Novel oxyfunctionalized phosphonite ligands for the hydroformylation of isomeric n-olefins

Article abstract of DOI:10.1002/(SICI)1521-3773(20000502)39:9<1639::AID-ANIE1639>3.0.CO;2-C

Industrially relevant selectivities and turnover frequencies of up to 18710 h^-1 are achieved with novel 2,2'-dihydroxybiphenyl phosphonite ligands such as 1 in the rhodium-catalyzed hydroformylation of internal octenes. R¹ = H, alkyl; R² = OMe, tBu.

Full text of DOI:10.1002/(SICI)1521-3773(20000502)39:9<1639::AID-ANIE1639>3.0.CO;2-C

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[6] a) T. Mennekes, P. Paetzold, R. Boese, D. Bläser, Angew. Chem. 1991,
103, 199; Angew. Chem. Int. Ed. Engl. 1991, 30, 173; b) C. J. Maier, H.
Pritzkow, W. Siebert, Angew. Chem. 1999, 111, 1772; Angew. Chem.
Int. Ed. 1999, 38, 1666.
[7] C. Dohmeier, C. Robl, M. Tacke, H. Schnöckel, Angew. Chem. 1991,
103, 594; Angew. Chem. Int. Ed. Engl. 1991, 30, 564.
[8] W. Uhl, W. Hiller, M. Layh, W. Schwarz, Angew. Chem. 1992, 104,
1378; Angew. Chem. Int. Ed. Engl. 1992, 31, 1364.
[9] W. Hiller, K.-W. Klinkhammer, W. Uhl, J. Wagner, Angew. Chem.
1991, 103, 182; Angew. Chem. Int. Ed. Engl. 1991, 30, 179.
[10] C. Klemp, R. Köppe, E. Weckert, H. Schnöckel, Angew. Chem. 1999,
111, 1852; Angew. Chem. Int. Ed. 1999, 38, 1740.
products for the plasticizer industry, with propylene as the
most important reagent.[1] Knowledge gained from experience
demonstrates the advantages of ester plasticizers with a low
degree of branching and C-numbers from nine upwards for
the alcohol components. An olefin raw material for this
application is a technical octene mixture, for which complete
conversion of all isomers present and control of regioselec-
tivity to the benefit of terminal aldehyde products are of equal
importance (Scheme 1). Hitherto, these two parameters could
[11] A distorted octahedral Al6tBu6À species has been detected in solution
by ESR spectroscopy: C. Dohmeier, M. Mocker, H. Schnöckel, A.
Lötz, U. Schneider, R. Ahlrichs, Angew. Chem. 1993, 105, 1491;
Angew. Chem. Int. Ed. Engl. 1993, 32, 1428.
a
b
À
[12] A distorted pentagonal-bipyramidal Ga9R6 species (R ˆ Si(SiMe3)3;
doubly capped by GaR) has been described by G. Linti: W. Köstler, G.
Linti, Angew. Chem. 1997, 109, 2758; Angew. Chem. Int. Ed. Engl.
1997, 36, 2644. A Ga8(C13H9)82À cluster has recently been prepared: A.
Schnepf, G. Stöûer, H. Schnöckel, Z. Anorg. Allg. Chem., in press.
[13] M. Charbonnel, C. Belin, J. Solid State Chem. 1987, 67, 210.
[14] All quantum-chemical calculations were performed with the RIDFT
module (Funktional-BP86) of the program TURBOMOLE with
SV(P) basis sets; a) TURBOMOLE: O. Treutler, R. Ahlrichs, J.
Chem. Phys. 1995, 102, 346; b) Funktional-BP86: A. D. Becke, Phys.
Rev. A 1998, 38, 3098; J. P. Perdew, Phys. Rev. B 1996, 33, 8822;
c) RIDFT: K. Eichkorn, O. Treutler, H. Öhm, M. Häser, R. Ahlrichs,
Chem. Phys. Lett. 1995, 242, 652; K. Eichkorn, F. Weigend, O. Treutler,
R. Ahlrichs, Theor. Chem. Acc. 1997, 97, 119.
c
OHC
d
+ CO/H2
cat.: [Rh]
CHO
Scheme 1. Isomerizing hydroformylation of internal olefins with the
example of 4-octene. a) hydroformylation, b) isomerization, c), d) hydro-
formylation.
[15] Similar to the decomposition of Ga2H6 at room temperature: R.
Pulham, A. J. Downs, M. J. Goede, D. W. H. Rankin, H. E. Robertson,
J. Am. Chem. Soc. 1991, 113, 5149.
[16] Q. Yu, A. Purath, A. Donchev, H. Schnöckel, Organometallics 1999,
584, 94.
[17] N. Wiberg, T. Blank, H. Nöth, W. Ponikwar, Angew. Chem. 1999, 111,
887; Angew. Chem. Int. Ed. 1999, 38, 839.
[18] L. Bosio, H. Curien, M. Dupont, A. Rimsky, Acta Crystallogr. Sect. B
1973, 29, 367.
only be fulfilled by cobalt catalysis under severe reaction
conditions. Characteristic productivities are 0.1 ± 0.4 tmÀ3 hÀ1
and selectivities for the terminal aldehyde of 50 ± 85%, which
are achieved with 0.1 ± 1% Co at pressures of 80 ± 350 bar and
temperatures of 160 ± 1908C, as well as an undesirable and
extensive hydrogenation activity.[1]
The elimination of these disadvantages by, for example, the
use of novel metal complexes, ligands, and technologies is one
of the current demands placed upon this area. Highly selective
rhodium catalysts based upon bidentate aryl phosphites and
diphosphanes with a large coordination angle already exist for
the conversion of terminal, long-chain olefins.[2] However,
where internal olefins are concerned, technically useful
activity is exhibited only with short-chain homologues such
as 2-butene.[1,3] Thermally more stable diphosphanes with
rigid, bidentate structure and a bias towards trans coordina-
tion give n-selectivities of up to 86% n-nonanal from trans-
octene-4 at very low turnover frequencies of 15 hÀ1.[4] In the
case of terminal olefins the regioselectivity targeted through
the use of diphosphanes of selected structure under the
assumption of irreversible olefin insertion may also be
reasoned on theoretical grounds.[5] On the other hand,
structure prediction for ligands which induce n-selectivity
and, within the context of target position, necessarily also
olefin isomerization is still nonexistent.
Novel Oxyfunctionalized Phosphonite Ligands
for the Hydroformylation of Isomeric n-Olefins
Detlef Selent,* Klaus-Diether Wiese, Dirk Röttger,
and Armin Börner*
Hydroformylation (oxo synthesis) is one of the most
important industrial procedures carried out under homoge-
À
neous catalysis. The high economic significance of this C C
coupling reaction results from the successful production of
over six million tonnes per year of aldehydes and subsequent
[*] Dr. D. Selent, Prof. Dr. A. Börner
Institut für Organische Katalyseforschung
an der Universität Rostock e.V.
Esters of phosphonous acids have hitherto found little
application as ligands in homogeneous catalysis.[6] There are
examples of oxo reactions with the highly reactive propylene
as reagent.[6c] Here we demonstrate that compounds of this
class are highly suitable for the hydroformylation of long-
chain olefins.
Buchbinderstrasse 5 ± 6, 18055 Rostock (Germany)
Fax : (‡49)381-4669324
E-mail: detlef.selent@ifok.uni-rostock.de,
armin.boerner@ifok.uni-rostock.de
Dr. K.-D. Wiese, Dr. D. Röttger
Oxeno Olefin GmbH
For our investigations we chose the readily available and
conformationally flexible phosphonites 4a ± d and 5, which in
each case contain a second donor function in the 2'-position.
Paul-Baumann-Strasse 1, 45764 Marl (Germany)
Supporting information for this article is available on the WWW under
http://www.wiley-vch.de/home/angewandte/ or from the author.
Angew. Chem. Int. Ed. 2000, 39, No. 9
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Table 1. Hydroformylation of 1-octene:[a] effect of the ligand.
[c]
Ligand
t [h]
Yield [%][b]
n/iso[b]
TOF [hÀ1
]
4a
4b
4c
4d
5
1.5
1.5
3
3
1
97
93
89
98
94
1.22
0.90
0.66
0.61
1.03
> 46000[d]
> 46000[d]
17570
O
R1
> 46000[d]
> 83600[d,e]
O
P
CH3
P
O
O
O
O
R
[a] The reactions were carried out in a 200-mL autoclave with [1-octene]0 ˆ
1.692m at 1208C in toluene under a constant pressure of 50 bar CO/H2 (1/1)
with [(acac)Rh(1,5-cyclooctadiene)] (acacˆ acetylacetonate anion) as cata-
lyst precursor. [Rh] ˆ 0.1078 mm, Rh:P:(1-octene) ˆ 1:5:15700. [b] Deter-
mined by gas chromatography, by iso all branched aldehydes are meant.
[c] Turnover frequency in mol aldehyde per mol catalyst per hour at 20%
turnover, calculated on the basis of gas consumption measured with a Hitec
gas flow meter from the company Bronkhorst (NL). [d] Limit of measure-
ment range. [e] 71% turnover in 8 min.
R2
R2
R
4a: R1=CH3, R2=OCH3
4b: R1=CH3, R2=tert-C4H9
5 : R1=H, R2=OCH3
4c: R=OCH3
4d: R=tert-C4H9
The phosphonite ethers 4a ± d are obtainable from the
corresponding bisphenols by partial deprotonation with
benzyl potassium, subsequent etherification with methyl
iodide, in situ formation of the lithium phenolate 1 with n-
butyllithium, and finally reaction with 6-chloro-6H-di-
benz[c,e]-1,2-oxaphosphorine (2)[7] or (2,4-di-tert-butylphe-
nyl)phenylphosphonityl chloride (3; Scheme 2). Phenol 5
was prepared by reaction of the monopotassium salt of the
corresponding bisphenol with 2. The formation of diaster-
eoisomers was confirmed spectroscopically for 4a ± d and 5.[8]
analysis and within the effective range of the recorded gas
uptake an average turnover frequency of over 83000 hÀ1 at up
to 71% conversion was measured. Additional information on
the activity of the catalyst formed with 5 was provided by the
investigation of temperature dependency (Table 2). Even at
608C a quantitative conversion with negligible double-bond
isomerization of the substrate is realizable. The maximum n-
selectivity at 808C can be explained by the different effects of
Ton the rate of isomerization of the substrate and the ratio of
the rates of hydrogenolysis of the intermediate acylrhodium
complexes (rn/riso), should this be the rate-determining step of
the catalysis.[9]
CH3
OH
R
OH
R
OLi
O
R
a – c
Table 2. Hydroformylation of 1-octene with 5: temperature dependency.[a]
[c]
T [8C]
t [h]
Yield [%]
n/iso
Int. aldeh.[b]
TOF [hÀ1
]
R
120
100
80
70
60
1
1
1
293
4
94
96
921.57
1.03
1.30
‡
83600[d,e]
> 46000[d]
45370
24020
7070
1
‡
(
‡)[f]
‡)[f]
d
1.43
(
[g]
98
1.39
±
a, d
[a] For the reaction conditions, except temperature, see Table 1. [b] 3-,4-
Aldehydes after double-bond isomerization (determined by gas chroma-
tography). [c] ± [e] See footnotes [c] ± [e] in Table 1. [f] 1.6% (at 808C) or
0.5% (at 708C) 2-ethylheptanal, no 2-propylhexanal. [g] 2-Octene chemo-
selectivity: 1.2%.
O
O P
+
Cl
P
+
2
Cl
3
5
4a,b
4c,d
Scheme 2. Synthesis of 4a ± d and 5: a) C7H7K (1 equiv), THF, 30 min at
08C; b) CH3I, THF, 8 h at 558C; c) nBuLi, THF/hexane, 30 min at À208C;
d) reaction with 2 or 3: 4 h at 2 58C; 55 ± 85%. Compound 2 was prepared as
described in ref. [7], 3 by reaction of PhPCl2 with 2,4-di-tert-butylphenol in
the presence of pyridine in THF/Et2O (85/15).
Investigations on isomerizing hydroformylation were car-
ried out with an n-octene mixture containing 3.3% 1-octene,
obtained by butene dimerization. At 1408C and 20 barÐ
favorable conditions for olefin isomerizationÐabout 35% n-
pelargonaldehyde was obtained with the catalyst formed with
4a, with activity increasing in parallel with the P:Rh ratio used
(Table 3).
A surprising result came from exchange of methyl ether 4a
with phenol 5 (Table 4). The n-selectivity increased above
P:Rh ratios of 10:1 to more than 45%.[10] The conversion rate
measured at threefold olefin concentration corresponds to
aldehyde yields of 287 kgmÀ3 hÀ1.
The catalytic properties of the new ligands was first tested
for the hydroformylation of 1-octene (Table 1). Even at low
rhodium concentrations of about 14 ppm, reactions with
exceptionally high initial activities and almost quantitative
conversions were obtained without detectable olefin hydro-
genation and alcohol formation. With respect to the ligand
effect, the most active catalysts proved to be the derivatives
4a,b, and 5, derived from the rigid oxaphosphorine 2.
Particularly notable is the catalyst with the phosphonite
phenol 5, a further prototype of a ligand class that has not yet
been established in hydroformylation. On the basis of GC
The properties of the catalyst formed from 5 are currently
being investigated in more detail. Of interest in this context
are literature references on the inhibition of hydroformyla-
tion as well as on the increase in olefin isomerization activity
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Table 3. Hydroformylation[a] of isomeric n-octenes[b] with 4a: effect of the
ligand:metal ratio.
Paulsen, E. W. Beuttenmueller, B. R. Proft, B. A. Matter, D. R.
Powell, J. Am. Chem. Soc. 1999, 121, 63 ± 70.
[3] E. Billig, A. G. Abatjoglou, D. R. Bryant (UCC Corp.), EP-B 0214622,
1987 [Chem. Abstr. 1987, 107, 25126m].
[c]
P:Rh
Yield [%]
TOF [hÀ1
]
n-Nonanal [%][d]
ROH [%][e]
[4] L. A. van der Veen, P. C. J. Kamer, P. W. N. M. van Leeuwen, Angew.
Chem. 1999, 111, 349 ± 351; Angew. Chem. Int. Ed. 1999, 111, 336 ± 338.
[5] D. Gleich, R. Schmid, W. A. Herrmann, Organometallics 1998, 17,
4828 ± 4834.
1:1
2:1
5:1
66
82
88
93
2270
3550
5350
7390
35.1
35.2
35.1
35.4
2.2
2.2
2.2
1.6
10:1
[6] As ligands in asymmetric hydrogenation: a) M. T. Reetz, A. Gosberg,
R. Goddard, S.-H. Kyung, Chem. Commun. 1998, 2077 ± 2078; b) D.
Haag, J. Runsink, H.-D. Scharf, Organometallics 1998, 17,398 ± 409; as
ligands in hydroformylation: c) H. Urata, Y. Wada (Mitsubishi
Chemical Corp.) WO-A 9843935, 1998 [Chem. Abstr. 1998, 129,
289879h].
[a] For the procedure see footnote [a] in Table 1. Conditions: Tˆ 1408C;
p ˆ 20 bar CO/H2 (1/1); t ˆ 6 h. [b] 3.3% 1-octene, 48.4% (Z)- and (E)-2-
octene, 29.2% (Z)- and (E)-3-octene, 16.4% (Z)- and (E)-4-octene, 2.1%
skeletal octene isomers, 0.6% octane. [c] Turnover frequency at 20%
conversion. [d] Fraction of the total amount of aldehydes (four isomers).
[e] Total alcohol yield relative to the amount of olefin used. n-Octane
selectivity: < 1.4%.
[7] H.-J. Kleiner (BASF AG) EP-B 0582957 A1, 1994 [Chem. Abstr. 1994,
120, 270819f].
[8] All new compounds were comprehensively characterized. Experi-
mental details are described in the Supporting Information.
[9] In the hydroformylation of styrene the rate of hydrogenolysis for the
n-acylrhodium compound increases more strongly with increasing
temperature than that of the isoacylrhodium compound owing to the
different activation parameters: J. Feng, M. Garland, Organometallics
1999, 18, 417 ± 427.
[10] In the rhodium-catalyzed hydroformylation of trans-2-butene, the
isomerization-active additive Ru3CO12 induces an increase in n-
selectivity: M. Beller, B. Zimmermann, H. Geissler, Chem. Eur. J.
1999, 5, 1301 ± 1305.
Table 4. Hydroformylation[a] of isomeric n-octenes[b] with 5: effect of the
ligand:metal ratio.
[c]
P:Rh
Yield [%]
TOF [hÀ1
]
n-Nonanal [%][d]
ROH [%][e]
1:1
5:1
21
38
540
1000
31.7
41.0
0.6
1.4
10:01
20:1
50:1
50:1[f]
5213427.8
1.4
77
86
73
3120
2840
18710
45.9
47.9
41.8
2.0
0.8
0.8
Â
[11] A. M. Trzeciak, J. J. Zioøkowski, T. Lis, R. Choukroun, J. Organomet.
Chem. 1999, 575, 87 ± 97.
[12] H. Schumann, V. Ravindar, L. Meltser, W. Baidossi, Y. Sasson, J.
Blum, J. Mol. Catal. A 1997, 118, 55 ± 61.
[a] ± [e] See footnotes [a] ± [e] in Table 3. [f] [Octene isomers]0 ˆ 5.08m.
upon use of rhodium catalysts with phosphane ligands that
were functionalized with Brùnstedt acids.[11, 12] Variation of the
active proton group in 5 with respect to donor capability and
acidity (SH, COOH, etc.) and the ring size of a potentially
hemilabile chelate complex offers potential for further ligand
modification.[13]
[13] The phosphonites 6-(2-tert-butyl-4-methoxyphenyl)dibenz[c,e]-1,2-oxa-
phosphorine and di(2,4-di-tert-butylphenyl)phenylphosphonite de-
rived from simple phenols gave n-selectivities of 37.1 and 32.3%,
respectively, under the conditions described in Table 4 and with a
Rh:P ratio of 1:10.
The results presented here show for the first time that the
productivities and selectivities of the technically established
high-pressure processes with rhodium catalysts can be ach-
ieved with greatly reduced metal concentration and mild
reaction conditions (ca. 20 ± 508 lower in temperature and ca.
60 ± 330 bar lower in pressure) and even exceeded with
respect to suppression of hydrogenation activity. The intro-
duction of additional oxy groups into monodentate phospho-
rus ligands ensures at the same time the necessary high
isomerization activity of the catalyst and the tendency
towards hydroformylation at the chain end. This generally
exceeds the optimistic estimates of the potential development
of rhodium catalyst for the isomerizing hydroformylation of
internal olefins.[4, 10]
First Noncovalently Bound
Calix[4]arene ± GdIII ± Albumin Complex
L. Henry Bryant, Jr.,* Alexander T. Yordanov,
Jenny J. Linnoila, Martin W. Brechbiel, and
Joseph A. Frank
Gadolinium(iii) in its chelated form has long-been recog-
nized as being useful as a contrast enhancement agent in
magnetic resonance imaging (MRI) because of its f7 electronic
configuration and long relaxation time. Noncovalent attach-
ment of low molecular weight GdIII complexes to serum
Received: November 24, 1999 [Z14311]
[*] Dr. L. H. Bryant, Jr., J. J. Linnoila, Dr. J. A. Frank
Laboratory of Diagnostic Radiology Research (CC)
Bldg. 10, Room B1N256
[1] a) C. D. Frohning, C. W. Kohlpaintner in Applied Homogeneous
Catalysis with Organometallic Compounds, Vol. 1 (Eds.: B. Cornils,
W. A. Herrmann), Wiley-VCH, Weinheim, 1996, pp. 3 ± 25; b) W. A.
Herrmann, B. Cornils, Angew. Chem. 1997, 109, 1074 ± 1095; Angew.
Chem. Int. Ed. Engl. 1997, 36, 1048 ± 1067.
[2] a) C. P. Casey, G. T. Whiteker, M. G. Melville, L. M. Petrovich, J. A.
Gavney, Jr., D. R. Powell, J. Am. Chem. Soc. 1992, 114, 5535 ± 5543;
b) M. Kranenburg, Y. E. M. van der Burgt, P. C. J. Kamer, P. W. N. M.
van Leeuwen, Organometallics 1995, 14, 3081 ± 3089; c) B. Moasser,
W. L. Gladfelter, D. C. Roe, Organometallics 1995, 14, 3832± 3838;
d) L. A. van der Veen, M. D. K. Boele, F. R. Bregman, P. C. J. Kamer,
P. W. N. M. van Leeuwen, K. Goubitz, J. Fraanje, H. Schenk, C. Bo, J.
Am. Chem. Soc. 1998, 120, 11616 ± 11626; e) C. P. Casey, E. L.
National Institutes of Health
Bethesda, MD 20892 (USA)
Fax : (‡1)301-594-2979
E-mail: blh@helix.nih.gov
Dr. A. T. Yordanov, Dr. M. W. Brechbiel
Radioimmune & Inorganic Chemistry Section
Bldg. 10, Room B3B69
Radiation Oncology Branch
NCI, National Institutes of Health
Bethesda, MD 20892 (USA)
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