more Mechanisms and kinetics of the reaction of atomic oxygen with acetone have been investigated using ab initio quantum chemistry methods and transition state theory. The structures of the stationary points along the possible reaction pathways were obtained using the second-order Møller-Plesset theory and the coupled-cluster theory with single and double excitations with the triple-zeta quality basis sets. The energetics of the reaction pathways were calculated at the reduced second-order Gaussian-3 level and the extrapolated full coupled-cluster/complete basis set limit. The rate coefficients were calculated in the temperature range 200-3000 K, with the detailed consideration of the hindered internal rotation and the tunneling effect using Eckart and the semiclassical WKB approximations. It is shown that the predominant mechanism is the direct hydrogen abstraction producing hydroxyl and acetonyl radicals. Although the nucleophilic OC addition/elimination channel leading to CH3 and CO2 involves comparable barrier with the direct hydrogen abstraction channel, kinetically it cannot play any role in the overall reaction. It is predicted that the rate coefficients show positive temperature dependence in the range 200-3000 K and strong non-Arrhenius behavior. The tunneling effect plays a significant role. Moreover, the reaction has strong kinetic isotope effect. The calculated results are in good agreement with the available experimental data. The present rigorous theoretical work is helpful for the understanding of the characteristics of the reaction of atomic oxygen with acetone.
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