Abstract
Primary benzylic alcohols are selectively oxidized to the corresponding aromatic aldehydes by molecular oxygen at atmospheric pressure, under Br2 -HNO3 catalysis in a biphasic medium (1,2-dichloroethane-water, 5:1) at 60 °C. Under paragonable experimental conditions the aliphatic alcohols are oxidized to esters.
Key words
alcohols - aldehydes - bromine - nitric acid - aerobic oxidation
References
1 Larock RC.
Comprehensive Organic Transformations
NCH;
New York:
1999.
p.1234
2 Trost BM.
Fleming I.
Ley SV.
Comprehensive Organic Syntheses
Vol. 7:
Pergamon;
Oxford:
1991.
3 Amati A.
Dosnaldo G.
Zhao L.
Bravo A.
Fontana F.
Minisci F.
Bjørsvik .
Org. Process Res. Dev.
1998,
2:
261
4 Minisci F.
Recupero F.
Rodinò M.
Sala M.
Schneider A.
Org. Process Res. Dev.
2003,
7:
794
5 Cecchetto A.
Fontana F.
Minisci F.
Recupero F.
Tetrahedron Lett.
2001,
42:
6651
6 Minisci F.
Recupero F.
Peduli GF.
Lucarini M.
J. Mol. Catal. A
2003,
204:
63
7a Zhan BZ.
Thompson A.
Tetrahedron
2004,
60:
2917
7b Sheldon RA.
Arends JWCE.
Brink GS.
Dijksman A.
Acc. Chem. Res.
2002,
35:
774
8a Mallat T.
Baiker A.
Chem. Rev.
2004,
104:
3037
8b Vinke P.
de Wit D.
de Goede ATJW.
van Bekkum H.
Stud. Surf. Sci. Catal.
1992,
72:
1
9
Standard Experimental Procedure: A mixture of benzyl alcohol (10 mmol), Br2 (2 mmol), HNO3 (3 mmol) in 20 mL of 1,2 dichloroethane and 4 mL of H2 O (biphasic system) was stirred for 24 h under oxygen atmosphere at 60 °C. p -chlorobenzaldehyde as internal standard. Conversion of benzyl alcohol was quantitative and benzaldehyde was formed in 96% yield.
10a under air and
10b under N2 atmosphere.
11 Deminov ET.
Denosava TG.
Handbook of Antioxidants
CRC Press;
New York:
2000.
12a Atkinsen R.
Baulsh DL.
Cox RA.
Hampson RF.
Kerr JA.
Rossi MJ.
Tral J.
J. Phys. Chem. Ref. Data
1999,
111:
4923
12b Luo YR.
Handbook of Bond Dissociation Energies in Organic Compounds
CRC Press;
New York:
2003.
p.62
