Wiberg Kenneth B, Wang Yi-gui, Wilson Shaun M, Vaccaro Patrick H, Cheeseman James R
Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, USA.
J Phys Chem A. 2005 Apr 21;109(15):3448-53. doi: 10.1021/jp0407371.
(S)-(-)-2-chloropropionitrile has been prepared from (S)-(+)-alanine, and the ORD curves have been obtained in several solvents and in the gas phase. A reaction field extrapolation of the solution data to the gas phase led to an estimated value of [alpha]D = -21 degrees, whereas the interpolated gas phase value is -8 degrees. The specific rotation was found to be temperature dependent in ethylcyclohexane solution over the range 0-100 degrees C. Although rotation of the methyl group leads to large calculated effects on the specific rotation, it does not lead to the temperature dependence. Rather, a low frequency mode at 224 cm(-1) was found to be responsible. This is a mixed mode involving methyl torsion and C-C[triple bond]N bending. The specific rotations calculated at the B3LYP/aug-cc-pVDZ level including electric field dependent functions are in very good agreement with the measured gas phase values.
(S)-(-)-2-氯丙腈由(S)-(+)-丙氨酸制备而成，并且已在多种溶剂及气相中获得了旋光色散（ORD）曲线。将溶液数据外推至气相的反应场方法得出[α]D的估计值为-21°，而内插得到的气相值为-8°。发现在0至100°C范围内，比旋光度在乙基环己烷溶液中与温度有关。尽管甲基的旋转对比旋光度有较大的计算影响，但它并不会导致温度依赖性。相反，发现224 cm⁻¹处的低频模式是造成这种情况的原因。这是一种涉及甲基扭转和C≡N弯曲的混合模式。在包含电场相关函数的B3LYP/aug-cc-pVDZ水平上计算得到的比旋光度与测量的气相值非常吻合。
