Experimental measurement and correlation of the solubilities of 2,4-dichloro-5-methoxypyrimidine in ethyl ethanoate, methanol, ethanol, acetone, tetrachloromethane, and heptane at temperatures between (295 and 320) K

Article abstract of DOI:10.1021/je9005689

The solid-liquid equilibrium of 2,4-dichloro-5-methoxypyrimidine was first determined in this article. Using a laser monitoring observation technique, the solubilities of 2,4-dichloro-5-methoxypyrimidine in ethyl ethanoate, methanol, ethanol, acetone, tetrachloromethane, and heptane have been determined experimentally from (295.60 to 316.39, 302.37 to 316.95, 299.44 to 316.61, 297.35 to 311.37, 298.60 to 312.15, and 298.10 to 320.08) K, respectively. The results are correlated with λ-h equation and Apelblat equation. The calculated results show that the correlation of the Apelblat model for six measured systems has less deviation than that of the λ-h equation.

Full text of DOI:10.1021/je9005689

1402
J. Chem. Eng. Data 2010, 55, 1402–1404
Experimental Measurement and Correlation of the Solubilities of
2,4-Dichloro-5-methoxypyrimidine in Ethyl Ethanoate, Methanol, Ethanol,
Acetone, Tetrachloromethane, and Heptane at Temperatures between (295 and
320) K
Yong-Jie Liu, Ting-Liang Luo, Xin-Ding Yao, Zhi-Bo Mao, and Guo-Ji Liu*
College of Chemical and Energy Engineering, Zhengzhou University, Zhengzhou 450002, Henan, China
The solid-liquid equilibrium of 2,4-dichloro-5-methoxypyrimidine was first determined in this article. Using
a laser monitoring observation technique, the solubilities of 2,4-dichloro-5-methoxypyrimidine in ethyl
ethanoate, methanol, ethanol, acetone, tetrachloromethane, and heptane have been determined experimentally
from (295.60 to 316.39, 302.37 to 316.95, 299.44 to 316.61, 297.35 to 311.37, 298.60 to 312.15, and 298.10
to 320.08) K, respectively. The results are correlated with λ-h equation and Apelblat equation. The calculated
results show that the correlation of the Apelblat model for six measured systems has less deviation than that
of the λ-h equation.
Introduction
Figure 1 shows the structure of 2,4-dichloro-5-methoxypy-
rimidine that is a type of white or pale yellow powdery crystal,
with a melting temperature of 342.15 K. It is an important raw
material widely used as an intermediate in the production of
medicine and pesticide as well as other substances.1-3 For these
processes, knowledge of solubility is an important physico-
chemical property. Indeed, solvating-out crystallization is used
to separate and recrystallize 2,4-dichloro-5-methoxypyrimidine,
and in this procedure solubility data is essential for engineering
design.
Figure 1. Structure of 2,4-dichloro-5-methoxypyrimidine.
However, there is no article found in the archival literature
reporting the solubility of 2,4-dichloro-5-methoxypyrimidine,
and thus, in this study, the solubility of 2,4-dichloro-5-
methoxypyrimidine in ethyl ethanoate, methanol, ethanol,
acetone, tetrachloromethane, and heptane has been measured.
The experimental data were correlated with the Apelblat
equation and the λ-h models.
RN 67-56-1] a mass fraction purity of 0.995, acetone [CAS RN
67-64-1] a mass fraction purity of 0.995, n-heptane [CAS RN
142-82-5] a mass fraction purity of 0.995, tetrachloromethane
[CAS RN 56-23-5] a mass fraction purity of 0.995, and ethyl
ethanoate [CAS RN 141-78-6] a mass fraction purity of 0.995.
Apparatus and Procedure. The normal melting temperature
Tm and melting enthalpy ∆fusH of 2,4-dichloro-5-methoxypy-
rimidine were determined by differential scanning calorimetry
(DSC, NETZSCH, type STA409PC-luxx) in the presence of
nitrogen with a rate of temperature increase with respect to time
of 0.05 K ·s-1. The normal melting temperature of 2,4-dichloro-
5-methoxypyrimidine is (342.15 ( 0.5) K, and its enthalpy of
Experimental Section
Materials. 2,4-Dichloro-5-methoxypyrimidine was produced
in our laboratory with the procedure reported in ref 4. In this
reaction, which was catalyzed by sodium, methyl methoxyac-
etate and ethyl methanoate were condensed in toluene, and the
intermediate product reacted by refluxing with urea in ethanol
to form 5-methoxy-1H-pyrimidine-2,4-dione that is then reacted
in toluene with phosphorus trichloride oxide to form 2,4-
dichloro-5-methoxypyrimidine. The product was further purified
by recrystallization from ethanol. After filtration and drying,
the mass fraction purity of 2,4-dichloro-5-methoxypyrimidine
was determined by high-performance liquid chromatography
(HPLC; Daojin LC-A) to be 0.998. The solvents were obtained
from were obtained from Tianjin Kermel Chemical Reagent Co.,
Ltd., China, with the following cited purities: ethanol [CAS RN
64-17-5] had a mass fraction purity of 0.997, methanol [CAS
fusion is (98.74 ( 0.1) J ·g-1, that is, (17674 ( 18) J ·mol-1
.
In this work, the solubilities of 2,4-dichloro-5-methoxypyri-
midine in each solvent were determined with the dynamic
method described elsewhere.5 The apparatus formed from a glass
dissolution flask of nominal volume of 50 cm3 was fitted with
an insulating jacket. The reactor was fitted with a magnetic
stirrer, and the flask also accommodated a thermometer, for
which the uncertainty, as determined by the Tianjin Metrology
Institute (Tianjin, China), was found to be ( 0.01 K.
The mass of about 0.01 g of 2,4-dichloro-5-methoxypyrimi-
dine to be dissolved in a solvent was determined with an
electronic balance (type AB204-N, produced by Mettler-Toledo
Group) with an uncertainty of ( 0.001 g. The temperature
increase was controlled to be less than 0.1 K ·h-1, especially
near the solid-liquid equilibrium temperature. A laser was shone
* Corresponding author. E-mail: guojiliu@zzu.edu.cn. Tel.: +86 371
67781101. Fax: +86 371 67781696.
10.1021/je9005689  2010 American Chemical Society
Published on Web 11/03/2009

Journal of Chemical & Engineering Data, Vol. 55, No. 3, 2010 1403
Table 1. Mole Fraction x Solubilities of 2,4-Dichloro-5-
methoxypyrimidine in Different Solvents at Temperature T
T/K
102 x
T/K
102 x
T/K
102 x
2,4-Dichloro-5-methoxypyrimidine + Methanol
302.37
303.78
305.44
306.57
5.977
6.585
7.338
8.030
308.12
309.67
311.15
312.43
8.933
10.15
11.43
12.97
313.55
314.81
315.80
316.95
14.58
16.28
18.15
20.23
2,4-Dichloro-5-methoxypyrimidine + Ethanol
299.44
301.27
303.17
305.17
4.743
5.266
5.839
6.554
307.06
309.05
310.73
312.58
7.451
8.551
9.721
11.04
314.00
315.47
316.61
12.54
14.11
15.77
2,4-Dichloro-5-methoxypyrimidine + Acetone
297.35
299.36
301.17
303.13
34.77
36.77
38.61
40.34
304.54
306.18
307.53
308.97
42.01
43.58
45.04
46.59
310.25
311.37
48.10
49.23
2,4-Dichloro-5-methoxypyrimidine + Tetrachloromethane
Figure 2. Solubilities of ethane 1,2-dicarboxylic acid in water: 9,
experimental data; O, literature data.10
298.60
299.42
300.63
301.97
12.28
13.01
14.34
15.91
303.35
304.82
305.80
306.87
17.77
19.59
21.43
23.66
308.20
309.57
310.90
312.15
26.11
28.77
31.49
34.32
onto the sample and the light detected on the opposite side of
the flask where the received light power was converted into
electrical signal; this system was fabricated by College of
Physical Science and Engineering, Zhengzhou University.6-9
When 2,4-dichloro-5-methoxypyrimidine was first placed into
the solvent, the laser beam was partly blocked by the unsolved
particles of 2,4-dichloro-5-methoxypyrimidine in the solution;
the intensity of the laser beam penetrating the vessel was lower.
The intensity increased with increasing time as the 2,4-dichloro-
5-methoxypyrimidine dissolved. The solid was assumed dis-
solved when the intensity of the received laser light reached
the largest value found for the pure solvent. The temperature
measured at the greatest light intensity was assumed to be the
temperature of the solid + liquid equilibrium. The laser used
was a He-Ne with a wavelength of 632.8 nm that gave an
approximate particle size detection limit of 1 nm.
Each solubility measurement was performed thrice to deter-
mine the reproducibility and standard deviation that was less
than 1 %. The uncertainty and reproducibility of the temperature
measurements was 0.01 K, which corresponds to a relative
deviation in composition less than 1 %. The uncertainty of the
measurement was determined with measurements of the solubil-
ity of ethane 1,2-dicarboxylic acid in water and the results,
shown in Figure 2, compared with values obtained from the
literature10 that differ by less than 1 %, confirming the cited
uncertainty.
2,4-Dichloro-5-methoxypyrimidine + Ethyl Ethanoate
295.60
296.53
298.25
300.66
302.28
28.83
29.49
31.11
33.01
34.73
304.15
305.62
307.47
309.19
311.16
36.45
38.18
40.07
42.16
44.35
313.07
314.57
316.39
46.75
49.04
51.28
2,4-Dichloro-5-methoxypyrimidine + Heptane
298.10
299.83
302.10
303.81
305.72
0.9404
1.039
1.162
1.285
1.415
307.55
309.57
310.97
312.89
315.04
1.566
1.737
1.921
2.139
2.391
317.15
318.83
320.08
2.679
2.960
3.241
listed in Table 2. An alternative representation of the measure-
ments can be obtained from the Apelblat equation13,14 given
by
K
T
ln x ) A + B
+ C ln(T/K)
(2)
(
)
where x is the mole fraction solubility of 2,4-dichloro-5-
methoxypyrimidine, T is the temperature, and A, B, and C are
constants determined by regression analysis with the results
listed in Table 3. The measurements and correlation given by
eq 2 are compared in Figure 3.
The average absolute deviation defined by:
n
xci - xi
1
Results and Discussion
σ )
(3)
∑
|
|
n i)1
xi
Experimental Results. The solubility of 2,4-dichloro-5-
methoxypyrimidine in ethyl ethanoate, methanol, ethanol,
acetone, tetrachloromethane, and heptane are listed in Table 1.
The comparisons between the calculated solubilities and the
experimental data (ln x) are shown in Figure 2.
can be used as a measure of the performance of the two models,
and the values obtained are listed in Table 4. In eq 3 xi is the
experimental solubility, xc,i the calculated value, and n the
number of measurements. The average absolute deviations for
the λ-h model and Apelblat model are less than 3.14 % and
0.59 %, respectively, and on the basis of this comparison the
Apelblat model is preferred.
The λ-h model11,12 given by
λ(1 - x)
K
T
K
Tm
ln 1 +
) λh
-
(1)
[
]
(
)
x
Conclusion
can be used to correlate the solubilities of 2,4-dichloro-5-
methoxypyrimidine in solvents. In eq 1, x is the mole fraction
of 2,4-dichloro-5-methoxypyrimidine, and Tm is normal melting
temperature of 2,4-dichloro-5-methoxypyrimidine. The values
of λ and h for each solvent obtained by regression analysis are
As shown in Table 1 and Figure 3, the solubilities of 2,4-
dichloro-5-methoxypyrimidine increase with an increase in
temperature. It can be observed from Table 1 that the solubilities
of 2,4-dichloro-5-methoxypyrimidine in six different organic

1404 Journal of Chemical & Engineering Data, Vol. 55, No. 3, 2010
Table 2. Parameters in the λ-h Equation for Different Solvents
mixture
λ
h
R2
2,4-dichloro-5-methoxypyrimidine + ethyl ethanoate
2,4-dichloro-5-methoxypyrimidine + methanol
2,4-dichloro-5-methoxypyrimidine + ethanol
2,4-dichloro-5-methoxypyrimidine + acetone
2,4-dichloro-5-methoxypyrimidine + tetrachloromethane
2,4-dichloro-5-methoxypyrimidine + heptane
0.78653
1.4191
0.58262
0.81013
5.4096
2991.1
5888.5
10665
2580.3
1606.5
99323
0.99968
0.99127
0.99314
0.99946
0.99868
0.99937
0.036720
Table 3. Parameters in Apelblat Equation for Different Solvents
mixture
A
B
C
R2
2,4-dichloro-5-methoxypyrimidine + methanol
2,4-dichloro-5-methoxypyrimidine + ethanol
2,4-dichloro-5-methoxypyrimidine + acetone
2,4-dichloro-5-methoxypyrimidine + tetrachloromethane
2,4-dichloro-5-methoxypyrimidine + ethyl ethanoate
2,4-dichloro-5-methoxypyrimidine + heptane
-2349.2
-1707.4
104.73
21.928
-104.29
-407.49
101040
72404
-6733.9
-7175.9
2482.0
13979
352.30
256.50
0.99976
0.99982
0.99975
0.99938
0.99981
0.99965
-14.599
0.00009
16.636
62.472
solvents follow the order acetone > ethyl ethanoate > tetrachlo-
romethane > methanol > ethanol > heptane, which is inconsistent
with the order of solvent polarity for these six solvents.
The experimental results also show that the change in the
solubility of ethanol with temperature is more sensitive, and
thus, ethanol is preferred for crystallization and purification
processes for 2,4-dichloro-5-methoxypyrimidine.
Literature Cited
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Figure 3. Comparison of experimental solubilities with calculated values
by the Apelblat model for 2,4-dichloro-5-methoxypyrimidine in different
solvents: 9, methanol; 2, acetone; 1, heptane; [, ethyl ethanoate; b,
tetrachloromethane; f, ethanol; solid line, Apelblat model.
Table 4. Comparison of Absolute Average Relative Deviation for
Different Models
100 σ
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dinitrosalicylic, and p-toluicacid, and magnesium-DL-aspartate in water
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mixture
λ-h Apelblat
2,4-dichloro-5-methoxypyrimidine + ethyl ethanoate
2,4-dichloro-5-methoxypyrimidine + methanol
2,4-dichloro-5-methoxypyrimidine + ethanol
2,4-dichloro-5-methoxypyrimidine + acetone
2,4-dichloro-5-methoxypyrimidine + tetrachloromethane 1.51
2,4-dichloro-5-methoxypyrimidine + heptane
0.46
3.14
2.58
0.33
0.28
0.46
0.40
0.12
0.59
0.56
0.40
Received for review July 6, 2009. Accepted October 23, 2009.
JE9005689
1.11
total average deviation
1.52