Carrasco Erica, Meloni Giovanni
Department of Chemistry , University of San Francisco , San Francisco , California 94117 , United States.
Department of Physical and Chemical Sciences , Università degli Studi de L'Aquila , L'Aquila , Italy.
J Phys Chem A. 2018 Jul 26;122(29):6118-6133. doi: 10.1021/acs.jpca.8b04140. Epub 2018 Jul 17.
At 298 K the reactions of 2,5-dimethlyfuran + CH(XΠ) and + CD radicals were investigated using synchrotron radiation coupled with multiplexed photoionization mass spectrometry at the Lawrence Berkeley National Laboratory. Reaction products were characterized based on their photoionization spectra and kinetic time traces. The CBS-QB3 level of theory was used for all energy calculations, and potential energy surface scans were used to determine thermodynamically favorable reaction mechanisms. The two entrance pathways observed in the reactions are CH insertion within the C-O bond and CH addition to the π-bond system. Both yield initial 6-membered ring radical intermediates. Primary products from the CH addition pathway were observed at m/ z = 108, 66, and 42. The two CHO isomers at m/ z = 108 formed are 1,2,4-heptatrien-6-one and 3-hepten-5-yne-2-one. At m/ z = 66, the three CH isomers observed are 1,3-cyclopentadiene, 3-penten-1-yne (E), and 1-pent-4-yne. Ketene ( m/ z = 42) is also observed. From CH insertion entrance channel, the three CH isomers produced are 1,2,4-hexatriene (Z), 2-hexen-4-yne (E), and 1,3,4-hexatriene. Patterns of H-loss, CHO-loss, and CO-loss observed were also in agreement with trends observed in other similar studies. H-assisted isomerization pathways have been considered as well for the formation of m/ z = 66, 80, and 108 isomers.
在298 K时，劳伦斯伯克利国家实验室利用同步辐射结合多路光电离质谱对2,5 - 二甲基呋喃与CH(XΠ)和CD自由基的反应进行了研究。根据反应产物的光电离光谱和动力学时间轨迹对其进行了表征。所有能量计算均采用CBS - QB3理论水平，并通过势能面扫描来确定热力学上有利的反应机制。在反应中观察到的两条进入途径是CH插入C - O键内以及CH加成到π键体系。两者均产生初始的六元环自由基中间体。在m/z = 108、66和42处观察到了CH加成途径的主要产物。在m/z = 108处形成的两种CHO异构体是1,2,4 - 庚三烯 - 6 - 酮和3 - 庚烯 - 5 - 炔 - 2 - 酮。在m/z = 66处观察到的三种CH异构体是1,3 - 环戊二烯、3 - 戊烯 - 1 - 炔（E）和1 - 戊 - 4 - 炔。还观察到了乙烯酮（m/z = 42）。从CH插入进入通道产生的三种CH异构体是1,2,4 - 己三烯（Z）、2 - 己烯 - 4 - 炔（E）和1,3,4 - 己三烯。观察到的H损失、CHO损失和CO损失模式也与其他类似研究中观察到的趋势一致。对于m/z = 66、80和108异构体的形成，也考虑了H辅助异构化途径。
