Jump to main content
Jump to site search
Access to RSC content Close the message box

Continue to access RSC content when you are not at your institution. Follow our step-by-step guide.


Issue 109, 2015
Previous Article Next Article

Sulfonated Schiff base copper(ii) complexes as efficient and selective catalysts in alcohol oxidation: syntheses and crystal structures

Author affiliations

Abstract

The reaction between 2-aminobenzenesulfonic acid and 2-hydroxy-3-methoxybenzaldehyde produces the acyclic Schiff base 2-[(2-hydroxy-3-methoxyphenyl)methylideneamino]benzenesulfonic acid (H2L·3H2O) (1). In situ reactions of this compound with Cu(II) salts and, eventually, in the presence of pyridine (py) or 2,2′-bipyridine (2,2′-bipy) lead to the formation of the mononuclear complexes [CuL(H2O)2] (2) and [CuL(2,2′-bipy)]·DMF·H2O (3) and the diphenoxo-bridged dicopper compounds [CuL(py)]2 (4) and [CuL(EtOH)]2·2H2O (5). In 2–5 the L2− ligand acts as a tridentate chelating species by means of one of the O-sulfonate atoms, the O-phenoxo and the N-atoms. The remaining coordination sites are then occupied by H2O (in 2), 2,2′-bipyridine (in 3), pyridine (in 4) or EtOH (in 5). Hydrogen bond interactions resulted in R22(14) and in R44(12) graph sets leading to dimeric species (in 2 and 3, respectively), 1D chain associations (in 2 and 5) or a 2D network (1). Complexes 2–5 are applied as selective catalysts for the homogeneous peroxidative (with tert-butylhydroperoxide, TBHP) oxidation of primary and secondary alcohols, under solvent- and additive-free conditions and under low power microwave (MW) irradiation. A quantitative yield of acetophenone was obtained by oxidation of 1-phenylethanol with compound 4 [TOFs up to 7.6 × 103 h−1] after 20 min of MW irradiation, whereas the oxidation of benzyl alcohol to benzaldehyde is less effective (TOF 992 h−1). The selectivity of 4 to oxidize the alcohol relative to the ene function is demonstrated when using cinnamyl alcohol as substrate.

Graphical abstract: Sulfonated Schiff base copper(ii) complexes as efficient and selective catalysts in alcohol oxidation: syntheses and crystal structures

Back to tab navigation

Supplementary files

Article information


Submitted
21 Sep 2015
Accepted
15 Oct 2015
First published
15 Oct 2015

RSC Adv., 2015,5, 90079-90088
Article type
Paper

Sulfonated Schiff base copper(II) complexes as efficient and selective catalysts in alcohol oxidation: syntheses and crystal structures

S. Hazra, L. M. D. R. S. Martins, M. F. C. Guedes da Silva and A. J. L. Pombeiro, RSC Adv., 2015, 5, 90079
DOI: 10.1039/C5RA19498A

Social activity

Search articles by author

Spotlight

Advertisements