Paper
Green Chemistry
geneous, and the immobilized catalysts are evidenced to be
stable and reusable. The reaction could be performed under
air conditions and the use of other additives such as H or
2
Experimental
Chemicals and equipment
Commercially available chemicals including transition metal alkene could be avoided. Considering the ultimate practical
precursors, carbon supported catalysts, inorganic bases, application, the catalytic activity and selectivity should be
organic reagents and GC standards were purchased from improved further, especially for ethanol condensation. In
SCRC, Alfa Aesar or TCI and used as received. Commercially addition, nearly stoichiometric amount of KOH solution is not
unavailable ligands were prepared according to the literature eco-friendly, which is also a common concern in the industrial
2
0
in ESI.† The concentration of ethanol or butanol usually processes catalyzed by bases. Such challenges are being
varied from 5% to 15% to mimic the primary fermentation addressed in our lab now.
solution.
Microwave irradiation experiments were performed on an
Anton Paar Synthos 3000. Experiments under conventional
thermal treatment were carried out in an autoclave and heated
Acknowledgements
using an oil bath or heating plate with magnetic stirring. GC Financial support from Shell Global Solutions under
analyses were carried out on a VARIAN 450-GC equipped with contract PT27918 is greatly acknowledged. We also thank
a DB-FFAP capillary column (30 m × 0.32 mm × 0.25 µm). the Natural Science Foundation of China (no. 21273260)
GC-MS analyses were carried out on an Agilent 7890A GC with and the Shandong Provincial Natural Science Foundation for
a 5975C MS-unit. TEM (transmission electron microscopy) Distinguished Young Scholar, China (no. JQ201305) for
images were obtained using a field emission H-7600 electron financial support.
microscope at 120 kV. AAS (atomic absorption spectroscopy)
was measured on an INESA 4510F.
Notes and references
Quantitative GC analyses
Generally all reactions in this research were carried out in
diluted aqueous solutions. Because the organic products
exhibit low solubility in water, it is necessary to collect the pro-
ducts by extraction. In addition, butanol is partly soluble in
water and ethanol is miscible with water, so that the analyses
of the aqueous phase are also necessary for the quantitative
determination. The internal standard method was used for the
analyses of the organic phase. Because the organic internal
standards were insoluble in water, a modified external
standard method was applied for the analyses of the aqueous
phase. The known concentrations of alcohol reactants and
products were analyzed using this method, and the obtained
results suggested its feasibility.
1 (a) J. Goldemberg, Science, 2007, 315, 808; (b) C. Angelici,
B. M. Weckhuysen and P. C. A. Bruijnincx, ChemSusChem,
2013, 6, 1595; (c) J. T. Kozlowski and R. J. Davis, ACS Catal.,
2013, 3, 1588.
2 (a) O. J. Sanchez and C. A. Cardona, Bioresour. Technol.,
2008, 99, 5270; (b) X. Gao, X. Zou, F. Zhang, S. Zhang,
H. Ma, N. Zhao and G. Zhu, Chem. Commun., 2013, 49,
8839.
3 (a) C. H. Christensen, B. Jørgensen, J. R. Hansen,
K. Egeblad, R. Madsen, S. K. Klitgaard, S. M. Hansen,
M. R. Hansen, H. C. Andersen and A. Riisager, Angew.
Chem., Int. Ed., 2006, 45, 4648; (b) J. C. S. Ruiz, R. Luque
and A. S. Escribano, Chem. Soc. Rev., 2011, 40, 5266.
4
A. J. O’Lenick, J. Surfactants Deterg., 2001, 4, 311.
5 G. E. Dobereiner and R. H. Crabtree, Chem. Rev., 2010, 110,
81.
C. J. Li, Chem. Rev., 2005, 105, 3095.
General reaction procedure
6
Take the butanol condensation using the IrCl
3
-phenanthroline
6
catalyst for example: butanol (1 g, 13.5 mmol), IrCl ·3H O
(
3
2
0.01 g, 2.8 × 10− mmol, 0.2 mol%) and phenanthroline
2
7 (a) C. Carlini, A. Macinai, A. M. R. Galletti and G. Sbrana,
J. Mol. Catal. A: Chem., 2004, 212, 65; (b) C. Carlini,
C. Flego, M. Marchionna, M. Noviello, A. M. R. Galletti,
G. Sbrana, F. Basile and A. Vaccari, J. Mol. Catal. A: Chem.,
hydrate (0.05 g, 0.25 mmol) were mixed in H O (9 mL). Then a
2
KOH solution (0.76 g, 13.5 mmol in 9 mL H O) was added.
2
The mixture was heated using microwave irradiation or an oil
bath without exclusion of air. After heating for a specified reac-
2004, 220, 215; (c) C. Carlini, M. Marchionna, M. Noviello,
A. M. R. Galletti, G. Sbrana, F. Basile and A. Vaccari, J. Mol.
Catal. A: Chem., 2005, 232, 13.
tion time, Et O was added for extraction. Both the organic and
2
aqueous phases were analyzed by GC. Products were identified
using pure chemicals and a GC-MS.
8
(a) T. Tsuchida, S. Sakuma, T. Takeguchi and W. Ueda,
Ind. Eng. Chem. Res., 2006, 45, 8634; (b) T. Tsuchida,
T. Yoshioka, S. Sakuma, T. Takeguchi and W. Ueda, Ind.
Eng. Chem. Res., 2008, 47, 1443; (c) M. León, E. Díaz and
S. Ordónez, Catal. Today, 2011, 164, 436.
Conclusions
Direct self-condensation of bio-alcohols including butanol and
ethanol in water has been successfully realized. Novel iridium
catalysts are rationally developed from homogeneous to hetero-
9 (a) T. Matsu-ura, S. Sakaguchi, Y. Obora and Y. Ishii, J. Org.
Chem., 2006, 71, 8306; (b) K. Koda, T. Matsuura, Y. Obora
and Y. Ishii, Chem. Lett., 2009, 38, 838.
3976 | Green Chem., 2014, 16, 3971–3977
This journal is © The Royal Society of Chemistry 2014