A Hafnium-based Metal-Organic Framework as a Catalyst for
Regioselective Ring-Opening of Epoxides with a Mild Hydride Source
– Supporting Information
Casey J. Stephenson1, M. Hassan Beyzavi1, Rachel Klet1, and Joseph T.
Hupp1,* and Omar K. Farha1,2,*
1Department
of Chemistry, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA
2Department
of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah, Saudi Arabia
Email: j-hupp@northwestern.edu; o-farha@northwestern.edu
Materials and Methods. All manipulations of air-sensitive materials were performed with
rigorous exclusion of oxygen and moisture in oven-dried Schlenk glassware on a dual manifold
Schlenk line under N2. Tetrahydrofuran used for catalytic experiments was purified according to
the method reported by Grubbs.1 NMR samples recorded in tetrahydrofuran-d4 (Cambridge
Isotope Laboratories, 99+ atom % D) were prepared from fresh ampules. Chloroform-d1
(Cambridge Isotope Laboratories, 99+ atom % D) and methanol-d4 (Cambridge Isotope
Laboratories, 99+ atom % D) were used as received. Sodium cyanoborohydride (Aldrich, 95%),
tetrabutylammonium borohydride (Aldrich, 98%) HfOCl2.8H2O (Strem Chemicals Inc., 98+%),
styrene oxide (Aldrich, 97%), (±)-propylene oxide (Aldrich, 95%), bromocresol green (Acros,
95%), acetic acid (Aldrich, 99.7%). Hf-NU-10002 was prepared according to literature
procedure, and Hf-NU-1000-dehydrated was prepared by adapting literature procedure.3 The
characterization and properties of Hf-NU-1000-dehydrated is the subject of another manuscript
from our group.
Physical and Analytical Measurements.
NMR spectra were recorded on Varian UNITY
INOVA-400 (400MHz, 1H; 100 MHz, 13C), Varian INOVA 400 (400 MHz, 1H; 100 MHz, 13C),
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Varian INOVA 500 (500 MHz, 1H), Bruker AVANCE III 500 (500 MHz, 1H; 125 MHz,
13
C)
NMR spectrometers. Chemical shifts (δ) for 1H and 13C are referenced to TMS, internal solvent
resonances relative to TMS. GC-TOF data were recorded on a Waters Micromass GCT Premier
time-of-flight GC mass spectrometer. Powder X-ray diffraction measurements were recorded on
a Rigaku SmartLab Thin-film Diffraction Workstation with 9 kW copper rotating
anode x-ray source is coupled to a multilayer optic.
Representative procedure for ring-opening of styrene oxide with sodium cyanoborohydride
and Hf-NU-1000. In a Schlenk flask equipped with stir bar and septa was charged with Hf-NU1000 (49 mg, 0.02 mmol), the flask was evacuated and backfilled three times before adding dry
tetrahydrofuran (1.9 mL), styrene oxide (24 L, 0.2 mmol), and sodium cyanoborohydride (39
mg, 0.65 mmol). The reaction was allowed to stir for 24 hours before the solvent was removed in
vacuo. Dichloromethane (10 mL) was added to the residue before 1 M HCl (1 mL) was added
and stirred for 20 minutes (Caution! This liberates hydrogen cyanide. Should trap HCN by
bubbling reaction gas through KOH solution). The biphasic solution was stirred for ~30
minutes before adding a saturated sodium carbonate solution until basic and then stirred for
another 30 minutes. The organic portion was separated from the aqueous and the aqueous portion
was extracted with dichloromethane (3 x 10 mL portions). The organics were combined and
washed with brine (5 mL) and dried over magnesium sulfate before the solution was transferred
to a flask and the solvent removed in vacuo. The crude product was purified by column
chromatography eluting with 25% dichloromethane in hexanes followed by 20% ethyl acetate in
hexanes (~15 mg, 0.13 mmol.); yield: 63%. . 1H NMR (CDCl3): 7.2-7.5 (m, Ar-H, 5H), 3.75 (t, CH2-, 2H, JHH = 6.70 Hz), 2.77 (t, -CH2-, 2H, JHH = 6.70 Hz), 2.01 (s, OH, 1H).
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Qualitative colorimetric reactions using bromocresol green. The reaction was prepared as
above except a very small amount of bromocresol green was added to the reaction (see Figure
S5).
Reaction of (±)-propylene oxide. A 25 mL round bottom flask equipped with stir bar and septa
was charged with Hf-NU-1000 (5.4 mg, 0.002 mmol). The round bottom was sparged with N2
gas before tetrahydrofuran (1.9 mL), (±)-propylene oxide (0.024 mL, 0.02 mmol), and sodium
cyanoborohydride (0.08 mmol, 5 mg) were added. The septa was replaced with a stopper and the
reaction was allowed to stir for 24 hours. The reaction solution was transferred via pipette to a J.
Young NMR tube. The round bottom was rinsed with MeOH-d4 which was added to the NMR
tube (See Figure S5). Yield: ~65%.
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Figure S1. 1H NMR of 2-phenylethanol (500 MHz in CDCl3 at room temperature).
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Figure S2. Stack plot of 1H (500 MHz) NMR of sodium cyanoborohydride and Hf-NU-1000
in tetrahydrofuran-d4. (top) after heating sample at 60 °C for 24 h., molecular hydrogen peak
is at δ = 4.53. (bottom) 1H spectrum before heating, after sitting at room temp. for 24 h;
molecular hydrogen peak is at δ = 4.53. The spectra were recorded on the same instrument
using the same delay time and number of scans.
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.
Figure S3. GC-TOF of reaction mixture of sodium cyanoborohydride, Hf-NU-1000, and
styrene oxide in tetrahydrofuran that was refluxed for 24 hrs. Aldehyde peak is found after
reaction workup.
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Figure S4. 1H NMR of the reaction of (±)-propylene oxide with Hf-NU-1000, sodium
cyanoborohydride (500 MHz in methanol-d4 at room temperature). There is a small peak at δ =
0.8 which corresponds to 1-propanol.
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Figure S5. Photographs of the reaction of sodium cyanoborohydride, Hf-NU-1000, styrene
oxide, and bromocresol green in tetrahydrofuran at the beginning (left) and after 24 hrs. (right).
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Figure S6. PXRD of Hf-NU-1000 before catalysis and after being used in catalytic experiments
one, two, and three times.
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References.
1.
Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.; Timmers, F. J. Organometallics, 15, 1518-
1520 (1996).
2.
Beyzavi, M. H.; Klet, R. C.; Tussupbayev, S.; Borycz, J.; Vermeulen, N. A.; Cramer, C. J.; Stoddart, J. F.;
Hupp, J. T.; Farha, O. K. Submitted, (2014).
3.
Valenzano, L.; Civalleri, B.; Chavan, S.; Bordiga, S.; Nilsen, M. H.; Jakobsen, S.; Lillerud, K. P.;
Lamberti, C. Chemistry of Materials, 23, 1700-1718 (2011).
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