Reactions within p-difluorobenzene/methanol heterocluster ions: a detailed experimental and theoretical investigation.
Reactions within p-difluorobenzene/methanol heterocluster ions: a detailed experimental and theoretical investigation.
复制标题
对二氟苯/甲醇杂簇离子内的反应：详细的实验和理论研究。
DOI：
10.1021/jp808413c
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
Garvey,JamesF
中科院分区：
文献类型：
--
作者：
Shores,KevinS;Charlebois,JayP;Chiang,Chi-Tung;DeLeon,RobertL;Freindorf,Marek;Furlani,ThomasR;Garvey,JamesF
The reactivity ofp-difluorobenzene/methanol cluster ions has been investigated by using triple quadrupole mass spectrometry and DFT calculations. The present study was performed in light of a recent investigation ofp-difluorobenzene/methanol (P = F-C6H4-F and M = CH3OH) heterocluster ions where the solvent-catalyzed formation ofp-fluoroanisole (A = CH3O-C6H4-F) was observed in P(M)2+clusters andnotin PM+clusters. The results of our mass selected cluster ion study and theoretical calculations confirm that a single extra molecule of methanol can lower the reaction activation energy barrier in agreement with previous work for smaller clusters (PM+and P(M)2+). However, we also observe that P(M)3+and P(M)4+clusters undergo evaporative loss of neutral methanol to establish the P(M)2+cluster before reacting. P(M)n>4+clusters are capable of reacting through multiple pathways, in some cases generating a 1,4-dimethoxybenzene (B = CH3O-C6H4-OCH3) product via two separate substitution reactions within the same cluster ion. DFT calculations were employed to model the structures of the parent cluster ions, and transition state calculations were used to evaluate the activation energy for thep-fluoroanisole-forming substitution reaction. The calculations suggest that the reaction proceeds through a transition state containing a six-member hydrogen-bonded ring involving a reacting methanol and a second methanol that significantly lowers the activation energy.
