465-36-1Relevant academic research and scientific papers
Sensory Importance and Mechanism of Photochemical Conversion of Carvone to Carvonecamphor in Ethanol-Water Mixtures
Refsgaard, Hanne H. F.,Nielsen, Bo R.,Skibsted, Leif H.
, p. 1177 - 1183 (2007/10/02)
Approximate odor thresholds for carvonecamphor, with camphor odor, and for the ester hexyl>acetate>, with sweet odor, were determined to be 2200-4100 and 1.8-2.5 ppb, respectively, by gas chromatographic effluent sniffing.The quantum yield of photochemical conversion of carvone to carvonecamphor showed no wavelength dependence but increased with decreasing ethanol content in ethanol-water mixtures: 0.049 +/- 0.008 mol*eistein-1 in 42percent ethanol (apparent activation energy of 19 kJ*mol-1) and 0.0033 +/- 0.00015 mol*einstein-1 in neat ethanol.The quantum yield of further conversion of carvonecamphor to the ester was approximately 0.1 mol*einstein-1.The triplet lifetime of carvone determined by laser flash spectroscopy in the absence of oxygen increased with decreasing ethanol content: 71 ns in neat, 76 ns in 80percent, and 98 ns in 42percent ethanol.Oxygen quenched the triplet excited state with kO2 ca.3*109 L*mol-1*s-1 whereas oxygen, piperylene, and diacetyl did not influence the photochemical conversion.Intramolecular electron transfer from an n?* singlet state of carvone is suggested to be responsible for the photocycloaddition reaction of carvone.Keywords: (+)-Carvone; carvonecamphor; ethyl 2-hexyl>acetate; odor thresholds; gas chromatography-olfactometry; photocycloaddition
