Night-time atmospheric chemistry of methacrylates
Night-time atmospheric chemistry of methacrylates
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DOI：
10.1007/s11356-011-0448-x
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发表时间：
2011-02
影响因子：
5.8
通讯作者：
M. S. Salgado;M. Paz Gallego-Iniesta;M. P. Martín;A. Tapia;B. Cabañas
中科院分区：
文献类型：
--
作者：
M. S. Salgado;M. Paz Gallego-Iniesta;M. P. Martín;A. Tapia;B. Cabañas
背景、目的和范围甲基丙烯酸酯是一种α，β-不饱和酯，广泛应用于高分子塑料和树脂的生产。NO3自由基反应的动力学信息特别缺乏，为了确定这些化合物在大气中的寿命并评估这些反应对臭氧和其他光氧化剂形成的影响，有必要很好地了解这些化合物的所有大气氧化过程。（N2作为浴气），使用气相色谱（GC）-火焰离子化检测器（FID）作为检测系统。采用固相微萃取（SPME）-气相色谱-质谱（GC-MS）联用技术和傅立叶变换红外光谱（FTIR）技术对产物进行分析（单位：cm 3分子-1s-1）：甲基丙烯酸甲酯+ NO3=（3.55 ± 0.62）× 10−15，甲基丙烯酸乙酯+ NO3=（5.42 ± 1.90）× 10−15，甲基丙烯酸丁酯+ NO3=（7.87 ± 3.86）× 10−15。在GC-MS分析中，丙酮酸甲酯、丙酮酸乙酯和丙酮酸丁酯/丁醇分别被鉴定为主要降解产物。硝酸盐化合物也被确定在FTIR study.DiscussionThe反应性增加的取代和与链的烷基基团在−C（O）OR。亲电加成机制被认为是主要的降解过程。对大气寿命的估计清楚地表明，甲基丙烯酸酯的主要大气损失过程是它们在白天与羟基自由基的反应。NO3和臭氧是夜间的主要氧化剂。建议和展望详细的产物分析，包括量化可以阐明丁醇生成甲基丙烯酸丁酯反应的机理。
Background, aim, and scopeMethacrylates are α, β-unsaturated esters that are widely used in the polymer plastics and resins production. Kinetic information of NO3radical reactions is especially scarce and a good understanding of all the atmospheric oxidation processes of these compounds is necessary in order to determine lifetimes in the atmosphere and to evaluate the impact of these reactions on the formation of ozone and other photooxidants.Materials and methodsThe experiments have been carried out using the relative technique in a static Teflon reactor at room temperature and atmospheric pressure (N2as bath gas) using gas chromatography (GC)-flame ionization detection (FID) as detection system. Products were analyzed using solid phase microextraction (SPME)-GC-mass spectrometry (MS) technique and Fourier transform infrared spectroscopy (FTIR) using air as bath gas.ResultsThe following rate coefficients were obtained (in cm3molecule−1s−1): methyl methacrylate + NO3= (3.55 ± 0.62) × 10−15, ethyl methacrylate + NO3= (5.42 ± 1.90) × 10−15, butyl methacrylate + NO3= (7.87 ± 3.86) × 10−15. Methylpyruvate, ethylpyruvate, and butylpyruvate/butanol were identified as main degradation products respectively in the GC-MS analysis. Nitrates compounds were also identified in the FTIR study.DiscussionThe reactivity increases with the substitution and with the chain of the alkyl group in −C(O)OR. An electrophilic addition mechanism is proposed as dominant degradation process. Estimations of the atmospheric lifetimes clearly indicate that the dominant atmospheric loss process for methacrylate esters is their daytime reaction with the hydroxyl radical. NO3and ozone are the main oxidants at night time.Recommendations and perspectivesA detailed products analysis including quantification could elucidate the mechanism for butanol generation for butyl methacrylate reaction.