The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluo...The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluorescence quenching of the n,π^*-excited state of covalent butanal with three paths: (1) The first path corresponds to direct S0-react reconstitution, which involves the first S1 decay by partial hydrogen atom transfer. (2) The second stepwise mechanism can be viewed as a full hydrogen atom transfer followed by a partial hydrogen atom back transfer, electron transfer (near S1/S0 or S0-TS) and finally a proton transfer to S0-react. (3) On the triplet surface, the surface crossing to the singlet state would be clearly much efficient at the T1/S0 region due to the large SOC value of 8.3 cm^-1. The S0-react decay route from T1/S0 was studied with an intrinsic reaction coordinate (IRC) calculation at the CASSCF level, resulting in the S0-React minimum.展开更多
Hydrogen abstraction reaction, H+C2H4 --H2+C2H2 was studied by using A initio SCF method. Ge-ometries were fully optimized at SCF level and energies were computed at STO-3G basis set for reactants and transition state...Hydrogen abstraction reaction, H+C2H4 --H2+C2H2 was studied by using A initio SCF method. Ge-ometries were fully optimized at SCF level and energies were computed at STO-3G basis set for reactants and transition state. Vibrational analysis was performed thereupon. Finally, the rate constant calculations were carried out at different temperatures for all range of reaction temperature according to Eyring's sbwlute reaction rate theory. The calculated activation energy is 12. 68 kcal/mol, lower than observed value (H. S kcal/mol) by 1. 82 kcal/mol only. The agreement of the calculated rate constants with the experiments is satisfactory.展开更多
Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical (OH) and 1,1,1-trichloroethane (CH3CCl3). The potential energy surface has been given acco...Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical (OH) and 1,1,1-trichloroethane (CH3CCl3). The potential energy surface has been given according to the relative energies calculated at the MP2/cc-pVTZ level after the spin projection (PMP2). Five reaction channels were identified and the intramolecular hydrogen bonding was observed in some transition state structures. The barrier heights and reaction enthalpies calculated for all possible channels show that the hydrogen abstraction channel is predominant kinetically and thermodynamically. The contribution from other channels was predicted to be minor.展开更多
This paper systematically studies the reaction mechanisms of formic acid catalyzed by transition metal oxide MoO. Three different reaction pathways of Routes I, Ⅱ and Ⅲ were found through studying the reaction mecha...This paper systematically studies the reaction mechanisms of formic acid catalyzed by transition metal oxide MoO. Three different reaction pathways of Routes I, Ⅱ and Ⅲ were found through studying the reaction mechanism of transition metal oxide MoO catalyzing the formic acid. The transition metal oxide MoO interacts with the C=O double bond to form chiral chain compounds(Routes I and Ⅱ) and metallic compound MoOH2(Route Ⅲ). In this paper, we have studied the mechanisms of two addition reaction pathways and hydrogen abstraction reaction pathway. Routes I and Ⅱ are both addition reactions, and their products are two different chiral compounds MoO3CH2, which are enantiomeric to each other. In Route Ⅲ, metal compounds MoOH2 and CO2 are obtained from the hydrogen abstraction reaction. Among them, the hydrogen abstraction reaction occurring in Route Ⅲ is more likely to occur than the others. By comparing the results of previous studies on the reaction of MxOy-+ ROH(M= Mo,W; R = Me, Et), we found that the hydrogen abstraction mechanism is completely different from the mechanism of oxygen-containing organic compound catalyzed by MxOy.展开更多
A dynamic method is employed to study the reaction mechanisms of CH3CH2OCF3 with the hydrogen trioxy (HOOO) radical. In our paper, the geometries and harmonic vibrational frequencies of all the stationary points and...A dynamic method is employed to study the reaction mechanisms of CH3CH2OCF3 with the hydrogen trioxy (HOOO) radical. In our paper, the geometries and harmonic vibrational frequencies of all the stationary points and minimum energy paths (MEPs) are calculated at the MPW1K/6-31+G(d,p) level of theory, and the energetic information along MEPs is further refined by the CCSD/6-31+G(df, p) level of theory. The rate constants are evaluated with the conventional transition-state theory (TST), the canonical variational transition-state theory (CVT), the microcanonical variational transition-state theory (μVT), the CVT coupled with the small-curvature tunneling (SCT) correction (CVT/SCT), and the μVT coupled with the Eckart tunneling correction μVT/Eckart) based on the ab initio calculations in the temperature range of 200-3000 K. The theoretical results are important in determining the atmospheric lifetime and the feasible pathways for the loss of HFEs.展开更多
In a polymerization model with low density polyethylene (LDPE) as the substrate and acrylic acid (AA) as the monomer, the performance of isopropylthioxanthone (ITX) in initiating surface photografting polymerization w...In a polymerization model with low density polyethylene (LDPE) as the substrate and acrylic acid (AA) as the monomer, the performance of isopropylthioxanthone (ITX) in initiating surface photografting polymerization was evaluated. The results show that the reactivity of photopolymerization and photografting of ITX locate between benzophenone (BP) and benzildimethylketal (BDK) for polymerization, BDK > ITX > BP; for surface grafting polymerization, BP > ITX > BDK. These results can be explained by a reaction mechanism of the inter-molecular or intra-molecular hydrogen abstraction reaction of ITX.展开更多
We propose the complicated catalytic mechanisms for the acetic acid molecule catalyzed by transition metal oxide MoO2 based on density functional theory calculations.The geometries and energetic values of all stationa...We propose the complicated catalytic mechanisms for the acetic acid molecule catalyzed by transition metal oxide MoO2 based on density functional theory calculations.The geometries and energetic values of all stationaries and transition states involved in the three different reaction pathways(ChannelsⅠ,ⅡandⅢ)are reported and analyzed.All reaction mechanisms are fully different from that of MoxOy catalyzing volatile organic compounds(VOCs)in previous studies.The completely new mechanisms catalyzed by MoO2 for acetic acid have been discovered for the first time.ChannelsⅠ(ⅠA andⅠB)andⅡare both addition reactions and channelⅢis hydrogen abstraction reaction by producing a leaving group.The barrier energies of reaction are also compared with other catalytic reactions,showing that MoO2 catalyst expresses a lower barrier energy(8.22 kcal/mol)by addition reaction,which represents MoO2 tends to absorb acetic acid pollution gas via addition reaction rather than release toxic substances.This also means that MoO2 is a more effective and representative catalyst and is suitable for further study of catalytic carboxylic acids,so the reaction mechanisms may provide a useful theoretical guidance and solution for the catalysis of carboxylic acids.展开更多
基金supported by ‘Qinglan’ Talent Engineering Funds and Key Subject of Inorganic Chemistry by Tianshui Normal University
文摘The excited-state intramolecular hydrogen abstraction reactions of butanal have been investigated using the CAS-MP2/6-311+G^*//CASSCF/6-31G^* methods. Calculated results show that the hydrogen transfer induced fluorescence quenching of the n,π^*-excited state of covalent butanal with three paths: (1) The first path corresponds to direct S0-react reconstitution, which involves the first S1 decay by partial hydrogen atom transfer. (2) The second stepwise mechanism can be viewed as a full hydrogen atom transfer followed by a partial hydrogen atom back transfer, electron transfer (near S1/S0 or S0-TS) and finally a proton transfer to S0-react. (3) On the triplet surface, the surface crossing to the singlet state would be clearly much efficient at the T1/S0 region due to the large SOC value of 8.3 cm^-1. The S0-react decay route from T1/S0 was studied with an intrinsic reaction coordinate (IRC) calculation at the CASSCF level, resulting in the S0-React minimum.
文摘Hydrogen abstraction reaction, H+C2H4 --H2+C2H2 was studied by using A initio SCF method. Ge-ometries were fully optimized at SCF level and energies were computed at STO-3G basis set for reactants and transition state. Vibrational analysis was performed thereupon. Finally, the rate constant calculations were carried out at different temperatures for all range of reaction temperature according to Eyring's sbwlute reaction rate theory. The calculated activation energy is 12. 68 kcal/mol, lower than observed value (H. S kcal/mol) by 1. 82 kcal/mol only. The agreement of the calculated rate constants with the experiments is satisfactory.
基金supported by the National Natural Science Foundation of China (No. 20573029)the Natural Science Foundation of Heilongjiang Province (No. B200905)
文摘Ab initio and density functional theory calculations have been carried out to investigate the reaction of hydroxyl radical (OH) and 1,1,1-trichloroethane (CH3CCl3). The potential energy surface has been given according to the relative energies calculated at the MP2/cc-pVTZ level after the spin projection (PMP2). Five reaction channels were identified and the intramolecular hydrogen bonding was observed in some transition state structures. The barrier heights and reaction enthalpies calculated for all possible channels show that the hydrogen abstraction channel is predominant kinetically and thermodynamically. The contribution from other channels was predicted to be minor.
基金supported by the National Natural Science Foundation of China(No.21373025)the major project of Tangshan Normal College(No.2017B01)
文摘This paper systematically studies the reaction mechanisms of formic acid catalyzed by transition metal oxide MoO. Three different reaction pathways of Routes I, Ⅱ and Ⅲ were found through studying the reaction mechanism of transition metal oxide MoO catalyzing the formic acid. The transition metal oxide MoO interacts with the C=O double bond to form chiral chain compounds(Routes I and Ⅱ) and metallic compound MoOH2(Route Ⅲ). In this paper, we have studied the mechanisms of two addition reaction pathways and hydrogen abstraction reaction pathway. Routes I and Ⅱ are both addition reactions, and their products are two different chiral compounds MoO3CH2, which are enantiomeric to each other. In Route Ⅲ, metal compounds MoOH2 and CO2 are obtained from the hydrogen abstraction reaction. Among them, the hydrogen abstraction reaction occurring in Route Ⅲ is more likely to occur than the others. By comparing the results of previous studies on the reaction of MxOy-+ ROH(M= Mo,W; R = Me, Et), we found that the hydrogen abstraction mechanism is completely different from the mechanism of oxygen-containing organic compound catalyzed by MxOy.
基金supported by the the National Natural Science Foundation of China(No.21373025 and 20933001)the Research Foundation of Education Bureau of Hebei Province(No.Z2011115)+3 种基金the 111 Project of China(No.B07012)the Natural Science Foundation of Hebei Province(No.B2012105002)the Research Foundation of Tangshan Administration of Science&Technology(131302115b)the Research Foundation of Tangshan normal college(2013A04)
文摘A dynamic method is employed to study the reaction mechanisms of CH3CH2OCF3 with the hydrogen trioxy (HOOO) radical. In our paper, the geometries and harmonic vibrational frequencies of all the stationary points and minimum energy paths (MEPs) are calculated at the MPW1K/6-31+G(d,p) level of theory, and the energetic information along MEPs is further refined by the CCSD/6-31+G(df, p) level of theory. The rate constants are evaluated with the conventional transition-state theory (TST), the canonical variational transition-state theory (CVT), the microcanonical variational transition-state theory (μVT), the CVT coupled with the small-curvature tunneling (SCT) correction (CVT/SCT), and the μVT coupled with the Eckart tunneling correction μVT/Eckart) based on the ab initio calculations in the temperature range of 200-3000 K. The theoretical results are important in determining the atmospheric lifetime and the feasible pathways for the loss of HFEs.
文摘In a polymerization model with low density polyethylene (LDPE) as the substrate and acrylic acid (AA) as the monomer, the performance of isopropylthioxanthone (ITX) in initiating surface photografting polymerization was evaluated. The results show that the reactivity of photopolymerization and photografting of ITX locate between benzophenone (BP) and benzildimethylketal (BDK) for polymerization, BDK > ITX > BP; for surface grafting polymerization, BP > ITX > BDK. These results can be explained by a reaction mechanism of the inter-molecular or intra-molecular hydrogen abstraction reaction of ITX.
基金Supported by the Shanxi Provincial Education Department(2019L0986)the 2016 annual major science and technology projects of Shanxi Province(MC2016-02/5)+4 种基金the Shanxi Advantageous and Characteristic Disciplines of“Project 1331”the school fund of Shanxi Institute of Technology(201605000120180010012 and 20190040013)the major project of Tangshan Normal College(Nos.2017B01 and B02)the 2019 abroad training project fund of Tangshan excellent young and middle-aged experts。
文摘We propose the complicated catalytic mechanisms for the acetic acid molecule catalyzed by transition metal oxide MoO2 based on density functional theory calculations.The geometries and energetic values of all stationaries and transition states involved in the three different reaction pathways(ChannelsⅠ,ⅡandⅢ)are reported and analyzed.All reaction mechanisms are fully different from that of MoxOy catalyzing volatile organic compounds(VOCs)in previous studies.The completely new mechanisms catalyzed by MoO2 for acetic acid have been discovered for the first time.ChannelsⅠ(ⅠA andⅠB)andⅡare both addition reactions and channelⅢis hydrogen abstraction reaction by producing a leaving group.The barrier energies of reaction are also compared with other catalytic reactions,showing that MoO2 catalyst expresses a lower barrier energy(8.22 kcal/mol)by addition reaction,which represents MoO2 tends to absorb acetic acid pollution gas via addition reaction rather than release toxic substances.This also means that MoO2 is a more effective and representative catalyst and is suitable for further study of catalytic carboxylic acids,so the reaction mechanisms may provide a useful theoretical guidance and solution for the catalysis of carboxylic acids.