Journal of Molecular Liquids, 50 (1991) 39-,52 39 E l sev i e r Sc i ence P u b l i s h e r s B.V., ~ , r n

Thermodynamic Studies on the Binary Liquid Hixtures Containing

Furan Derivatives: Furfural t Allphatic Ketches

Homendra Naorem and Sushll K. Suri ~ Department of Chemistry,

Indian Institute of Chemistry, Delhi Hau~ Khas. New Delhi - 110016. (India)

( R e c e i v e d 22 O c t o b e r 1 9 9 0 )

ABSTRACT

The excess molar volumes,V E . isentroplc compressibillties,

K E , and viscositles, R E , of mixing for the binary liquid mixtures

of fu~fural with acetone, 2-butanone, and 2-penta.one

over the entire composition range have been determined and

reported. The V E and K E for all the mixtures studied were found

to be negative and the E for the mixtures containing acetone and

2-butanone were positive over the entire composition range while

it was negative for the 2-pentanone mixtures. The results have

been discussed in the light of the specific intermolecular

interactions between the component molecules in the mixtures_

INTRODUCTION

Thermodynamic studies on ~he solution behavlour of binary

liquid mixtures of tetr~hydrofuran (THF) with various

hydrocarbons have reveal~d the presence of strong unlike speelflc

interactions between the component molecules (I-ii). These

interactions were found to be stronger than those expected from

dlsper~lon or induced dlpole-dlpole forces. The binary mixtures

of furan with aromatic hydrocarbons exhibited a similar behavlour

expect for the weakening of the unlike 5-~ interactions in the

0167-7322 /91 /$03 .D0 O 1991 m E l sev i e r S c i e n c e P u b l i s h e m B.V. Al l r i g h t s r e se rved

furan mixtures due to the presence of fl-alctron cloud In the

furan molecule (12). The introduction of a functional group in

the furan ring was found to bring about a significant change ln

the s01uti0a behavfour. In binary mixtures containing a

substituted furan viz. furfural or furfural aloohol the overall

solution behaviour of the mixtures was determined by the

struoture breaking effect of the dipolar associatea of the

furfural or furfuryl alcohol molecules (11-15). The strength of

unlike interaotions in binary mixtures of furfural with self

associated aliphatic alcohola were observed to be relatively

stronger than those of the hydrocarbon mixtures (14.16). These

were attributed to the presence of hydrogen bond interactions

between the carbonyl group of furfural and the -08 group of the

alcohol and the stre,ngth of the interaotion waa found to decrease

as the chain length of the alkyl group of the alcohol increases_

In continuation to our investigations on aolution behaviour of

binary liquid mixtures containing a substittited furan. we have

determined the molar excess volumes, BXC6SS isentropic

compresaibilitias. and excess visoosities for the mixtures of

furfural wfth three aliphatlc ketones namely, acetone, 2-

butanona. and 2-pentanone over the entire composition range. The

purpose of these investigations is to provide more informations

Oil the solution behavior of binary mixtures of furfural with

organic solvents of varying polarities in order to have a better

understanding of the type and the nature of the unlike

interactions present in these mixtures.

EXPEEIMMTAL

The laboratory reagent grade samples of X-butanone and 2-

pentanone supplied by E Merck, India were treated (17.18) with

aqueous potassium carbonate solution and the mixture was

distilled to remove most of the water. The sample was dried for

4-5 days over anhydrous sodium sulfate and then stored over

anhydrous potassium uarbonate. The liquid was decanted and

fractionally distilled through a Im long fractionating column.

Spectroscopic grade sample of acetone supplied by EMerck was used

as such without any further purification treatment. The sample of

furfural was the one used In our previous studies (13). The

purified liquids were stored in brown bottles and fractionally

distilled immediately before use. The densities and the

refractive indexes of the purified solvents are compared with the

accepted literature values (17,181 in Table 1,

The molar excess volumes of mixing were computed from the

experimental density data. IJenaities of the liquids and the

liuuid mixtures were measured using a vibrating tube digital

density meter (UMA 60/602. Anton Paar). The details of the

experimental techniques have been described earlier(l2)_

Table l_ Densities and Refractive indexes of the liquiLds used at 298,15K,

-_--_------_----_______~-___-~______---____---_--_---_~~--~-----

Denfsitfea Refract+ve Indexes LIquida -----------------_---- ___-__---_____--____----

our value lit, value* our value lit, value* __---_----_-----________------_--_____-________--~~---~~---__---~

Furfural l-15493 l-1545 l-5236 l-52345

Acetone O-78451 o-7844 l-3569 l-3661

2-Butanonet O-79981 O-7997 l-3670 l-3761

2-Pentanone O-80158 -- 1-3857 --

s Ibference 17

42

Duplicate density measurement of the liquids and liquid mixtures

agreed to within + 5x10-5 -3 g-cm . This propagates a maximum

uncertainty of 3.008 cm3.mol -' in the VE values reported in this

paper.

The isentropic compressibilities (k,) were calculated from

the experimental density (p) and ultrasonic sound speed (u) of the

liquids using the relation :

k, = (u2. p)-l (1)

Tha ultrasonic speeds of sound were measured using a single

crystal path variable interferometer (Model F-81. Mittal

Enterprise, New Delhi, India) operating at a fixed frequency of

2 Ml%. The excess isentropic compressibility. ICE, of the mixtures

were computed from the relation:

KE= ks -&k,1 -+s2 (2) -

where #i and k,i are the volume fraction and isentropic

compressibility of the component Y' in the mixtures. The maximum

error in the measurement of 'u' was estimated to be 0.15 percent

and this propagates an unaertainty of +2 TPa-' in Lhe k, values

calculated using equation (2)-

The visaosities (7) of the liquids were measured using a

viscometer similar to the Ubbelohde suspended level viscometer

calibrated using purified benzene. toluene and water as reference

liquids. Kinetic energy corrections were applied to the

experimental data. The viscositY values were reproducible to

within 0.002 of a centipoise.

The solutions were prepared by weight in pyrex glass bottles

covered tightly with teflon septuma_ Details of the technique for

preparation of the solutions have been described earlier (12)-

Ketones being more volatile were introduced into the bottle first

43

and weighed, Furfural was then introduced into the bottle and the

content of the bottle were thoroughly mixed and weighed.

Corrections for bouyancy were applied to all the wsighings.

RESULTS AND DISCUSSION

The E experimental V . KE and?= for the binary mIxt.ures are

given in Tables 2-4 and shown graphically in Figures l-3

Table 2 5 Molar exaez3s volumes of mm, VE <am3aol-1) for the binary mixtures of furfural with aliphatia ketones-

-_-_____-_-__-_-_____-__~~~_~~__~_-_---~-~-~-~-_--------

x V= x V= _------_---_-_-_-____~---~-~-_---~-~-~~~-~~--~-~-~-~~~~~~

298_15K 308_15K

furfund+ acotona

0,0827 -0.25s O-1922 -0,438 0,274o -0-546 O-3508 -0,627 O-4264 -0,644 O-5247 -0-625 0_6096 -0,598 0-8395 -0,296 O-9236 -0,142

0_1070 O-1938 0.2776 O-4047 O-4843 0.5874 O-6605 O-7553 O-8714

0_0835 -0,258 0.2293 -0,557 O-2952 -0,649 O-4181 -0,736 O-4630 -0,725 O-5401 -0.702 Om6009 -0,656 O-7445 -0-482 O-8795 -0,235

furfural + 2-lmAJ3noneJ

O-0751 -0,142 0.1497 -0.273 O-2344 -0,292 O-3351 -0,487 O-4185 -0-531 0.5071 -0,529 0.6237 -0-467 O-7186 -0,382 O-8272 -0,254 -_-___---------- _-------

-0.227 0.0948 -0,229 -0-366 O-1895 -0,403 -0,471 O-3447 -0,562 -0,542 O-4605 -0-598 -0,553 O-5703 -0,570 -0,521 0.6449 -0,502 -0,462 0.7336 -0,408 -0.368 O-8022 -0,331 -0,218 O-9132 -0-162

fu.rFuraI + 2-pentanone

----__--

O-0898 -0,160 O-2113 -0-343 0,317o -0,453 O-4064 -0-490 O-5338 -0,485 O-5969 -0,444 O-6886 -0-377 O-7840 -0,285 O-8674 -0-188

,_-----_-_-_ --_-a .-----w--s

44

Table 3 = Volums fraction, @. density .Qm speed of sound. u. isentrophz comgreasibflity, k,, mnd BXc888

iSf3M2OpiC aompm3saibility. BF. for IACJ binary mix-txlrea of furfural with aliphatic ketones at

308-15 K_ __--_______---_--_----------~~~--_____~~--__-__--------_--_~-

k TPa=-1

O-0 O-1381 0.2660 0,4057 O-4628 O-5731 O-6900 0_7311 O-8517 O-9562 1-O

o-77337 1115 1040 Q-82831 1166 888 O-87839 1208 780 O-93217 1264 684 O-95373 1267 653 o-99431 1295 600 1103639 1328 547 l-05093 1338 532 1,093Ol 1366 490 1.12882 1392 457 l-14372 1404 444

furfural + z-butJ%none

O-0 O-1350 0_2166 O-3149 O-4460 O-4814 O-6192 0.7705 0.8335 o_s570 1.0

Oe78935 1155 950 O-84022 1195 833 0.87053 1225 765 O-90653 1244 713 o-s5390 1278 642 O-96647 1286 626 l-01482 1322 564 l-06678 1357 509 1,08810 1371 489 l-12944 1395 455 l-14372 1404 444

furfural + 2-pentanon

O-0 0.79047 1183 901 O-0936 0.82525 1202 839 O-1227 O-83566 1217 808 0_2693 0.88984 1246 724 O-3812 0.93018 1274 662 O-4548 O-95635 1291 627 O-5351 0_98460 1312 590 O-7081 1.04450 1343 531 O-8364 l-08958 1366 492 O-9246 l-11822 1385 466 l-00 1.14372 1404 444

furfural + acetone

-70 -101 -114 -111 -98 -82 -72 -42 -13

-

-49 -74 -78 -82 -80 -73 -51 -39 -11

-19 -37 -54 -65 -66 -66 -46 -27 -12

4s

Table 4 : lDeslit*~ (p.&K+. vlacosltlaa (92. cp) and excess vimzositias (q . cp) for the binary mlxturea of furfural with aU.phatic Latin05

__--__-__________~_-_~---_--_------__--_---_--__--__--___-------_--_------

furfural + acotona

308.15E

0.0964 O-1804 0.2705 O-3561 O-4327 O-5118 O-6013 O-7513 0.8688 0*8159 O-8517 O-8891 O-9232 0.9527 O-9822 l-0142 l-0653 1.1088 0.414 O-524 O-634 O-735 0.819 0.903 O-993 l-136 l-263 O-022 o-041 O-054 O-063 0.064 0.063 0.056 0.037 O-018

303.15 R

3c O-1083 0.2488 O-3465 0_4336 O-5007 O-6620 O-7622 0.8403 0.9253 P O-8262 O-8866 O-9248 0.9581 0_9833 l-0267 l-0742 l-0996 l-1263 %s 0,432 O-639 0.763 0.861 0.9s4 1.081 l-203 I-282 l-365 'I. 0.011 0.058 O-071 O-069 O-066 o-054 O-036 0.026 O-012

288-15 K

x O-0927 0_1922 0.2740 O-3508 O-4284 O-5247 0.6038 0.8S95 O-9236 0.8264 O-8677 0.9012 0_9320 O-9618 O-9975 l-0261 l-1051 1.1315 0.44s O-591 O-702 0,804 0.893 I.001 l-090 1.328 1.424 0.020 0,052 O-066 0,076 O-073 O-066 0.061 O-018 O-014

furfural + 2-butJxnona

308-15 K

0.1002 O-2134 0.3087 O-4301 : 0.8245 O-8643

0.5163 O-5746 O-6278 O-7079 O-8414 O-8980 O-9409 O-9715 0_9921 l_OllO l-0394 l-0869

0.460 O-587 0,694 O-822 o-911 0.967 1.018 l-094 1.218 O-010 0.022 0.031 0.036 0.037 0.033 O-030 0,025 0.013

303-15 K

b 0.1238 0.2186 O-3164 0.4005 0.5146 O-6332 O-7244 O-8024 0.9061 3 0.8378 O-516 O-016 0.8714 0.628 O-026 0.9059 0,744 O-037 0-9357 0.839 0.042 O_BY62 0,960 0.041 O-032 1.021 1.0183 O-026 1.0506 1.104 0.019 l-174 1.0783 O_OOB l-285 l-1155

298-15 K

"p O-1070 0.8373 O-1938 0_8879 O-2776 O-8976 O-4047 O-9426 O-4843 O-9709 0.5874 l-0076 0.6605 1.0335 O-7553 1.0673 0.8714 l-1089 h 0.517 0.625 0.729 O-881 O-969 l-078 l_lS6 1.255 l-973 5 O-015 O-026 O-036 O-046 0.046 o-039 O-035 0.026 O-016

fux-furel + 2-pentanonar

308.15 K

"p O-1062 O-8229 0.1754 O-8439 O-2946 0.8616 0.3839 0.9108 O-4777 0.9426 O-6010 O-9861 O-6837 1_0165 0.7683 l-0487 0.8639 l-0866 O-548 O-649 O-729 0.813 0.930 1.026 I-115 l-219

-0,027 -0.041 -0.047 -0-053 -0.046 -0.037 -0,030 -0,017

46

303-1s K

O-4426 0_5830 0_9357 O-9848 0.813 0_961

-0.056 -0.052

298-15 K

0.4064 0.5338 O-9287 O-9727 0,806 0.943

-0,060 -0.058 ---1---------

F 0_1134 0_8299

%c 0_516

"L -0-018

x 0_0896

O-1968 0.8556 O-587

-0-032

O-2113 0_3170 O-8652 0_8991 O-621 0.720

-0.035 -0.049 -------- -------

O-3042 O-8887 0,681

-0-047

O-6634 O-7580 O-8362 0-9118 l-0141 1_0499 1.0807 l-1115 l-052 l-157 l-246 1.335

-0.043 -0.034 -0,025 -0-013

0.5969 0.6886 0.7840 0_9951 1_0289 1.0657 l-013 l-120 l-233

-0,056 -0.047 -0.036 --------_ _--a-P --------

O-8674 1.0991 1.337

-0,022 ll_-----

r93pect1ve1y. The experimental excess values, YE(=VE ortE), were

fitted into a smoothing equations of the type :

YE = x1.x2CA0 + A1(x1-x2) + A2(x1-x21' + A3(~1-x~)~l (3a)-

KE= 1_ 2C% + AIC+l-~) + A2(#'l-fi)2 + A,(e-%)3l (3b).

where xi and#i are the mole fraction and the volume fraction of

the component 'i' in the mixture and Ai's are constants. The

values of the constants determined by method of least smxares are

given in Table 5 along with the standard deviation 6(YK) of the

fit. Since the 6(YE) values for all ths mixtures are less than

the experimental uncertainty involved in the measurement of YE.

the constants Ai's can be used to represent the experimental

results.

It is observed from figures 1 and 2 that the VE and KE

values for all the mixtures studied are negative over the entire

composition range. The q" for binary mixtures of furfural

containing acetone and 2-butanone are positive while for mixtures

containing 2-pentanone found to be negative over the entire

composition range (Figure 3). The plota of YE vs. composition are

more or less symmetrical to the composition axis with a maxima

(or minima) at around x=0.45 to 0.55. To the best of our

Table 5, values of p"pm eters Zm Eqs.<3a and 3bl and standard deviation 6<~ ) of exp~~imtmtal results at 308-15E-

Furfural +

Acetone -2-8860 O-5963 0.2068 0,2155 0,006 2-butanone -2,354o O-5346 0_0069 -0-2278 0,006 z-_pentanone -2.0867 -0.0641 O-5320 O-6292 0.008

Acetone -433 163 -52 23 3 L-butanone -325 102 -58 14 3 2-p43ntanona -264 83 57 36 4

Aaetona O_ 2525 -0.0956 -0,056O 0.0731 O-001 P-butanone O-1440 -0wO328 -0-0718 O-Q284 0.001 2-Pent.anona -0,200Q O-0335 O-0764 -0.0224 0_.002

x 00 0.2 0-L 0.0

on

-0.2

‘; ; -u

E

? -Q6

%

+.“I~ Fig.1 -VE Vs. x for the systems turfural+ acetone(o), + Zbutanone(v)

+ 2-pentanoneto 1 at 308.15K (broken lines at 298_15K I.

Fig.2 KEVs.@ f or the binary mixtures of turfural with acetone (0 1,

2-butanOne (v), and 2-pentonone(a1 at 308.15.

?, I-

! Fig.3.$ Vs. x for turfural + acetone (0 1. 2-buta none{ b), 2-pentononek)

at 29&15(O), 303_15(fi), and 308.15K(0) respectively.

48

knowledge there are no data available for any of the mixtures

considered here in the literature to compare our results-

The molecules of furfural are known to exist a5 dipolar

associates in the pure state(l9). The addition of a non-polar

solvent to furfural leads to breaking of these dipclar

associates. As the polarity of the solvent is increased Ii-e. on

gohf3 from a hydrocarbon to an aluohol) there is a decrease in

the 'structure breaking' and as a consequence thereof an increase

in the strength of the unlike interactions in the resultant

binary mixtures(l3.16)_

The m;>lecules of ketones also exist in the assouiated form

through dipolar interactions in pure state. Radojkovic et al<201

reported that addition of an alkane to an aliphatic ketone leads

to breaking UP of the dipclar associates. However, the presence

of strong unlike interaction between the component molecules of

binary mixtures containing a ketone and an aromatic hydrocarbon

has been reported in the literature (20-22).

In view of the above, the overall solution behaviour of the

binary mixtures under investigation may be envisaged as the

resultant of the two opposing effects namely 'structure breaking'

and 'structure making' effects in each of the components of the

binary mixtures_

The observed negative V E value8 for the binary mixtures

(Figure 1.) suggest that the unlike dipolar Interactions are

fairy strong and predominant over the structure breaking effects

in the mixtures. The large negative VB values as compared to the

binary mixtures of furfural with aliphatic alcohola are

indicative of the presenae of relatively stronger unlike

interactions in the mixtures containing ketones and hence follow

the expeuted trend.

50

At equimolar ooacentration. VK 0.5 follows the order:

acetone< Z-butanonec Z-pentanone indicating that the strength of

the unlike interactions decrease with the increase in t,he size of

the alkyl group of the ketone.. This may arise from I Ci) an

increase in the distance of olosest approach of the molecule and

(ii) also a decrease in dispersive interactions in the mixtures-

The observed negative temperature oo-effioient of VE (Figure 1)

appears to be due to the decrease in the molar volume of the

binary mixture formed from specifiu intermolecular interactions

which more than compensates for the volume changes arising from

the decrease in the extent of unlike dipolar interactions with

increase in temperature.

It is established that the presence of specifio interactions

between the aomponent molecules in liquid mixtures leads to a

decrease in the free-space thereby uontributing to a pO3itiVO

&viation in speeds of sound and negative exceaa isentropic

oompressibilities (23-26). The KE values are expected to become

increasingly negative as the strength of the unlike interactions

in the mixture increases. The large negative KE values observed

for these mixtures under consideration suggest the presence of

strong unlike dipole-dipole interaotions in the mixturas which

more than compensates the positive contribution to KE arising

from the mutual rupturing of the dipolar aggregates in furfural

and ketones by each other. A comparison of the KE values for the

furfural binary mixtures containing a ketone with those

containing an alcohol reveals that unlike interactions present in

the former systems are relatively stronger (16). It is also

observed form Figure 2. that KS increases as the chain len&h of

the alkyl group of the ketone increases which is indicative of

61

relatively weaker unlike interactions in the mixtures containing

higher ketones. These conclusions are in good agreement with the

conclusions arrived from the volumetric studies.

The observed positive rE values for the mixtures that

follows the trend acetone> 2-butanone> 2-pentanone Indicates the

presence of a relatively stronger dipolar interactions between

the unlike molecules in binary mixtures containing acetone and 2-

butanone as compared tp the ones containing 2-pentanone.

Further for mixtures containing acetone and 2-butanone ,)LE

decreases with the increase of temperature while an opposite

trend was observed for mixtures containing 2-pentanone. A

decrease in '2E with increasing temperature is expected in the

mixtures wherein strong unlike interactions are present. The.

strong dipolar interactions between the molecules would tend to

dissociate more at higher temperature resulting into a lesser

resistance to flow and hence a dearease in TE. The positive

temperature co-efficient for the mixtures containing '2-pentanone

indicates the predominance of the increased hindrance of rotation

over a decrease :n the resistance of flow due to decrease in

unlike interactions and corroborates the conclusions drawn from

the VE and KE studies.

References

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2. A.W. Andrews and K.W. Morkom. J.Chem.Thermodyn. 1971, 3, 513

3. D.D. Dsshpande and 6-L. Oswal. ibid. 1975. 1. 155.

4. R. Meyer, G. Guiati. M. Meyer and E.J. Vincent. Thermochim. Acta 1975, 13, 379.

5. M.D. Guillen and C.G. Losa. J.Chsm.Thermodyn. 1978. UT, 567

s2

6. H.V. Rehiaian. J.P.E. Grolier and G.C. Benson. J.Chem.Phya. 1978. B. 1031.

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