Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 Ta-Hsueh Rd., Hsinchu 30010, Taiwan.
J Chem Phys. 2012 Aug 28;137(8):084310. doi: 10.1063/1.4745075.
The reactions of chlorine and hydrogen atoms with trans-1,3-butadiene in solid para-hydrogen (p-H(2)) were investigated with infrared (IR) absorption spectra. When a p-H(2) matrix containing Cl(2) and trans-1,3-butadiene was irradiated with ultraviolet light at 365 nm, intense lines at 650.3, 809.0, 962.2, 1240.6 cm(-1), and several weaker ones due to the trans-1-chloromethylallyl radical, ●(CH(2)CHCH)CH(2)Cl, appeared. Observed wavenumbers and relative intensities agree with the anharmonic vibrational wavenumbers and IR intensities predicted with the B3PW91/6-311++g(2d, 2p) method. That the Cl atom adds primarily to the terminal carbon atom of trans-1,3-butadiene is in agreement with the path of minimum energy predicted theoretically, but in contrast to the reaction of Cl + propene in solid p-H(2) [J. Amicangelo and Y.-P. Lee, J. Phys. Chem. Lett. 1, 2956 (2010)] in which the addition of Cl to the central C atom is favored, likely through steric effects in a p-H(2) matrix. A second set of lines, intense at 781.6, 957.9, 1433.6, 2968.8, 3023.5, 3107.3 cm(-1), were observed when the UV-irradiated Cl(2)/trans-1,3-butadiene/p-H(2) matrix was further irradiated with IR light from a SiC source. These lines are assigned to the trans-1-methylallyl radical, ●(CH(2)CHCH)CH(3), produced from reaction of 1,3-butadiene with a H atom resulted from the reaction of Cl atoms with solid p-H(2) exposed to IR radiation.
用红外（IR）吸收光谱研究了氯原子和氢原子与固态仲氢（p-H(2)）中反式-1,3-丁二烯的反应。当含有 Cl(2)和反式-1,3-丁二烯的 p-H(2) 基质在 365nm 的紫外光下照射时，在 650.3、809.0、962.2、1240.6cm(-1)处出现强谱线，以及几个由于反式-1-氯甲基丙烯基自由基，●(CH(2)CHCH)CH(2)Cl，而出现的较弱谱线。观察到的波数和相对强度与用 B3PW91/6-311++g(2d, 2p)方法预测的非谐振动波数和 IR 强度一致。氯原子主要添加到反式-1,3-丁二烯的末端碳原子上，这与理论上预测的最小能量路径一致，但与氯在固态 p-H(2)中与丙烯的反应[J. Amicangelo 和 Y.-P. Lee, J. Phys. Chem. Lett. 1, 2956 (2010)]相反，在该反应中，Cl 添加到中心 C 原子上是有利的，可能是通过 p-H(2) 基质中的空间位阻效应。当用 SiC 源的 IR 光进一步照射紫外光照射的 Cl(2)/反式-1,3-丁二烯/p-H(2)基质时，观察到第二组谱线，在 781.6、957.9、1433.6、2968.8、3023.5、3107.3cm(-1)处强度很高，这些谱线被分配给反式-1-甲基丙烯基自由基，●(CH(2)CHCH)CH(3)，由 Cl 原子与暴露于 IR 辐射的固态 p-H(2)反应生成的 H 原子与 1,3-丁二烯反应产生。
