Protonated 4-isopropyltropolone (H2L+) was produced by the addition of methanesulfonic or trifluoromethanesulfonic acid to 4-isopropyltropolone (hinokitiol: HL) dissolved in a protophobic aprotic solvent, acetonitrile, with poor solvation of anions and cations. The formation was confirmed by UV-visible and 13C NMR spectroscopy as well as theoretical calculations using the Gaussian03 quantum chemistry package. The 13C chemical shifts of all C-atoms in the seven-membered ring were properly assigned for H2L+ and HL as well as for the deprotonated species, L-. The influence of residual water in the organic solvent was regarded as negligible because such a water is in the "dihydrogen ether" condition.
ASJC Scopus subject areas
- Chemical Engineering(all)