UVA Self-Photosensitized Oxygenation of b-Ionone

CLAUDIO D. BORSARELLI*1, MIRTA MISCHNE2, AGUSTINA LA VENIA2 AND FAUSTINO E. MORA´N VIEYRA1

PHOTOCHEMISTRY AND PHOTOBIOLOGY

Wiley

Año: 2007 vol. 83 p. 1313 - 1318

0031-8655

The steady-state 1 UVA (350 nm) photolysis of (E)-b-ionone (1) in aerated toluene solutions was studied by 1H NMR spectroscopy. The formation of the 1,2,4-trioxane (2) and 5,8-endoperoxide (5) derivatives in the ratio of 4:1 was observed. Time-resolved laser induced experiments at 355 nm, such as laser-flash photolysis, photoacoustic and singlet oxygen 1O2 phosphorescence detec- tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 The formation of the 1,2,4-trioxane (2) and 5,8-endoperoxide (5) derivatives in the ratio of 4:1 was observed. Time-resolved laser induced experiments at 355 nm, such as laser-flash photolysis, photoacoustic and singlet oxygen 1O2 phosphorescence detec- tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 aerated toluene solutions was studied by 1H NMR spectroscopy. The formation of the 1,2,4-trioxane (2) and 5,8-endoperoxide (5) derivatives in the ratio of 4:1 was observed. Time-resolved laser induced experiments at 355 nm, such as laser-flash photolysis, photoacoustic and singlet oxygen 1O2 phosphorescence detec- tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 The formation of the 1,2,4-trioxane (2) and 5,8-endoperoxide (5) derivatives in the ratio of 4:1 was observed. Time-resolved laser induced experiments at 355 nm, such as laser-flash photolysis, photoacoustic and singlet oxygen 1O2 phosphorescence detec- tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 1 UVA (350 nm) photolysis of (E)-b-ionone (1) in aerated toluene solutions was studied by 1H NMR spectroscopy. The formation of the 1,2,4-trioxane (2) and 5,8-endoperoxide (5) derivatives in the ratio of 4:1 was observed. Time-resolved laser induced experiments at 355 nm, such as laser-flash photolysis, photoacoustic and singlet oxygen 1O2 phosphorescence detec- tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 The formation of the 1,2,4-trioxane (2) and 5,8-endoperoxide (5) derivatives in the ratio of 4:1 was observed. Time-resolved laser induced experiments at 355 nm, such as laser-flash photolysis, photoacoustic and singlet oxygen 1O2 phosphorescence detec- tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 tion, confirmed the formation of the excited triplet state of 1 with a quantum yield FT = 0.50 as the precursor for the generation of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 of singlet oxygen 1O2 ( D = 0.16) and the isomeric a-pyran derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with rate constants of 1.0 · 106 and 2.5 · 108 rate constants of 1.0 · 106 and 2.5 · 108 derivative (3), which was a reaction intermediate detected by NMR. In turn, the reaction of 1O2 with 1 and 3 occurred with