Novel application of a solid super acid, sulfated zirconia, as a catalyst for Koch carbonylation reaction

Article abstract of DOI:10.1246/cl.2000.136

A solid superacid, sulfated zirconia, worked well in the Koch reaction. Under optimized conditions, tertiary alcohols were selectively transformed to the corresponding carboxylic acids (34-72%), while primary alcohols were transformed to the corresponding ethers (58-72%).

Full text of DOI:10.1246/cl.2000.136

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Chemistry Letters 2000
Novel Application of a Solid Super Acid, Sulfated Zirconia,
as a Catalyst for Koch Carbonylation Reaction
Hajime Mori, Aya Wada, Qiang Xu, and Yoshie Souma*
Osaka National Research Institute, AIST, MITI, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577
(Received October 28, 1999; CL-990918)
A solid superacid, sulfated zirconia, worked well in the
mmol), hexane (50 mL), and ca. 2.0 g of a solid acid catalyst.
The obtained results are partly summarized in Table 1. Among
all sulfated metal oxides, zirconia showed the highest activity
Koch reaction. Under optimized conditions, tertiary alcohols
were selectively transformed to the corresponding carboxylic
acids (34-72%), while primary alcohols were transformed to
the corresponding ethers (58-72%).
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for this reaction, while other metal oxides, with the exception
Direct transformation from alcohols and carbon monoxide
to carboxylic acids is a very attractive process in both industri-
al and synthetic organic chemistry. Although numerous
attempts related to the above transformation in strong liquid-
acid media, such as concentrated H SO , have been reported so
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far by Koch and other groups, many of them were carried out
under extremely severe conditions such as high carbon monox-
ide pressure and high temperature. We have already reported
that Cu(I), Ag(I), Au(I), and Pd(I) carbonyl complexes in con-
centrated H SO showed a high catalytic activity for the car-
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bonylation of alcohols, enabling us to perform this reaction at
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ambient temperature and pressure. H SO and related strong
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acids have toxicity, corrosion, and disposal problems. Therefore,
from both the industrial and the environmental point of view,
this carbonylation process needs to be more environmentally
benign by using solid super acids. About twenty years ago, it
was reported that sulfated zirconia and related metal oxides
showed remarkable strong acidity and had high ability for the
of titania, lacked it. A higher yield of carboxylic acids was
obtained by freshly prepared sulfated zirconia. Then, the sol-
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vent effect was investigated under the same condition as above
(Table 2). Chlorine-containing solvents, except for carbon
tetrachloride, were remarkably effective, while fluorobenzene
showed no contribution to this reaction. The solvent effect
described above may be understood by either the in situ forma-
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isomerization of alkanes. Many research groups have investi-
gated their character and structure up to now.4 In particular,
considerable attention has been paid to the reason for their
superacidity. Although sulfated zirconia and related metal
oxides showed curiously stronger acidity than other solid acids
such as zeolites, Nafion-H, and heteropolyacids, their applica-
tion was limited to petrochemistry because of their high ability
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tion of HCl gas or that of superacidic halomethyl cation,
which would be produced from solvent and Lewis acidic sul-
fated zirconia. Pivalic acid was obtained with moderate selec-
tivity in all solvents, and the polymerization was a main prob-
lem under this reaction condition.
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for isomerization and oligomerization of alkanes. Very few
application studies on synthetic organic chemistry compared
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with those on other solid acids have been reported so far, and
their potential in this field has not been fully explored. In this
paper, as a new application of sulfated zirconia, we describe
the carbonylation of tert-alcohols with a solid super acid, sul-
fated zirconia, to form tert-carboxylic acids (Eq. (1)). The
attempt described here is a novel application of sulfated zirco-
nia to synthetic chemistry which provides a new insight of its
catalytic ability.
After the discovery of sulfated zirconia, it was reported
that various sulfated metal oxides and modified substrates also
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exhibited superacidity. We first investigated their catalytic
activity for Koch carbonylation. The reaction was carried out
in a stainless steel autoclave at 150 °C with a carbon monoxide
(5 MPa: initial charge) atmosphere, using tert-butyl alcohol (20
Copyright © 2000 The Chemical Society of Japan

Chemistry Letters 2000
137
We also studied the effect of temperature and pressure of
carbon monoxide, finding that the reaction at 150 °C under 5
MPa pressure of CO was the most favorable for the high-yield
preparation of tert-carboxylic acids. Although high CO pres-
sure is generally advantageous for Koch carbonylation, the
comparatively reduced character of sulfated metal oxides10
might not accept the above generality.
alcohol to tert-carboxylic acid and has a promising potential as
a solid catalyst for ether formation from primary alcohols.
In conclusion, we have demonstrated a convenient method
for the preparation of tert-carboxylic acid by sulfated zirconia
and reported a newly discovered possibility of using sulfated
zirconia in synthetic organic chemistry.
Then, we carried out the carbonylation of various alcohols
under a well-defined condition (Table 3). Interestingly, pri-
mary alcohols selectively gave the corresponding ethers in
good yield,11 and no carboxylic acid was obtained at all
We thank Professor K. Arata for helpful suggestions.
References and Notes
1
“New Synthesis with Carbon Monoxide,” ed by J. Falbe,
(
entries 1-3). In comparison with the liquid-acid process, in
Springer, Berlin(1980), p. 372.
which primary alcohols are easily converted to the correspon-
ding tert-carboxylic acids, sulfated zirconia turned out to have
2
Cu, Ag: Y. Souma and H. Sano, J. Org. Chem., 38, 3633
(1973); Y. Souma, H. Sano, and J. Iyoda, J. Org. Chem.,
38, 2016 (1973); Y. Souma and H. Sano, Bull. Chem. Soc.
Jpn., 47, 1717 (1974); Y. Souma and H. Kawasaki, Catal.
Today, 36, 91 (1997); Y. Souma, H. Sano, H. Miwa, H.
Kawasaki, and O. Ichikawa, J. Synth. Org. Chem. Jpn., 48,
92 (1990). Au: Q. Xu, Y. Imamura, M. Fujiwara, and Y.
Souma, J. Org. Chem., 62, 1594 (1997). Pd: Q. Xu, Y.
Souma, J. Umezawa, M. Tanaka, and H. Nakatani, J. Org.
Chem., 64, 6306 (1999).
H. Hino, S. Kobayashi, and K. Arata, J. Am. Chem. Soc.,
101, 6539 (1979); M. Hino and K. Arata, J. Chem. Soc.,
Chem. Commun., 1980, 851; K. Tanabe, K. Akiyama, and
T. Yamaguchi, J. Chem. Soc., Chem. Commun., 1981, 602.
For a review, see: A. Corma, Chem. Rev., 95, 559 (1995).
Section D: Sulfated Metal Oxides.
To our knowledge, the application of sulfated zirconia is
limited, in the basic reaction, to esterification, hydrolysis
of esters, Friedel-Crafts reaction, and isomerization of
alkanes, among other processes; Esterification: M. Hino
and K. Arata, Chem. Lett., 1981, 1671; Hydrolysis of
esters: T. Okuhara, M. Kimura, T. Kwai, Z. Xu, and T.
Nakato, Catal Today, 45, 73 (1998); Friedel-Crafts reac-
tion: M. Hino and K. Arata, J. Chem. Soc., Chem.
Commun., 1985, 112; T. Yamaguchi, A. Mitou, K.
Akiyama, and K. Tanabe, Shokubai, 25, 127 (1983);
Isomerization of alkanes: Ref. 3.
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poor ability for the carbonylation of primary alcohols, because
it would be poisoned to some extent by the starting substrates.
In the case of secondary alcohols, the complex mixture, which
did not contain neither carboxylic acids nor ethers, was obtained.
The higher yield was observed at the series with lower
amounts (5 mmol) of tertiary alcohols (entries 6−9) and higher
selectivity of pivalic acid was also observed (entry 6). Thus,
reaction with tert-butyl alcohol, 1-adamantanol, 3-methyl-3-
pentanol, and 2-methyl-2-butanol gave the corresponding car-
3
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2
boxylic acids in a yield above 60%, and the generality for
various tertiary alcohols was demonstrated. In addition, the
used sulfated zirconia could be easily recycled by calcination
again, and the reformed catalysts showed almost the same
results as the new ones (entry 6). Although the above results
demonstrate that sulfated zirconia has some limitations for car-
bonylation, it is disclosed that it can effectively convert tertiary
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5
6
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For a review, see: K. Arata, Appl. Catal. A: General., 146,
3
(1996).
No catalytic activity was shown either at other super acids
such as WO /ZrO , MoO /ZrO , B O /ZrO , and
3
2
3
2
2
3
2
Fe O /ZrO . In all solid acids, calcination was carried out
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at the temperature recommended in Ref 6.
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The calcination was carried out at 600 °C and the calcina-
tion temperature (550~650 °C) did not significantly affect
the yield of carboxylic acids.
P. Batamack, I. Bucsi, Á. Molnár, and G. A. Olah, Catal.
Lett., 25, 11 (1994); I. Akhrem, Topics in Catalysis, 6, 27
(
1998); I, Akhrem, A. Orlinkov, L. Afansa’eva, P.
Petrovskii, and S. Vitt, Tetrahedron Lett., 49, 5897 (1999).
0 T. Jin, M. Machida, T. Yamaguchi, and K. Tanabe, Inorg.
Chem., 23, 4396 (1984).
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1 Di-n-hexyl ether and di-n-octyl ether were identified by
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the previous H and C NMR spectral data; G. A. Olah, T.
Shamma, and G. K. S. Prakash, Catal. Lett., 46, 1 (1997).
2 In the case of tertiary alcohols, starting substrates were not
recovered at all.
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