Article pubs.acs.org/jced
Fullerene Bromides C70Brn (n = 8, 10, 14) Synthesis and Identification and Phase Equilibria in the C70Brn (n = 8, 10, 14)/Solvent Systems Konstantin N. Semenov,*,† Nikolai A. Charykov,‡ and Andreii S. Kritchenkov† †
Saint-Petersburg State University, Universitetskii pr. 26, St. Petersburg, Russia, 198504 ILIP Ltd (Innovations of Leningrad Universities and Enterprises), Instrumentalnaya ul. 6, St. Petersburg, Russia, 197022
‡
S Supporting Information *
ABSTRACT: The paper presents experimental data on synthesis and identification (IR, UV spectra, TG, DTG, DTA analysis) of the fullerene bromides C70Brn (n = 8, 10, 14). The data on the temperature dependence of solubility in aromatic solvents (1,2-dichlorobenzene, benzene, 1-methylbenzene, 1,2-dimethylbenzene) in the temperature range (293 to 353 )K are presented and characterized; compositions of equilibrium solid phases in binary C70Brn (n = 8, 10, 14) + aromatic solvents system are determined.
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INTRODUCTION It is known that there are a sufficiently large number of methods of synthesis and identification of the light fullerenes C60 and C70 in literature,1,2 so on this point, we shall not dwell. Also, many papers are devoted to the study of solubility (including in polythermal conditions) of the light fullerenes C60 and C70 in various solvents.3−16 As a matter of fact, a significantly smaller number of works is dedicated to the synthesis and identification of derivatives of the light fullerenes C60 and C70, including bromoderivatives like CnBrm (n = 60, 70; m = 6, 8, 10, 24).17−19,24,25 A certain part of the works has been devoted to the study of solubility of the bromoderivatives C60 in various individual organic solvents,20,22,23 as well as in mixed aqueous-alcoholic solvents in isothermal conditions.21 To the best of our knowledge, there are no data on the solubility of the other bromoderivatives of the fullerene C70 in the literature. The aims of this work are the following: (i) the synthesis and identification of the C70 fullerene bromoderivatives C70Brn (n = 8, 10, 14) by methods of electronic, infrared spectroscopy and by thermogravimetric analysis; (ii) the study of the solubility of the bromoderivative in aromatic solvents (1,2-dichlorobenzene, benzene, 1-methylbenzene, 1,2-dimethylbenzene) in the temperature range (20 to 60) °C. Synthesis and identification of the light fullerene bromoderivatives (among other halogenoderivatives, C60Haln and C70Haln (Hal = F, Cl, Br, I; n = 6, 8, 10, 14, 24) is sufficiently convenient and at the same time actual for the following reasons: bromoderivatives can be easily obtained in almost quantitative yields under mild conditions without the use of aggressive reagents such as free halogens (fluorine and chlorine), fluoro- and chloro anhydrides of some mineral acids in the highest oxidation state of nonmetals; bromoderivatives of light fullerenes © 2013 American Chemical Society
are sufficiently thermally and chemically stable, in contrast to, for example iododerivatives (moreover, the reaction to produce iododerivatives is substantially reversible); further bromoderivatives can be used in organic synthesis (preparation of water-soluble fullerenoles24 such as C70(OH)n, or for example in polymerization reactions which are modified Wurtz−Fittig coupling reactions: C70Brn + n Li(Na, K, Rb, Cs, 1/2Mg, 1/2Ca...) → n LiBr + carbon polymer of C70
(1)
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EXPERIMENTAL SECTION For the current work we used the C70 fullerene (purity of 99.5 wt %) with the main determined admixture of C60 (about 0.5 wt %), by production of ILIP Ltd. (Innovations of Leningrad Universities and Enterprises, St. Petersburg). The other reagents used were reagent grade o-xylene, benzene, o-dichlorobenzene, 1-chloronaphthalene, and bromine (purchased from Vecton, St. Petersburg). The synthesis of the C70Br8 bromoderivatives was performed according to the method proposed in ref 24. For the synthesis the individual C70 fullerene (200 mg) was taken, to which 10 mL of Br2 was added. The resulting mixture was stirred at room temperature on a magnetic stirrer for (4 to 5) min to give a homogeneous solution. The resulting solution was distilled under vacuo (p ≈ 15 mmHg), to remove an excess of Br2, and a black crystalline precipitate of the bisolvate bromide C70Br8·2Br2 was formed. The precipitate was filtered on a filter paper “Sinyaja Lenta” and dried at 70 °C at 15 mmHg for the destruction of the solvate and the formation of the individual bromoderivatives Received: August 29, 2012 Accepted: February 18, 2013 Published: February 28, 2013 570
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Figure 1. Optical spectra of the C70Br8 (a), C70Br10 (b), and C70Br14 (c) in 1,2-dichlorobenzene (dashed line), 1,2-dimethylbenzene (dotted line), and benzene (dashed dotted line). D is the optical density; λ is the wavelength.
Figure 2. Concentration dependencies of the optical densities of solutions of C70Br8 (a), C70Br10 (b), and C70Br14 (c) in □, 1,2dichlorobenzene; ○, 1,2-dimethylbenzene; △, 1-chloronaphthalene; ▼, benzene. D is the optical density; S is a solubility of C70Brn (n = 8, 10, 14).
C70Br8 (yield ca. 73%). For the C70Br10 synthesis the mixture of the individual fullerene C70 (200 mg) and Br2 (10 mL) was stirred at room temperature on a magnetic stirrer for 48 h. After removal of Br2 under vacuo (p ≈ 15 mmHg), light yellow precipitate of the monosolvate C70Br10·Br2 was obtained in almost quantitative yield. The precipitate was filtered on a filter paper “Sinyaja Lenta” and dried at 70 °C at 15 mmHg for the destruction of the solvate and the formation of the individual bromoderivatives C70Br8 (yield 91%). The synthesis of C70Br14 was performed according to slightly modified method described in ref 25. To the individual fullerene C70 (25 mg) was added
3.2 mL of Br2. The reaction mixture was stirred under argon atmosphere for 8 days at (18 to 22) °C. Unreacted bromine was removed under vacuo 20 mmHg. The residue obtained was dried in air. The yield is almost quantitative (53.9 mg). The purity of the obtained compounds was determined using liquid chromatography method (chromatograph Lumachrom from Lumex, St. Petersburg, Russia) with the absorption detection. The purity of the C70Brn (n = 8, 10, 14) derivatives was equal to 99 wt %. The infrared spectra of the bromoderivatives C70Brn (n = 8, 10, 14) were recorded on the Shimadzu FTIR-8400S 571
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Table 1. Concentration Dependencies of the Optical Densities of Solutions of C70Br8, C70Br10, and C70Br14 in 1,2-Dichlorobenzene, 1,2-Dimethylbenzene, 1-Chloronaphthalene, and Benzene at 0.1 MPaa D/a.u.
S/g·L−1
C70Br8 + 1,2-Dichlorobenzene 0.702 0.0200 0.413 0.0109 0.223 0.0055 0.125 0.0027
a
w/%
0.0015 0.0008 0.0004 0.0002
C70Br10 + 1,2-Dichlorobenzene 0.054 1.5000 0.038 1.0375 0.019 0.7875 0.009 0.4001
0.1145 0.0792 0.0601 0.0305
C70Br14 + Benzene 1.100 0.0551 0.938 0.0440 0.475 0.0222 0.275 0.0111 0.151 0.0061
0.1251 0.1067 0.0540 0.0313 0.0172
D/a.u.
S/g·L−1
C70Br8 + 1,2-Dimethylbenzene 1.250 0.0325 0.888 0.0216 0.500 0.0108 0.263 0.0054 0.145 0.0027 C70Br10 + 1,2-Dimethylbenzene 1.401 0.0500 0.725 0.0250 0.375 0.0125 0.145 0.0037
w/%
D/a.u.
S/g·L−1
w/%
C70Br8 + 1-Chloronaphthalene 1.750 0.0450 1.100 0.0257 0.575 0.0129 0.325 0.0064 0.188 0.0032 C70Br10 + 1-Chloronaphthalene 1.910 0.0657 0.967 0.0328 0.500 0.0164 0.333 0.0082 0.166 0.0041
0.0037 0.0025 0.0012 0.0006 0.0003
0.0057 0.0028 0.0014 0.0004
D/a.u.
S/g·L−1
w/%
C70Br8 + Benzene 0.0038 0.0022 0.0011 0.0006 0.0003
1.638 1.263 0.663 0.350
0.0466 0.0350 0.0175 0.0088
0.0053 0.0040 0.0020 0.0010
C70Br10 + Benzene 0.0056 0.0028 0.0014 0.0007 0.0004
2.650 1.102 1.003 0.560 0.300
0.2101 0.0420 0.0350 0.0190 0.0095
0.0239 0.0048 0.0040 0.0022 0.0011
D is the optical density; S is the solubility of C70Brn (n = 8, 10, 14).
To test the feasibility of Bouguer−Lambert−Beer law we obtained the dependences of optical density on concentration at a wavelength λmax ≃ 379 nm for C70Br8 and C70Br10 bromoder1 ivatives and at a wavelength λ1max ≃ 330 nm for C70Br14 bromoderivative. The authors propose the following formula to calculate the concentrations of C70Brn (n = 8, 10, 14) in solution independently of the solvent:
spectrometer. The samples were deposited on top of a KBr pill. A comparison of the spectra (see Supporting Information) with those given in the literature showed their good agreement in the long-wave area of the spectra (ν̃ = 450/1100 cM−1).24,25 Moreover, bromoderivatives are characterized by almost the same characteristic absorption frequencies (varying intensity) in that area. Thus, according to our data, for example, there are well-defined triplets ν̃(C70Br8) ≈ 795 ↔ 776 ↔ 755 cm−1, ν̃(C70Br10) ≈ 796 ↔ 776 ↔ 749 cM−1, the same triplets, according to ref 24 have the following frequency coordinates: ν̃(C70Br8) ≈ 793 ↔ 777 ↔ 750 cm−1, ν̃(C70Br10) ≈ 793 ↔ 778 ↔ 752 cm−1. The same applies to the characteristic peaks at wavelengths ν̃(C70Br8) ≈ 577 ± 3, 672 ± 3, 1035 ± 5 cm−1 etc. In the case of C70Br14 in the most informative long-wave area of the spectrum the following main absorption peaks were revealed (ν̃ ≈ 1083, 1038, 890, 776, 584 cM−1). According to ref 25 the same peaks have the following frequency coordinates: (1080, 1040, 890, 776, 587 cM−1). The absorption spectra were obtained using the SPECORD M-32 spectrophotometer in quartz cuvettes “κB-1” 1 cm in width in the wavelength range (300 to 900) nm. The accuracy of wavelength maintenance was ± 0.5 nm, the photometric accuracy (ΔD) was equal to ± 0.005 (a.u.), and the absorption layer was 1 cm thick. The absorption spectra of C70Brn (n = 8, 10, 14) in some aromatic solvents (benzene, o-xylene, o-dichlorobenzene, 1-chloronaphthalene) are presented in Figure 1. Figure 1 clearly shows that solutions C70Brn (n = 8, 10) in all solvents in the visible and near-UV region have well-defined absorption peaks at wavelengths λmax ≃ 379 ± 4 nm and λmax ≃ 1 2 373 ± 6 nm, besides the absorption maxima for C70Br10 are slightly shifted to shorter wavelengths. On the contrary the absorption spectrum of C70Br14 does not display any absorption peaks, in contrast to the other bromides C70Br10 and C70Br8. In general, the UV spectra of the C70Br14 solutions were found to be not enough informative. Nevertheless the spectra can be successfully used to determine the concentration of C70Br14, for example, in aromatic solvents media according to the Bouguer−Lambert−Beer law at noncharacteristic wavelengths.
C(C70Br8)[g·L−1] = 0.0257D379
(2)
C(C70Br10)[g·L−1] = 0.041D379
(3)
C(C70Br14)[g·L−1] = 0.047D330
(4)
where C(C70Brn, n = 8, 10, 14) are the concentrations of C70Brn (n = 8, 10, 14); D379 and D330 are the optical densities of solutions of the bromoderivatives C70Brn (n = 8, 10, 14) at the wavelengths 379 and 330 nm at spectrophotometric cell with the width of L = 1 cm. Figure 2 and Table 1 show the feasibility of the Bouguer− Lambert−Beer law in the example of solutions of C70Brn (n = 8, 10, 14). As can be seen, the law holds in the entire investigated range of optical densities of the solutions that allows to use formulas 2 to 4. For the C70 fullerene bromide identification we have also conducted the thermogravimetric analysis on a Q-1500 derivatograph (Hungary). An analysis was performed at a heating rate of 5 K·min−1 in an air atmosphere, and the weight of each portion of the sample was about 100 mg. Exemplarily, let us discuss the obtained thermogravimetric curves for the C70Br14 (M = 1960 g·mol−1) sample. The data obtained are presented in Figure 3. Figure 3c displays that at relatively low temperatures the sample starts to produce a molecular Br2 according to the reaction: C70Br14 → C70 + 7.0Br2 572
(5)
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Figure 3. Derivatograms of C70Brn, n = 8 (a), 10 (b), and 14 (c) obtained in air at a 5 K·min−1 heating rate: solid line, thermogravimetric curve; dotted line, differential thermogravimetric curve; dashed line differential thermal analysis curve.
Figure 4. Dependencies of solubility of C70Br8 (a), C70Br10 (b), and C70Br14 (c) in □, 1,2-dichlorobenzene; ○, benzene; △, 1-methylbenzene; ▼, 1,2-dimethylbenzene. S is a solubility of C70Brn (n = 8, 10, 14); t is temperature (°C).
The temperature of the maximum of the first effect is equal to 373 ± 10 K, the temperature interval of the first effect is (333.15 to 413.15) K, and the mass loss during the first effect in the temperature range (333.15 to 413.15) °C is 58 ± 3 % (58 ± 3 mg). The latter value is almost identical to the theoretical one for process 5, 57 % (57 mg). The total loss in mass during the “extended first effect” in the temperature range (293 to 473) K has the value Δm ≈ 68 ± 5 % (68 ± 5 mg) (Figure 3c). The latter fact can be explained by the following reasons: due to the presence of certain amounts of adsorbed Br2 in the primary sample of C70Br14; due to the beginning of the oxidative degradation process of products of thermal decomposition of C70Br14 in air at (413 to 473) K. The second effect, namely, the sublimation of the volatile residues of thermal decomposition of
C70Br14 in air in the temperature range (523 to 1023) K (Δm ≈ 75/100 %, (75 to 100) mg), does not have the temperature extremum on the DTG curve (Figure 3c) and corresponds to the complete evaporation of the sample. The thermogravimetric curves for C70Br8 and C70Br10 bromoderivatives are presented in Figure 3a,b, and the heat effects are presented in Table 2. The experimental study of the temperature dependence of solubility of the C70Brn (n = 8, 10, 14) bromoderivatives was performed using the isothermal saturation method. Solutions of C70Brn (n = 8, 10, 14) were prepared in the following solvents 573
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For such aromatic solvents as benzene, toluene, o-xylene, and o-dichlorobenzene the temperature dependences of solubility are characterized by significant increase in solubility values of C70Brn (n = 8, 10) Ssolvent(C70Br8) in a series of solvents: SC6H6(C70Br8) < SC6H5CH3(C70Br8) < So-C6H4(CH3)2(C70Br8) < So-C6H4Cl2(C70Br8). For the solid solvates a composition determination of the thermogravimetric analysis was performed on a Q-1500 derivatograph (Hungary). An analysis of the thermogramms reveals that the only solid phase coexisting with the saturated solution is nonsolvated C70Brn (n = 8, 10, 14).
Table 2. Heat Effects of the C70Br8, C70Br10, and C70Br14 Samples in the Process of Heating in the Temperature Range (20 to 900) °C at 0.1 MPaa no. Textr/K 1.1 1.2 1.3 1.4 2.1 2.2 2.3 3.1 3.2
ΔT/K
reaction
C70Br8 C70Br8 → C70Br7 + 0.5Br2 C70Br7 → C70Br5 + 1.0Br2 C70Br5 → C70 + 2.5Br2 sublimation of the volatile residuals of the C70Br8 C70Br10 100 353 to 388 C70Br10 → C70Br6 + 3.0Br2 120 383 to 403 C70Br6 → C70 + 2.0Br2 473 to 1173 sublimation of the volatile residuals of the C70Br10 C70Br14 100 333 to 413 C70Br14 → C70 + 7.0Br2 573 to 1053 sublimation of the volatile residuals of the C70Br14 353 333 to 383 443 413 to 493 673 553 to 893 873 to 1223
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CONCLUSIONS The methods of the C70Brn (n = 8, 10, 14) bromoderivative synthesis are developed. The bromoderivative identification was carried out by the methods of IR spectroscopy, UV spectroscopy, and by the thermogravimetric analysis method. By the isothermal saturation method the solubility of the C70Brn (n = 8, 10, 14) bromoderivatives in aromatic solvents (benzene, 1-methylbenzene, 1,2-dimethylbenzene, 1,2-dichlorobenzene) in the temperature range (293 to 333) K was investigated. Using thermogravimetric analysis it was determined that nonsolvated bromoderivatives C70Brn (n = 8, 10, 14) are in equilibrium with saturated solution in the whole temperature range.
Textr is the temperature of the heat effect extremum (°C). ΔT is the temperature interval of the heat effect (°C).
a
(benzene, toluene, o-xylene, o-dichlorobenzene). In all cases the significant excess of the fullerenes bromides was taken, up to 300 mg of fullerene per 10 mL of the solvent. Then the heterogeneous mixtures were stirred in the temperature range (20 to 60) °C in a thermostatic shaker (accuracy of temperature control ± 0.05 °C) for 10 h at each temperature. The determination of the concentration after each stage of saturation by C70Brn (n = 8, 10, 14) was carried out spectrophotometrically using a spectrophotometer SPECORD-32 at a wavelength of λ = 379 nm (in the case of C70Brn (n = 8, 10)) and at a wavelength of λ = 330 nm (in the case of C70Br14).
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ASSOCIATED CONTENT
S Supporting Information *
IR spectra of the C70Brn (n = 8, 10, 14) bromoderivatives. This material is available free of charge via the Internet at http:// pubs.acs.org.
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RESULTS AND DISCUSSION Figure 4 shows the solubility polyterms in binary systems C70Brn (n = 8, 10, 14) + aromatic solvents (benzene, toluene, o-xylene, o-dichlorobenzene) in the temperature range (293 to 333) K. From Figure 4a−c and Table 3 it can be clearly seen that: all of the C70 bromoderivatives are relatively well soluble in solvents studied; the solubility depending on the type of solvent and temperature varies from tenths to a few tens of g·L−1; in all cases the solubility increases monotonically with the increasing of the temperature: dSsolvent(C70Brn)/dT > 0.
AUTHOR INFORMATION
Corresponding Author
*Tel.: (812)3476435; fax: (812)2349859. E-mail address:
[email protected] (K.N.S.). Funding
This work was supported by the Russian Foundation of Fundamental Researches (Projects No. 12-03-90849-mol_rf_nr, 11-08-00219-a, 12-03-31380-mol_a) and by the Grant of Ministry of Education and Science of Russian Federation No. 2011-1.3.1207-008-058 (GC 16.740.11.0658_02.06.2011).
Table 3. Temperature Dependence of the Solubility of the C70Br8, C70Br10, and C70Br14 Bromoderivatives in Aromatic Solvents (Benzene, 1-Methylbenzene, 1,2-Dimethylbenzene, 1,2-Dichlorobenzene) at 0.1 MPaa solubility of C70Br8 T/K
S/g·L−1
293.15 313.15 333.15
3.89 4.67 5.45
0.44 0.53 0.62
293.15 313.15 333.15
1.29 2.24 2.93
0.15 0.25 0.33
293.15 313.15 333.15 353.15
1.63 1.96 2.28 2.61
0.19 0.22 0.26 0.30
w/% Benzene
S/g·L−1
w/%
S/g·L−1
w/%
1-Methylbenzene 1,2-Dimethylbenzene 5.45 0.63 9.99 1.14 7.01 0.81 11.8 1.34 8.17 0.94 13.6 1.43 Solubility of C70Br10 0.086 0.01 3.53 0.40 0.431 0.05 3.88 0.44 2.24 0.26 4.22 0.48 Solubility of C70Br14
S/g·L−1
w/%
1,2-Dichlorobenzene 20.7 1.59 21.9 1.68 29.1 2.23 8.06 10.4 22.3
0.62 0.80 1.71
a
The overall accuracy of determining concentrations of the C70Br8, C70Br10, and C70Br14 fullerene bromides in a saturated solution was no more than 5 %. T is temperature (K). 574
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α-chloroand α-Bromonaphthalene in the temperature range 10−60 °C. Russ. J. Phys. Chem. 2011, 85, 62−67. (24) Troshin, P. A.; Astakhova, A. S.; Lyubovskaya, R. N. Synthesis of fullerenols from halofullerenes. Fullerenes, Nanotubes, Carbon Nanostruct. 2005, 13, 331−343. (25) Waidmann, G.; Jansen, M. Synthesis and characterization of C70Br14. Zeit. Anorg. Allg. Chem. 1997, 623, 623−626.
Notes
The authors declare no competing financial interest.
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REFERENCES
(1) Sidorov, L. N.; Yurovskaya, M. A. Fullerenes; Ekzamen: Moscow, 2005. (2) Piotrovskij, L. B.; Kiselev, O. I. Fullerenes in biology; Rostok: Saint-Petersburg, 2006. (3) Semenov, K. N.; Charykov, N. A. Solubility of light fullerenes and their derivatives; LAMBERT Academic Publishing: Russia, 2011. (4) Semenov, K. N.; Charykov, N. A.; Keskinov, V. A.; Piartman, A. K.; Blokhin, A. A.; Kopyrin, A. A. Solubility of light fullerenes in organic solvents. J. Chem. Eng. Data 2009, 55, 13−36. (5) Ruoff, R. S.; Tse, D.; Malhorta, R.; Lorents, D. C. Solubility of fullerene C60 in a variety of solvents. J. Phys. Chem. 1993, 97, 3379− 3383. (6) Sivarman, N.; Dhamodaran, R.; Kallippan, I.; Srinivassan, T. G.; Vasudeva, P. R.; Mathews, C. K. Solubility of C60 in organic solvents. J. Org. Chem. 1992, 57, 6077−6079. (7) Heyman, D. Solubility of C60 in alcohols and alkanes. Carbon 1996, 34, 627−631. (8) Chen, W.; Xu, Z. Temperature dependence of C60 solubility in different solvents. Fullerene Sci. Technol. 1998, 6, 285−290. (9) Semenov, K. N.; Arapov, O. V .; Charykov, N. A. The solubility of fullerenes in n-alkanols-1. Russ. J. Phys. Chem. 2008, 82, 1318−1326. (10) Kulkarni, P. P.; Jafvert, C. T. Solubility of C60 in solvent mixtures. Environ. Sci. Technol. 2008, 42, 845−851. (11) Zhou, X.; Liu, J.; Jin, Z.; Gu, Z.; Wu, Y.; Sun, Y. Solubility of fullerene C60 and C70 in toluene, o-xylene and carbon disulfide at various temperatures. Fullerene Sci. Technol. 1997, 5, 285−290. (12) Stukalin, E. B.; Avramenko, N. V.; Korobov, M. V.; Ruoff, R. Ternary system of C60 and C70 with 1,2,-dimethylbenzene. Fullerene Sci. Technol. 2001, 9, 113−130. (13) Doome, R. J.; Dermaut, S.; Fonseca, A.; Hammida, M.; Nagy, J. B. New evidence for the anomalous temperature-dependent solubility of C60 and C70 fullerenes in various solvents. Fullerene Sci. Technol. 1997, 5, 1593−1606. (14) Letcher, T. M.; Domanska, U.; Goldon, A.; Mwenesongole, E. M. Solubility of buckminsterfullerene in terahydrofuran, thiophene, terahydrothiophene, 1,2-dichlorobenzene, 1,2,4-trichlorobenzene and n-butilamine. S.-Afr. J. Chem. 1997, 50, 51−53. (15) Beck, M. T.; Mandi, G. Solubility of C60. Fullerene Sci. Technol. 1997, 5, 291−310. (16) Korobov, M. V.; Smith, A. L. Solubility of Fullerenes. In Physics and Technology; Kadish, K. M., Ruoff, R. S., Eds.; John Wiley & Sons: New York, 2000; pp 53−59. (17) Troshin, P. A.; Kolesnikov, D.; Burtsev, A. V.; Lubovskaya, R. N.; Denisenko, N. I.; Popov, A. A.; Troyanov, S. I.; Boltalina, O. V. Bromination of [60]fullerene. I. High-yield synthesis of C60Brx (x = 6, 8, 24). Fullerenes, Nanotubes, Carbon Nanostruct. 2003, 11, 47−60. (18) Djordjevic, A.; Vojinovic-Miloradov, M.; Petranovic, N.; Devečerski, A.; Lazar, D.; Ribar, B. Catalytic preparation and characterization of C60Br24. Fullerene Sci. Technol. 1998, 6, 689−694. (19) Birkett, P. R.; Hitchcock, P. B.; Kroto, H. W.; Taylor, R.; Walton, D. R. M. Preparation and characterization of C60Br6 and C60Br8. Nature 1992, 357, 479−481. (20) Semenov, K. N.; Charykov, N. A.; Axelrod, B. M. Solubility of bromoderivatives C60Brn (n = 6, 8, 24) in 1-chloronaphthalene and 1bromonaphthalene in the temperature range (10 to 60) °C. J. Chem. Eng. Data 2010, 55, 3662−3666. (21) Semenov, K. N.; Charykov, N. A.; Keskinov, V. A.; Pyartman, A. K.; Arapov, O. V. Solubility of bromofullerenes C60Brn (n = 6, 8, 24) in aqueous-ethanolic mixtures at 25 °C. Russ. J. Appl. Chem. 2010, 83, 997−1000. (22) Semenov, K. N.; Charykov, N. A.; Keskinov, V. A.; Pyartman, A. K.; Yakovlev, V. V.; Arapov, O. V. The solubility of C60Brn (n = 6, 8, 24) in organic solvents. Russ. J. Phys. Chem. 2009, 83, 1935−1939. (23) Semenov, K. N.; Letenko, D. G.; Nikitin, V. A.; Charykov, N. A.; Aksel’rod, B. M. Solubility of bromine derivatives of C60Brn fullerene in 575
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