U. Rosenthal, W. Mꢀller et al.
our guests Nicole Feiling and Bernhard Bauer for performing a lot of cat-
alytic tests.
tion of Cr and Al interacting with Cl is important, and by
this fact the influence of the ratio of pre-catalyst to the acti-
vator (Cr to Al and hence Cr/Al/Cl), in agreement with the
findings of earlier parameter studies.[12] This suggests an en-
tangled equilibration between the strong Lewis acids Crn+
and Al3+ and the strong Lewis base chloride. The indepen-
Keywords: aluminium · amides · chromium · homogeneous
catalysis · oligomerization
ACHTUNGTRENNUNGdent use of a chromium source, like chromium acetylaceto-
nate, an aluminiumalkyl and a chloride-containing modifier
offers a promising opportunity to enhance catalytic activity
of the described trimerization system. We assume that this
principle of optimized Cr/Al/Cl ratios can be extended to
other selective ethene oligomerization systems.[7]
ces cited therein; b) P. W. N. M. van Leeuwen, N. D. Clꢃment, M. J.-
L. Tschan, Coord. Chem. Rev. 2010, DOI: 10.1016/j.ccr.2010.10.009,
in press.
[4] J. T. Dixon, M. J. Green, F. M. Hess, D. H. Morgan, J. Organomet.
Experimental Section
[5] S. Peitz, N. Peulecke, B. R. Aluri, S. Hansen, B. H. Mꢀller, A. Span-
nenberg, U. Rosenthal, M. H. Al-Hazmi, F. M. Mosa, A. Wçhl, W.
[6] P. M. Fritz, H. Bçlt, A. Wçhl, W. Mꢀller, F. Winkler, A. Wellenhof-
er, U. Rosenthal, M. Hapke, N. Peulecke, B. H. Mꢀller, M. H. Al-
Hazmi, V. O. Aliyev, F. M. Mosa (Linde AG/SABIC), WO 2009/
006979 A2, 2009.
[7] A. Wçhl, U. Rosenthal, B. H. Mꢀller, N. Peulecke, S. Peitz, W.
Mꢀller, H. Bçlt, A. Meiswinkel, R. B. Aluri, M. Al-Hazmi, M. Al-
Masned, K. Al-Eidan, F. Mosa (Linde AG/SABIC), WO 2010/
115520A1, 2010.
and references cited therein.
[9] A. Jabri, C. B. Mason, Y. Sim, S. Gambarotta , T. J. Burchell, R.
[10] B. Reddy Aluri, N. Peulecke, S. Peitz, A. Spannenberg, B. H. Mꢀller,
S. Schulz, H.-J. Drexler, D. Heller, M. H. Al-Hazmi, F. M. Mosa, A.
[11] S. Peitz, N. Peulecke, B. R. Aluri, B. H. Mꢀller, A. Spannenberg, U.
Rosenthal, M. H. Al-Hazmi, F. M. Mosa, A. Wçhl, W. Mꢀller,
[12] A. Wçhl, W. Mꢀller, S. Peitz, N. Peulecke, B. R. Aluri, B. H. Mꢀller,
D. Heller, U. Rosenthal, M. H. Al-Hazmi, F. M. Mosa, Chem. Eur. J.
[13] W. Mꢀller, A. Wçhl, S. Peitz, N. Peulecke, B. R. Aluri, B. H. Mꢀller,
D. Heller, U. Rosenthal, M. H. Al-Hazmi, F. M. Mosa, ChemCatCh-
Ph2PN
method.[5,6,16] [Ph4P]Cl, p-toluidine hydrochloride (ACROS), [HN(Et)3]Cl
(Fluka), [H3N(iPr)]Cl (TCI), [Et4N]Br, [Et4N]Cl, [Et4N]BF4, [Pr4N]Cl,
(tri-n-butyl)n-tetradecylphosphonium chloride, and dimethyldistearylam-
monium chloride (Alfa Aesar) were used as received. [CrCl3A(thf)3] (97%
ACHTUNGTRENNUNG(iPr)P(Ph)NACHTUNGTRENNUNG(iPr)H was prepared according to a published
ACHTUNGTRENNUNG
CTHUNGTRENNUNG
purity) and a solution of AlEt3 in toluene (1.9 molLÀ1) were obtained
from Sigma–Aldrich and used without further purification; toluene
(>99.9% purity) was obtained from Merck Chemicals and was dried
over sodium with benzophenone and was then distilled in an inert gas at-
mosphere (Ar); argon 5.0 and ethene 3.0 were purchased from Linde
Gas and used as received.
For the oligomerization of ethene an apparatus described earlier[12] was
used. Before conducting an experiment, the reactor was heated to 1008C
at reduced pressure for several hours to eliminate traces of water and
oxygen. For the catalyst preparation, the suitable amounts of the
PNPNH-ligand, chromium precursor [CrCl3ACHTNUGTRNNEUG(thf)3]/[CrACHTUTGNREN(NUGN acac)3], and the
modifier were weighed in and charged to a Schlenk tube under inert at-
mosphere. A volume of 100 mL anhydrous toluene was added and the so-
lution was stirred by means of a magnetic stirrer. After dissolving the Cr-
compound, ligand and modifier, the required amount of a 1.9 mollÀ1 so-
lution of TEA in toluene was added. The solution was immediately trans-
ferred to the reactor and the reaction was started by opening the ethene
supply.
After the residence time, the reaction in the liquid phase was quenched
by transferring the liquid inventory by means of the ethene pressure to a
glass vessel filled with water (ca. 100 mL). The mass balance of the ex-
periment was determined via quantification and GC-FID analysis of the
gaseous and liquid product separately, followed by comparison with the
ethene uptake data. Through the closed mass balance selectivity of 1-
hexene could be easily determined, when 1-hexene was used as solvent.
[14] I. Thapa, S. Gambarotta, I. Korobkov, R. Duchateau, S. V. Kulan-
[15] a) S. Peitz, PhD Thesis, University of Rostock, 2010; b) S. Peitz, N.
Peulecke, B. H. Mꢀller, A. Spannenberg, H. J. Drexler, U. Rosen-
thal, M. H. Al-Hazmi, K. E. Al-Eidan, A. Wçhl, W. Mꢀller, Organo-
Based on the measured data, the overall yields and selectivities were de-
termined.
[16] S. Peitz, N. Peulecke, B. R. Aluri, B. H. Mꢀller, A. Spannenberg, U.
Rosenthal, M. H. Al-Hazmi, F. M. Mosa, A. Wçhl, W. Mꢀller, Orga-
Acknowledgements
Received: November 30, 2010
We would like to express our gratitude to Linde Engineering and SABIC
for the permission to publish this work. Furthermore, we whish to thank
Revised: March 2, 2011
Published online: May 10, 2011
6938
ꢂ 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Eur. J. 2011, 17, 6935 – 6938