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K. Abe et al. / Catalysis Today 164 (2011) 419–424
or excessive dehydration, respectively. The second route pro-
duces oxacycloheptane via intramolecular etherification. Over
Sc2O3, however, a little amount of oxacycloheptane is produced
from 1,6-hexanediol, whereas 1,4-butanediol mainly produces
tetrahydrofuran in the dehydration. The third route produces
cyclopentanol and cyclopentanone in the dehydrogenation of 1,6-
hexanediol to 6-hydroxyhexanal and to 1,5-hexanedial followed
by the formation of cyclic intermediate via aldol addition. Since
the ratio of cyclopentanone in the cyclic compounds is large, this
reaction preferably proceeds over Sc2O3. The last route is similar to
the third route: -caprolactone is produced via 6-hydroxyhexanal
with the selectivity higher than 70 mol%. Heavy REOs such as Lu2O3
as well as monoclinic ZrO2 show moderate catalytic activity in
the dehydration of the terminal diols, while their selectivity was
lower than Sc2O3. CeO2, which is an excellent catalyst in the for-
mation of 2-propen-1-ol from 1,3-propnediol, was less selective
in the dehydration of terminal diols than the other REOs. In the
reaction of cyclohexanol, Sc2O3 was the most selective catalyst
for the dehydration to produce cyclohexene, while the other REOs
predominantly catalyzed the dehydrogenation to produce cyclo-
hexanone.
as an intermediate. Since
a little amount of -caprolactone
References
is produced, this route does not proceed favorably over
Sc2O3.
[1] A.J. Lundeen, R.V. Hoozer, J. Org. Chem. 32 (1967) 3386–3389.
[2] J.M. Trillo, S. Bernal, J. Catal. 66 (1980) 184–190.
[3] S. Sato, R. Takahashi, T. Sodesawa, N. Honda, H. Shimizu, Catal. Commun. 4
(2003) 77–81.
[4] A. Igarashi, N. Ichikawa, S. Sato, R. Takahashi, T. Sodesawa, Appl. Catal. A 300
(2006) 50–57.
[5] M. Kobune, S. Sato, R. Takahashi, J. Mol. Catal. A 279 (2008) 10–19.
[6] S. Sato, R. Takahashi, T. Sodesawa, N. Yamamoto, Catal. Commun. 5 (2004)
397–400.
[7] A. Igarashi, S. Sato, R. Takahashi, T. Sodesawa, M. Kobune, Catal. Commun. 8
(2007) 807–810.
[8] S. Sato, R. Takahashi, T. Sodesawa, A. Igarashi, H. Inoue, Appl. Catal. A 328 (2007)
109–116.
[9] S. Sato, R. Takahashi, N. Yamamoto, E. Kaneko, H. Inoue, Appl. Catal. A 334
(2008) 84–91.
[10] S. Sato, R. Takahashi, M. Kobune, H. Inoue, Y. Izawa, H. Ohno, K. Takahashi, Appl.
Catal. A 356 (2009) 64–71.
Over CeO2, cyclohexanone and cyclohexanol are observed. They
would be produced from 6-hydroxyhexanal, but the mechanism is
unclear. However, cyclopentanone is a major product over CeO2
in the reaction using aqueous 1,6-hexanediol as a feed solution
instead of ethanol solution [21]. Although pure ethanol dose not
react over REOs at 350 ◦C, ethanol solvent used in the feed solution
may affect the catalytic dehydration. We need further investigation
on the dehydration of terminal diols using direct feed of terminal
diols melted.
4. Conclusions
[11] H. Gotoh, Y. Yamada, S. Sato, Appl. Catal. A 377 (2010) 92–98.
[12] N. Yamamoto, S. Sato, R. Takahashi, K. Inui, Catal. Commun. 6 (2005) 480–484.
[13] N. Yamamoto, S. Sato, R. Takahashi, K. Inui, J. Mol. Catal. A 243 (2006) 52–59.
[14] M. Segawa, S. Sato, M. Kobune, T. Sodesawa, T. Kojima, S. Nishiyama, N.
Ishizawa, J. Mol. Catal. A 310 (2009) 166–173.
The catalytic activity of several REOs such as Sc2O3, CeO2,
Y2O3, Yb2O3, and Lu2O3 was investigated in the vapor-phase
catalytic reactions of terminal diols with carbon numbers from
6 to 12, such as 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol,
1,9-nonanediol, 1,10-decanediol, and 1,12-dodecanediol. Sc2O3
showed the highest selectivity to the corresponding unsaturated
alcohols in the dehydration of the terminal diols. For instance,
5-hexen-1-ol was produced as a dehydration product of 1,6-
hexanediol with the selectivity over 60 mol%, together with
by-products of -caprolactone and oxacycloheptane. In the dehy-
dration of 1,10-decanediol over Sc2O3, 9-decen-1-ol was produced
[15] S. Kobayashi, I. Hachiya, M. Araki, H. Ishitani, Tetrahedron Lett. 34 (1993)
3755–3758.
[16] K. Otsuka, K. Jinno, A. Morikawa, Chem. Lett. (1985) 499–500.
[17] M.D. Fokema, J.Y. Ying, Appl. Catal. B 18 (1998) 71–77.
[18] T. Yamanaka, T. Imai, Bull. Chem. Soc. Jpn. 54 (1981) 1585–1586.
[19] S. Sato, R. Takahashi, M. Kobune, H. Gotoh, Appl. Catal. A 356 (2009) 57–63.
[20] R.D. Shanon, Acta Crystallogr. A32 (1976) 751–767.
[21] T. Akashi, S. Sato, R. Takahashi, T. Sodesawa, K. Inui, Catal. Commun. 4 (2003)
411–416.