Air Pollution Research Center, University of California , Riverside, California 92521, United States.
Environ Sci Technol. 2011 Mar 1;45(5):1859-65. doi: 10.1021/es103207k. Epub 2011 Feb 10.
Furan and alkylfurans are present in the atmosphere from direct emissions and in situ formation from other volatile organic compounds. The OH radical-initiated reactions of furan and alkylfurans have been proposed as relatively clean in situ sources of unsaturated 1,4-dicarbonyls, some of which are otherwise not readily available. Using a relative rate method, rate constants at 296 ± 2 K for the gas-phase reactions of OH radicals with 2- and 3-methylfuran, 2,3- and 2,5-dimethylfuran, and Z- and E-3-hexene-2,5-dione have been measured, of (in units of 10(-11) cm(3) molecule(-1) s(-1)): 2-methylfuran, 7.31 ± 0.35; 3-methylfuran, 8.73 ± 0.18; 2,3-dimethylfuran, 12.6 ± 0.4; 2,5-dimethylfuran, 12.5 ± 0.4; Z-3-hexene-2,5-dione, 5.90 ± 0.57; and E-3-hexene-2,5-dione, 4.14 ± 0.02. Products of the OH radical-initiated reaction of 2,5-dimethylfuran were investigated, with 3-hexene-2,5-dione being formed with molar yields of 24 ± 3% in the presence of NO and 34 ± 3% in the absence of NO. Direct air sampling atmospheric pressure ionization mass spectrometry showed the formation of additional products of molecular weight 114, attributed to CH(3)C(O)CH ═ CHC(O)OH and/or 5-hydroxy-5-methyl-2-furanone, and 128, attributed to CH(3)C(O)OC(CH(3)) = CHCHO.
呋喃和烷基呋喃存在于大气中，来自直接排放和其他挥发性有机化合物的原位形成。OH 自由基引发的呋喃和烷基呋喃反应被认为是不饱和 1,4-二羰基化合物的相对清洁的原位来源，其中一些在其他情况下不易获得。使用相对速率法，在 296 ± 2 K 下测量了 OH 自由基与 2-和 3-甲基呋喃、2,3-和 2,5-二甲基呋喃以及 Z-和 E-3-己烯-2,5-二酮的气相反应的速率常数，（单位为 10(-11) cm(3) molecule(-1) s(-1))：2-甲基呋喃，7.31 ± 0.35；3-甲基呋喃，8.73 ± 0.18；2,3-二甲基呋喃，12.6 ± 0.4；2,5-二甲基呋喃，12.5 ± 0.4；Z-3-己烯-2,5-二酮，5.90 ± 0.57；和 E-3-己烯-2,5-二酮，4.14 ± 0.02。研究了 OH 自由基引发的 2,5-二甲基呋喃反应的产物，在存在 NO 的情况下，3-己烯-2,5-二酮的形成摩尔产率为 24 ± 3%，在不存在 NO 的情况下为 34 ± 3%。直接空气采样大气压电离质谱显示形成了分子量为 114 的其他产物，归因于 CH(3)C(O)CH ═ CHC(O)OH 和/或 5-羟基-5-甲基-2-呋喃酮，以及分子量为 128 的产物，归因于 CH(3)C(O)OC(CH(3)) = CHCHO。
