Oxidation of Metallic Copper
with Complexones in Organic Media
E. S. Klimov, O. A. Davydova, M. V. Buzaeva, V. V. Dubrovina, and E. N. Kalyukova
Ul’yanovsk State Technical University, Ul’yanovsk, Russia
Received March 17, 2010
Abstract—Direct oxidation of copper in organic media with complexones (sterically hindered o-quinones;
acetylacetone and pyridine as stabilizing ligands) was studied. From the complexes obtained, the initial
components can be regenerated.
ISSN 1070-4272, Russian Journal of Applied Chemistry, 2010, Vol. 83, No. 9, pp. 1657–1659. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © E.S. Klimov, O.A. Davydova, M.V. Buzaeva, V.V. Dubrovina, E.N. Kalyukova, 2010, published in Zhurnal Prikladnoi Khimii, 2010,
Vol. 83, No. 9, pp. 1561–1563.
Widely used copper etching solutions such as iron
chloride, copper chloride, ammonia, and persulfate
solutions lead to formation of environmentally
hazardous wastes. Wastewaters from etching enter-
prises contain heavy metal ions, ammonium salts, and
hydrogen peroxide. Utilization of spent solutions is
unprofitable . The use of organic reagents for
copper etching is practically unknown. One of ac-
ceptable ways to dissolve metals with a high ionization
potential is complexation.
In this study we examined the possibility of
dissolving metallic copper in organic media in the
presence of sterically hindered o-quinones.
The starting o-quinones were prepared by the
procedures described in . As complexones we used
3,5-di-tert-butyl-1,2-benzoquinone (Q) and tetra-
chloro-1,2-benzoquinone (Cl–Q); QH
denote the reduced forms of the o-quinones
(catechols), and (Cl–Q)Cu·2Рy denotes copper
tetrachlorocatecholate (D = Py):
The copper dissolution kinetics was studied by
monitoring the increase in the intensity of the ESR
signal of the paramagnetic copper ion . We used an
SE/Х-2543 radiospectrometer, with 2,2,6,6-tetra-
methylpiperidine-1-oxyl as reference. Because measu-
rement of the absolute concentrations of radicals in
ESR spectroscopy involves significant errors, we
measured relative changes in the ESR signal intensity
with time in evacuated systems.
Dissolution of metallic copper was performed as
(1) Degreased copper plate (1.6 g) was placed in a
solution of 3,5-di-tert-butyl-1,2-benzoquinone (5.5 g)
and acetylacetone (5.2 g) in 50 ml of THF. The
reaction mixture was refluxed for 6 h, and the
precipitated crystals of copper acetylacetonate were
filtered off, washed with THF, and dried. Yield of the
complex 4.6 g (70%). Amount of dissolved copper 1.1 g.
(2) To 2.15 g of tetrachloro-1,2-benzoquinone we
added a solution of 1.7 g of pyridine in 100 ml of THF.
A copper plate was placed in the solution (1.6 g). A
brown precipitate rapidly formed. The mixture was
refluxed for 2 h, and the precipitate of copper
tetrachlorocatecholate was filtered off, washed with
THF, and dried. Yield 4.0 g (90%). Amount of
dissolved copper 0.58 g.
Decomposition of the solid tetrachlorocatecholate
complex in a vacuum (Т > 120°С) leads to the
formation of the corresponding quinone, pyridine, and
metallic copper. Thermal decomposition of p-xylene
As stabilizing ligands we used acetylacetone
(АcАc) and pyridine (Рy) in THF solution.
Q, Cl-Q QH