Laser Flash Photolysis of <i>tert</i>-Butyl Aroylperbenzoates: Kinetics of the Singlet and Triplet States and the Aroylphenyl Radicals<sup>1</sup>
作者:Bipin K. Shah、Douglas C. Neckers
DOI:10.1021/ja030231g
日期:2004.2.1
aroylperbenzoates (1−4) were studied by laser flash photolysis (LFP). LFP (380 nm, pulse width ∼350 fs) of 2 and 3 allowed direct observation of their singlet states, which showed broad absorption (λmax ∼ 625 nm; τ ∼ 20 and ∼7.9 ps, respectively). The triplet state of each (λmax ∼ 530−560 nm) rapidly dissociates by O−O cleavage as indicated by the short triplet lifetimes (e.g., triplet lifetime of 3 ∼0.74 ns). The
通过激光闪光光解 (LFP) 研究了叔丁基芳酰基过苯甲酸酯 (1-4)。2 和 3 的 LFP(380 nm,脉冲宽度 ∼350 fs)允许直接观察它们的单线态,显示出广泛的吸收(λmax ∼ 625 nm;τ ∼ 20 和 ∼7.9 ps,分别)。每个(λmax ∼ 530-560 nm)的三重态通过 O-O 裂解迅速解离,如三重态寿命短(例如,三重态寿命为 3 ∼0.74 ns)所示。从 1、2 和 4 的 355 nm LFP(脉冲宽度~7 ns)获得的~550 nm 吸收已分配给相应的芳酰基苯基。详细研究的两个代表性基团(4-苯甲酰基苯基 5 和 3-(4'-甲基苯甲酰基)苯基 6)显示出依赖于溶剂的寿命。已观察到这些自由基与各种猝灭剂(包括含双键单体)反应的绝对双分子速率常数在室温下在 CCl4 中为 7.56 × 107 至 1.68 × 109 M-1 s-1。芳酰基苯基自由基的可能结构和负责的转变