Organic Process Research & Development
Article
3
%) was dissolved in 1,2,4-trimethylbenzene (150 mL) to
which 3 (1.40 g, 5.0 mmol) was added by stirring at 25 °C for 1
min under a nitrogen atmosphere. After 4 h, the purity of C60
was >98%. Insoluble impurities were removed by filtration. C60
was crystallized by adding 2-propanol (600 mL) as a poor
solvent at 40 °C, and the resulting precipitate was collected by
filtration and dried under reduced pressure (100 °C, 1 mmHg)
to yield 1.87 g of pure C60 (purity, 98.8%; yield, 94%).
Purification Using Triphenylphosphine (4). C O-
6
0
containing [60]fullerene (2.02 g; 2.80 mmol; C , 97%;
6
0
C O, 3%) was dissolved in 1,2,4-trimethylbenzene (150 mL)
60
to which 4 (1.31 g, 5.0 mmol) was added by stirring at 100 °C
for 1 min under a nitrogen atmosphere. After 4 h, the purity of
C was >98%. Insoluble impurities were removed by filtration.
60
Figure 6. Purity of C60 obtained from C O-containing [60]fullerene
of various concentrations by using trin-butylphosphine 1 (2.0 equiv).
60
C60 was crystallized by adding 2-propanol (600 mL) as a poor
solvent at 40 °C, and the resulting precipitate was collected by
filtration and dried under reduced pressure (100 °C, 1 mmHg)
to yield 1.82 g of pure C60 (purity, 98.3%; yield, 90%).
from the viewpoint of solubility, 1,2,4-trimethylbenzene was
most suitable for this purification method.
EXPERIMENTAL SECTION
■
CONCLUSION
We have developed a facile purification method that reduces
60]fullerene containing C O to obtain high-purity C (up to
9.9%) at room temperature. The effective reduction of C O
60
using trialkylphosphines such as tri-n-butylphosphine and tri-n-
octylphosphine provides a pragmatic [60]fullerene purification
method. We determined the optimal reaction conditions for
this method. Furthermore, experimental results showed that, as
compared to the conventional chromatography method, the
present method is facile, efficient, and easy to scale up. Thus,
this method can be used for industrial-scale separation. We
believe that our purification method will contribute greatly to
future developments in the field of fullerene science and
technology.
■
Methods and Materials. Trialkylphosphinestri-n-butyl-
phosphine (1), tri-n-octylphosphine (2), and tricyclohexyl-
phosphine (3)and triphenylphosphine (4) (Figure 1) were
used for the experiment. An unrefined C O-containing
[
60 60
9
6
0
[
60]fullerene (C , 97%; C O, 3%) sample was supplied by
60 60
Frontier Carbon Corporation. 1, 2, and 4 were purchased from
Tokyo Chemical Industry Corporation, and 3 was purchased
from Sigma-Aldrich Corporation. 1,2,4-Trimethylbenzene and
2
-propanol were purchased from Wako Pure Chemical
Industries and used as received. The sample was produced by
the combustion synthesis method, and it mainly contained the
desired C60 and small amounts of fullerene oxides (composed
mostly of C O, as indicated by the HPLC results shown in
60
Figure 2).
All the reactions were carried out under a nitrogen
atmosphere, and the resulting products were analyzed by
reversed-phase HPLC (column, YMC-Pack ODS-AM; particle
size, 3 μm; i.d., 4.6 mm × 75 mm; flow rate, 1.0 mL/min;
eluent, methanol/toluene = 6/4; detection wavelength, 290
nm).
AUTHOR INFORMATION
Corresponding Author
■
Notes
The authors declare no competing financial interest.
Purification Using Tri-n-butylphosphine (1). C O-
60
containing [60]fullerene (2.01 g; 2.79 mmol; C , 97%;
60
ACKNOWLEDGMENTS
C O, 3%) was dissolved in 1,2,4-trimethylbenzene (150 mL)
■
60
to which 1 (34 mg, 0.17 mmol) was added by stirring at 25 °C
for 1 min under a nitrogen atmosphere. After 1 h, the purity of
C was >99%. Insoluble impurities were removed by filtration.
We thank Prof. Eiichi Nakamura for the technical consultation
offered during the course of this work. We also acknowledge
the useful suggestions provided by the Mitsubishi Chemical
Group Science and Technology Research Center, Inc. Y.M.
thanks the Funding Program for Next Generation World-
Leading Researchers.
60
C60 was crystallized by adding 2-propanol (600 mL) as a poor
solvent at 40 °C, and the resulting precipitate was collected by
filtration and dried under reduced pressure (100 °C, 1 mmHg)
to yield 1.88 g of pure C60 (purity, 99.7%; yield, 94%).
Purification Using Tri-n-octylphosphine (2). C O-
REFERENCES
60
■
containing [60]fullerene (2.00 g; 2.78 mmol; C , 97%;
60
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C O, 3%) was dissolved in 1,2,4-trimethylbenzene (150 mL)
60
to which 2 (62 mg, 0.17 mmol) was added by stirring at 25 °C
for 1 min under a nitrogen atmosphere. After 1 h, the purity of
C60 was >99% (Figure 3). Insoluble impurities were removed
by filtration. C60 was crystallized by adding 2-propanol (600
mL) as a poor solvent at 40 °C, and the resulting precipitate
was collected by filtration and dried under reduced pressure
(
1
(
(
100 °C, 1 mmHg) to yield 1.85 g of pure C60 (purity, 99.9%;
yield, 93%).
Purification Using Tricyclohexylphosphine (3). C O-
60
containing [60]fullerene (2.00 g; 2.78 mmol; C , 97%; C O,
6
0
60
6
45
dx.doi.org/10.1021/op200376w | Org. Process Res. Dev. 2012, 16, 643−646