1324
Russ.Chem.Bull., Int.Ed., Vol. 58, No. 6, June, 2009
Mekhaev et al.
Dechlorination of hydrolyzed PCB was carried out in an
aqueous solution of NaOH. After neutralization, the reaction
mixture was extracted twice with dichloromethane, the extract
was dried and analyzed by GLC.
Hydrogenation of biphenyl on Pd—C was carried out similarly
to dechlorination for 10 h. The catalyst was separated by
centrifugation, the solution was concentrated and analyzed
by 1Н NMR and GLC. The experiment was repeated with
refluxing.
palladium are the most active. The carbonꢀcovered sysꢀ
tems are the most stable. The possibility of using catalysts
for hydrodechlorination of PCB was shown. The Pd—C
catalyst can be employed for dechlorination of hydroꢀ
lyzed PCB.
Experimental
Hydrolysis of PCB. To a reactor equipped with a reflux
condenser and a mechanical stirrer, 4.5 mL of DMSO, 1.5 g
of 50% aqueous solution of KOH (13 mmol) and 1.06 g of PCB
(3.25 mmol) were placed. The reaction mixture was heated
at 140—150 °C for 3 h with constant stirring. After cooling,
the mixture was diluted with 23 mL of water and 1.18 mL of
conc. HCl (34%, d = 1.17) was added. Extraction was carried
out with dichloromethane (2×10 and 5 mL). The extract was
washed with water (3×20 mL) and dried with sodium sulfate for
24 h. The solvent was evaporated in vacuum. The obtained
product was analysed by GLC and 1Н NMR .
Nanopowders of metals and metal—carbon nanocomposites
were prepared by gasꢀphase synthesis. For preparing metal
nanoparticles, the unit developed at the Institute of Metal
Physics, Urals Branch of the Russian Academy of Sciences, was
used, which allow carring out contactless levitation melting in a
highꢀfrequency field and evaporation of the molten metal in
a stream of an inert gas. Similarly, in the environment containing
butane and argon, metal nanocrystalline samples (Fe, Ni, Pd),
covered with carbon were synthesized. Condensation of metal
vapor in a colder part of the reactor near the evaporator zone
was accompanied by hydrocarbon decomposition on a surface
of metal nanoparticles that formed. The carbon coating thus
produced prevented further agglomeration of the metal nanoꢀ
particles.
Gas—liquid chromatography was carried out on an Agilent
7890A MS 5975C Inert XL chromatograph with a quartz capillary
column HPꢀ5ꢀMS (30 m × 0.26 mm × 0.25 μm). 1Н NMR
spectra were recorded with a spectrometer AVANCE DRXꢀ400
(Bruker BioSpin) (400 MHz) in DMSOꢀd6. The elemental
analysis of catalysts’ surface was performed with an analytical
complex on the basis of a scanning electron microscope VEGA
II LMH and a system of energyꢀdispersive microanalysis INCA
ENERGY. The powder structure was studied by electron
microscopes Jemꢀ200CX and Philips CMꢀ30. For ultrasonic
disintegration, an ultrasonic homogenizer Sonoplus HD 3200
was used.
Dechlorination of PCB on Pd—C. Ethanol (10 mL), Pd—C
(0.2 g), PBC (0.2 g, 0.61 mmol), and NaOH (0.1424 g, 3.05 mmol)
were placed in a reactor equipped with a reflux condenser.
Hydrogen was passed (30—40 mL min–1) for 5 h through a
magnetically stirred mixture. The catalyst was separated by
centrifugation. Based on the results of titration of an aliquot of
the reaction solution, the extent of dechlorination was deterꢀ
mined. A portion of the reaction mixture (5 mL) was treated
with 3 ml of 0.1 М HCl, potassium carbonate (8 g) was added
to the emulsion formed, and the resulting mixture was kept for
24 h. The upper layer was separated, concentrated to 0.5 mL and
analyzed by 1Н NMR and GLC.
This work was carried out with a financial support
of the Ministry of Industry, Energy, and Science of
the Sverdlovsk region (contract № OFꢀ4/08) and the
Russian Foundation for Basic Research (Project
no. 08ꢀ03ꢀ99045ꢀr_ofi).
References
1. L. N. Zanaveskin, V. A. Averyanov, Usp. Khim. (in Russian),
1998, 67, 788 [Russ. Chem. Rev. (Engl. Transl.), 1998, 68].
2. E. LorencꢀGrabowska, J. Yperman, G. Gryglewicz, S. Hoste,
R. Carieer, Fuel, 2006, 85, 374.
3. K. Venkatachalam, X. Arzuaga, N. Chopra, V. G. Gavalas,
J. Xu, D. Bhattacharyya, B. Henning, L. G. Bachas, J. Hazard.
Mater., 2008, 159, 483.
4. Weygand—Hilgetag, Organish—chemishe Experimentier Kunst,
Johann Ambrosius Barth, Leipzig, 1964.
5. O. N. Zabelina, V. E. Kirichenko, M. G. Pervova, Yu. G.
Yatluk, V. I. Saloutin, Analitila i Kontrol (in Russian), 2006,
10, 32.
6. O. N. Zabelina, V. E. Kirichenko, M. G. Pervova, Yu. G.
Yatluk, V. I. Saloutin, Zh. Prikl. Khim. (in Russian), 2006, 79,
801 [Russ. J. Appl. Chem. (Engl. Transl.), 2006, 79, 791].
Similarly, dechlorination of other aromatic chloro derivatives
was carried out with the use of catalysts on the basis of Fe and Ni
nanopowders. For magnetic stirring, the reaction vessel was
placed in a sychronous micromotor DSD2ꢀP1 instead of a rotor.
Received April 9, 2009;
in revised form April 27, 2009