Reactions in Zeolites
2368±2376
Experimental Section
Acknowledgements
The authors sincerely thank Dr. V. N. Romannikov for the synthesis of the
sample of zeolite H-ZSM-5. This research was supported by joint RFBR-
INTAS (Grant No. 95-IN-RU-194). A.S. is grateful to the Locker Hydro-
carbon Institute (U.S.C., Los Angeles) for financial support.
Sample preparation for NMR experiments: Zeolite H-ZSM-5 (Si/Al 49)
was synthesized according to reference [
44]
and characterized by X-ray
powder diffraction and chemical analysis. According to chemical analysis,
the content of iron in the sample was 27 ppm (0.0036 wt%Fe ). The
2
O
3
zeolite (ꢁ0.1 ± 0.15 g) was loaded into a glass tube and the sample was
heated at 723 K for 2 h in air to remove atmospheric moisture, and for 4 h
À3
under vacuum at 10 Pa. After cooling the sample to ambient temperature
[
1] a) H. S. Bloch, H.Pines, L.Schmerling, J. Am. Chem. Soc. 1946, 68,
53; b) G. A. Olah, A. Molnar, Hydrocarbon Chemistry, Wiley, New
(
296 K), equal amounts of alkane, CO and water (ꢁ1 equiv of each
1
À1
coadsorbate per Al atom, 300 mmolg ) were frozen out onto H-ZSM-5
under vacuum at the temperature of liquid nitrogen, and the glass tube with
the zeolite was then sealed off from the vacuum system. The sample was
then heated at 373 ± 573 K for 1 ± 10 h for the reaction to proceed under
static conditions in the sealed tube. After quenching the tube with the
sample to room temperature, it was tightly packed into a 7 mm zirconia
NMR rotor for NMR analysis. The reaction products were analyzed in situ
York, 1995.
[
2] H. Hogeveen, G. F. Bickel, J. Chem. Soc. Chem. Commun. 1967, 635 ±
6
36.
[
3] a) G. A. Olah, J. Lukas, J. Am. Chem. Soc. 1967, 89, 4739 ± 4744;
b) G. A. Olah, G. K. S. Prakash, J. Sommer, Superacids, Wiley, New
York, 1985.
[
4] S. Delavarenne, M. Simon, M. Fauconet, J. Sommer, J. Am. Chem. Soc.
1
3
1
directly inside the zeolite pores by both C and H NMR. To facilitate
NMR analysis, the alkanes and CO with selective C labels (80 ± 99% of
C isotope enrichment) were employed.
1
989, 111, 383 ± 384.
1
3
[
5] S. Delavarenne, M. Simon, M. Fauconet, J. Sommer, J. Chem. Soc.
Chem. Commun. 1989, 1049 ± 1050.
1
3
NMR analysis of the reaction products: 13C NMR spectra with high-power
proton decoupling and magic angle spinning (MAS) and with or without
[6] a) J. Sommer, J. Bukala, Acc. Chem. Res. 1993, 26, 370 ± 376; b) J.
Sommer, J. Bukala, M. Hachoumy, R. Jost, J. Am. Chem. Soc. 1997,
119, 3274 ± 3279; c) J. Sommer, M. Hachoumy, J. C. Culmann, J.
Bukala, New J. Chem. 1997, 21, 939.
1
3
13
cross-polarization (CP) (denoted below as C CP/MAS NMR and
C
1
MAS NMR), and H MAS NMR spectra were recorded at 100.613 MHz
1
3
1
[7] H. Koch, Brennstoff-Chemie 1955, 36, 321 ± 328.
(
C) and at 400.13 MHz ( H) (magnetic field of 9 Tesla), respectively, on a
[
8] H. Bahrmann, in New Syntheses with Carbon Monoxide (Ed.: J.
Falbe), Springer, Berlin, 1980, p. 372.
Bruker MSL-400 spectrometer at 296 K. The following conditions were
used for recording spectra with CP: proton high-power decoupling field
1
[9] a) A. G. Stepanov, M. V. Luzgin, V. N. Romannikov, K. I. Zamaraev, J.
Am. Chem. Soc. 1995, 115, 3615 ± 3616; b) A. G. Stepanov, M. V.
Luzgin, V. N. Romannikov, V. N. Sidelnikov, K. I. Zamaraev, J. Catal.
1
1.7 G(5.0 ms length of 908 H pulse); contact time 5 ms at Hartmann ±
Hahn matching condition of 50 kHz; delay time between scans 3 s. One-
pulse excitation 1 C MAS spectra were recorded with 458 flip angle;
3
13
C
1
996, 116, 411 ± 421.
10] J. Sommer, M. Hachoumy, F. Garin, J. Am. Chem. Soc. 1995, 117,
135 ± 1136.
pulses of 2.5 ms duration, and 10 ± 15 s recycle delay, which satisfied a 10T
1
[
[
condition. High-power proton-decoupling in these experiments was used
only during the acquisition time. This eliminated Nuclear Overhauser
Enhancement of the signal areas and allowed quantitative assessment of
1
11] a) J. Sommer, D. Habermacher, M. Hachoumy, R. Jost, A. Reynaud,
Appl. Catal. 1996, 146, 193 ± 205; b) J. Sommer, R. Jost, M. Hachoumy,
Catal. Today 1997, 38, 309; c) A. G. Stepanov, H. Ernst, D. Freude,
Catal. Lett. 1998, 54, 1 ± 4.
[
45]
1
the signal areas.
One-pulse excitation H MAS NMR spectra were
1
3
recorded with 458 flip angle pulses of 5 ms duration and 5 s recycle delay.
C
1
and H chemical shifts (d) for carbon nuclei of adsorbed organic species
were measured with respect to TMS as the external reference with accuracy
Dd Æ 0.5. Precision in the determination of the relative line position was
[
[
12] J. Engelhardt, W. K. Hall, J. Catal. 1995, 151, 1 ± 9.
13] J. Sommer, D. Habermacher, R. Jost, A. Sassi, A. G. Stepanov, M. V.
Luzgin, D. Freude, H. Ernst, J. Martens, J. Catal. 1999, 181, 265 ± 270.
14] F. C. Jentoft, B. C. Gates, Topics in Catalysis 1997, 4, 1 ± 13.
15] B. W. Wojciechowski, A. Corma, Catalytic Cracking: Catalysts,
Chemistry and Kinetics; Dekker, New York, 1986.
1
3
1
Dd 0.1 ± 0.15 for C NMR and Dd 0.05 for H NMR. The temperature
of the samples during acquisition of NMR spectra was controlled with a
BVT-1000 variable-temperature unit.
[
[
[
16] A. G. Stepanov, V. N. Sidelnikov, K. I. Zamaraev, Chem. Eur. J. 1996,
Sample preparation for GC analysis: The reaction was carried out in a glass
2
, 157 ± 167.
reactor equipped with a septum (static conditions). H-ZSM-5 (ꢁ3.6 g,
[17] E. Breitmaier, W. Voelter, in 13C NMR Spectroscopy, Methods and
Applications in Organic Chemistry, Verlag Chemie, Weinheim, 1978,
p. 159.
1
mmol H ) was pretreated at 723 K under vacuum for 1 h. Isobutane or
2
propane (0.89 mmol), CO (1.34 mmol), and H O (0.9 mmol) were intro-
duced at 273 K with a syringe. For the reaction with isobutane, ethane was
added to the system and used as an internal standard (i.e. 1.2% of ethane in
isobutane was used as starting material, considering the low reactivity of
ethane). The reactor was heated (ꢂ13 h) at 423 K for the reaction with
isobutane and at 473 K (ꢂ20 h) with propane. The head-space gas phase
was analyzed by GC.
[
[
18] M. W. Anderson, J. Klinowski, J. Am. Chem. Soc. 1990, 112, 10 ± 16.
19] E. J. Munson, N. D. Lazo, M. E. Moellenhoff, J. F. Haw, J. Am. Chem.
Soc. 1991, 113, 2783 ± 2784.
[
[
20] M. V. Luzgin, V. N. Romannikov, A. G. Stepanov, K. I. Zamaraev, J.
Am. Chem. Soc. 1996, 118, 10890 ± 10891.
21] 13CO gaseous or adsorbed, as a mobile and hydrogen-free species,
could be usually observed in 13C NMR spectra recorded without cross-
1
3
13
Hydrocarbons: [2- C]Propane (99% C enrichment) was purchased from
1
3
polarization, see, for example, refs. [9, 18±20] and Figure 1b.
IC Chemikalien GmbH, Germany. [2- C]Isobutane was prepared by a five-
1
3
13
[22]
1
H NMR chemical shifts (d) in solution: methane 0.22; ethane 0.85;
propane 0.90 (CH ), 1.34 (CH ); isobutane 0.89 (CH ), 1.56 (CH); H
4.51; IBA 1.20 (CH ); TMAA 1.23(CH ). See: F. A. Bovey, NMR Data
Tables for Organic Compounds, Vol. 1, Wiley, New York, 1967.
step synthesis, starting from [1- C]acetic acid (82% C enrichment).
Propane purchased from Alphagaz (purity: N35) was used after a purity
check by GC. Isobutane purchased from Alphagaz (purity: N35) was
liberated from isobutene impurities (<1000 ppm) by hydrogenation at
3
2
3
2
3
3
3
53 K on Pt (Adams) under H
2
and then filtered at room temperature on
[23] a) V. M. Mastikhin, O. B. Lapina, React. Kinet. Catal. Lett. 1979, 11,
353 ± 358; b) K. F. M. G. J. Sholle, A. P. M. Kentgens, W. S. Veeman, P.
Frenken, G. P. M. van der Velden, J. Phys. Chem. 1984, 88, 5 ± 8; c) M.
Hunger, D. Freude, H. Pfeifer, J. Chem. Soc. Faraday Trans. 1991, 87,
657 ± 662.
[24] W. O. Haag, R. M. Dessau, in Proceedings 8th Intern. Congress on
Catalysis, Berlin, 1984, 2, p. 305, Dechema, Franfkurt am Main.
[25] D. H. Marr, Org. Magn. Reson. 1981, 15, 22.
fresh H-ZSM-5 (used after activation at 773 K).
GC analysis of the reaction products: Hydrocarbons were analyzed by GC
with a Girdel300 chromatograph equipped with a column (2 m, 1/8ª) filled
with a HayesepA 80/100 porous polymer. The helium pressure in the
column was 2 bar and the analysis temperature was constant at 363 K.
Hydrogen was analyzed with an Intersmat IGC112M chromatograph
equipped with a 2 m column filled with a 5 molecular sieve and a
[26] J. Bendiera, Y. Ben Taarit, Appl. Catal. 1990, 62, 309 ± 316.
[27] Y. Souma, H. Sano, J. Iyoda, J. Org. Chem. 1973, 38, 2016 ± 2020.
[28] Y. W. Bizreh, B. C. Gates, J. Catal. 1984, 88, 240 ± 243.
À1
catharometric detector. The Ar flow rate was 14 mLmin and the
temperature was constant at 323 K.
Chem. Eur. J. 2000, 6, No. 13
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2000
0947-6539/00/0613-2375 $ 17.50+.50/0
2375