Analysis of vibrational spectra of 3-halo-1-propanols CH(2)XCH(2)CH(2)OH (X is Cl and Br)

作者：Badawi Hassan M^*; Foerner Wolfgang

来源：Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy , 2008, 71(3): 1095-1101.

DOI：10.1016/j.saa.2008.03.002

• Conformational stability
• Potential energy curves
• Vibrational spectra
• Normal coordinate analyses
• Solvent effect
• 3-Chloro-1-propanol
• 3-Bromo-1-propanol

The conformational stability and the three rotor internal rotations in 3-chloro- and 3-bromo-1-propanols were investigated by DFT-B3LYP/6-311 +G** and ab initio MP2/6-311 + G**, MP3/6-311 + G** and MP4(SDTQ)//MP3/6-311 + G** levels of theory. On the calculated potential energy surface twelve distinct minima were located all of which were not predicted to have imaginary frequencies at the B3LYP level of theory. The calculated lowest energy minimum in the potential Curves of both molecules was predicted to correspond to the Gauche-gauche-trans (Ggt)conformer in excellent agreement with earlier microwave and electron diffraction results. The equilibrium constants for the conformational inter-conversion of the two 3-halo-1-propanols were calculated at the B3LYP/6-311 +G** level of calculation and found to correspond to an equilibrium mixture of about 32% Ggt, 18% Ggg1, 13% Tgt, 8% Tgg and 8% Gtt conformations for 3-chloro-1-propanol and 34% Ggt, 15% Tgt, 13% Gggl, 9% Tgg and 7% Gtt conformations for 3-bromo-1-propanol at 298.15 K. The nature of the high energy conformations was verified by carrying Out solvent experiments using formamide (epsilon = 109.5) and MP3 and MP4//MP3 calculations. The vibrational frequencies of each molecule in its three most stable forms were computed at the B3LYP level and complete vibrational assignments were made based on normal coordinate calculations and comparison with experimental data of the molecules.

• 出版日期2008-12-1
• 单位中国石油大学（北京）