（E）－2－甲基－1，3－戊二烯的振动光谱及其稳定构象的研究

Studies of Molecular Conformation of (E)-2-Methyl-1,3-pentadiene with Vibrational Spectra

记录了（Ｅ）－２－二甲基－１，３－戊二烯的固、液、气态ＦＴＩＲ光谱（４００～４０００ｃｍ^（－１））和固、液态Ｒａｍａｎ光谱（５０～４０００ｃｍ^（－１）），观测了６８５及６５８ｃｍ^（－１）谱线的变温ＦＴＩＲ光谱（－７３～１０℃）．对所得谱图进行的指认分析发现，该化合物存在两种单键旋转构象异构体ｓ－ｔｒａｎｓ和ｓ－ｃｉｓ，由变温ＦＴＩＲ光谱峰强度随温度的变化得到这两种构象互变的ΔＨ~０和ΔＳ~０。

Vibrational spectra of (E)-2-methyl-1,3-pentadiene have been recorded over a range of temperature for three phases, and completely assigned.The investigation of a pair bands 658 and 686 cm￣(-1) by dynamic FTIR spectra shows that the compound existed as a mixture of s-trans and s-cis conformers of single bonding rotation. By means of observed changes of the peak intensities of FTIR spectra with variable temperature, the values of ΔH￣0 and ΔS￣0of the isomer inversion have been deduced to be 5.36 kJ/mol and 7. 66 J/mol* K respectively.