Phthalocyanineꢀcatalyzed chlorination of arenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 8, August, 2008
1679
the chlorination of oꢀxylene. According to the mass specꢀ
trometric data, up to five chlorine atoms incorporate into
the macrocycle due to further passing of chlorine through
the reaction mixture during 5 h of xylene chlorination.
We studied the transformations of complex 2 during
the chlorination reactions. Diphthalocyanine, as well as
other phthalocyanine complexes, undergo changes upon
its introduction into the reaction of toluene chlorination.
Its absorption spectrum exhibits more considerable changes
than those observed in the spectra of the monophthaloꢀ
cyanine complexes. The Q band is split, and the treatꢀ
ment of the reaction mixture with triethylamine after the
reaction transforms this band into the shape characteristic
of the neutral form of diphthalocyanines with the bathoꢀ
chromic shift by 17 nm. It is most likely that the twoꢀdeck
phthalocyanine is oxidized with chlorine, inducing the Q
band splitting, and then it is chlorinated remaining in the
oxidized form. As a result, the neutral diphthalocyanine
containing the chlorine atoms in the macrocycles is
formed after the treatment with triethylamine.
All solvents were distilled prior to use.
The phthalocyanine catalysts (cobalt, nickel, chromium, and
palladium tetra(tertꢀbutyl)phthalocyanines and terbium octaꢀ
(
tertꢀbutyl)diphthalocyanine) were synthesized using standard
7
,8
procedures.
General experimental procedure. The controlled chlorine flow
–1
(
10—50 mL min ) was passed through a solution of a phthaloꢀ
cyanine catalyst in a substrate or carbon tetrachloride containing
10% of the substrate. After the end of the reaction, a chlorine
excess was removed with argon blown through the reaction
mixture. The reaction mixture was chromatographed on silica
gel (Merck, 60—200 mesh) with nꢀhexane to separate the
catalyst. After the reaction products were removed, the catalyst
was eluted with benzene and analyzed by spectrophotometry
and mass spectrometry. The qualitative and quantitative comꢀ
positions of the reaction mixtures were analyzed on a gasꢀliquid
chromatograph using individual standards and by mass spectroꢀ
metry and chromatography combined with mass spectrometry.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 05ꢀ03ꢀ33202)
and the Presidium of the Russian Academy of Sciences
(Program “Development of Methods for the Synthesis of
Chemical Substances and Design of New Materials”).
In summary, we showed that the phthalocyanine comꢀ
plexes of different structures are efficient catalysts for the
chlorination of the aromatic compounds. The transforꢀ
mations of the catalysts were also studied under the reacꢀ
tion conditions.
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3
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3
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–
1
2
50 °С with a rate of 20 deg min
.
The mass spectra of the organic substrates and phthalocyanine
complexes were recorded on a Finnigan MAT INCOSꢀ50
instrument (EI, 70 eV; chemical ionization).
Received April 9, 2008;
in revised form May 28, 2008