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Excess enthalpies of binary mixtures of 2-ethyl-1-butanol with hexane isomers
Fluid Phase Equilibria, 9 (I 982) 99- 104 Elsevier Scientific Publishing Company, Amsterdam-Printed
99 in The Netherlands
EXCESS ENTHALPIES OF BINARY MIXTHRES I-IF2-ETHYL-l-RUTANOL WITH HEXANE ISOMERS* FUMIII KIMURA** and GEORGE C. RENSDN
Division of Chemistry, National Research CounciZ of Canada, Ottawa, Ontario KZA OR6
iCcma&i
(Received May 3rd, 1982)
ABSTRACT Kimura, F. and Benson, G. C., 1982. Excess enthalpies of binary mixtures of 2-ethyl-l-butanol with hexane isomers. Fluid Phase k?quiZibria.9:99-104. Molar excess entlialpies, measured at 298.15 K in a flow microcalorfmeter, are reported for binary mfxtures of 2-ethvl-1-butanol with the five fsomerfc hexanes. The results are compared with previously publfshed excess enthalpfes for mixtures of 1-hexanol and 2-methyl-1-pentanol with the same hexane isomers.
INTROflIJCTION Recent papers from our laboratory reported the excess enthalpies of binary mixtures of the five hexane Isomers with I-hexanol (Kimura and Renion, 19Rl) and with P-methvl-1-pentanol (Kimura and Renson, 19821.
These fnvestfqatfons were
undertaken to study the effect of molecular shape on the thermodynamic propertfes of alcohol + hydrocarbon systems.
The present paper continues this work by descrfbina
measurements of excess enthalpfes for binary mixtures of yet another primary hexanol , ?-ethyl-1-hutanol, with the same set of hexane Isomers:
n-hexane
(n-Ccl,
Z-nethylpentane 12-MPl, 3-methylpentane 13-MP), Z.Z-dfmethylbutane (2,2-WI). 2,3-dimethylhutane (7,3-OMR).
*Issued as NRCC No. 20111 **National Research Council of Canada Research Associate
0378-3812/82/0000-0000/.$02.75
0 1982 Elsevier Scientific Publishing Company
and
EXPERIMENTAL
The Z-ethyl-1-butanol
(Aldrich Chemical Co.) was purfffed chromatographically
using two columns, each 1.8 m long, connected in series and containing 60/AO mesh Chromosorb W as substrate.
One column was loaded with 10 per cent (by mass)
squalane, and the other with 10 per cent OV-101.
Prior to the calorimetric
measurements, the alcohol was stored over a molecular sieve (BDH type 34). At -3 and 1.47065, 298.15 K, its density and refractive Index (n,) were R29.14 kq m respectively. n-Hexane
(Phil1ips Petroleum Co., Pure Grade reagent) and 2,3-dimethylhutane
(Aldrich Chemical Co.) were also purified chromatoqraphicallv. containing BY-101 was used for both materials.
The column
The other hexane isomers were
Phillips Petroleum Co. Research Grade reagents wfth puritfes of 99.RB mole per cent or greater; they were used without further purification.
The densities and
refractive indices of all of the isomeric hexanes were nearly identical to those of the samples used in our earlier investigations (Yimura and Benson, 1981. 19A2).
An LKB flow mfcrocalorimeter enthalpies.
(Model 107nD-1)
was used
to determine the excess
The thermopile output was measured with a Keithley IS0 Diqita'l
Nanovoltmeter.
Mixtures with preselected mole fractfons known to better than 0.1
per cent were produced by a pair of piston displacement pumps.
netails of the
equipment and operational procedure are described by Tanaka et al. (1975).
The
error of the excess enthalpfes is estimated to be less than 0.5 per cent over most of the mole fraction ranqe.
RESULTS AND DISCUSSION Experimental values of the molar excess enthalpies WE of binary mixtures of 2-ethyl-1-butanol with the five isomeric hexanes at 29R.15 K are listed in Table 1, and plotted in Fiq. 1 where for clarity of presentation the data For different systems are displaced by successfve multiples of loo J mol-'. denotes the mole fraction of alcohol.
In all cases, x
TABLE 1 Experimental values of the molar excess enthalpies HE for binary mixtures of Z-ethyl-1-hutanol with hexane isomers at 298.15 K
X
C6H140
0.05
0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 n.s0 0.55 0.60 0.65 0.70 0.75 O.RO O.R5 '1.90 0.95
HE/J mol-L n-C6 379.39 476.14 _. 534.37 577.90 609.85 634.55 653.17 664.67 fi64.64 662.73 663.27 646.87 614.27 575.94 522.N 457.20 3AO.20 293.78 199.80 100.75
2-MP
3-MP
2,2-DMR
2,3-DMB
374.86 467.40 525.20 565.74 506.49 619.39 637.55 6413.03 651.15 645.36 645.50 629.08 599.47 558.0X 505.99 443.R9 366.1R 2R1.65 192.07 94.30
374.3R 466.48 522.Rl 566.45 595.00 618.22 635.43 646.04 645.65 641.21 641.03 622.89 593.50 552.11 499.43 434.30 35q.w 276.57 lRA.41 94.79
368.77 459.75 514.R7 553.32 582.26 603.89 620.20 62R.41 624.77 619.07 619.R3 59R.R6 567.45 526.21 477.10 414.93 345.52 267.45 lR3.90 93.90
372.67 463.36 518.77 559.20 5RR.11 610.57 62R.09 637.39 6-iR.16 629:iE 629.96 610.31 570.65 53R.55 486.70 423.37 351.70 271.67 105.32 93.19
A skewed Redlich-Kister equation (Myers and Scott, 1963) HE/J mol-l = [x(1-x)/{l-k(l-2x)}]&hj(l-2x)j-'
(1)
was fitted to each set of results by the method of least-squares with all pofnts weighted equally.
Values of the coefficients hj, the skewinq parameter k (which was
also adjusted), and the standard deviation o are summarized in Table 2.
The curves
in Fig. 1 were calculated from these representations. We are unaware of any prevfous calorfmetric studies of the present systems.
The
skewed parabolic dependence of HE on x, shown in Fig. 1, is similar to that found for mixtures of the hexane isomers with l-hexanol (Kimura and Benson, lgR1) and wfth
102 Z-methyl-l-pentanol (Kimura and Renson, 1982).
A comparison of the smoothed results
for the three alcohols wfth n-hexane is shown in Fig. 2 and is typical of the behaviour of these alcohols with the other isoneric hexanes.
The magnitude of HE
decreases in the order: 2-ethyl-1-butanol > Z-methyl-l-pentanol 5 l-hexanol and the skew of the curves decreases in the reverse order.
600
500
-h 400 E
T
z
h .
UlT = 3'Oc
“r
‘,,. ‘\\ ‘.
\
‘.
200
\ .. \ .. \
‘: \ \.. \
100
Fig. 1.
‘..,f
Molar excess enthalpy HE of binary mixtures of Z-ethyl-1-butanol with hexane isomers at 299.15 K vs. the mole fractfon x of 2-ethyl-1-butanol. Points, experimental values: 0, t&6; V, 2-MP;e, 2.3~DMB.
Fig. 2.
3-MP;n.
2,2-DMR;Cl,
Curves calculated from eqn. (1) with parameters from Table ?.
Molar excess enthalpy HE of binary mixtures of an isomeric hexanol with n-hexane at 295.15 K vs. the mole fraction x of the hexanol isomer. Curves: -,
present smoothed results for P-ethyl-l-butanol;
---,
2-methyl-1-pentanol (Kimura and Renson, 19821; .. .. . 1-hexanol (Kimura and Senson, 1981).
103 TABLE 2 Coefficients hj, skewinq factor k, and standard deviation o for least-squares representations of HE/J mol-' for binary mixtures of Z-ethyl-1-butanol with hexane isomers at 299.15 K by eqn. (1)
Hexane isomer n-C6
Z-MP 2580.70 -211R5.4 13.6 1177.5 -3fl?.O -398.0
2651.67 -2145.3 59.0 825.2 -321.g -299.6
hl
hz h3 h, hs hs h7 k 0
3-MP 2563.76 -2030.1 -45.1 1163.4 -281.3 -395.6
0.9R14 0.8R
0.9746 0.45
700
V'---__
-_
2516.35 -1933.7 -155.3 654.3 116.6 -265.4 -330.8 0.9875 0.42
q-------
A
--o_ ---
6CX-
7 B 3 2 52 i 500-
2476.14 -185'3.2 -195.2 554.2 283.9 -270.6
,
4
-4
--__
2,3-DMB
-386.7 0.9R55 0.63
0.9826 0.69
I
2,2-DMR
-n_
0 --__ 0
--__
"-""..o.......+
.. ....
""""...a...,Q,...,, 400' 05
IO
15
2.0
2.5
3.0
% Ff9. 3.
Molar excess enthalpies HE(0.5) of equimolar mixtures Of an isomeric hexanol with hexane isomers at 298.15 K vs. 7 9, the mean number of qauche conformations A,
of the hexane isomer.
2,2-DMfl;r~, 2,3-OHB.
(r = -0.76); ---, Z-methyl-1-pentanol 1982);
.... .
Points:~,
Least-sprares
n-C6; 0,
lines: -, (r = -0.89:
%-MP;Q
3-MP;
2-ethyl-1-butanol Kimura and Renson.
I-hexanol (r = -0.92; Kfmura and Renson, 1981).
104 The curves for Z-ethyl-1-butanol with the hexane isomers fall in the order: n-C6 > 2-MP > 3-MP > 2,3-DMB > 2.2-DMB This differs from the order found for the two other alcohols by the interchange of 2,3-DMB and 2,2-DMB.
Previously we noted that for both 1-hexanol and Z-methyl-l-
pentanol, there was a roughly linear correlation between HE for equimolar mixtures and the Zg parameter (Mann, 19671 of the hexane isomer. for the three sets of systems in Fig. 3.
This relationship is shown
For 2-ethyl-l-butanol mixtures, the
coefficient of correlation, r = -0.76, is somewhat smaller in magnitude than the values found previously for 1-hexanol mixtures (r = Xl.921 and Z-methyl-1-pentanol mixtures (r = -n,P91.
ACKNOWLEDGEMENTS The authors are indebted to C.J. Halpin and P.J. D'Arcy for technical assistance during this investigation.
REFERENCE< Mann, G., 1967. Konformation und physikalische Daten von Alkanen und Cyclanen - I iber lineare Beziehungen zwischen der Konformation und den physikalischen Daten isomerer Kohlenwasserstoffe.
Tetrahedron, 23: 3375-339?.
Myers, D.B. and Scott, R.L., 1963.
Thermodynamic
functions of nonelectrolyte
solutions. Ind. Enq. Chem., 65: 43-46. Kimura, F. and Benson, G.C.. 19Rl. Excess enthalpies of binar.y mixtures of l-hexanol with hexane isomers at 29R.15 K. J. them. Eng. Data, 26: 317-314. Kimura, F. and Benson, G.C., 1982. Excess enthalp,ies of binary mixtures of 2-methyl-1-pentanol with hexane isomers.
Fluid Phase Equilibria, 8:
Tanaka, R.. D'Arcy, P.J. and Benson, G.C... 1975.
calorimeter to determine the excess enthalpies of binary mixtures of nonelectrolytes.
107-112.
Application of a flow micro-
Thermochim. Acta, 11: 163-175.
99 in The Netherlands
EXCESS ENTHALPIES OF BINARY MIXTHRES I-IF2-ETHYL-l-RUTANOL WITH HEXANE ISOMERS* FUMIII KIMURA** and GEORGE C. RENSDN
Division of Chemistry, National Research CounciZ of Canada, Ottawa, Ontario KZA OR6
iCcma&i
(Received May 3rd, 1982)
ABSTRACT Kimura, F. and Benson, G. C., 1982. Excess enthalpies of binary mixtures of 2-ethyl-l-butanol with hexane isomers. Fluid Phase k?quiZibria.9:99-104. Molar excess entlialpies, measured at 298.15 K in a flow microcalorfmeter, are reported for binary mfxtures of 2-ethvl-1-butanol with the five fsomerfc hexanes. The results are compared with previously publfshed excess enthalpfes for mixtures of 1-hexanol and 2-methyl-1-pentanol with the same hexane isomers.
INTROflIJCTION Recent papers from our laboratory reported the excess enthalpies of binary mixtures of the five hexane Isomers with I-hexanol (Kimura and Renion, 19Rl) and with P-methvl-1-pentanol (Kimura and Renson, 19821.
These fnvestfqatfons were
undertaken to study the effect of molecular shape on the thermodynamic propertfes of alcohol + hydrocarbon systems.
The present paper continues this work by descrfbina
measurements of excess enthalpfes for binary mixtures of yet another primary hexanol , ?-ethyl-1-hutanol, with the same set of hexane Isomers:
n-hexane
(n-Ccl,
Z-nethylpentane 12-MPl, 3-methylpentane 13-MP), Z.Z-dfmethylbutane (2,2-WI). 2,3-dimethylhutane (7,3-OMR).
*Issued as NRCC No. 20111 **National Research Council of Canada Research Associate
0378-3812/82/0000-0000/.$02.75
0 1982 Elsevier Scientific Publishing Company
and
EXPERIMENTAL
The Z-ethyl-1-butanol
(Aldrich Chemical Co.) was purfffed chromatographically
using two columns, each 1.8 m long, connected in series and containing 60/AO mesh Chromosorb W as substrate.
One column was loaded with 10 per cent (by mass)
squalane, and the other with 10 per cent OV-101.
Prior to the calorimetric
measurements, the alcohol was stored over a molecular sieve (BDH type 34). At -3 and 1.47065, 298.15 K, its density and refractive Index (n,) were R29.14 kq m respectively. n-Hexane
(Phil1ips Petroleum Co., Pure Grade reagent) and 2,3-dimethylhutane
(Aldrich Chemical Co.) were also purified chromatoqraphicallv. containing BY-101 was used for both materials.
The column
The other hexane isomers were
Phillips Petroleum Co. Research Grade reagents wfth puritfes of 99.RB mole per cent or greater; they were used without further purification.
The densities and
refractive indices of all of the isomeric hexanes were nearly identical to those of the samples used in our earlier investigations (Yimura and Benson, 1981. 19A2).
An LKB flow mfcrocalorimeter enthalpies.
(Model 107nD-1)
was used
to determine the excess
The thermopile output was measured with a Keithley IS0 Diqita'l
Nanovoltmeter.
Mixtures with preselected mole fractfons known to better than 0.1
per cent were produced by a pair of piston displacement pumps.
netails of the
equipment and operational procedure are described by Tanaka et al. (1975).
The
error of the excess enthalpfes is estimated to be less than 0.5 per cent over most of the mole fraction ranqe.
RESULTS AND DISCUSSION Experimental values of the molar excess enthalpies WE of binary mixtures of 2-ethyl-1-butanol with the five isomeric hexanes at 29R.15 K are listed in Table 1, and plotted in Fiq. 1 where for clarity of presentation the data For different systems are displaced by successfve multiples of loo J mol-'. denotes the mole fraction of alcohol.
In all cases, x
TABLE 1 Experimental values of the molar excess enthalpies HE for binary mixtures of Z-ethyl-1-hutanol with hexane isomers at 298.15 K
X
C6H140
0.05
0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50 n.s0 0.55 0.60 0.65 0.70 0.75 O.RO O.R5 '1.90 0.95
HE/J mol-L n-C6 379.39 476.14 _. 534.37 577.90 609.85 634.55 653.17 664.67 fi64.64 662.73 663.27 646.87 614.27 575.94 522.N 457.20 3AO.20 293.78 199.80 100.75
2-MP
3-MP
2,2-DMR
2,3-DMB
374.86 467.40 525.20 565.74 506.49 619.39 637.55 6413.03 651.15 645.36 645.50 629.08 599.47 558.0X 505.99 443.R9 366.1R 2R1.65 192.07 94.30
374.3R 466.48 522.Rl 566.45 595.00 618.22 635.43 646.04 645.65 641.21 641.03 622.89 593.50 552.11 499.43 434.30 35q.w 276.57 lRA.41 94.79
368.77 459.75 514.R7 553.32 582.26 603.89 620.20 62R.41 624.77 619.07 619.R3 59R.R6 567.45 526.21 477.10 414.93 345.52 267.45 lR3.90 93.90
372.67 463.36 518.77 559.20 5RR.11 610.57 62R.09 637.39 6-iR.16 629:iE 629.96 610.31 570.65 53R.55 486.70 423.37 351.70 271.67 105.32 93.19
A skewed Redlich-Kister equation (Myers and Scott, 1963) HE/J mol-l = [x(1-x)/{l-k(l-2x)}]&hj(l-2x)j-'
(1)
was fitted to each set of results by the method of least-squares with all pofnts weighted equally.
Values of the coefficients hj, the skewinq parameter k (which was
also adjusted), and the standard deviation o are summarized in Table 2.
The curves
in Fig. 1 were calculated from these representations. We are unaware of any prevfous calorfmetric studies of the present systems.
The
skewed parabolic dependence of HE on x, shown in Fig. 1, is similar to that found for mixtures of the hexane isomers with l-hexanol (Kimura and Benson, lgR1) and wfth
102 Z-methyl-l-pentanol (Kimura and Renson, 1982).
A comparison of the smoothed results
for the three alcohols wfth n-hexane is shown in Fig. 2 and is typical of the behaviour of these alcohols with the other isoneric hexanes.
The magnitude of HE
decreases in the order: 2-ethyl-1-butanol > Z-methyl-l-pentanol 5 l-hexanol and the skew of the curves decreases in the reverse order.
600
500
-h 400 E
T
z
h .
UlT = 3'Oc
“r
‘,,. ‘\\ ‘.
\
‘.
200
\ .. \ .. \
‘: \ \.. \
100
Fig. 1.
‘..,f
Molar excess enthalpy HE of binary mixtures of Z-ethyl-1-butanol with hexane isomers at 299.15 K vs. the mole fractfon x of 2-ethyl-1-butanol. Points, experimental values: 0, t&6; V, 2-MP;e, 2.3~DMB.
Fig. 2.
3-MP;n.
2,2-DMR;Cl,
Curves calculated from eqn. (1) with parameters from Table ?.
Molar excess enthalpy HE of binary mixtures of an isomeric hexanol with n-hexane at 295.15 K vs. the mole fraction x of the hexanol isomer. Curves: -,
present smoothed results for P-ethyl-l-butanol;
---,
2-methyl-1-pentanol (Kimura and Renson, 19821; .. .. . 1-hexanol (Kimura and Senson, 1981).
103 TABLE 2 Coefficients hj, skewinq factor k, and standard deviation o for least-squares representations of HE/J mol-' for binary mixtures of Z-ethyl-1-butanol with hexane isomers at 299.15 K by eqn. (1)
Hexane isomer n-C6
Z-MP 2580.70 -211R5.4 13.6 1177.5 -3fl?.O -398.0
2651.67 -2145.3 59.0 825.2 -321.g -299.6
hl
hz h3 h, hs hs h7 k 0
3-MP 2563.76 -2030.1 -45.1 1163.4 -281.3 -395.6
0.9R14 0.8R
0.9746 0.45
700
V'---__
-_
2516.35 -1933.7 -155.3 654.3 116.6 -265.4 -330.8 0.9875 0.42
q-------
A
--o_ ---
6CX-
7 B 3 2 52 i 500-
2476.14 -185'3.2 -195.2 554.2 283.9 -270.6
,
4
-4
--__
2,3-DMB
-386.7 0.9R55 0.63
0.9826 0.69
I
2,2-DMR
-n_
0 --__ 0
--__
"-""..o.......+
.. ....
""""...a...,Q,...,, 400' 05
IO
15
2.0
2.5
3.0
% Ff9. 3.
Molar excess enthalpies HE(0.5) of equimolar mixtures Of an isomeric hexanol with hexane isomers at 298.15 K vs. 7 9, the mean number of qauche conformations A,
of the hexane isomer.
2,2-DMfl;r~, 2,3-OHB.
(r = -0.76); ---, Z-methyl-1-pentanol 1982);
.... .
Points:~,
Least-sprares
n-C6; 0,
lines: -, (r = -0.89:
%-MP;Q
3-MP;
2-ethyl-1-butanol Kimura and Renson.
I-hexanol (r = -0.92; Kfmura and Renson, 1981).
104 The curves for Z-ethyl-1-butanol with the hexane isomers fall in the order: n-C6 > 2-MP > 3-MP > 2,3-DMB > 2.2-DMB This differs from the order found for the two other alcohols by the interchange of 2,3-DMB and 2,2-DMB.
Previously we noted that for both 1-hexanol and Z-methyl-l-
pentanol, there was a roughly linear correlation between HE for equimolar mixtures and the Zg parameter (Mann, 19671 of the hexane isomer. for the three sets of systems in Fig. 3.
This relationship is shown
For 2-ethyl-l-butanol mixtures, the
coefficient of correlation, r = -0.76, is somewhat smaller in magnitude than the values found previously for 1-hexanol mixtures (r = Xl.921 and Z-methyl-1-pentanol mixtures (r = -n,P91.
ACKNOWLEDGEMENTS The authors are indebted to C.J. Halpin and P.J. D'Arcy for technical assistance during this investigation.
REFERENCE< Mann, G., 1967. Konformation und physikalische Daten von Alkanen und Cyclanen - I iber lineare Beziehungen zwischen der Konformation und den physikalischen Daten isomerer Kohlenwasserstoffe.
Tetrahedron, 23: 3375-339?.
Myers, D.B. and Scott, R.L., 1963.
Thermodynamic
functions of nonelectrolyte
solutions. Ind. Enq. Chem., 65: 43-46. Kimura, F. and Benson, G.C.. 19Rl. Excess enthalpies of binar.y mixtures of l-hexanol with hexane isomers at 29R.15 K. J. them. Eng. Data, 26: 317-314. Kimura, F. and Benson, G.C., 1982. Excess enthalp,ies of binary mixtures of 2-methyl-1-pentanol with hexane isomers.
Fluid Phase Equilibria, 8:
Tanaka, R.. D'Arcy, P.J. and Benson, G.C... 1975.
calorimeter to determine the excess enthalpies of binary mixtures of nonelectrolytes.
107-112.
Application of a flow micro-
Thermochim. Acta, 11: 163-175.