Atmospheric aqueous phase radical chemistry of the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic acid and acrylic acid--kinetics and product studies.
Atmospheric aqueous phase radical chemistry of the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic acid and acrylic acid--kinetics and product studies.
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DOI：
10.1039/c3cp54859g
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发表时间：
2014-03
期刊：
影响因子：
--
通讯作者：
L. Schöne;J. Schindelka;Edyta Szeremeta;T. Schaefer;D. Hoffmann;K. Rudzinski;R. Szmigielski;H. He
中科院分区：
文献类型：
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作者：
L. Schöne;J. Schindelka;Edyta Szeremeta;T. Schaefer;D. Hoffmann;K. Rudzinski;R. Szmigielski;H. He
利用激光闪光光解技术和反速率动力学方法研究了异戊二烯氧化产物甲基丙烯醛、甲基乙烯基酮、甲基丙烯酸和丙烯酸与水溶液中羟基、硝酸根和硫酸根阴离子反应的动力学和机理。采用高效液相色谱/质谱法对产物进行分析。动力学研究表明，羟基自由基的反应性最高，其次是硫酸根和硝酸根自由基。对于甲基丙烯醛和甲基乙烯基酮，在298 K下测定了下列速率常数：K（OH+甲基丙烯醛）=（9.4 ± 0.7）× 10（9）M（-1）s（-1），k（OH+甲基乙烯基酮）=（7.3 ± 0.5）× 10（9）M（-1）s（-1），k（NO3+甲基丙烯醛）=（4.0 ± 1.0）× 10（7）M（-1）s（-1），k（NO3+甲基乙烯基酮）=（9.7 ± 3.4）× 10（6）M（-1）s（-1），k（SO 4（-）+甲基丙烯醛）=（9.9 ± 4.9）× 10（7）M（-1）s（-1），k（SO 4（-）+甲基乙烯基酮）=（1.0 ± 0.2）× 10（8）M（-1）s（-1）。得到了OH、NO_3和SO_4（-）与甲基丙烯醛、甲基乙烯基酮、甲基丙烯酸和丙烯酸反应的温度和pH依赖性以及Arrhenius参数，并进行了讨论。对OH自由基诱导的甲基丙烯醛和甲基乙烯基酮的氧化产物进行了研究。在甲基丙烯醛+ OH的反应中，丙酮醛和羟基丙酮被确定为第一氧化产物，产率分别为0.099和0.162。丙酮醛主要由甲基乙烯基酮氧化生成，产率为0.052。对于这两种前体化合物的乙醇醛的形成，首次观察到的产率为0.051和0.111的甲基丙烯醛和甲基乙烯基酮的氧化，分别。此外，高度官能化的C4化合物从两种前体化合物的氧化确定，但第一次为甲基乙烯基酮。基于已知的过氧自由基反应机理开发了反应方案。第一代异戊二烯氧化产物的水相转化可以潜在地有助于重要的羰基和二羰基组分的对流层水相预算，这些组分预期有助于aqSOA的形成。
Kinetic and mechanistic studies were conducted on the isoprene oxidation products methacrolein, methyl vinyl ketone, methacrylic and acrylic acid reacting with hydroxyl and nitrate radicals and sulfate radical anions in aqueous solution by use of the laser flash photolysis technique and a reversed-rate method for kinetics. High-performance liquid chromatography/mass spectrometry was applied for product analysis. The kinetic investigations show the highest reactivity of the hydroxyl radical followed by sulfate and nitrate radicals. For methacrolein and methyl vinyl ketone the following rate constants have been determined at 298 K: k(OH+methacrolein) = (9.4 ± 0.7) × 10(9) M(-1) s(-1), k(OH+methyl vinyl ketone) = (7.3 ± 0.5) × 10(9) M(-1) s(-1), k(NO3+methacrolein) = (4.0 ± 1.0) × 10(7) M(-1) s(-1), k(NO3+methyl vinyl ketone) = (9.7 ± 3.4) × 10(6) M(-1) s(-1), k(SO4(-)+methacrolein) = (9.9 ± 4.9) × 10(7) M(-1) s(-1) and k(SO4(-)+methyl vinyl ketone) = (1.0 ± 0.2) × 10(8) M(-1) s(-1). Temperature and pH dependencies of the reactions of OH, NO3 and SO4(-) with methacrolein, methyl vinyl ketone, methacrylic and acrylic acid as well as Arrhenius parameters have been obtained and discussed. Product studies were performed on the OH radical induced oxidation of methacrolein and methyl vinyl ketone. In the reaction of methacrolein + OH methylglyoxal and hydroxyacetone were identified as first oxidation products with yields of 0.099 and 0.162. Methylglyoxal was primarily produced in the oxidation of methyl vinyl ketone with a yield of 0.052. For both precursor compounds the formation of glycolaldehyde was observed for the first time with yields of 0.051 and 0.111 in the oxidation of methacrolein and methyl vinyl ketone, respectively. Furthermore, highly functionalised C4 compounds were determined from the oxidation of both precursor compounds, but for the first time for methyl vinyl ketone. Reaction schemes were developed based on known peroxyl radical reaction mechanisms. The aqueous phase conversion of the first generation isoprene oxidation products can potentially contribute to tropospheric aqueous phase budgets of important carbonyl and dicarbonyl components which are expected to be conducive to the formation of aqSOA.