Moreno Juan Ramón Avilés, Ureña Francisco Partal, González Juan Jesús López
University of Jaén, Department of Physical and Analytical Chemistry, Campus Las Lagunillas, Jaén, E-23071, Spain.
Phys Chem Chem Phys. 2009 Apr 14;11(14):2459-67. doi: 10.1039/b815541k. Epub 2009 Feb 12.
S-(-)-Limonene oxide (4-isopropenyl-1-methyl-7-oxabicyclo[4.1.0]heptane) is a secondary metabolite and an atmospheric pollutant product of oxidation of other terpenes, such as limonene and alpha-pinene, among others. For the first time, a theoretical study of the molecular structure and a theoretical and experimental analysis of the infrared and Raman spectra of this chemical species are presented. Theoretical calculations reveal the existence of two conformers depending on the position of the isopropenyl group (axial and equatorial) and twelve rotamers (six equatorials and six axials), with the six equatorial ones as the most stable (around 97%) on the basis of Boltzmann's distribution law. In the current work, from a reliable assignment of the IR and Raman spectra and with the help from the study of the VCD spectrum of the title compound, five rotamers have been detected experimentally in the liquid phase. The present work reveals that IR, Raman and VCD are helpful complementary techniques to characterize flexible systems, as terpenes, which present several conformers.
S-(-)-氧化柠檬烯(4-异丙烯基-1-甲基-7-氧杂双环[4.1.0]庚烷)是一种次生代谢产物,也是其他萜类化合物(如柠檬烯和α-蒎烯等)氧化产生的大气污染物。本文首次对该化学物质的分子结构进行了理论研究,并对其红外光谱和拉曼光谱进行了理论与实验分析。理论计算表明,根据异丙烯基的位置(轴向和赤道向)存在两种构象异构体以及十二种旋转异构体(六种赤道向和六种轴向),基于玻尔兹曼分布定律,六种赤道向异构体最为稳定(约97%)。在当前工作中,通过对红外光谱和拉曼光谱的可靠归属,并借助对标题化合物振动圆二色光谱的研究,在液相中实验检测到了五种旋转异构体。本工作表明,红外光谱、拉曼光谱和振动圆二色光谱是表征具有多种构象的柔性体系(如萜类化合物)的有用互补技术。