2668 Journal of Chemical & Engineering Data, Vol. 54, No. 9, 2009
Table 1. Thermodynamic Equilibria between Various Polyalcohols and Cyclic Ethers in High-Temperature Liquid Water at 573 K
YEa/%
Kb
polyalcohol
cyclic ether
polyalcohol
cyclic ether
mol ·dm-3
1,4-butanediol (1,4-BDO)
1,2,4-butanetriol (1,2,4-BTO)
1,4-pentanediol (1,4-PDO)
1,5-pentanediol (1,5-PDO)
1,2,5-pentanetriol (1,2,5-PTO)
1,2,5-pentanetriol (1,2,5-PTO)
tetrahydrofuran (THF)
13 ( 3
28 ( 3
27 ( 3
29 ( 3
15 ( 3
15 ( 3
87 ( 3
72 ( 3
73 ( 3
71 ( 3
73 ( 3
12 ( 3
337 ( 120
128 ( 21
132 ( 23
125 ( 20
238 ( 71
39 ( 22
3-hydroxytetrahydrofuran (3-HTHF)
2-methyltetrahydrofuran (2-MTHF)
tetrahydropyran (THP)
tetrahydrofurfuryl alcohol (THFA)
3-hydroxytetrahydropyran (3-HTHP)
b
a Equilibrium yields (YE) were measured with 1.0 mol ·dm-3 polyalcohols at 573 K. Kpolyalcohol,cyclic
.
ether
difficult at this stage to nonempirically estimate the effect of
hydrogen bonding and the thermodynamic equilibrium constant
in high-temperature water. Therefore, we determined the
thermodynamic equilibrium constants empirically by measuring
the concentrations of polyalcohols and cyclic ethers.
Thermodynamic Equilibria among 1,2,5-Pentanetriol,
Tetrahydrofurfuryl Alcohol, and 3-Hydroxytetrahydropyran
in High-Temperature Liquid Water at 573 K. The dehydration
of 1.0 mol ·dm-3 of 1,2,5-PTO also proceeded in water at 573
K and provided two products: THFA and 3-HTHP (Scheme 2,
Figure 2). The yields of 1,2,5-PTO, THFA, and 3-HTHP at
thermodynamic equilibrium were [(15 ( 3), (73 ( 3), and (12
( 3)] %, respectively. The thermodynamic equilibrium constant
between 1,2,5-PTO and THFA (K1,2,5-PTO,THFA) and that between
1,2,5-PTO and 3-HTHP (K1,2,5-PTO,3-HTHP) are represented as
follows
THP (0.63 ·10-3 mol·dm-3 ·s-1).2 The thermodynamic equilib-
rium constants between butanepolyols or pentanepolyols and
five-membered or six-membered cyclic ethers were within a
range from (39 to 337) mol ·dm-3. We determined the thermo-
dynamic equilibrium values between polyalcohols and cyclic
ethers to develop an efficient conversion process of biomass
derivatives to useful materials in high-temperature liquid water.
Conclusion
Thermodynamic equilibrium constants between polyalcohols
and cyclic ethers in water at 573 K were determined by
measuring their concentrations after the long-term reaction in
a batch reactor. The thermodynamic equilibrium constants
between butanepolyols or pentanepolyols and corresponding
cyclic ethers ranged from (39 to 337) mol ·dm-3
.
Literature Cited
[THFA][H2O]
K1,2,5-PTO,THFA
)
(3)
(4)
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[1,2,5-PTO]
[3-HTHP][H2O]
[1,2,5-PTO]
K1,2,5-PTO,3-HTHP
)
where [THFA], [3-HTHP], and [1,2,5-PTO] were the concentra-
tions of THFA, 3-HTHP, and 1,2,5-PTO at thermodynamic
equilibrium, respectively. THFA and 3-HTHP should be equili-
brated via the formation of 1,2,5-PTO, as shown in Scheme 2,
and the thermodynamic equilibrium constant between THFA
and 3-HTHP (KTHFA,3-HTHP) is represented as follows
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K1,2,5-PTO,3-HTHP
[3-HTHP]
[THFA]
KTHFA,3-HTHP
)
)
(5)
K1,2,5-PTO,THFA
K1,2,5-PTO,THFA, K1,2,5-PTO,3-HTHP, and KTHFA,3-HTHP were calculated
to be (238 ( 71) mol·dm-3, (39 ( 22) mol·dm-3, and (0.16 (
0.05) mol ·dm-3, respectively, from their yields at thermody-
namic equilibrium, indicating that THFA is more stable in high-
temperature water than 3-HTHP thermodynamically.
Thermodynamic Equilibria between Various Polyalcohols
and Cyclic Ethers in High-Temperature Liquid Water at
573 K. The thermodynamic equilibrium constants between
various polyalcohols and cyclic ethers in high-temperature liquid
water at 573 K are summarized in Table 1. The thermodynamic
equilibrium constants of K1,4-PDO,2-MTHF [(132 ( 23) mol ·dm-3
]
and K1,5-PDO,THP [(125 ( 20) mol ·dm-3] were quite similar; in
contrast, the dehydration rate of 1,4-PDO to 2-MTHF (8.6 ·10-3
mol·dm-3 ·s-1) was ten times larger than that of 1,5-PDO to
Received for review February 12, 2009. Accepted May 13, 2009.
JE900173T