Kinetics and product study of the OH- and NO2-initiated oxidation of 2,4-hexadiene in the gas phase
Kinetics and product study of the OH- and NO2-initiated oxidation of 2,4-hexadiene in the gas phase
复制标题
OH 和 NO2 引发的 2,4-己二烯气相氧化的动力学和产物研究
DOI：
10.1021/jp034053p
复制
发表时间：
2003
影响因子：
2.9
通讯作者：
T. Wallington
中科院分区：
文献类型：
--
作者：
M. Jenkin;M. Sørensen;M. D. Hurley;T. Wallington
用长光程傅里叶变换红外光谱（FTIR）研究了2，4-己二烯在296 K和700 Torr下的OH-和NO2-引发氧化反应动力学和产物。采用相对速率法测定了2，4-己二烯/CH 3 ONO/NO/空气混合物的光解速率常数k（OH +2，4-己二烯）=（1.76 ′ 0.58）× 10 - 10 cm 3 molecule - 1 s - 1 . OH引发氧化2，4-己二烯得到乙醛、反式巴豆醛和2，5-二甲基呋喃，摩尔收率分别为（30.6 ′ 5.0）%、（12.9 ′ 2.0）%和（5.6 ′ 1.0）%。这些产品表明，OH引发的氧化的2，4-己二烯的收益，至少部分地，通过类似于那些报道的1，3-丁二烯和异戊二烯的途径。由2，4-己二烯在过量NO2存在下的准一级衰变，导出k（NO2 + 2，4-己二烯）=（3.11 ′ 0.18）× 10 - 19 cm 3 molecule - 1 s - 1.反应的化学计量和产品进行了研究，在没有O2的存在下，在O2的存在下，在O2和NO的存在下。反应机理与观察一致。在NO和O2的存在下，NO2引发的化学反应导致NO向NO2的转化，并以显着的产率形成HOx自由基，从而通过与NO2和OH的反应发生2，4-己二烯的去除。结果与HOT产率高达0.75 ′ 0.05一致，取决于实验条件。NO与OH和NO2与2，4-己二烯反应生成过氧自由基的反应中，硝酸根生成通道占（25 ′ 5）%。结果的影响范围内的共轭二烯的大气化学进行了讨论。作为这项工作的一部分，确定了NO 2与1，3-丁二烯和苯乙烯以及NO与2，4-己二烯反应的速率系数：K（NO 2 + 1，3-丁二烯）=（2.54 '0.15）x 10 - 2 0，k（NO 2 +苯乙烯）=（1.4' 0.3）x 10 - 2 0，且k（NO +2，4-己二烯）≤ 2 × 10 - 2 1 cm 3 molecule - 1 s - 1。
The kinetics and products of the OH- and NO 2 -initiated oxidation of 2,4-hexadiene have been investigated at 296 K and 700 Torr by long-path Fourier transform infrared (FTIR) spectroscopy. Relative rate methods were employed for the photolysis of 2,4-hexadiene/CH 3 ONO/NO/air mixtures to measure k(OH + 2,4-hexadiene) = (1.76 ′ 0.58) x 10 - 1 0 cm 3 molecule - 1 s - 1 . The OH-initiated oxidation of 2,4-hexadiene gave acetaldehyde, trans-crotonaldehyde, and 2,5-dimethylfuran, with molar yields of (30.6 ′ 5.0)%, (12.9 ′ 2.0)%, and (5.6 ′ 1.0)%, respectively. These products suggest that the OH-initiated oxidation of 2,4-hexadiene proceeds, at least partially, by pathways analogous to those reported for 1,3-butadiene and isoprene. From the pseudo-first-order decay of 2,4-hexadiene in the presence of excess NO 2 , a value of k(NO 2 + 2,4-hexadiene) = (3.11 ′ 0.18) x 10 - 1 9 cm 3 molecule - 1 s - 1 was derived. The reaction stoichiometry and products were investigated in the absence of O 2 , in the presence of O 2 , and in the presence of O 2 and NO. Reaction mechanisms consistent with the observations are presented. In the presence of NO and O 2 , the NO 2 -initiated chemistry leads to NO-to-NO 2 conversion, and the formation of HO x radicals in significant yield, such that 2,4-hexadiene removal occurs by reaction with both NO 2 and OH. The results are consistent with HOT yields of up to 0.75 ′ 0.05, depending on the experimental conditions. The results also suggest that the nitrate forming channels account for (25 ′ 5)% of the reactions of NO with peroxy radicals formed from the reactions of both OH and NO 2 with 2,4-hexadiene. The implications of the results are discussed within the context of the atmospheric chemistry of conjugated dienes. As part of this work, rate coefficients were determined for the reactions of NO 2 with 1,3-butadiene and styrene and for NO with 2,4-hexadiene: k(NO 2 + 1,3-butadiene) = (2.54 ′ 0.15) x 10 - 2 0 , k(NO 2 + styrene) = (1.4 ′ 0.3) x 10 - 2 0 , and k(NO + 2,4-hexadiene) ≤ 2 × 10 - 2 1 cm 3 molecule - 1 s - 1 .