The interconversion between the two distinct isomers of methyl vinyl ether （MVE）, the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the sub...The interconversion between the two distinct isomers of methyl vinyl ether （MVE）, the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the subsequent fragmentation were studied using quantum chemical methods at the BHandHLYP/6311＋＋G（d,p） level of theory for optimized geometries and frequency calculations and at the QCISD/631G（d,p） level for the single point energy calculations. The rate coefficients were calculated for the temperature range 280-440 K by using the canonical transition state theory （TST）. For ozone addition to MVE, there are two different possibilities discussed on the basis of two different possible orientations for ozone attack. The results of the theoretical study indicate that although the synperiplanar-MVE is 7.11 kJ/mol more stable than the antiperiplanar-MVE, the antiperiplanar-MVE plays a more important role in formation of the primary ozonides because the primary ozonides formed from the ozone addition antiperiplanar-MVE are more stable and the energy barriers corresponding to transition states are lower. The intereonversion between the primary ozonides formed from the ozone addition to antiperiplanar-MVE is the most accessible compared with the transformations between other primary ozonides. The cleavage of the primary ozonides mainly leads to the formation of the CH2OO, which is in agreement with the experimental estimates. The calculated overall rate constant for the ozone-initiated reactions is 4.8× 10^-17 cm^3/（molecule.s） at 298.15 K, which agrees with the experimental value for ethyl vinyl ether.展开更多
This letter reports a study on producing gas-phase O 2(a 1Δ) by decomposition of triphenyl phosphite ozonide ((C 6H 5O) 3PO 3, TPPO 3) under a number of reaction conditions. For the first time, the cooperative emissi...This letter reports a study on producing gas-phase O 2(a 1Δ) by decomposition of triphenyl phosphite ozonide ((C 6H 5O) 3PO 3, TPPO 3) under a number of reaction conditions. For the first time, the cooperative emission at wavelengths 634 and 703 nm of O 2(a 1Δ) generated by TPPO 3 decomposition are observed. Specifically, under the condition of catalyzed decomposition by pyridine of TPPO 3 solution in CFCl 3 at low temperature, the emission spectrum is the same as that from the basic hydrogen peroxide plus chlorine reaction. This shows the feasibility of developing a new source for singlet delta oxygen. However, in the experiments of spontaneous decomposition of solid TPPO 3 and thermal decomposition of TPPO 3 solution on a high temperature surface, the spectra have a wide emission background around the 634 and 703 nm peaks, which indicates the production of some excited species than O 2(a 1△). Besides, there are about 2%～3%CO and 1.5%～2%CO 2 in the gaseous products together with a small amount of insoluble in acetone solid product, which imply that other than the formation of O 2(a 1△) and TPPO by unimolecular decomposition of TPPO 3, more complicated reactions may take place. The study of the reaction mechanism, the optimization of the expertise of O 2(a 1△) generation by TPPO 3 decomposition as well as measurement of absolute concentration of O 2(a 1△) are under way.展开更多
文摘The interconversion between the two distinct isomers of methyl vinyl ether （MVE）, the formation of the primary ozonides from O3-initated reactions of MVE, the transformation between the primary ozonides, and the subsequent fragmentation were studied using quantum chemical methods at the BHandHLYP/6311＋＋G（d,p） level of theory for optimized geometries and frequency calculations and at the QCISD/631G（d,p） level for the single point energy calculations. The rate coefficients were calculated for the temperature range 280-440 K by using the canonical transition state theory （TST）. For ozone addition to MVE, there are two different possibilities discussed on the basis of two different possible orientations for ozone attack. The results of the theoretical study indicate that although the synperiplanar-MVE is 7.11 kJ/mol more stable than the antiperiplanar-MVE, the antiperiplanar-MVE plays a more important role in formation of the primary ozonides because the primary ozonides formed from the ozone addition antiperiplanar-MVE are more stable and the energy barriers corresponding to transition states are lower. The intereonversion between the primary ozonides formed from the ozone addition to antiperiplanar-MVE is the most accessible compared with the transformations between other primary ozonides. The cleavage of the primary ozonides mainly leads to the formation of the CH2OO, which is in agreement with the experimental estimates. The calculated overall rate constant for the ozone-initiated reactions is 4.8× 10^-17 cm^3/（molecule.s） at 298.15 K, which agrees with the experimental value for ethyl vinyl ether.
文摘This letter reports a study on producing gas-phase O 2(a 1Δ) by decomposition of triphenyl phosphite ozonide ((C 6H 5O) 3PO 3, TPPO 3) under a number of reaction conditions. For the first time, the cooperative emission at wavelengths 634 and 703 nm of O 2(a 1Δ) generated by TPPO 3 decomposition are observed. Specifically, under the condition of catalyzed decomposition by pyridine of TPPO 3 solution in CFCl 3 at low temperature, the emission spectrum is the same as that from the basic hydrogen peroxide plus chlorine reaction. This shows the feasibility of developing a new source for singlet delta oxygen. However, in the experiments of spontaneous decomposition of solid TPPO 3 and thermal decomposition of TPPO 3 solution on a high temperature surface, the spectra have a wide emission background around the 634 and 703 nm peaks, which indicates the production of some excited species than O 2(a 1△). Besides, there are about 2%～3%CO and 1.5%～2%CO 2 in the gaseous products together with a small amount of insoluble in acetone solid product, which imply that other than the formation of O 2(a 1△) and TPPO by unimolecular decomposition of TPPO 3, more complicated reactions may take place. The study of the reaction mechanism, the optimization of the expertise of O 2(a 1△) generation by TPPO 3 decomposition as well as measurement of absolute concentration of O 2(a 1△) are under way.
