Micellar effects in olefin hydroformylation catalysed by neutral, calix[4]arene-diphosphite rhodium complexes

Article abstract of DOI:10.1002/adsc.200900074

The combination of calixarene-derived surfactants and neutral rhodium complexes containing a hemispherical "1,3-calix-diphosphite" ligand led to efficient catalysts for the hydroformylation of octene and other olefins in water. While the surfactants allowed the formation of micelles that dissolve both the catalyst and the alkene, thereby resulting in high olefin :rhodium ratios, the diphosphite provided a tight envelope about the catalytic centre able to drive the reaction towards the linear aldehydes. Best results in the hydroformylation of 1-octene were obtained when using [tetra(p-sulfonato)]- (tetra-nbutoxy)-calix[4]arene as surfactant. With this additive remarkable linear to branched aldehyde ratios of up to 62 were obtained, the corresponding activities being higher than those observed when operating in an organic solvent [turnover frequencies (TOFs) up to 630 mol(converted 1-octene)-mol(Rh) ^-1·h^-1].

Full text of DOI:10.1002/adsc.200900074

FULL PAPERS
DOI: 10.1002/adsc.200900074
Micellar Effects in Olefin Hydroformylation Catalysed by
Neutral, Calix[4]arene-Diphosphite Rhodium Complexes
a
a,
a,
b
Laure Monnereau, David Sꢀmeril, * Dominique Matt, * and Loꢁc Toupet
a
Laboratoire de Chimie Inorganique Molꢀculaire et Catalyse, Institut de Chimie UMR 7177, Universitꢀ de Strasbourg,
rue Blaise Pascal, 67008 Strasbourg Cedex, France
1
Fax : (+33)-3-9024-1749; e-mail: dmatt@chimie.u-strasbg.fr or dsemeril@chimie.u-strasbg.fr
Groupe Matiꢂre Condensꢀe et Matꢀriaux, UMR 6626, Universitꢀ de Rennes 1, Campus de Beaulieu, 35042-Rennes
cedex, France
b
Received: February 3, 2009; Revised: May 18, 2009; Published online: June 16, 2009
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.200900074.
Abstract: The combination of calixarene-derived sur- butoxy)-calix[4]arene as surfactant. With this addi-
factants and neutral rhodium complexes containing a tive remarkable linear to branched aldehyde ratios
hemispherical “1,3-calix-diphosphite” ligand led to of up to 62 were obtained, the corresponding activi-
efficient catalysts for the hydroformylation of octene ties being higher than those observed when operat-
and other olefins in water. While the surfactants al- ing in an organic solvent [turnover frequencies
lowed the formation of micelles that dissolve both (TOFs) up to 630 mol(converted 1-octene)·
À1 À1
the catalyst and the alkene, thereby resulting in high mol(Rh) ·h ].
olefin:rhodium ratios, the diphosphite provided a
tight envelope about the catalytic centre able to
drive the reaction towards the linear aldehydes. Best Keywords: catalysis in water; hemispherical diphos-
results in the hydroformylation of 1-octene were ob- phites; hydroformylation; large bite angles; micelles;
tained when using [tetra(p-sulfonato)]-(tetra-n- surfactants
Introduction
having both phosphorus atoms substituted by the
bulky 1,1’-binaphthalene-2,2’-dioxy (“bino”) moiety
[
9,10]
Hydroformylation is a major industrial process that (Figure 1).
The high regioselectivity observed with
produces aldehydes from olefins, carbon monoxide these ligands toward the production of linear alde-
and hydrogen. It is classically carried out in the pres- hydes was attributed to the ability of the diphosphites
[
1,2]
ence of a cobalt or a rhodium catalyst.
The most to form upon chelation a tight molecular pocket able
important applications of the industrially produced al- to control the shape of the outcoming product. The
dehydes are plasticizers and detergent alcohols. Hy-
droformylation can be achieved in biphasic aqueous
systems using water-soluble phosphines. For example,
Ruhrchemie and Rhꢃne–Poulenc developed the in-
dustrial propene hydroformylation using the tris-sul-
[
3,4]
fonated triphenylphosphine (TPPTS). Nevertheless,
due to low solubility of long-chain olefins in water,
this catalytic system can only be applied to short-
chain olefins. A possible way to overcome this issue is
[
5]
[6–8]
to add surfactants to the reaction mixture.
Results and Discussion
Recently, we reported on the remarkable olefin hy- Figure 1. General formula of hemispherical “1,3-calix[4]ar-
droformylation properties of 1,3-calix[4]-diphosphites ene diphosphites”.
Adv. Synth. Catal. 2009, 351, 1629 – 1636
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Laure Monnereau et al.
FULL PAPERS
Scheme 1. Synthesis of complexes 4–6.
pocket is formed by the presence of the bino substitu- which is imposed by the calixarene backbone and
ents and two alkoxy groups connected to the calixar- which prevents formation of a chelate ring with an
eneꢅs lower rim. Thus, these diphosphites, the natural ideal bite angle of 908. Note that the value of the PÀ
bite angles of which are close to 1038, provide a “tri- MÀP angle is close to the one found in the recently
[
9]
dimensional” metal embrace and therefore were re- reported structure of [Pd ACHTUNGTENRUNG( C H )·1]PF . The coordi-
3 5 6
ferred to as “hemispherical” ligands. Their ability to nation environment deviates from the planar geome-
envelope the catalytic centre is much more pro- try generally adopted by [Rh(acac)(diphosphane)]
This is best seen by considering the
Pursuing our efforts to develop envi- non-zero dihedral angle between the PRhP and
ronmentally friendly reactions, we now describe the ORhO planes (16.38). This distortion obviously mini-
use of neutral [Rh(acac)(1,3-calix-diphosphite)] com- mises the steric interactions between the binaphthyl
AHCTUNGTRENNUNG
[
21]
nounced than with other diphosphanes having a large complexes.
[11–20]
bite angle.
AHCTUNGTRENNUNG
plexes in aqueous hydroformylation. These experi- units and the flat acetylacetonate ligand. In fact, the
ments were carried out with particular surfactants, rhodium-acac moiety sits deep in a molecular pocket
namely sulfonated-calix[4]arenes, a type of surfactant generated by two symmetrically located naphthyl
which to date was not used in catalytic reactions. In moieties. It is further noteworthy that, owing to the
this study we also report the first X-ray structure of a presence of a typically flattened cone conformation,
rhodium chelate complex containing a hemispherical the O-propyl groups are pushed towards the rhodium
diphosphite.
Reaction of the cone-calixarenes 1–3 with metal centre (Figure 2).
Rh(acac)(CO) ] in CH Cl gave the chelate com- We began the catalytic study by assessing two of
plexes 4–6, respectively, in yields of between 70 and these [Rh(acac)L] complexes (4 and 5) in the hydro-
0% after work-up (Scheme 1). Each mass spectrum formylation of 1-octene at 508C in toluene under
centre, thereby increasing the confinement of the
[
ACHTUNGTRENNUNG
2
2
2
AHCTUNGTRENNUNG
8
+
shows a strong peak corresponding to the [M ] ion. 20 bar using 2:1, 1:1 and 1:2 CO/H2 mixtures
All NMR spectra are consistent with a C -symmetri- (Scheme 2 and Table 1). The tests were carried out
2
31
cal molecule. For example, the P NMR spectrum of without addition of free ligand. Increasing the partial
4
shows a doublet centred at 126.6 ppm (JRh,P
=
pressure of hydrogen induced significants rate en-
1
328 Hz), while the corresponding H NMR spectrum hancement. For example, with 5, after 2.5 h of reac-
displays two AB systems for the ArCH Ar methylenic tion time the conversion increased from 6.8 to 38.8%
2
protons.
when the V(CO)/V(H ) ratio passed from 1:1 to 1:2
2
The solid state structure of 4 was determined by a (Table 1, entries 2 and 3). This increase cannot be ex-
single X-ray diffraction study, which confirmed the plained by standard kinetics, which predict that a
chelating behaviour of the disphosphite. The observed 30% increase of the partial H pressure would at most
2
[
22]
large PÀRhÀP angle, 101.58, reflects the relatively double the rate.
A possible explanation for this
large separation between the two phosphorus atoms, phenomenon is the existence of equilibria involving
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Adv. Synth. Catal. 2009, 351, 1629 – 1636

Micellar Effects in Olefin Hydroformylation
FULL PAPERS
regioselectivities were lower with 4 than 5 (Table 1,
entries 3 and 4).
For the catalytic study carried out in water, only
the precatalyst giving the best results in toluene,
namely complex 5 (with benzyl substituents) was
used. The experiments were done in the presence of
various upper rim-sulfonated calixarenes (7–10). The
Figure 2. Molecular structure of 4 (S,S). PÀRhÀP angle
101.58. Dihedral angles between facing phenoxy rings of the
calixarene: 4.68 (O3/O4), 82.98 (O5/O8). Dihedral angle be-
tween PÀRhÀP and acac: 16.38. The molecule crystallises
with 2/3 molecule of CHCl lying out of the cavity (not
shown).
3
calixarenes 8–10, bearing linear alkyl chains at the
lower rim, were prepared according to a general
method reported by Shinkai starting from the tetra-
[
24–26]
sulfonated calix[4]arene 7.
Typically, 7 was alky-
lated by the appropriate alkyl halide in the presence
of NaOH in a mixture of water and dimethyl sulfox-
1
ide. The H NMR data of these sulfonated compounds
are all consistent with the formation of calixarenes in
the cone conformation.
Three olefins were used, namely 1-octene, 1-hexene
and styrene. The tests were carried out in 8 mL of
Scheme 2. Hydroformylation of 1-octene in toluene (using 4
and 5).
water, at 508C and under 20 bar of CO/H with a
2
V(CO)/V(H ) ratio of 1:2 (Scheme 3). The rhodium
an inactive [RhL(CO) ] dimer, which owing to the complex was first dissolved in the olefin, before being
2
[
23]
2
2
particular confinement created in this dimer by the introduced into the autoclave. At the end of each run
two hemispherical ligands would render difficult the performed in the presence of any surfactant, an emul-
formation of active hydrido-carbonyl species at lower sion was recovered, which remained stable after
partial hydrogen pressures. We noted that the rate in- standing for several days. In the absence of surfactant,
crease was not accompanied by a significant modifica- two phases could be observed. In this case, the cata-
tion of the regioselectivity. As previously observed in lyst was contained in the organic phase.
[
9,10]
reactions performed at higher temperatures,
the
[a]
Table 1. Rhodium-catalyzed hydroformylation of 1-octene using complexes 4 and 5 in toluene.
[b]
[c]
[d]
Entry
[Rh]
P
A
H
U
G
R
N
U
G
Conv. [%]
TOF
Product distribution
Isomer. olefins [%] Aldehydes [%]
l:b
2
V(CO)
V(H2)
1
2
3
4
5
5
5
4
2
1
1
1
1
1
2
2
1
10
70
390
420
1.0
1.2
4.6
1.1
traces
98.8
95.4
6.8
38.8
42.3
16.8
14.5
6.1
98.9
[
a]
1-Octene (5 mmol), [Rh] (2 mmol), 1-octene/Rh=2500, P ACHTUNGNTERNUNG( CO/H ) =20 bar, T=508C, 2.5 h, toluene/n-decane (15 mL/
2 total
0
.5 mL). Stainless steel autoclave, 100 mL.
[
[
[
b]
c]
d]
Determined by GC using decane as standard.
Mol(converted 1-octene)·mol(Rh) ·h .
The l:b aldehyde ratio takes into account the branched aldehydes (which consist mainly of 2-methyloctanal).
À1 À1
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Laure Monnereau et al.
FULL PAPERS
stead of 50 mg of sulfonated calixarene led to a
higher activity without a significant loss of selectivity.
For example, the TOF increased from 420 to 550 mol-
À1 À1
A
H
U
G
R
N
U
G
when, respectively, 50 and
1
00 mg of surfactant 7 were used (Table 1, entries 4
and 5). Further, changing the alkyl substituents of the
surfactant induced considerable variations of the cata-
lytic results. The n-butyl substituted calixarene 8 gave
Scheme 3. Hydroformylation experiments performed with
complex 4 and sulfonated calixarenes 7–10 in water.
the
(octene)·mol(Rh) ·h at a conversion of 44.7% after
1 hour] and the highest regioselectivity (l:b>100)
see Supporting Information, Table S2, entry 6). We
The outcome of the catalytic runs strongly depended finally found that the activity as well as the selectivity
on the presence of surfactant. When the catalysis was drastically droped when using [Rh(acac)(CO) ] alone
highest
TOF
[TOF=1160
mol-
À1 À1
AHCTUNGTRENNUNG
1-Octene Hydroformylation
(
AHCTUNGTRENNUNG
2
performed without surfactant (Table 1, entry 1), the (that is in the absence of diphosphite) (Table 2, en-
hydroformylation process occurred in the octene tries 11 and 12). Overall, operating in a water/surfac-
layer, in which the catalyst was found to be soluble. tant medium led to higher activities than in an organ-
These conditions led to an activity of the catalyst of ic medium, both media giving high linear selectivities.
À1 À1
3
60 mol ACHTUNGTRENNUNG( octene)·mol(Rh) ·h , which nearly corre-
sponds to the activity observed when operating in tol-
uene. The addition of surfactant modified the reaction 1-Hexene Hydroformylation
mixture and led to the formation of micelles. We ob-
served that high linear to branched aldehyde ratios These experiments were carried out with complex 5.
(
l:b> 20) were only observed when the catalytic reac- As above, a CO:H ratio of 1:2 and ligand:[Rh] ratio
2
tion was carried out in the presence of diphosphite in of 10 were used. The highest activity, 750 mol ACHTUNGTRENNUNG( hex-
À1 À1
excess. With ligand 2, for example, the l:b ratio in-
ACHTUNGTRENNGNUe ne)·mol(Rh) ·h , was observed in the presence of
creased from 3.2 to 61.8 on going from an L:Rh ratio the butyl-substituted surfactant 8. In this case, the cor-
of 1 to an L:Rh ratio of 10 (Table 2, entries 3 and 6). responding l:b ratio was 15.7 (Table 3, entry 2). For
As observed by other authors, excess ligand is neces- comparison, when repeating these experiments in tol-
sary to prevent the formation of “naked” rhodium, uene, the activity was 4 times lower than when oper-
[
27]
which behaves as an unselective catalyst. As a gen- ating in the water/8 system (same selectivity). As with
eral trend, excepted with 10, the use of 100 mg in- 1-octene, the other surfactants (7, 9, and 10) led to
[a]
Table 2. Rhodium-catalyzed hydroformylation of 1-octene.
[b]
[c]
[d]
Entry
Sulfonated-calixarene
Conv. [%]
TOF
Product distribution
Isomer. olefins (%) Aldehydes (%)
l:b
[
[
[
[
[
[
[
[
[
f]
e]
e]
f]
f]
f]
f]
f]
f]
[
1
2
3
4
5
6
7
8
9
1
1
1
/
36.1
54.2
65.0
42.4
55.2
63.1
56.5
60.2
48.2
42.1
13.3
14.9
360
540
650
420
550
630
570
600
480
420
60
1.5
0.5
1.4
2.4
3.0
1.8
2.6
1.3
1.9
7.7
7.9
4.9
34.6
53.7
63.6
40.0
52.2
61.3
53.9
58.9
46.3
34.4
5.4
24.1
2.1
3.2
25.7
14.2
61.8
27.6
21.2
6.4
8 (50 mg) (R=n-C H )
8 (100 mg) (R=n-C H )
7 (50 mg) (R=H)
7 (100 mg) (R=H)
8 (100 mg) (R=n-C H )
9 (50 mg) (R=n-C H )
9 (100 mg) (R=n-C H )
10 (50 mg) (R=n-C H )
4
9
4
9
4
9
6
13
6
13
8
17
f]
0
1
2
10 (100 mg) (R=n-C H )
5.8
2.0
1.9
8
17
[
[
g]
g]
/
8 (100 mg) (R=n-C H )
70
10.0
4
9
[
a]
1
-Octene (2.5 mmol), 5 (1 mmol), 1-octene/Rh=2500, V(H )/V(CO)=2/1, P
A
H
U
G
R
N
U
G
2
2
total
2
decane (8 mL/0.1 mL). Stainless steel autoclave, 100 mL.
Determined by GC using decane as standard.
Mol(converted 1-octene)·mol(Rh) ·h .
The l:b aldehyde ratio takes into account the branched aldehydes (which consist mainly of 2-methyloctanal).
No excess of 2.
[
[
[
[
[
[
b]
c]
d]
e]
f]
À1 À1
Addition of an excess of 10 equiv./5 of 2.
g]
Catalyst used with no additional ligand: [Rh ACHTUNGTERNN(UGN acac)(CO) ] (2 mmol).
2
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Micellar Effects in Olefin Hydroformylation
FULL PAPERS
[a]
Table 3. Hydroformylation of 1-hexene and styrene using complex 5.
[b]
[c]
[d]
Entry
Sulfonated-calixarene (R)
Conv. [%]
TOF
Product distribution
Isomer. olefins [%] Aldehydes
l:b
l (%)
b (%)
1
1
2
3
4
5
-hexene
7 (R=H) (100 mg)
21.4
59.6
37.4
28.0
39.4
270
750
470
350
490
37.4
3.2
traces
traces
3.0
58.4
91.0
91.6
88.5
88.3
4.2
5.8
8.4
11.5
8.7
13.9
15.7
10.9
7.7
8 (R=n-C H ) (100 mg)
4
9
9 (R=n-C H ) (100 mg)
6
13
10 (R=n-C H ) (50 mg)
8
17
/
10.1
styrene
6
7
8
9
7 (R=H) (100 mg)
12.5
22.7
27.0
37.7
8.9
80
/
/
/
/
/
54.4
46.7
63.5
66.7
78.7
45.6
53.3
36.5
33.3
21.3
1.2
0.9
1.7
2.0
3.7
8 (R=n-C H ) (100 mg)
140
170
230
60
4
9
9 (R=n-C H ) (100 mg)
6
13
10 (R=n-C H ) (50 mg)
8
17
10
/
[
a]
Olefin (2.5 mmol), 5 (1 mmol), olefin/Rh=2500, excess of 10 equiv./5 of 2, V(H )/V(CO)=2/1, P ACTHUNGTRNEUNG( CO/H ) =20 bar, T=
2 total
2
5
08C, 4 h, H O/n-decane (8 mL/0.1 mL). Stainless steel autoclave, 100 mL.
2
[
[
[
b]
Determined by GC using decane as standard.
Mol(converted olefin)·mol(Rh) ·h .
The l:b aldehyde ratio takes into account the branched aldehydes.
c]
À1 À1
d]
lower activities and selectivities (Table 3, entries 1–4). and 58.4% of linear aldehyde. Operating in a water/
We noted that when 5 was used without any surfac- surfactant medium significantly improved the activity
tant (that is, operating in a two phase water/olefin of the catalyst [TOFs up to 230 mol-
À1 À1
system; see Table 3, entry 5), the activity and the se-
ACHTUNGTRENNGNU( styrene)·mol(Rh) ·h ]. We noted that both the ac-
lectivity were comparable to those obtained with 9, tivity and the selectivity increased when the alkyl sub-
while being superior to those found with 7 and 10. stituants of the sulfonated calixarenes became longer
Overall, these findings clearly demonstrate the useful- (Table 3, entries 6–9). With the more efficient additive
ness of surfactant 8 for carrying out the hydroformy- 10 (octyl substituents) an activity of 230 mol-
À1 À1
lation of 1-hexene in an aqueous medium.
ACHTUNGTRENNU(GN styrene)·mol(Rh) ·h and a regioselectivity toward
the linear product of 66.7% were obtained (Table 3,
entry 9). It is worth mentioning here that in these re-
actions, which were all carried with optically pure
Styrene Hydroformylation
(
S,S)-5, the branched aldehyde was produced in
It is well-known that with conventional rhodium- modest optical yields (ees ranging from 21 to 27%).
phosphine catalysts, styrene leads mainly to the corre-
sponding branched aldehyde, namely 2-phenylpropa-
nal. When operating in water and without using a sur- Asymmetric Hydroformylation of Norbornene
factant, complex 5, in the presence of 10 equiv. of free
ligand, produced the linear aldehyde with 78.7% se- Complex 6, which was obtained from the optically
À1 À1
lectivity
[TOF=60
mol AHCTUNTGERNNUN(G styrene)·mol(Rh) ·h ; pure calixarene 3 (having appended fluorenyl groups)
Table 3, entry 10]. For comparison, operating in tolu- was assessed in the aqueous asymmetric hydroformy-
ene with the same complex, but without adding free lation of norbornene (Scheme 4). This reaction led
À1 À1
ligand, led to a TOF of 70 mol
A
H
U
G
R
N
U
G
mainly to the endo-aldehyde, thus contrasting with
Scheme 4. Asymmetric hydroformylation of norbornene. These experiments were carried out with complex 6 and sulfonat-
ed-calixarenes 7–10 in water.
Adv. Synth. Catal. 2009, 351, 1629 – 1636
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Laure Monnereau et al.
FULL PAPERS
[a]
Table 4. Rhodium-catalyzed hydroformylation of norbornene.
[b]
[b]
Entry
Sulfonated-calixarene (R)
Conv. [%]
Product distribution
[c]
endo (%)
ee (endo) (%)
exo (%)
1
2
3
4
5
7 (R=H) (100 mg)
93.0
66.2
38.0
37.7
64.7
100
100
100
84.0
88.3
3 (R)
traces
traces
traces
16.0
8 (R=n-C H ) (100 mg)
39 (R)
33 (R)
36 (R)
35 (R)
4
9
9 (R=n-C H ) (100 mg)
6
13
10 (R=n-C H ) (50 mg)
8
17
/
11.7
[
a]
Norbornene (0.4 mmol), 6 (2 mmol), norbornene/Rh=200, excess of 10 equiv./6 of 3, V(H )/V(CO)=2/1, P
A
H
U
G
E
N
N
=
2
2
0 bar, T=508C, 24 h, H O/n-decane (8 mL/0.1 mL). Stainless steel autoclave, 100 mL.
2
[
[
b]
c]
Determined by GC using decane as standard.
Determined by GC using a chiral column (Chirasil-DEX CB, 25 mꢆ0.25 mm) after reduction into the alcohols and using
decane as standard.
[
10]
our previous experiments performed in toluene. We types of compounds were identified, non-micellar cal-
have no rationale for this change in behaviour. Note ixarenes (e.g., for R=methyl), micelle-forming calix-
that in the presence of sulfonated calixarenes bearing arenes (e.g., for R=butyl), and unimolecular micellar
H, n-C H , or n-C H substituents at the lower rim, calixarenes (e.g., for R=dodecyl). Light-scattering
4
9
6
13
the endo selectivity was close to 100% (Table 4, en- measurements made on these calix[6]arenes (concen-
À3
tries 1–3). The n-butyl-substituted surfactant 8 gave tration in water: 1.0ꢆ10 M) gave an estimation of
the highest optical induction, ee=39%, the absolute the aggregation number at 308C. The study showed
conformation being R (Table 4, entry 3). Although that the C -substituted calix[6]arene formed small mi-
6
the observed ees were moderate, the enantioselectivi- celles constituted of 6 calixarenes, while the C -sub-
12
ty observed with complex 6 is one of the highest re- stituted calix[6]arene gave smaller aggregates (dimer
[
24]
ported yet for norbornene hydroformylation experi- or trimer). In the Shinkaiꢅs classification, the sulfo-
[
10,28–30]
ments that lead to endo aldehydes.
nated calix[4]arene 8 (n-butyl substituents), which
gave the best results in octene and hexene hydrofor-
mylations, belongs to the micelle-forming calixarenes
group. It appears therefore likely that in the hydrofor-
mylation reactions presented above the catalytic spe-
cies operates inside the micelle, with the lipophilic C4-
Remarks about the Regioslectivity of the Catalyst
and the Role of the Surfactant
The results presented above unambiguously show that chains acting as an efficient solvent for the catalyst/
when operating in an olefin-water-surfactant medium, olefin mixture. This creates locally high Rh:alkene
the linear aldehyde selectivities obtained with “1,3- ratios, which incidentally lead to high activities. If the
calix diphosphite” 5 are almost as high as those ob- length of the surfactant substituents is changed, the
served in toluene. This suggests that in both media, catalyst environment also changes and, logically, its
water or toluene, the selectivity of the system is performance may be drastically modified.
mainly controlled by the intrinsic properties of the
ligand, notably its shape. As confirmed for the first
time by an X-ray diffraction study, the rhodium atom Conclusions
(
see above) of the catalytic precursor is deeply em-
bedded in a molecular pocket formed by two almost In conclusion, in water and in the presence of sulfo-
parallel naphthyl planes and the two propyloxy nated calix[4]arenes the neutral calix-diphosphite rho-
groups. The net result is a restricted reaction domain, dium complex 5 efficiently drives olefin hydroformy-
with the outcoming aldehyde adopting the shape lation reactions towards the formation of linear alde-
(
namely as elongated as possible) which best fits with hydes. The presence of the surfactant had a direct
that of the catalytic pocket. impact on both catalyst activity and regioselectivity of
In most examples outlined above, the reactivity in the reaction. The performance of the catalytic system
the water/surfactant medium was higher than when was shown to be strongly dependent on the nature of
operating in organic solvents. One may wonder what the lipophilic tails, the best results being obtained
the role of the surfactant is in these systems. As estab- with the n-butyl-substituted calixarene in the case of
lished by Shinkai et al., the aggregation properties of 1-octene. Obviously, micelles were formed in this
calixarene sulfonates in water are strongly dependent case, which allow the formation of microenvironments
[
26]
upon the length of the appended alkyl groups. In characterised by a high metal:olefin ratio. Overall,
the case of (RO) -calix[6]arene hexasulfonates, three this study shows, for the first time, that highly regiose-
6
1634
asc.wiley-vch.de
ꢄ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2009, 351, 1629 – 1636

Micellar Effects in Olefin Hydroformylation
FULL PAPERS
lective hydroformylation can be carried out in water
without water-soluble phosphines.
Crystals of 4 (yellow) suitable for X-ray diffraction were
obtained by slow diffusion of hexane into a CHCl solution
3
of 4.
Crystal Structure of 4·2/3 CHCl3
Experimental Section
Mr=1643.32, monoclinic, P2 , a=12.726(2), b=20.115(3),
1
3
General Methods
c=17.111(3) ꢇ, b=102.440(10), V=4277.3(13) ꢇ , Z=2,
À3
À1
D =1.276 mgm , l
A
H
U
G
R
N
U
G
x
Ka
All syntheses were performed in Schlenk-type flasks under
dry nitrogen. Solvents were dried by conventional methods
AHCTUNGTRENNUGN( 000)=1722, T=90(2) K. Data were collected on a Oxford
Diffraction Xcalibur Saphir 3 diffractometer (graphite MoKa
1
and were distilled immediately prior to use. Routine H,
13
1
31
1
radiation, l=0.71073 ꢇ). The structure was solved with
C{ H} and P{ H} NMR spectra were recorded by using a
[31]
1
SIR-97,
which revealed the non-hydrogen atoms of the
Bruker AVANCE 300 spectrometer. H NMR spectra were
referenced to residual protonated solvents (7.26 ppm for
molecule. After anisotropic refinement, many hydrogen
atoms were found with a Fourier difference analysis. The
whole structure was refined with SHELX-97
matrix least-square techniques (use of F ; x, y, z, b for P, C
13
CDCl ), C chemical shifts are reported relative to deuter-
3
[32]
3
1
and full-
ated solvents (77.16 ppm for CDCl ) and the P NMR data
are given relative to external H PO . Elemental analyses
were performed by the Service de Microanalyse, Institut de
Chimie, Universitꢀ de Strasbourg. The catalytic solutions
were analysed by using a Varian 3900 gas chromatograph
3
2
ij
3
4
and O atoms, x, y, z in riding mode for H atoms; 1009 varia-
bles and 10539 observations with I> 2.0 s(I); calcd.
2
2
2
2
2
w=1/[s
ACHTUNGTRNENU(G F ) + (0.0943P) ] where P=(F +2F )/3. R1=
0
o
c
À3
0
.0681, wR2=0.1570, S =0.925, D1 <0.56eꢇ , Flack pa-
w
equipped with
a WCOT fused-silica column (25 mꢆ
rameter=À0.04(3). CCDC 705626 contains the supplemen-
tary crystallographic data for this paper. These data can be
obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/
cif. The “Alerts Level A” in the checkcif are mainly due to
the tert-butyl groups, which display a large thermal motion
0.25 mm; used for the aldehyde detection) or with a Chira-
sil-DEX CB column (25 mꢆ0.25 mm; used for the ee deter-
mination after reduction of the aldehydes into alcohols).
[
10]
The calixarene-diphosphites 1–3,
the sulfonated-calixar-
[24]
[10]
[10]
enes 7–10 and the complexes 5 and 6 were prepared
according to literature procedures.
(
near disorder or free rotation for the C48 and C52 quater-
nary CMe atoms).
3
ACHTUNGTRENNUNG( S,S)-Acetylacetato-{5,11,17,23-tetra-tert-butyl-25,27-
dipropyloxy-26,28-bis(1,1’-binaphthyl-2,2’-
dioxyphosphanyloxy)calix[4]arene}rhodium(I) (4)
General Procedure for the Hydroformylation
Experiments
A solution of Rh
5 mL) was added to a solution of (S,S)-5,11,17,23-tetra-tert-
butyl-25,27-dipropyloxy-26,28-bis(1,1’-binaphthyl-2,2’-dioxy-
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(acac)(CO) (0.094 g, 0.36 mmol) in CH Cl
The hydroformylation experiments were carried out in a
glass-lined, 100-mL stainless steel autoclave containing a
magnetic stirring bar. In a typical run, the autoclave was
charged successively under nitrogen with [Rh AHCTUNGTRENNUN(G acac)L] (L=
1–3) dissolved in the olefin, ligand, solvent (toluene or a
2
2
2
(
phosphanyloxy)calix[4]arene (1) (0.500 g, 0.36 mmol) in
CH Cl (250 mL). The solution turned from green to yellow
2
2
within a few minutes. After 16 h, the solvent was evaporated
to dryness. The yellow solid was washed with cold hexane
water-surfactant mixture), and 0.1 mL of decane. Once
closed, the autoclave was flushed twice with syngas (CO/H
1:1 v/v), then pressurised with a CO/H mixture and heated
2
(
(
À788C), then dried under vacuum; yield: 0.458 g (80%). IR
2
À1
1
KBr): n=1514, 1579 (acac) cm ; H NMR (300 MHz,
at 508C. During the experiments, several samples were
taken and analysed by GC. At the end of the runs per-
formed with a surfactant an emulsion was recovered, which
remained stable for long periods (whatever the sulfonated
calixarene used). In the absence of surfactant, two phases
could be observed. In this case, the catalyst was contained in
the organic phase. All reactions were performed at a pres-
sure of 20 bar. This value corresponds to a pressure fre-
3
CDCl ): d=8.07 (d, J =8.7 Hz, 2H, CH arom), 7.75 (d,
3
H,H
3
3
JH,H =8.8 Hz, 4H, CH arom), 7.70 (d, JH,H =8.2 Hz, 2H,
3
CH arom), 7.48 (d, J =7.6 Hz, 2H, CH arom), 7.30–7.21
H,H
(
m, 8H, CH arom), 7.11–6.99 (m, 6H, CH arom), 6.93 (d,
4
4
JH,H =2.3 Hz, 2H, m-ArH), 6.53 (d, J =2.2 Hz, 2H, m-
ArH), 6.40 (d, J =2.2 Hz, 2H, m-ArH), 6.25 (d, J
2
1
1
H,H
4
4
=
=
=
H,H
H,H
2
.2 Hz, 2H, m-ArH), 5.42 and 3.42 (AB system, JH,H
2.6 Hz, 4H, ArCH Ar), 5.27 and 2.86 (AB system, J
2
[1]
quently used in the literature.
2
H,H
3.0 Hz, 4H, ArCH Ar), 4.55 (s, 1H, CH-acac), 4.43–4.28
2
(
C
C
m, 4H, OCH ), 2.30–2.22 (m, 4H, CH CH ), 1.08 [s, 18H,
2
2
3
3
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH ) ], 1.00 (t, J =7.4 Hz, 6H, CH CH ), 0.78 [s, 18H,
3
3
H,H
2
3
1
3
1
A
C
H
T
U
N
G
T
R
E
N
N
U
N
G
(CH ) ], 0.28 (s, 6H, CH3 of acac); C{ H} NMR
3
3
Acknowledgements
(
75 MHz, CDCl ): d=183.45 (s, CO-acac), 152.31–118.99
3
(
arom Cꢅs), 98.15 (s, CH of acac), 77.32 (s, OCH ), 33.86 (s,
2
The Universitꢀ de Strasbourg and the French Agence Natio-
nale de la Recherche (WATERCAT Program) are gratefully
acknowledged for financial support.
ArCH Ar), 33.77 (s, ArCH Ar), 33.62 [s, C ACHTUNGTRNEGNU( CH ) ], 33.53 [s,
2
2
3 3
C ACHTUNGTRENNUNG( CH ) ], 31.24 [s, C ACHTUGNTRENUNG( CH ) ], 31.05 [s, C ACTHNUGTRNENUG( CH ) ], 25.26 (s,
3 3 3 3 3 3
31 1
CH of acac), 23.10 (s, CH CH ), 10.33 (s, CH CH ); P{ H}
3
2
3
2
3
NMR (121 MHz, CDCl ): d=126.6 (d, J =328 Hz); MS
3
P, Rh
+
+
(
[
ESI TOF): m/z=1586.55 [M+Na] , 1563.56 [M] , 1463.52
+
MÀC H O (acac)] expected isotopic profiles; anal. calcd.
5
7
2
for C H O P Rh: C 72.97, H 6.25; found: C 72.91, H 6.31.
9
5
97 10 2
Adv. Synth. Catal. 2009, 351, 1629 – 1636
ꢄ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
asc.wiley-vch.de
1635

Laure Monnereau et al.
FULL PAPERS
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