Spectroscopic and computational chemistry studies on terpene related compounds

• Main Author: Allpress, Stephanie Marie
• Other Authors: Evans, Corey ; Monks, Paul
• Published: University of Leicester 2016
• Subjects: 547
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.694168

The millimetre wave spectrum of linalool (C10H18O) was recorded and assigned in the region 48-63 GHz whilst the millimetre wave spectrum of verbenone (C10H14O) was recorded and assigned in the region 48-69 GHz. Calculations at the MP3/6-31++g(d,p) and B3LYP/aug-cc-pVTZ levels of theory on both molecules, identified around 60 conformers of linalool and a single conformer of verbenone. The lowest energy conformers of linalool and verbenone are in good agreement with the fitted rotational and centrifugal distortion constants. Calculations using the B3LYP functional with the 6-31G(d,p) and 6-31++G(d,p) basis sets investigated the barrier for internal rotation of the methyl groups to explore the potential splitting of the spectral lines. The barrier for internal rotation for linalool (305 cm-1) resulted in the splitting of the spectral lines, whereas the barrier for internal rotation for verbenone (741 cm-1) did not result in such splitting. There have been no previous theoretical studies examining the products of the ozonolysis of terpinolene. The reaction mechanism for the ozonolysis of terpinolene has been explored at the B3LYP/6-31++G(d,p) and MPW1K/6-31++G(d,p) levels of theory. Single point calculations of the energy minima, transition state structures and possible reaction products were conducted at the MPW1K/6-31++G(3df,3dp) in order to improve the electronic energies. Work was also carried out on a White-type multi-traversal absorption cell. The old 4 m cell possessed a leak, which inhibits it from being used to study terpinolene ozonolysis products over prolonged time periods. Alterations to improve this system were discussed and resulted in the design and construction of a new 64 m absorption cell in which to study these ozonolysis products.