Mendeleev Commun., 2008, 18, 322–323
dissociative interaction of carbon tetrachloride with metal nano-
particles accompanied by formation of a metal monochloride:
Table 2 Yield of C Cl depending on the metal concentration (mol%) in
2 6
the specimen (reaction time, 30 h; T = 30 °C).
M + CCl = MCl + CCl .
(1)
Silver
Copper
4
3
The subsequent recombination of trichloromethyl radicals results
in the final reaction product, viz., hexachloroethane:
Metal concen-
Yield (%) with
Metal concen-
Yield (%) with
tration (mol%) respect to theory tration (mol%) respect to theory
0.41
0.78
2.0
25
49
48
1.7
3.0
3.4
0.60
1.0
0.82
·
CCl + ·CCl = C Cl .
(2)
3
3
2
6
The probable overall stoichiometric reaction equation is
a
Table 3 Yield of C Cl depending on the reaction time (T = 30 °C).
2
6
2
M + 2CCl = 2MCl + C Cl .
4 2 6
(3)
Cu1
Yield (%)
Cu2
Yield (%)
Ag1
Yield (%)
Ag2
Yield (%)
If the process occurs completely, 0.5 mol of hexachloro-
ethane should be formed per a mole of consumed metal. X-ray
diffraction data (Figure 2) suggest that almost 100% silver nano-
particles are converted into silver monochloride. The possibility
Time/h
with respect with respect with respect with respect
to theory
to theory
to theory
to theory
0
10
20
0
—
—
0.82
1.09
1.12
0
0
0
+
of oxidation of nanoscale silver particles (Ag ® Ag ) with CCl
0.37
0.70
0.84
—
12.0
24.0
44.2
60.6
67.0
11.5
23.8
48.3
62.6
68.2
4
15
has also been shown elsewhere. The yield of hexachloroethane
is somewhat lower than the theoretical value with respect to the
metal; it depends on the metal concentration in a complex way.
The yield of hexachloroethane increases up to 2–3 mol% with
an increase in the metal concentration in the reaction system con-
taining excess carbon tetrachloride (Table 2). A further increase
in the metal concentration does not increase the product yield,
presumably due to secondary reactions occurring on the surfaces
of nanoparticles.
3
5
0
0
200
—
aFor compositions of the specimens, see Table 1.
with carbon tetrachloride in a liquid phase at room temperature
to give hexachloroethane. The process selectivity is close to
100%. The product yield with respect to the metal ranges from
a few percent for copper nanoparticles to 60–70% for silver nano-
particles. It increases with an increase in the metal concentra-
tion from 0.4 to 2 mol% silver and from 1 to 3 mol% copper.
Table 3 shows the yields of the reaction product (C Cl ) as a
2
6
function of the reaction time. The maximum yield of hexa-
chloroethane is 60–70% for specimens containing 1–2 mol%
silver; it is almost reached in 50 h at 30 °C. For copper speci-
mens (3–4 mol% of the metal) the yield is up to 1% under the
conditions used.
We are grateful to N. N. Shchegolev for electron microscopic
analyses and to G. V. Ivanov and V. S. Gaviko for X-ray dif-
fraction studies.
The small yield of hexachloroethane in copper-containing
specimens may be due to side reactions of nanoscale copper and
to the presence of reaction products with dissolved oxygen; these
partially consist of copper oxide, which can react with carbon
tetrachloride to give carbon dioxide. The Debye crystallogram
of a specimen of copper nanoparticles after exposure to carbon
tetrachloride shows a small percentage of the copper mono-
chloride (CuCl) phase. However, the strongest phase of the
This work was supported in part by the Russian Foundation
for Basic Research (grant no. 08-03-00798a).
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q/°
Figure 2 X-Ray diagram of the solid phase of the reaction mixture of
silver nanoparticles with carbon tetrachloride. Phase composition: AgCl,
97.4%; Ag, 2.6%.
Received: 28th April 2008; Com. 08/3131
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