Highly Selective Biphasic Telomerization of Butadiene with Glycols: Scope and Limitations

Article abstract of DOI:10.1002/adsc.200303087

Highly selective telomerization reactions of a number of short-chain glycol nucleophiles with 1,3-butadiene have been achieved in aqueous biphasic systems employing the water-soluble catalyst system Pd(acac)₂/TPPTS. For all substrates the selectivity for the obtained monotelomers 5-7 reached ≥95% whereas butadiene dimers 3, octadienols 4 and ditelomers like 2 were produced only in trace amounts. The order of reactivity is ethylene glycol >> 1,3-propylene glycol ≈ glycerol > 1,4-butylene glycol, which is in agreement with generally observed trends. The scope and limitations of these reactions are discussed in terms of obtained yields and achievable catalyst productivities (total turnover numbers).

Full text of DOI:10.1002/adsc.200303087

FULL PAPERS
Highly Selective Biphasic Telomerization of Butadiene with
Glycols: Scope and Limitations
Arno Behr,* Michael Urschey
Lehrstuhl f¸r Technische Chemie A, Universit‰t Dortmund, Emil-Figge-Str. 66, 44227 Dortmund, Germany
Fax: ‡ 49-231-755-2311, e-mail: behr@bci.uni-dortmund.de
Received: May 2, 2003; Accepted: June 23, 2003
Abstract: Highly selective telomerization reactions of l>>1,3-propylene glycol ꢁ glycerol > 1,4-butylene
a number of short-chain glycol nucleophiles with 1,3- glycol, which is in agreement with generally observed
butadiene have been achieved in aqueous biphasic trends. The scope and limitations of these reactions
systems employing the water-soluble catalyst system are discussed in terms of obtained yields and achiev-
Pd(acac)2/TPPTS. For all substrates the selectivity for able catalyst productivities (total turnover numbers).
the obtained monotelomers 5 7 reached ꢀ 95%
whereas butadiene dimers 3, octadienols 4 and Keywords: alcohols; biphasic catalysis; butadiene; C-
ditelomers like 2 were produced only in trace C coupling; homogeneous catalysis; palladium; telo-
amounts. The order of reactivity is ethylene glyco- merization
Introduction
The palladium-catalyzed telomerization of 1,3-dienes,
originally discovered by Smutny in 1967,[1] still receives a
great deal of attention in both academia and industry
since the reaction offers great synthetic potential
combined with broad scope.[2] Beller et al. reported
significant improvements in the industrially interesting
telomerizationof butadiene (Bu) with methanol.[3 5] The
industrial interest in this reaction is emphasized by
patents[6,7] published recently. While monofunctional
Scheme 1. Telomerization of butadiene with ethylene glycol.
alcohols and other simple nucleophiles have been
intensively studied over the past decade, di- und
polyfunctional substrates like ammonia[8] have not
been examined in such detail. In the past years, sucrose
From an industrial point of view, however, only the
has been successfully telomerized to complex mixtures monotelomers 1 are of considerable interest as their
of sucrose ethers[9,10] suitable for specific applications. saturated analogues can be used as plasticizer alcohols
However, the production of 2,7-octadien-1-ol by hydro- for polymers like PVC.[13] Other patents also focus on
dimerization of butadiene is the only example of an applications in the field of cosmetics and surfac-
industrial telomerization process so far in operation.[11] tants.[14 16] On the other hand, the ditelomers 2 and
This is in part the consequence of problems often butadiene dimers 3 are of lower interest. As a conse-
encountered in selectivity control and optimization of quence, efficient selectivity control is one major issue in
catalyst performance as well as catalyst recycling.
these reactions. Also, the problem of effective catalyst
Telomerization reactions with glycols such as ethylene recycling remains, which has to be solved in order to
glycol (EG) demand effective methods of selectivity establish an industrially feasible process. Both issues
control if specific products are to be synthesized because cannot be managed easily in homogeneous liquid single
the monotelomers primarily produced still possess phase systems.
reactive functionalities for consecutive reactions. The
Biphasic catalysis provides the potential to resolve
reaction of butadiene with ethylene glycol yields com- both problems outlined above at the same time. The
plex mixtures of monotelomers 1, ditelomers 2 and reader is referred to a review by Behr[17] and a very
butadiene dimers 3 when performed in single liquid recent one by Keim.[18] Lately, we[19] have demonstrated
phase systems[12] as shown in Scheme 1. The telomers a highly selective telomerization reaction of butadiene
usually contain about 5 10% branched isomers.
with ethylene glycol in aqueous biphasic systems
1242
¹ 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/adsc.200303087
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Biphasic Telomerization of Butadiene with Glycols
FULL PAPERS
employing Pd(acac)2/TPPTS as a water-soluble in-situ
catalyst. The observed increase in selectivity is attrib-
uted to combined ligand and in-situ extraction effects.
The desired monotelomers 1 were obtained in yields up
to 80% and selectivities exceeding 95% while effective
catalyst recycling was achieved using the liquid-liquid
two-phase technique. Dimers 3, ditelomers 2 and
octadienols 4 were obtained as byproducts only in yields
of 1 2% each. Octadienols 4 are formed in aqueous
biphasic telomerization reactions of butadiene as a
consequence of nucleophilic activity of the water
solvent. We have also described the application of a
Scheme 2. Biphasic telomerization of butadiene with glycol
substrates.
All monotelomer products 5 to 7 were synthesized
telomerization-hydrogenation sequence as part of our with very good selectivity (ꢀ95%) whereas butadiene
green chemistry efforts.[20]
dimers 3, octadienols 4 and the corresponding ditelom-
In this paper, we report the successful expansion of ers were only produced as byproducts in yields of about
this reaction to a series of glycol substrates, namely 1,3- 1 2% each. The aqueous-alcoholic catalyst phases
propylene glycol (PG), 1,4-butylene glycol (BG) and obtained after the reactions were successfully recycled
glycerol (Gly) as the products efficiently and selectively several times leading to high catalyst productivities. The
obtained are a useful addition to the group of mono- results obtained for the different substrates are sum-
telomer compounds. The reactivity of the different marized in Tables 1 to 3.
substrates is also compared in terms of yields and overall With 1,3-propylene glycol (PG) and glycerol (Gly)
catalyst productivities. Finally, the scope and limitations maximum yields of telomers of roughly 60% were
of this reaction are discussed.
obtained (Nos. 3 and 12) while the maximum yields
achievable with 1,4-butylene glycol (BG) were much
lower (about 30%; No. 7). With PG and Gly, good yields
of monotelomers could be achieved in four and three
consecutive runs, respectively. With BG, however, al-
ready the first recycling run (No. 8) led to a poor result,
which could not be improved in the following runs. As a
consequence, total turnover numbers (TTNs) for mono-
telomer production of several thousands could be
reached with the substrates PG and Gly, while the
Results and Discussion
Aqueous Biphasic Telomerization of Butadiene with
Short-Chain Glycol Substrates
In order to extend the recently reported aqueous overall catalyst productivity remained below 1500 when
biphasic telomerization methodology,[19] the substrates BG was used as substrate. Obviously, the reactivity of
1,3-propylene glycol (PG), 1,4-butylene glycol (BG) and the substrates depends on their molecular size or chain
glycerol (Gly) have been telomerized with 1,3-buta- length. The decreasing catalyst activity observed is
diene to yield the monotelomer products 5 to 7 as shown attributed to catalyst decomposition partly caused by
in Scheme 2.
oxidation of TPPTS to the corresponding phosphine
Table 1. Results of aqueous biphasic telomerization of butadiene with 1,3-propylene glycol.
À1 [c]
No.
Recycle
Products
TON
TOF[h
]
TTN[d]
Yield 5 [%][a]
3 [%][b]
1
2
3
4
5
6
Start
32
51
56
55
18
29
2
2
2
2
1
2
534
856
946
928
296
480
134
214
237
232
74
534
1390
2336
3264
3560
4040
1
2
3
4
5
120
Conditions: Bu/PG ˆ 2.5/1; catalyst concentration: 0.06 mol % Pd(acac)2 (based on PG) ‡ TPPTS; P/Pd ˆ 5/1; TPPTS
supplementation: 2.5 equivs. per recycle; 10 mL H2O; 25 mL PG; 808C; 4 h; stirrer velocity ˆ 1200 rpm.
[a]
Based on PG.
Wt % of butadiene dimers in reaction mixture.
Average over total reaction time.
Total turnover number.
[b]
[c]
[d]
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Arno Behr, Michael Urschey
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Table 2. Results of aqueous biphasic telomerization of butadiene with 1,4-butylene glycol.
À1 [c]
No.
Recycle
Products
TON
TOF[h
]
TTN[d]
Yield 6 [%][a]
3 [%][b]
7
8
9
Start
31
21
17
17
2
3
3
2
527
359
286
292
132
90
72
527
886
1172
1464
1
2
3
10
73
Conditions: Bu/BG ˆ 2.5/1; catalyst concentration: 0.06 mol % Pd(acac)2 (based on BG) ‡ TPPTS; P/Pd ˆ 5/1; TPPTS
supplementation: 2.5 equivs. per recycle; 10 mL H2O; 25 mL BG; 808C; 4 h; stirrer velocity ˆ 1200 rpm.
[a]
Based on BG.
Wt % of butadiene dimers in reaction mixture.
Average over total reaction time.
Total turnover number.
[b]
[c]
[d]
Table 3. Results of aqueous biphasic telemerization of butadiene with glycerol.
À1 [c]
No.
Recycle
Products
TON
TOF[h
]
TTN[d]
Yield 7 [%][a]
3 [%][b]
11
12
13
14
15
Start
41
58
52
20
23
< 1
< 1
< 1
< 1
< 1
694
990
887
333
389
174
248
222
83
694
1684
2571
2904
3293
1
2
3
4
97
Conditions: Bu/Gly ˆ 2.5/1; catalyst concentration: 0.06 mol % Pd(acac)2 (based on Gly) ‡ TPPTS; P/Pd ˆ 5/1; TPPTS
supplementation: 2.5 equivs. per recycle; 10 mL H2O; 25 mL Gly; 808C; 4 h; stirrer velocity ˆ 1200 rpm.
[a]
Based on Gly.
Wt % of butadiene dimers in reaction mixture.
Average over total reaction time.
Total turnover number.
[b]
[c]
[d]
oxide. This effect has already been observed by another
group[21] examining biphasic telomerization reactions
with this catalyst system. One source of TPPTS oxida-
tion is contamination with air during work-up of the
biphasic reaction mixture, which cannot be totally
avoided. To compensate for the loss of ligand by
oxidation and decomposition, the separated aqueous
catalyst phase was supplemented with an appropriate
amount of fresh ligand solution prior to each recycle run.
The leaching of palladium into the organic product
phase associated with a residual water content of about
0.3 wt % has been previously examined[19] and is not
considered to be the crucial cause of decreasing activity
and yields. Unavoidable catalyst decomposition leading
to palladium metal is responsible for these effects.
In order to compare the reactivity of all the glycol
substrates examined, the overall catalyst productivities
Figure 1. Overall catalyst productivities obtained during
telomerization experiments with glycol substrates. Condi-
(TTNs) including those reported earlier for ethylene
glycol[19] are given in Figure 1 as a function of the
tions: Bu/glycol ˆ 2.5/1; cat. 0.06 mol % (based on glycol)
experiment number. The experimental series were
continued until the obtained yields remained at a low
level.
Pd(acac)2 ‡ 5 equivs. TPPTS; ligand supplementation: 2.5
equivs. per recycle; 10 12 mL H2O; 20 30 mL glycol; 808C;
&
*
~
!
1200 rpm; 4 h. Substrates: EG ( ), PG ( ), BG ( ), Gly ( ).
1244
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Adv. Synth. Catal. 2003, 345, 1242 1246

Biphasic Telomerization of Butadiene with Glycols
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Ethylene glycol (EG) is by far the most reactive Conclusion
substrate. A total turnover number in the range of 9000
is possible after seven runs, which is more than twice as The aqueous biphasic telomerization methodology
high as the value obtained with PG, the substrate reported earlier[19] has been successfully transferred to
possessing the second highest reactivity. PG and glycerol sterically undemanding primary C3 C4 glycols and
roughly show the same reactivity while BG is by far the glycerol. The corresponding monotelomers 5 to 7 have
least reactive substrate. Based on these data, the order been synthesized with high selectivity ( ꢀ 95%) and in
of reactivity for the glycol substrates studied is: good yields (up to 60%). Byproduct formation was
EG>>PG ꢁ Gly > BG which is in agreement with the limited to butadiene dimers 3, octadienols 4 and the
general trends reported in the literature. As a conse- corresponding ditelomers being produced in yields of
quence, catalyst recycling using biphasic techniques is 1 2% each. The catalyst system Pd(acac)2/TPPTS
possible up to six times if EG is used as substrate. The could be recycled up to five times and for some
catalyst phases can be successfully recycled four to five substrates total turnover numbers of several thousands
times with PG and Gly as substrates and with BG only a were achieved. The reactivity order of the substrates is
three-fold recycling is attractive. The best chances for an consistent with general trends reported in the literature
industrial application of this biphasic telomerization with ethylene glycol showing the highest activity. The
process are seen with ethylene glycol as substrate and catalyst system does not tolerate increased steric
therefore we are currently studying this reaction using demands or functional groups like multiple bonds,
the established miniplant technology.[22]
carbonyl or carboxylic acid groups in the glycol sub-
strates. Therefore, the application of the presented
methodology is limited to the reported substrates. An
industrially feasible telomerization process is envi-
sioned using ethylene glycol (EG) as substrate, which
Limitations of the Catalyst System Pd(acac)2/TPPTS
In order to explore the limits of the catalyst system, is currently under investigation using miniplant tech-
many glycol substrates related to those described above nology.[22]
have been tested. Special focus was laid on tolerance of
increasing steric demands and different functional
groups. Unfortunately the catalyst system Pd(acac)2/
TPPTS does not tolerate increasing steric demand at all.
Experimental Section
À
Both 1,2-propylene glycol [CH3-CH(OH) CH2-OH]
À
and 2,2-dimethyl-1,3-propylene glycol [HO CH2-
C(Me)2-CH2-OH] were not telomerized to a significant
degree under standard conditions. To test functional
group tolerance, a range of different substrates was
tested. The inability of the catalyst system to convert 2-
Reagents, Catalysts and Handling
1,3-Butadiene (99.5%) and argon (99.998%) used as dried inert
cover gas were purchased from Messer-Griessheim. Palladi-
um(II) bis(acetylacetonate), Pd(acac)2, was synthesized ac-
cording to the literature.[23] Triphenylphosphinetrisulfonate
(TPPTS) was obtained from Celanese AG as a 25 wt %
aqueous solution of the trisodium salt. All other chemicals
were purchased from common suppliers. All solvents were
degasified and used saturated with argon. All reactions and
handling were done under dry argon using standard Schlenk
tube techniques.
À
ˆ
À
cis-butene-1,4-diol [HO CH2-CH CH CH2-OH] and
À
ꢂ À
2-butyne-1,4-diol [HO CH2-C C CH2-OH] revealed
its sensitivity against multiple bonds in the substrate,
which apparently block the active species. Carboxylic
acid functionalities are also not tolerated as both
glycolic acid (HOOC CH2OH) and oxalic acid
(HOOC COOH) were not converted either as free
acids or as sodium salts. The pH value of the solution
does not seem to play a major role here. Finally, 1,3-
dihydroxyacetone [HO CH2-C(O) CH2-OH] was test-
ed without success both in presence and absence of 1
À
À
Aqueous Biphasic Telomerization of Butadiene with
Glycol Substrates
À
À
63 mg (0.2 mmol) of Pd(acac)2 and 2.3 g (1 mmol) of aqueous
equiv. NaOH indicating intolerance against the carbon- TPPTS solution were dissolved in 10 mL of deionized water
and mixed with the appropriate amount of glycol substrate
(25 30 mL; 0.35 mol), giving a clear bright yellow solution,
which was transferred into an evacuated 300-mL stainless steel
autoclave. 49 g (0.9 mol) of butadiene were condensed into the
autoclave. The vessel was heated to 808C and stirred at
1200 rpm for 4 h. Consumption of butadiene could be followed
by pressure drop from about 10 to about 5 bar. The vessel was
cooled to ambient temperature and unreacted butadiene was
burnt through a custom-made safety nozzle. The autoclave was
opened and the biphasic content poured into a separating
funnel. 100 mL of cyclohexane were added, the mixture was
yl group.
These results show that the catalyst system Pd(acac)2/
TPPTS is only suitable for the selective telomerization
of sterically undemanding short chain glycol substrates
such as primary C2 C4 glycols and glycerol as well as for
the unselective telomerization of sugar substrates as
found by others.[10] The best results in selective reactions
can be obtained with the most reactive substrate ethyl-
ene glycol (EG).
Adv. Synth. Catal. 2003, 345, 1242 1246
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Arno Behr, Michael Urschey
FULL PAPERS
shaken vigorously and the phases were allowed to separate
over a period of 15 minutes. The lower phase consisting of the
aqueous catalyst solution and unreacted substrate was sepa-
rated and stored under argon. Cyclohexane was removed from
the upper organic phase under reduced pressure (200 mbar,
508C) and recycled. The residue was analyzed by GC and Karl-
Fischer titration. The catalyst solution obtained was supple-
mented with 1.15 g (0.5 mmol) aqueous TPPTS solution and
mixed in a Schlenk-tube with the appropriate amount of glycol
substrate, giving a clear yellow solution that was used once
again for the telomerization reaction as described above.
[4] F. Vollm¸ller, W. M‰gerlein, S. Klein, J. Krause, M.
Beller, Adv. Synth. Catal. 2001, 343, 29.
[5] R. Jackstell, M. G. Andreu, A. Frisch, K. Selvakumar, A.
Zapf, H. Klein, A. Spannenberg, D. Rˆttger, O. Briel, R.
Karch, M. Beller, Angew. Chem. 2002, 114, 1028; Angew.
Chem. Int. Ed. 2002, 41, 986.
[6] D. Rˆttger; A. Tuchlenski (Oxeno Olefinchemie GmbH,
Marl, Germany), German Patent DE 10105751 A1, 2002.
[7] D. Rˆttger, M. Beller, R. Jackstell, H. Klein, K.-D. Wiese
(Oxeno Olefinchemie GmbH, Marl, Germany), German
Patent DE 10128144 A1, 2002.
[8] T. Prinz, W. Keim, B. Drie˚en-Hˆlscher, Angew. Chem.
1996, 108, 1835; Angew. Chem. Int. Ed. Engl. 1996, 35,
1708.
Analysis and Product Characterization
[9] K. Hill, S. Axt, K. J. Weese (Henkel Corporation,
Plymouth Meeting, USA), International Patent WO
9302032, 1993.
[10] V. Desvergnes, C. Pinel, P. Gallezot, Green Chemistry
2001, 3, 175.
[11] N. Yoshimura, in Aqueous-Phase Organometallic Catal-
ysis (Eds.: B. Cornils, W. A. Herrmann), Wiley-VCH,
Weinheim, 1998, p. 408.
[12] U. M. Dzhemilev, R. V. Kunakova, N. Z. Baibulatova,
G. A. Tolstikov, A. A. Panasenko, J. Org. Chem. USSR
1980, 16, 999.
[13] M. G. Romanelli, R. J. Kelly, N. J. Iselin (Esso Research
and Engineering Co., Linden, N. Y., USA), US Patent
2,011,163, 1970.
[14] B. Gruber, K. J. Weese, S. M. Hoagland, H. P. Mueller, K.
Hill, A. Behr (Henkel Research Corporation, Santa
Rosa, USA), International Patent WO 9013531, 1990.
[15] B. Fabry, B. Gruber (Henkel KGaA, D¸sseldorf, Ger-
many), German Patent DE 4020973, 1992.
[16] K. Hill, B. Gruber, K. J. Weese, Tetrahedron Lett. 1994,
35, 4541.
Routine gas chromatographic analyses were done on an HP
6890 instrument (Hewlett-Packard GmbH, Waldbronn, Ger-
many) equipped with an FI detector and an HP-INNOWax
capillary column (30 m, coating polyethylene glycol, diameter
0.25 mm, film thickness 0.25 mm) in connection with an
autosampler. GC/MS data were recorded on a HP 5973
instrument coupled with a HP 6890 (30 m HP 5-MS column,
coating 5%-diphenyl-95%-dimethyl-polysiloxane, diameter
0.25 mm, film thickness 0.25 mm) in connection with an
autosampler. FTIR spectra were recorded on a Nicolet Impact
400d FTIR-spectrometer using KBr plates. NMR spectra were
recorded on a DRX 400 spectrometer (Bruker Instruments
Inc., Billerica, MA, USA) using CHCl3 as internal standard.
Water contents were determined by Karl-Fischer titration on a
652-KF-Coulometer (Metrohm, Herisau, Switzerland). All
reaction mixtures were analyzed by gas chromatography using
external calibration with pure compounds. All products were
characterized by IR, standard NMR techniques (1H, 13C,
DEPT) and GC/MS. The obtained NMR data matched
simulated values.[24]
[17] A. Behr, Chem. Ing. Tech. 1998, 70, 685.
[18] W. Keim, Green Chemistry 2003, 5, 105.
[19] A. Behr, M. Urschey, J. Mol. Catal.: A 2003, 197, 101.
[20] A. Behr, M. Urschey, V. A. Brehme, Green Chemistry
2003, 5, 198.
Acknowledgements
We thank the OMG group and the Celanese AG for supply of
transition metal compounds and TPPTS solution, respectively.
A scholarship fromthe ™Studienstiftung des deutschen Volkes∫
(M. U.) is gratefully acknowledged.
[21] T. Prinz, B. Drie˚en-Hˆlscher, Chem. Eur. J. 1999, 5,
2069.
[22] A. Behr, M. Heite, Chem. Ing. Tech. 2000, 72, 58.
[23] G. K¸nstle, H. Siegel (Wacker-Chemie GmbH, M¸n-
chen, Germany), German Patent DE 2402383, 1975.
[24] ACD NMR simulation software, version 2.1, 1997,
Advanced Chemistry Development Inc., Toronto, Can-
ada.
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1246
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Adv. Synth. Catal. 2003, 345, 1242 1246