Intermolecular Hydrogen Abstraction from Hydroxy Group and Alkyl by T1(ππ) of 1‑Chloro-4-nitronaphthalene
Intermolecular Hydrogen Abstraction from Hydroxy Group and Alkyl by T1(ππ) of 1‑Chloro-4-nitronaphthalene
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1-氯-4-硝基萘的T1(β)从羟基和烷基夺分子间氢
DOI：
10.1021/acs.jpca.7b11146
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
薛佳丹
中科院分区：
文献类型：
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作者：
Di Zhang;Peipei Jin;Meng Yang;Yong Du;Xuming Zheng;薛佳丹
利用纳秒瞬态吸收和理论计算研究了1-氯-4-硝基萘在有机溶剂中被激发时，由最低激发三重态（T1）从醇和1-萘酚中提取氢的过程。t1从1-萘酚羟基上的氢提取是通过电子转移和质子转移进行的，通过氢键相互作用，速率常数为~ 109M-1s-1。氢键在这个过程中是至关重要的，当增加1-萘酚的浓度时，t1的产率降低了一半。通过提高溶剂极性和氢键给体能力，可以减缓吸氢的速度。在醇溶剂中，1-氯-4-硝基萘的t1可以一步从烷基氢中提取H原子，速率常数为~ 104M-1s-1，并产生自由基中间体，最大吸收波长为368 nm。DFT计算结果表明，硝基上的两个氧都是吸氢的活性位点，两个自由基异构体形成的激活垒差仅为1.0 kcal/mol。
Nanosecond transient absorption and theoretical calculations have been used to investigate the intermolecular hydrogen abstractions from alcohols and 1-naphthol by the lowest excited triplet (T1) of 1-chloro-4-nitronaphthalene upon excitation of the compound in organic solvents. The hydrogen abstraction of T1from hydroxy group of 1-naphthol takes place through an electron transfer followed by a proton transfer through hydrogen bonding interaction with rate constants of ∼109M–1s–1. Hydrogen-bonding is crucial in this process, indicated by the observation of a half reduction for T1yield when increasing the concentration of 1-naphthol. The hydrogen abstraction in this way can be decelerated by increasing solvent polarity and hydrogen-bonding donor ability. The T1of 1-chloro-4-nitronaphthalene can undergo one-step H atom abstraction from alkyl hydrogen in alcoholic solvents, with rate constants of ∼104M–1s–1, and produce radical intermediates with the absorption maximum at 368 nm. DFT calculation results indicate both oxygens of the nitro group are active sites for hydrogen abstraction, and the difference of activation barriers for formation of two radical isomers is only 1.0 kcal/mol.