通过时间分辨X射线液体成像直接观察溶液中碘仿光解过程中瞬态形成的异构体
Direct Observation of a Transiently Formed Isomer During Iodoform Photolysis in Solution by Time-Resolved X-ray Liquidography.
作者信息
Ahn Chi Woo, Ki Hosung, Kim Joonghan, Kim Jeongho, Park Sungjun, Lee Yunbeom, Kim Kyung Hwan, Kong Qingyu, Moon Jiwon, Pedersen Martin Nors, Wulff Michael, Ihee Hyotcherl
机构信息
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST) , Daejeon 305-701, Republic of Korea.
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS) , Daejeon, 34141, Republic of Korea.
出版信息
J Phys Chem Lett. 2018 Feb 1;9(3):647-653. doi: 10.1021/acs.jpclett.7b03125. Epub 2018 Jan 22.
Photolysis of iodoform (CHI) in solution has been extensively studied, but its reaction mechanism remains elusive. In particular, iso-iodoform (iso-CHI-I) is formed as a product of the photolysis reaction, but its detailed structure is not known, and whether it is a major intermediate species has been controversial. Here, by using time-resolved X-ray liquidography, we determined the reaction mechanism of CHI photodissociation in cyclohexane as well as the structure of iso-CHI-I. Both iso-CHI-I and CHI radical were found to be formed within 100 ps with a branching ratio of 40:60. Iodine radicals (I), formed during the course of CHI photolysis, recombine nongeminately with either CHI or I. Based on our structural analysis, the I-I distance and the C-I-I angle of iso-CHI-I were determined to be 2.922 ± 0.004 Å and 133.9 ± 0.8°, respectively.
碘仿（CHI₃）在溶液中的光解已得到广泛研究，但其反应机理仍不清楚。特别是，异碘仿（iso-CHI₃-I）是光解反应的产物之一，但其详细结构尚不清楚，并且它是否是主要的中间物种一直存在争议。在此，通过使用时间分辨X射线液体成像技术，我们确定了碘仿在环己烷中的光解离反应机理以及异碘仿的结构。发现异碘仿和碘仿自由基均在100皮秒内形成，分支比为40:60。在碘仿光解过程中形成的碘自由基（I）与碘仿或碘非成对地重新结合。基于我们的结构分析，确定异碘仿的I-I距离和C-I-I角度分别为2.922±0.004 Å和133.9±0.8°。
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