Photochemical & Photobiological Sciences
Paper
4-methoxybenzyl alcohol derivatives: role of the sensitizer,
Phys. Chem. Chem. Phys., 2008, 10, 200–210.
Notes and references
1 (a) K. N. Rankin, Q. Liu, J. Handri, H. Yee, N. A. Noureldin
and D. G. Lee, Mechanisms for the oxidation of para-substi-
tuted benzyl alcohols and benzyl ethers by permanganate,
Tetrahedron Lett., 1998, 39, 1095–1098; (b) W. Wang, T. Li
and G. Attardo, Synthetic study of selective benzylic oxi-
dation, J. Org. Chem., 1997, 62, 6598–6602; (c) E. Baciocchi,
A. Piermattei, C. Rol, R. Ruzzuconi and G. V. Sebastiani,
One electron oxidations of benzyl and 2-phenylethyl phenyl
8 V. Wintgens, J. Kossanyi and M. Sinalty, Emission proper-
ties of a series of pyrylium salts. Temperature effects, Bull.
Soc. Chim. Fr., 1983, 11, 115–120.
9 N. Miyagawa, T. Karatsu, Y. Futami, T. Kunihiro, A. Kiyota
and A. Kitamura, Photoinduced electron-transfer reaction
of (Phenylazo)triphenylmethane (PAT). Behavior of gen-
erated trityl cation, Bull. Chem. Soc. Jpn., 1996, 69,
3325–3329.
ethers. The fate of the intermediate radical cations, Tetra- 10 B. Branchi, M. Bietti, G. Ercolani, M. A. Izquierdo,
hedron, 1989, 22, 7049–7062.
M. A. Miranda and L. Stella, The role of aromatic radical
cations and benzylic cations in the 2,4,6-triphenylpyrylium
tetrafluoroborate photosensitized oxidation of ring-meth-
oxylated benzyl alcohols in CH2Cl2 solution, J. Org. Chem.,
2004, 69, 8874–8885.
2 (a) I. Leray, M. Aydim, C. Otterans, J. L. Habib Jiwan and
J. Ph. Soumillion, Photoinduced electron transfer sensiti-
zation of anisyl ether cleavage: studies in homogeneous
solution and at the surface of one or two solids, J. Photo-
chem. Photobiol. A, 2000, 132, 43–52; (b) N. D’Alessandro, 11 Similar products were obtained in the oxidation of 4-meth-
M. Mella, E. Fasani, L. Toma and A. Albini, The photo-
chemical reaction between 1,4-dicyanonaphthalene and
benzyl ethers, Tetrahedron, 1991, 27, 5043–5050.
3 (a) M. Bettoni, T. Del Giacco, C. Rol and G. V. Sebastiani,
Photo-oxidative dealkylation of α-alkylbenzyl methyl ethers
induced by titanium dioxide in acetonitrile, J. Phys. Org.
Chem., 2006, 19, 18–24; (b) T. Del Giacco, C. Rol and
oxybenzyl alcohol derivatives photosensitized by N-methyl-
quinolinium tetrafluoroborate.7.
12 The deuterated solvent allowed us to analyze the mixture,
not only by gas chromatographic analysis, but with
1H-NMR spectra too, without the necessity to evaporate the
solvent, that should have implied the loss of volatile pro-
ducts such as acetone and tert-butanol.
G. V. Sebastiani, Involvement of adsorption effects in the 13 D. Jacobi and W. Abraham, Generation of aryltropylium
TiO2-sensitized photooxidation rate of benzylic derivatives
in CH3CN, J. Phys. Org. Chem., 2003, 16, 127–132;
ions by photoinduced and thermal electron transfer, Tetra-
hedron Lett., 1996, 37, 7493–7496.
(c) E. Baciocchi, M. Bietti, M. I. Ferrero, C. Rol and 14 M. Fujita, A. Ishida, S. Takamuku and S. Fukuzumi,
G. V. Sebastiani, Photo-oxidative fragmentation of some
alpha-alkyl substituted 4-methoxybenzyl alcohols and
methyl ethers sensitized by TiO2, Acta Chem. Scand., 1998,
52, 160–164.
4 (a) E. Baciocchi, M. Bietti and O. Lanzalunga, Mechanistic
aspects of β-bond-cleavage reactions of aromatic radical
cations, Acc. Chem. Res., 2000, 33, 243–251; (b) E. Baciocchi,
Addition versus oxygenation of alkylbenzenes with
10-methylacridinium ion via photoinduced electron trans-
fer, J. Am. Chem. Soc., 1996, 118, 8566–8574.
15 E. Baciocchi, M. Bietti and S. Steenken, Kinetic and
product studies on the side-chain fragmentation of 1-aryl-
alkanol radical cations in aqueous solution: oxygen versus
carbon acidity, Chem.–Eur. J., 1999, 5, 1785–1793.
T. Del Giacco and F. Elisei, Proton-transfer reactions of 16 R. Akaba, H. Sakuragi and K. Tokumaru, Detection of
alkylaromatic cation radicals. The effect of α-substituents
on the kinetic acidity of p-methoxytoluene cation radicals,
J. Am. Chem. Soc., 1993, 115, 12290–12295; (c) A. Anne,
P. Hapiot, J. Moiroux, P. Neta and J.-M. Savéant, Dynamics
dimeric radical cations of trans-stilbene in 2,4,6-triphenyl-
pyrylium tetrafluoroborate-sensitized electron transfer
reactions in dichloromethane, Chem. Phys. Lett., 1990, 174,
80–84.
of proton transfer from cation radicals. Kinetic and ther- 17 R. A. McClelland, C. Chan, F. Cozens, A. Modro and
modynamic acidities of cation radicals of NADH analogues,
J. Am. Chem. Soc., 1992, 114, 4694–4701.
5 J. H. Penn and Z. Lin, Substituent dependence of the
π-acceptor induced bond cleavage reactions of benzyl
phenyl ethers, J. Org. Chem., 1990, 55, 1554–1559; R. Lines
S. Steenken, Laser flash photolysis generation, spectra, and
lifetimes of phenylcarbenium ions in trifluoroethanol and
hexafluoroisopropyl alcohol. On the UV spectrum of the
benzyl cation, Angew. Chem., Int. Ed. Engl., 1991, 30,
1337–1339.
and J. H. P. Utley, Electro-organic reactions. Part 10. Mecha- 18 I. R. Gould, D. Ege, J. E. Moser and S. Farid, Efficiencies of
nism of anodic cleavage of dibenzyl ether, J. Chem. Soc.,
Perkin Trans. 2, 1977, 803–809.
6 T. Del Giacco, L. Lipparoni, M. Ranchella, C. Rol and
G. V. Sebastiani, Mechanism of the oxidation of benzylic
photoinduced electron-transfer reactions: role of the
Marcus inverted region in return electron transfer within
geminate radical–ion pairs, J. Am. Chem. Soc., 1990, 112,
4290–4301.
ethers photosensitized by a 2,4,6-triphenylpyrylium salt, 19 K. P. Dockery, J. P. Dinnocenzo, S. Farid, J. L. Goodman,
J. Chem. Soc., Perkin Trans. 2, 2001, 1802–1807.
7 T. Del Giacco, A. Faltoni and F. Elisei, Anomalous reactivity
of radical cations produced by photosensitized oxidation of
I. R. Gould and W. P. Todd, Nucleophile-assisted cleavage
of benzyltrialkylsilane cation radicals, J. Am. Chem. Soc.,
1997, 119, 1876–1883.
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