Dielectric and calorimetric behaviour of liquids systems containing halogenotoluenes

Journal of Molecular Liquids, 32 (1986) 209-218 Elsevier Science Publishers B.V.,Amsterdam - Printedin The Netherlands

DIELECTRIC

AND

CONTAINING

HALOGENOTOLUENES

J.M.

BEHAVIOUR

OF

LIQUIDS

SYSTEMS

FORNIES-MARQUINA

Departamento Facultad 50009

S.

CALORIMETRIC

209

de

de

Zaragoza

OTIN,

50009

J.

MUGOZ

de

Ciencias,

de

Zaragoza

(Received

y Electrenica,

Universidad

de

Zaragoza,

(Espafia)

Departamento Facultad

Electricidad

Ciencias,

EMBID

and

Quimica

C.

GUTIERREZ

LOSA

Fisica, Unlversidad

de

Zaragoza,

(Espafia) 1986)

7 April

ABSTRACT

A

study

of

halogenotoluenes constants 9.23

and

at

from

carried

and

GHz,

energies

Eyring On

dielectric

2 MHz

15.05

activation

the was

the

equimolecular E H were x=0.5' energies of

0167-7322/86/$03.50

and

Bauer

other

determined the

complex

pure

0

by

in

the

range

the

relaxation

models

at

the

and

correlated

mono-

their

- 323.15 process,

303.15

excess

the

dielectric

permittivities

293.15

halogenotoluene

polar

of

measuring

dielectric

of

hand,

binary

relaxation out

K. were

at

The obtained

K.

molar

enthalpies

+ benzene with

the

components.

1986 Elsevier Science Publishers B.V.

of

mixtures, activation

the

210 INTRODUCTION

This which

contribution

intends

dielectric

to

relaxation

thermodynamic mixtures. and

with

From

the

the and

15.05

toluenes

of

we the

excess

polar

+ non-polar

techniques,

about

the

afford

binary

the

relaxation

a reciprocally

molecular

follow

the

dielectric

will

structure.

study

of

the

monohalogenotoluenes

enthalpy

experimental

and

[ll monohalogenotoluene

of

have

been of

to

obtained

the

of

to as

and

Eyring

with

the

of

its +

303.15

a

were

the

and

calculated The

polar

excess with

GHz

symmetric

type,

models.

of

mixtures

9.23

monohalogeno-

to

theoretical

corresponding

and

the

process

constants

at

Cole-Cole

energies

binary

pressure

K,

belonging

times

activation

dielectric

323.15

relaxation

equimolecular

atmospheric

K

for

permittivities

classified

relaxation

Bauer

for

correlated

their

293.15

energies

according

results

dielectric

from

GHz,

activation

of

and

their

work,

complex

distribution

were

molecule

work

mixtures.

2 MHz

and

a polar

mixtures,

relaxation

relation

of

of

information

general the

properties

present

a more

between

both

the

of

relation

of

dielectric

at

of

basis

the

process

behaviour

complementary In

the

Application

excess

benzene

is

investigate

values

compounds

molar

enthalpies

benzene,

at

K.

EXPERIMENTAL

Dielectric

measurements

Static with

a DMOl

Corporation) of

21

per

obtained

accuracy

constant, (Kahl

according cent).

in

the

the

at

values

E S' Scientific hetrodyne

dielectric

a modified

waveguide

respectively.

to

Complex

following

rectangular

cent

dielectric Dipolmeter

of

9.23 E'

Experimental

at

2 MHz

beat

permittivities - Hippel

GHz

15.05

and E"

measured

method

Roberts

and

were

Instruments

better

temperatures

(accuracy were [Z]

method

GHz than

and

with

2 and

ranged

in an

4 per

from

211

293.15 the

K to

323.15

dielectric

proximity points and

of

K,

theory

K,

liquid-solid components

using

with

using

is

the

Temperature

of

application

anomalies or

case

was

Haake

of

caused

to

the

of

by

the

freezing

parabromotoluene

controlled

regulator

to

enthalpies

a isobaric

is

an

limbs

the

two

liquids

of

Electric

energy

temperature

the

cell.

was

to

within

system.

quantities

continuous

in

the

the

agreement

with

cent

central

the

was

data

reported of

than

of

0.5

[31 . vacuum

liquids

movement

absence

hexane

under

two

to

phase.

cent

within

was

better

and 0.002

+ cyclohexane

[4]

in

permits

vapour

per

controlled

against

range

the

pendular

better

were

calorimeter filled

of

complete to

checked

mixtures

quasi-isothermic

thermostat

per

equimolecular

receptacle

measured

was

over

A

mix

water

calorimeter

and

weighed

to

of

for

anchor-shaped

isolate

the

The

validity the

transformations as

a Neslab/

molar

cell Hg

the

measurements

Excess obtained

excluding

the

Calorimetric

Mixing

ensure

to

paraiodotoluene.

zO.05

to by

and

than

0.5

concentration.

Materials

moles

The

liquids

per

cent

were

used

as

were

carried

used

purity.

purity out

reproducibility

were

Fluka

criteria.

with

the

better

indices

and

Refractive

help

+O.OOOOZ

of

products

Refractive

of

for

indices

Abbe's

Sodium

than

g.1.c.

99.5

analysis

measurements

Refractometer

with

a

D-line.

RESULTS The with In

l/T, figure

toluenes; whose

experimental in

accordance

1,

Es

the

with

plotted

corresponding

E s values

included.

is

values

Static

were

obtained

dielectric

of the

ES,

against plot in

show

a linear

equation l/T for

E for

the

S

= a

+ b/T.

monohalogeno-

halogenobenzenes

a previous

constant

(Tl

the

variation

increases

work

151

in

the

are

also

sequence

K.

212 orthohalogenotoluene

< halogenobenzene except

parahalogenotoluene, a value

of

ES

higher

than

for that

< metahalogenotoluene

the for

chlorobenzene,

which

< shows

metachlorotoluene.

%

;*:I

6.0 5.5 5.0

4.5

:I:.e”3.1

MO-

4.0 3.3

3.2

3.4

3.1

3.2

103/T E

E

s 6.0

s

3.4

(d)

5.5

5.5

5.0

5.0

/

4.5

-

4.5

3.3

103/T

Ho-

p-

-Ill-

-

7

4.0

4.0 3.1

3.2

3.3

3.4

Figure

3.1

3.2

3.3 103/T

103/T 1. Plots of Es against

103/T for monohalogenobenzenes

monohalogenotoluenes.

(a) fluoroderivatives;

(c) bromoderivatives;

(d) iododerivatives.

and

(b) chloroderivatives;

3.4

213

In plotted and

figure

the

2,

against

the

square

of

molecular

halogenobenzenes;

as

refractive

weight

it

is

I

2.5'

I Br 0

Br

Cl

the

both

seen,

n:,

&'

of

2 nb,

indices,

are

halogenotoluenes

types

of

compounds

show

a

similar

behaviour.

This

relationship

is

important

taking

into

the

number

of

small

of

the

dielectric

at

high

account

references

constants

PF

F

.4+

these

2.0

frequency, molecules

approximate molecular

the

weight

E=,

for

lead us to 2 = n D to study

Em

dielectric

relaxation

process. Figure

2. ni against molecular

of the

(A) monohalogenobenzenes,

weight We and

have

applied

the

(0) different

empirical

models

monohalogenotoluenes. of

relaxation

to

experimental assuming

that

the

E*tW,To)/Es-Em that

at

temperature

method

a

let

belonging of

the

limited

us to

Cole-Cole

obey

a fixed

to a

in

range

classify

of the

symmetrical

type,

in

polarization,

temperature,

angular

E*(Wo,T)/Es-Em,

in

reduced

, at constant

obtained

Argand,

orientational

is

frequency, a complex

coincident wo,

and

A

fitting

monohalogenotoluenes

the

of

complex

as

relaxation

dielectric

times permittivity

1

- Em 5

ES(T)

time whose

7 of

of numerical

equation E*(W,T)

where

with

varying

representation

temperature.

distribution

which

the

results,

is the

value

the

value

of

distribution, is

kept

the

(1) 1 +

- Em most

and

probable

u the

independent

(jwr)r-'

of

macroscopic

characteristic temperature

relaxation parameter,

in

the

studied

range. Eyring relaxation

rate

equation

was

used

to

study

the

variation

of

times ln(7T)

= ln(h/k)

- AS/R

+ AA~/RT

(21

214 where the

is E dielectric

molar and

the

hH

account have

and

the

AS

R,

constants,

used

enthalpy

process,

entropy, Plank

molar

k

is

and

activation

the

h,

the

model,

of

in

the

to

change

perfect

gas,

Moreover,

structure

Bauer

associated

corresponding

are

respectively.

molecular

the

of

taking

studied

of

the

Boltzmann into

compounds,

we

which, W

ln(TT*) being

related

AB

molecule

and

process.

From

against table

is

WB

the we

l/T, 1,

with

these

excess

are

the

+

inertia

of

the

obtained

moment

the

together for

of

303.15

of

the

ln(TT)

with

the

to

the

dielectric

or

thermodynamic

ln(TT+) parameters.

dielectric

monohalogenotoluenes,

equimolecular

at

associated

energy

parameters of

(3)

plot

parameters

show,

+

activation

slope

enthalpies

mixtures

the

have

characteristic

= lnAB

In

relaxation and

(a halogenotoluene

the

+ benzene)

K.

DISCUSSION

From a of

the

table

distribution

of

halogenotoluenes halogen

atom

molecular show

to

le

accused

the

observed

that

times

size in

of

the

PI . On

previously

oortho

configuration,

apparent

relaxation

with

that

studied

sequence

a more

clearly

Cole-Co

similar

the

it's

a variation

halogenobenzenes follows

1,

from

the

in

case

of

the

other

that

simple

the

substituent

hand,

according

< cx para' into account

taking

parameter

follows the

the

< ameta

deviation

the

to

the

CI the

paraisomers

relaxation

of

Debye. Macroscopic

relaxation

atomic

weight

of

out

Kwhaja

[6],

of

by

energy being

of the

a stronger the

hand,

the

show

for

interaction in

with

according

to

this

process the

times

variation, work.

The

the to

show

the

increasing the

and also

corresponds

to

trend

in

the

activation

the

metaderivates,

this

points

medium

or

to

spherical

model.

On

the

relaxation

moments

observed

dielectric

a higher

pointed

inertia

smallest

orthohalogenotoluenes;

with

relation

fluorotoluenes

increase

atom,

a linear in

relaxation

times

relaxation

which,

studied

greatest

cavity the

halogen

in

halogenobenzenes

halogenotoluenes

of

the

to

a strain

frequency

other than

1

‘I

0.092

18.19 25.64 35.76 35.70

p-bromotoluene

o-iodotoluene

m-iodotoluene

p-iodotoluene

*Average value

0.080

16.38

m-bromotoluene

in the studied

3.6328

2.4307

3.1477

2.5581

range of temperature

0.170

0.118

0.046

1.8609

2.3654

2.4254

0.037

13.40

o-bromotoluene

2.0337

2.0889

0.056

14.46

p-chlorotoluene

1.5270

1.5864

0.037

12.07

m-chlorotoluene

2.0184

1.8143

0.029

11.40

o-chlorotoluene

3.6107

2.2891

3.0889

1.2219

-2.7481

0.2788

-0.9847

2.4977

-0.8153

-2.3365

-3.3763

-2.5106

69.62

64.83

58.13

41.15

48.56

42.58

34.21

44.50

34.93

27.75

23.00

-2.1984

K-l

31.34

-1

HE x=0.5 x lo -1 Kcal mol

enthalpies,

-3.8132

-3.9690

Kcal mol

-3.0897

-1

As x lo3

excess

1.8028

1.7310

1.7915

0.055

9.38

p-fluorotoluene

1.0570

6.93

m-fluorotoluene

1.1198

4.10

o-fluorotoluene 0.040

Kcal mol 0.6999

-1

B

0.7565

Kcal mol

W

for the halogenotoluenes,and

AHE

Results

at 303.15 K.

0.032

+ benzene)

(ps)

of (a halogenotoluene BE x=0.5'

Values of T, a, and Eyring and Bauer Analysis

TABLE

3

216

I

I

I

1.0

Figure

3. Relation

between

and the activation

obtained

from Eyring

the this

other

(Vl, and Bauer

fluorine

to

the excess molar E A increases x=0.5' atom in the polar

so,

and

absence

it

of

W,

fluoroderivatives;

(0) iododerivatives.

seems

reasonable

atomic

to

d orbitals

in

relate the

atom.

Halogenotoluene

group

(0) models.(o)

(0) bromoderivatives;

the

+ benzene

energy of the polar pure component,

halogenotoluenes,

bahaviour

I

4.0

HE x=o 5 for monohalogenotoluene

mixtures

(A) chloroderivatives;

I

2.0 -1 3*0 W/Kcal mol

and

with

the

atom

in

containing

mixtures

at

The the

are

endothermic,

equimolecular

size

molecule,

halogen

mixtures

+ benzene

enthalpies

of

the

substituent

relative

aromatic

metaisomers

and

composition, halogen

position ri,ng is

show

of

methyl

important,

a greater

value

and of

BE than those containing orthoor parahalogenotoluenes. x=0.5 This behaviour could be attribued to the different inductive and atom

resonance in In

effects

meta

position,

figure

3,

halogenotoluene activation from

the

with

W,

excess

models

of of

the

that

molecular

in

the

Eyring

a greater

metahalogenotoluenes. accepting

as

+ benzene

energy

with

in

polar

molecule

contrasted molar

with

enthalpy

mixtures

is

polar

pure

and

Bauer.

intercept This

the

the

for

non

the

other

x=0.5

halogen isomers.

for

against

monothe

component, W, obtained E Hx,, 5 increases linearly

behaviour

of

at

plotted

mixtures

containing

could

explained

metahalogenotoluene

interactions

with the

polar

be

+ benzene character

mixtures and

basically

217 those

of

those

for

halogen

On Eyrinq only

atom

mixtures the

other

equation in

the

increases

aromatic-n

hand,

is

case

with

-

containing the

more

of

System

ortho-

mixtures

to

are

entropy

in

weaker

linear

from

errors,

metaisomers a

than

obtained

experimental

containing

entropy

type

paraderivatives.

activation

sensitive

increasing

or

the

H

and E x=0.5

form.

CONCLUSION

From could depends small

on

dielectric that

the

values

mechanism the

this

conclude

study

the

seems

the

relaxation

times

in

the

corresponding

of

the

molecular

of

of

not The

to

strongly

the this

affected

differences

point

the

only

for

observed

metafluorotoluenes

chloroderivatives on

account

molecules,

small

and

on

process

into

these be

very

ortho-

surrounding

halogenotoluenes

Taking

moments

interactions.

in

the

relaxation

radical.

dipole

relaxation

molecular

on

orientational

halogenate

of

of

the

to

dielectric

a

and

low

incidence

relaxation

mechanism. Moreover, for

the

orthoisomers,

possible

existence

determined atom.

by

Meta-

energies

of

the

and

Waals

values for

of

of

to

a

methyl

distances

for

group

show

stronger

favours

relaxation

mechanism

both

parahaloqenotoluenes

which

the

the

dipole-dipole

suggest

the

of

relaxation

and

fluorine

highest

interaction

a plane-parallel

which

frequency

orthofluorotoluene,

a complementary

rotation

corresponding

surroundings, der

highest

specially

activation

with

the

structure

at

interactions

Van are

weak. The

calorimetric

benzene

mixtures

opposit

effect

aromatic ixtures group

will

and be,

atom-

enthalpies the

group

the

on

toluenes

due

its

the

the

the

endothermic

different

and

this

these

inductive to

methyl

than

sequence

containing

are

the the

intermolecular

Mixtures

ring.

on

of

important

position

aromatic

+

account

group

relative

the

most

into

methyl

the

more

Moreover,

to

halogenotoluene

character

to

effects, ones.

and

and

endothermic

related

atom

the

taking

atom

principle,

IT-system be

of

explained,

the

system

will

halogen

be

halogen

so,

in

-aromatic-n

halogen

of

could of

ring,

behaviour

the

the

of character methyl

metahalogeno-

behaviour

could

be

218

attributed the

to

a stronger

methyl

metahalogenotoluene

group

-n-system

+ benzene

mixtures.

J.

J.M.

effect

in

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M.J.

C.

Gutierrez

and

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Muiioz,

Fluid

Loss,

Phase

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I.

Equilibria,

VelaSCO.

20

(1985)

131. 2 F.J.

Arcega,

J.M.

Fornies-Marquina,

Rosa

and

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(1982)

1783. 3 c.

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Quim. 4 A.

de

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5 J.M.

Zaragoza,

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(1981)

1.

Adv.

Fis.-

101.

SOC., S.

de

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(1973)

F.J. p.

349,

387.

Arcega, Ed,

G.

Vicq

Universidad

(1985)

Khwaja,

Processes,

Gracia,

(1971)

Fornies-Marquina,

Algunas

6 H.A.

M.

Mol.

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Interaction

de