Resonance Raman Studies of Benzene Derivatives with Methoxy Substitution: Conformational Symmetry-Breaking Effects

✍ Scribed by Horst B. Lueck; Bruce S. Hudson; Donald M. Friedrich; Marek Z. Zgierski

• Book ID: 101246055
• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 328 KB
• Volume: 28
• Category: Article
• ISSN: 0377-0486
• DOI: 10.1002/(sici)1097-4555(199706)28:6<455::aid-jrs123>3.0.co;2-c

✦ Synopsis

Resonance Raman intensities show that methoxy substitution induces considerable allowed character to the L a transition of benzene. In symmetric 1,3,5-trisubstituted benzene derivatives the induced allowed character should cancel by symmetry. However, in 1,3,5-trimethoxybenzene the resonance Raman spectrum shows a strong fundamental transition of the clear signature of an allowed transition. It is shown that this is due to the presence of a m 8 , conformer of 1,3,5-trimethoxybenzene in which one of the three methoxy groups is rotated relative to the other C s two. This is supported by ab initio calculations of conformational energy, induced transition moment and the splitting of the band.