Vasiliou AnGayle K, Hu Hui, Cowell Thomas W, Whitman Jared C, Porterfield Jessica, Parish Carol A
Department of Chemistry and Biochemistry, Middlebury College , Middlebury, Vermont 05753, United States.
Department of Chemistry, Gottwald Center for the Sciences, University of Richmond , Richmond, Virginia 23713, United States.
J Phys Chem A. 2017 Oct 12;121(40):7655-7666. doi: 10.1021/acs.jpca.7b07582. Epub 2017 Oct 2.
The thermal decomposition mechanism of thiophene has been investigated both experimentally and theoretically. Thermal decomposition experiments were done using a 1 mm × 3 cm pulsed silicon carbide microtubular reactor, CHS + Δ → Products. Unlike previous studies these experiments were able to identify the initial thiophene decomposition products. Thiophene was entrained in either Ar, Ne, or He carrier gas, passed through a heated (300-1700 K) SiC microtubular reactor (roughly ≤100 μs residence time), and exited into a vacuum chamber. The resultant molecular beam was probed by photoionization mass spectroscopy and IR spectroscopy. The pyrolysis mechanisms of thiophene were also investigated with the CBS-QB3 method using UB3LYP/6-311++G(2d,p) optimized geometries. In particular, these electronic structure methods were used to explore pathways for the formation of elemental sulfur as well as for the formation of HS and 1,3-butadiyne. Thiophene was found to undergo unimolecular decomposition by five pathways: CHS → (1) S═C═CH + HCCH, (2) CS + HCCCH, (3) HCS + HCCCH, (4) HS + HCC-CCH, and (5) S + HCC-CH═CH. The experimental and theoretical findings are in excellent agreement.
噻吩的热分解机理已通过实验和理论进行了研究。热分解实验是使用一个1毫米×3厘米的脉冲碳化硅微管反应器进行的，CHS + Δ → 产物。与以往的研究不同，这些实验能够识别出噻吩的初始分解产物。噻吩被夹带在氩气、氖气或氦气载气中，通过一个加热到300 - 1700 K的碳化硅微管反应器（停留时间约≤100微秒），然后进入真空室。产生的分子束通过光电离质谱和红外光谱进行探测。还使用CBS - QB3方法，采用UB3LYP/6 - 311++G(2d,p)优化几何结构，对噻吩的热解机理进行了研究。特别是，这些电子结构方法被用于探索元素硫形成的途径以及HS和1,3 - 丁二炔形成的途径。发现噻吩通过五条途径进行单分子分解：CHS → (1) S═C═CH + HCCH，(2) CS + HCCCH，(3) HCS + HCCCH，(4) HS + HCC - CCH，以及(5) S + HCC - CH═CH。实验和理论结果吻合得非常好。
