Probing the Methyl Torsional Barriers of the E and Z Isomers of Butadienyl Acetate by Microwave Spectroscopy

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• 作者：Atef Jabri ; Vinh Van ; Dr. Ha Vinh Lam Nguyen ; Prof.Dr. Wolfgang Stahl and Dr. Isabelle Kleiner
• 刊名：ChemPhysChem
• 出版年：2016
• 出版时间：September 5, 2016
• 年：2016
• 卷：17
• 期：17
• 页码：2660-2665
• 全文大小：805K
• ISSN：1439-7641

文摘

The Fourier transform microwave spectra of the E and Z isomers of butadienyl acetate were measured in the frequency range from 2 to 26.5 GHz under molecular-jet conditions. The most stable conformer of each isomer, in which all heavy atoms are located in a symmetry plane, was identified after analyzing the spectrum by comparison with the results from quantum-chemical calculations. The barriers to internal rotation of the acetyl methyl group were found to be 149.1822(20) and 150.2128(48) cm⁻¹ for the E and Z isomers, respectively, which are similar to that of vinyl acetate. A comparison between two theoretical approaches treating internal rotation, the rho axis method and combined axis method, was also performed. The influence of the alkyl R chain on the methyl torsional barriers in CH₃-COOR acetates was explored.