Eskola Arkke J, Wojcik-Pastuszka Dorota, Ratajczak Emil, Timonen Raimo S
Laboratory of Physical Chemistry, PO Box 55 (A.I. Virtasen aukio 1), FIN-00014 University of Helsinki, Finland.
J Phys Chem A. 2006 Nov 9;110(44):12177-83. doi: 10.1021/jp064197e.
The kinetics of the CH2I + NO2, CH2Br + NO2, and CHBrCl + NO2 reactions have been studied at temperatures between 220 and 360 K using laser photolysis/photoionization mass spectrometry. Decays of radical concentrations have been monitored in time-resolved measurements to obtain reaction rate coefficients under pseudo-first-order conditions. The bimolecular rate coefficients of all three reactions are independent of the bath gas (He or N2) and pressure within the experimental range (2-6 Torr) and are found to depend on temperature as follows: k(CH2I + NO2) = (2.18 +/- 0.07) x 10(-11) (T / 300 K)(-1.45) (+/- 0.22) cm3 molecule(-1) s(-1) (220-363 K), k(CH2Br + NO2) = (1.76 +/- 0.03) x 10(-11) (T/300 K)(-0.86) (+/- 0.09) cm3 molecule(-1) s(-1) (221-363 K), and k(CHBrCl + NO2) = (8.81 +/- 0.28) x 10(-12) (T/300 K)(-1.55) (+/- 0.34) cm3 molecule(-1) s(-1) (267-363 K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measured bimolecular reaction rate coefficients are about +/-25%. In the CH2I + NO2 and CH2Br + NO2 reactions, the observed product is formaldehyde. For the CHBrCl + NO2 reaction, the product observed is CHClO. In addition, I atom and iodonitromethane (CH2INO2) or iodomethyl nitrite (CH2IONO) formations have been detected for the CH2I + NO2 reaction.
利用激光光解/光电离质谱法，在220至360K的温度范围内研究了CH2I + NO2、CH2Br + NO2和CHBrCl + NO2反应的动力学。在时间分辨测量中监测自由基浓度的衰减，以获得准一级条件下的反应速率系数。所有三个反应的双分子速率系数在实验范围（2 - 6 Torr）内与缓冲气体（He或N2）和压力无关，并且发现其与温度的关系如下：k(CH2I + NO2) = (2.18 ± 0.07) x 10(-11) (T / 300 K)(-1.45) (± 0.22) cm3 molecule(-1) s(-1)（220 - 363K），k(CH2Br + NO2) = (1.76 ± 0.03) x 10(-11) (T/300 K)(-0.86) (± 0.09) cm3 molecule(-1) s(-1)（221 - 363K），以及k(CHBrCl + NO2) = (8.81 ± 0.28) x 10(-12) (T/300 K)(-1.55) (± 0.34) cm3 molecule(-1) s(-1)（267 - 363K），不确定性以一标准偏差给出。测量的双分子反应速率系数的估计总不确定性约为±25%。在CH2I + NO2和CH2Br + NO2反应中，观察到的产物是甲醛。对于CHBrCl + NO2反应，观察到的产物是CHClO。此外，在CH2I + NO2反应中检测到了I原子以及碘硝基甲烷（CH2INO2）或碘代亚硝酸甲酯（CH2IONO）的形成。
