Relaxation phenomenon of water in aqueous solutions of organic substances

213

Journal of Mokccular Liquids, 45 (1990) 213-230 Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands

RELAXATION

PHENOMENON

OF WATER

1N AQUEOUS SOLUTIONS

OF ORGANIC

SUBSTANCES

GIANFRANCESCO

BERCHIESI.

Dipartimento

Scienze

(Received

di

GIOVANNI

Chimiche

18 September

VITAL1

and

MARCO DE ANGELIS

dell’Universith,

62032 Camerino

(Italy)

1989)

ABSTRACT

Ultrasonic in

menon ne.

The

water

relaxation

aqueous

mixtures

results

and

spectroscopy

confirm

are

treated

of

that as

throws

N-methyl an

light

piperazine

equilibrium

having

on

been

pheno-

(NMP)

and of p-dioxa... between two states of

exists

carrred

relaxation

out

previously

111.

INTRODUCTION

In

a previous

ted

aqueous

bed

to an

vated). of

ted

and

system

both are

ding

if

are

published components in

change

methods

the

micellar

N-methyl

is

to

ultrasonic structure

mixtures reported

0167-7322/90/$03.50

two

be

at

(A=amides,

nearly

to assume

micellar. observed

With in

NMMNO solutions p-dioxane,

the

this we

N-methyl

herewith.

0

1990 Elsevier Science Publishers B.V.

and

be

sol-

that

calculain

observed

high

ascri-

proper-

may

(as

the

was

volumetric

to believe

in

concentra-

bulk

mixtures

2 mole/kg that

(i.e.:

111 the

It is reasonable

considered

the

densrty

highly

(NMMNO)

water

water+NMMNO

relaxation of

of

of

occurs and

states

of

the

in

N-oxide

values

Fig. 1.

Ill)

relaxation

morpholtn

involving

reported

solution

A+water sults

the

a phase

the

the

the

111, ultrasonic

of

equilibrium

ultrasonic ge

solutions

From

ties

paper

this

also

by

concentration aim

system decided piperazine)

of is

ran-

understanconnected

to study and

to

other the

re-

214

m3 mole-’ 100

m3mole-’ 100

d 10'Kg mS3 1.3 1.2 1.1 1.0

0 Fig. top le,

1.

Volumetric

: apparent and

10

of

molar

water

(*I,

properties

of

volume;

partial

right

30 m/mdeKg-’

20

scale;

the

NMMNO solutions molar

density.

volume

of

at

lOT,

from

NMMNO (01,

left

the sca-

215 RESULTS

The 12-41,

ultrasonic

density

PAAR

experimental

and

(Austria)

viscosity

vibrating

methods

are

measurements capillary

reported

were

densimeter

in

carried and

previous out

by

capillary

papers

means

of

rheometer

respectively.

p-Dioxane

The Fig.2.

volumetric

The

rection.

The

-30

does

not

show

The

trasonic table

of

of

as The

the

a dependence

of

( Crfe2)

tion

as

previously

equation

(crf

where

-2

A is

2

trend,

show

absorption

the

shows

in

from

that

mixtures

of

table

in

dioxane

the

same

di-

a maximum

pure

p-dioxane

frequency

the

density

range, and

ul-

== ( cYf-2) classic’ exp with the experimental

water

frequency, and

shown

( CYfe2)

together

12.71,

of

investigated

given

on the

given

1 = A/(l+(f/fr)

the

contrary

indicated

151 are

of

this

is

increasing in

in

is

the

increases

151 calculated

viscosity

GI

with

ultrasonic

viscosity

mixture

dioxane

a result

absorption

volume

of

phenomena

161 and

p-dioxane-water

decreases

volume

dioxane.

classical

the

water

values,

relaxation

1 the

of

molar

employed.

treated

tion

the

velocity

values bit

volume

density

mole/kg

FIgiS.

In

molar

whereas

molality,

at

behaviour

and

Fig.4. the

p-dioxane

The

exhi-

curves

were

of

relaxa-

parameters

the

2:

1 + B

amplitude,

B the

classical

absorption

and

fr

the

relaxa-

frequency.

N-methyl

Piperazine

The

volumetric

volume

of

ximum

and

scosity,

H 0 and 2

(NMP

behaviour NMP as

a minimum

Fig.6,

and

1

is

presented

a function

respectively.

viscoelastic

of

in

A plot

m exhibits

Moreover behaviour,

Fig.5.

the Fig.7,

of

a trend mixtures in

the

with exhibit

a wide

molar a mahigh

concentration

vi-

216

m3 mole-’ 85

-c

80

lOGILI m3 mole-’ 85

- 18 80

d lo3 Kg n-i3 1.05

1.00

6

-

0

Fig.

2.

the

top:

left

scale,

50

Volumetric apparent and

of

properties

of

molar

volume;

water

(x1

right

m/mole

the

p-dioxane

partial scale;

molar

Kg-’

100

solutions volume

density.

of

at

lOT,

p-dioxane

from to),

range. ves

Mixtures

and

curves

showed are

the

other

ried

out

1)

versus

and

ultrasonic. the

wq/G_

of

The

two

from

relaxation of

K”

and

R values)

is

with Fig.8.

The

processes

the

longitudinal

two

one

wa-

relaxation

viscoelastic

processes

has

and

been

car-

ways:

absorption

from

,and

two

examined

phenomena,

separation

following

(calculated

NMP were

relaxation

comprehensive

in

G”

water

extended

calculated

M”,

with

of

ultrasonic

in

calculated.

velocity,

a M”/G,

or

is

G”/G,

The

dependence

the

classical

of

compared

reduced K”

plot

on o

gives

K2

and r, 2)

The

ultrasonic

losses

( 01f-2-B 1-l versus intercept The

allow

values

f2

higher

( w h ere

than B stands

us to calculate

obtained

are

for

classical

A (consequently

reported

in

ones

table

are

plotted

as

Slope

and

losses).

K2)

and

fr.

3.

Amides

Mixtures in

a wide excess

rich

in 4,

water

with

concentration

only

table

of

sound

acetamide

range.

absorption

amide

show

the

deduced

high

or

propionamide

Relaxation

phenomena

was

dispersion

volume

Fig.9.

observed, principally

viscosity

is

were

also

were

not

Moreover

at

low

studied evident,

the

mixtures

temperatures.

In

given.

DISCUSSION

In red

the

in

previous

the

measurable

of

NMMNO (m z-101.

be

ascribed

with the

to the

different

mole/kg, increasing shows

of

a volumic as

In

order

invoked

of

previously

v 2 increasing

and

only

to confirm mechanism

dioxane view:

m and

if

and

frequency at

the

very

1,

NMP present

111, for

high

studied

2 and

NMMNO mixtures out

of

relaxation

111, we

Figures

pointed of

relaxation

range

behaviour.

NMMNO, point

functions

111 the

frequency

volumic

solutions

from

paper

change

v

is a decreasing 1 51 decreasing with m;

as

appea-

molality

values

observed other

is

to

mixtures

5 clearly very

m >2

water

show

different

behaviour

structure

mole/kg

0,

function

of

that

at and m;

a consequence,

m -2 d are

dioxane d exhi-

218

100 80 120Ip -4

I

, I

7

Fig.

3.

Ultrasonic

a/f2

1

losses

of

pure

p-dioxane

at

*

8

log(f/Hz)

lg.g”C.

,o-f5s2 m-i

120 100 -

:

80 60 -

7 Fig.

4.

Ultrasonic

the frequency: (01 -1 and T=5.4”C. kg

8 losses m=102.44

of

the mole

p-diotane -1 and kg

sdutims T=20.2“C;

log (f/Hz) as (x)

a function

of

m=31.97

mole

219 bits

a maximaa versus

m.

NMF’ values

with

m.

in

dioxane

wer

than

ter

is

It

means in

NMP or

very

m >f+

for

beyond

it.

For

In

of

for

C~8.75

centration,

for

centration.

The

in

dm mole

concentration to 30.5

the

water-NMP

solutions1

range.

concentration

as

in

the

of

dependence

plot).

occurs

between

mum in

the

is

bulk

water

predominates.

In

for

some

on T is In

not

is dm

dioxane

increasing

or

Fig.10

mole

increasing

dm -3

in

-3

as

.

con-

water

(expressed

con-

molali-

corresponding

to the

on temperature

fact

The

same

it

occurs

of

relaxation

feature

concentration

connected,

for

density. separates

words,

the

the

evident

/kg

(nearly

the

to the

position

of

the

concentration one

results

here

a change

reason,

The

and

measu-

density/molaiity

this

two

the

frequency

which

mole

in

(concer-

in

is

at

is -12

maximum

predominates

other

fr

CC 8.75

with

mole

, that

plot

structure

with

dependence

different

density/composition

(at

temperature

or

frequency

-3

wa-

Fig.2.

to the

of

investigated

composition

the

dm

lo-

range

extrapolation.

increases

The

relaxation

the

C ~-8.75

shown.

6 mole

structures

in

correct,

dioxane.

corresponds

observed

librium

structure

is

of

the

Fig.11

bulk

occurs,

dependence

relaxation

NMP is

with

which

The

where

of

mixtures

composition

In

much

0.186

the

plot,

is

and

frequency

8.75

is

density/molality

frequency

fr

0.138

mixtures

increases -‘3

mole/kg)

the

0.026,

and

measurable

for

value

the

solvated

is

our

lowest

f

dm

of

on the

where

are

equimaxi-

zones:

bulk

solute

consistent

with

model:

A

where

each

mole

the

-3

of

water

markdly

NMP respectively.

error

evident

dependence

rable

the

the

The ning

the

of

are

CC 8.75

corresponds

maximum

sometimes

on C for

fr

is

of

and d change with

dioxane-water

limit

reason

: two dependences

fact

one

upper

a consequence

dependence

shown

ty

this

structure

NMMNO and of

VI

interaction

Av,/Am

frequency the

the

fact

dioxane,

in

as

correct, the

In

relaxation

concentrations,

the

NMMNO and

different.

mole/kg) The

that

of v2 and

bulk

+A

A stands

substance) species

-A

free

for this

and

solv

solvent

or

equilibrium

the

limit

of

+A

solute. exists this

(2)

free

The in

range

problem a wide is

is

that

(according

concentration

indicated

by

the

range maximum

to for in

220

locQv ’ ma mole4

1O‘Vi n+mole-’

- 15

93

d 10')Kgt-6' 1.02 1.01

0.99

10

D Fig.

5.

Volumetric

apparent

molar

of

(x1,

water

properties

volume; right

30

20

partial

scale;

of

the

molar

density.

m/inole Kg-'

NMP solutions volume

of

NMP

at

lOT, (01,

from left

the

scale,

top and

221

the densit y/co

nposit ion plot.

as an assembly

of molecules

1 and 2 may be arranged be considered

Fig.12

in the relaxation volume

in the density/molality

plot.

an increasing

frequency

thod employed

previously

at 5.2OC:

solutions

gives

Also in the plot

to the composition

Treating

the data

(those

concentration)

the following

108(s mole)-‘dm3,

water-dioxane.

of the maximum

of Fig.10

water

data

n=0.2.

Analogous

of r] v on

showing

with the mefor dioxane The n value

calculation

on NMP

= 3.8 107(s mole)-‘dm3 and n=3.8 at -10°C. 12+k21 the n value highlights high solvent-solute interaction.

to the fact

that

show micelle

In

k

The relaxation

highly

species.

involved

show the hi-

where the dependence

11I, we obtain

a low interaction

case

and bulk

similar

k12+k2L = 1.1

of the process

for NMP and NMMNO which

with increasing

indicates

this

that the energy

the composition

is strongly

v

mean value.

of solvated

Fig.13,

changes

mixtures

in structures

demonstrates

difference

must not be considered

or 5 2. But both components 1 of different volume, and vi must

of volumes

is much higher

vv/composition, molality

all

as the resultant

Moreover

ghest

That is the mixture

seems to be present it appears

formation.

interacting

in dioxane

The amplitude

systems

not only

in micellar

mixtures

where our data

of the phenomenon

(NMMNO, NMP) where n is very

systems

is very

owing

do not high

in

high.

TABLE 1 Ultrasonic

velocity,

absorption

of p-dioxane -1

density,

shear

and volume

viscosity

and classic

mixtures

-3 m

T/Y

U/m s

11.7

1404.0

1.04295

0.0014

13.0

0.0136

19.9

1369.7

1.03367

0.0012

12.0

0.0131

29.8

1327.7

1.02247

0.0009

10.9

0.0125

d/103kg

q,/Pa

s

(cYf-2)/10-15s2m1 TV/Pa s

222 TABLE Density,

T/Y

2 viscosity

rls/Pa

and

s

ultrasonic

d/103kg

properties

-3 m

of

U/m

mdlox/mole

s

dioxane

-1

fr/MHz

solutions

17,/Pa

s

~,/?j,

kg-l=102.44

5.4

0.0020

1.05281

1492.5

>300

0.0145

7.25

10.3

0.0018

1.04767

1474.3

>300

0.0127

7.06

20.2

0.0015

1.03728

1437.5

w300

0.0116

7.91

25.3

0.0013

>300

0.0109

8.21

1.03193

1418.6 mdiox/mole

kg-l=53.83

5.4

0.0027

1.05419

1533.5

270

0.0169

6.40

10.3

0.0023

1.04959

1517.7

260

0.0159

6.90

20.2

0.0018

1.04019

1485.4

229

0.0127

7.20

25.3

0.0016

1.03559

1469.6

0.0106

6.80

mdiox/mole

>300

kg-‘=31.97

5.4

0.0029

1.05409

1571.6

192

0.0187

6.60

10.3

0.0025

1.04963

1553.2

212

0.0160

6.40

20.2

0.0020

1.04105

1517.7

251

0.0113

5.70

25.3

0.0018

1.03650

1498.9

0.0085

4.80

mdiox/mole

>300

kg-l=30.58

5.4

0.0028

1.05432

1548.7

246

0.0175

6.30

10.5

0.0024

1.04973

1533.1

250

0.0145

6.00

277

0.0159

4.80

mdiox/mole

kg-l=25.19

5.4

0.0033

1.05344

1584.3

10.3

0.0028

1.04929

1570.8

w300

0.0144

5.20

20.2

0.0020

1.04091

1543.6

>300

0.0103

5.20

25.1

0.0017

1.03659

1529.5

>300

0.0097

5.70

mdiox/mole

kg-l=21.57

5.4

0.0031

1.05029

1605.1

=-300

0.0150

4.80

10.3

0.0027

1.04640

1594.4

-

0.0110

4.10

20.2

0.0020

1.03877

1573.5

-

0.0086

4.30

25.1

0.0017

1.03480

-

0.0073

4.30

1562.6

223

Fig

0.07

-

0.05

-

0.03

-

6.

Viscosity

of

I

I

10

20

the NW

solutions

at

* Kg-’

m/mole

15.3”C.

d R-’ (G Fai

+I

I

’

-20

-40 Fig. versus

7.

dR -2 T.

*

concerning

the

T/X 20.26

mole kg_lNMP

solution

at

121.3 MHz

224

TABLE

3

Relaxation

T’C

0.0

-

9.8

parameters

of

solutions

mNMF/mole

kg-’

K2/N

m-*

f/MHz

U/m

3.75

loa

a7

1746.0

1000.60

3.28

10’

1780.2

1008.50

26.04

5.21

26.04

of

10’

5.37 -20.0 0.0

-

9.8

-20.0

0.0

-

9.8

-20.0

-

Piperazin

-1

d/kg

76* 33

loa

s

34’

26.04

5.78

10’

13

1815.8

1016.80

20.26

3.85

10’

a2

1831.8

1011.05

3.71

loa

7a*

5.82

10’

25

1876.8

1018.30

5.53

loa

30”

6.67

10’

11

1921.3

1025.48

6.67

10’

10”

2.94

loa

54

1817.2

1016.97

3.02

10’

5a*

4.67

10’

27

1854.2

1025.82

4.46

10’

26*

6.14

10’

10

1891 .g

1034.85

6.47

10’

9*

20.26

20.26

18.88

18.88

18.88

0.0

13.21

3.86

10’

So*

1856.7

1027.78

9.8

13.21

6.83

10’

23”

1890.1

1036.30 1044.64

13.21

9.60

10’

9*

1922.9

0.0

9.69

3.63

10’

93*

1903.1

1032.24

9.8

9.69

5.49

loa

56*

1939.1

1040.65

9.69

8.30

10’

25*

1975.0

1049.07

-20.0

-

N-methyl

-20.0

* Values

calculated

following

the

second

method

-3 m

225

--

II

7 Fig. a,

8.

Ultrasonic

classical

8

losses

of

the

20.26

log (f/Hz)

mole

kg

-1

NMP solution

at

-9.8”C,

losses.

a/f2 ,o-15szm-l 100 0

0

0

0”

0 0

50

x.

a

x

x

x

b

Fig.

9.

-4.6

OC (0)

“C and

Ultrasonic

20.2T

and

20.2

losses ‘C

respectively.

of (xl;

the

9.99

a and

mole b are

kg-’ the

acetamide classical

solution losses

at

at -4.6

226 L f, /MHZ

300

-

200

-

100 -

/ -%

8

7

9

m

10

C

mole drn-j Fig. 10. function

Relaxation

frequency

of the molarity,

measured

in p-dioxane

soIutions

as a

at 5.4”C.

f,/MHz

c

5

6

7

8

C

mole dm-” Fig.

11.

(01,

-9.8”C

Relaxation (XI.

-2OT

frequency 1.1.

as a function

of NMP molarity

at O°C

TABLE 4 Shear

and volume

solutions

of acetamide

m/mole

T/“C

density

viscosity,

kg -’

(a)

and ultrasonic

and propionamlde

rjs/Pa

s

d/kg

velocity

in aqueous

(b)

-3 m

U/m s

-1

rl,/Pa

s rl,/rl,

a 20.2

9.99

0.2 -5.0 20.2

20.04

0.2 -5.0 0.2

26.42

-4.0 0.2

32.11

-4.0

0.0020

1024.22

1648.6

0.0036

1.8

0.0038

1035.74

1651.6

0.0082

2.1

0.0045

1038.50

1651.6

0.0136

3.6

0.0037

1035.40

1678.1

0.0051

1.4

0.0058

1047.74

1706.8

0.0157

2.7

0.0067

1051.44

1715.5

0.0204

3.0

0.0082

1052.27

1714.3

0.0162

2.1

0.0097

1055.09

1721.4

0.0208

2.1

0.0102

1054.61

1713.5

0.0187

1.8

0.0127

1058.10

1722.3

0.0273

2.1

b 20.1

16.24

0.0028

1015.92

1687.2

0.0113

4.0

20.1

26.34

0.0052

1015.05

1663.1

0.0127

2.4

20.1

31.94

0.0054

1014.36

1654.3

0.0127

2.4

CAPTIONS 01 Ultrasonic Amplitude

absorption

coefficient

of the ultrasonic

losses

(mole dmv3)

Density rlS Shear viscosity viscosity

Frequency

fr Relaxation

frequency

Apparent

molar

G” Imaginary

losses

Concentration

f

%

G

Classical

rl,Volume

I

Elastic

volume

elastic

modulus

modulus at infinite

frequency K” Imaginary

compressional

modulus

Relaxation K2 m molality

compressional

modulus

M" Imaginary

longitudinal

n

solvation

w

angular

number velocity

modulus

228

3 -

10' -

loo -

10-l 1o-2

0 i,yp,,

-4

Fig.

12.

3.3

3.4

Volume viscosity

NMP solutions

3.5

:

l

NMMNOsolutions

: *

p-Dioxane

: o

Acetamide

:0

Propionamide

: A

Real part

the reciprocal -1 9.69 mole kg -1 26.04 mole kg -1 26.56 mole kg -1 25.19 mole kg -1 26.42 mole kg -1 26.34 mole kg

of the mechanical

impedance T

Temperature

r

Relaxation

3.8

3.7

versus

: x

R

3.6

U

VI Partial

time

103K/T

temperature:

Ultrasonic

i-th

3.9

velocity

molar

component

volume

of the

229

0.8

0.6 30

m/mole

Kg-’

w

50

Fig.

13.

Volume

viscosity

l

NMP at

OT,

0

NMP at

-2O”C,

left

o

Dioxane

at

5.4”C

x

Dioxane

at

25.3”C

100

as a function

of the

m/mole

Kg-’

molality:

scale

right

scale

REFERENCES

1

G.Berchiesi,

2

L.Amici.

J.Molecular P.Passamonti,

Liquids, G.Vitali,

38 (1988) G.Berchiesi,

73 G.Gioia

Lobbia,

Adv.

230 Molecular 3

G.Berchiesi, Liquids,

4

Relax.

A.Amico, 33

G.Berchiesi,

(1987)

79 (1983)

5

A.J.Matheson,

6

G.Vitali, 109 (1979) G.Berchiesi,

( 1984 1 3665

(1982)

213

L.Amici,

P.Litargini,

J-Molecular

157 P.Passamonti,

R.Plowiec,

J.Chem.Soc.Faraday

1257

Molecular

G.Berchiesi,

23

G.Vitali,

G.Vitali,

frans.11,

7

IntProcesses,

Acoustics, M.A.Berchiesi.

J.Wiley,

London

V.Valenti,

(1971)

9

Gazz.Chim.

(Rome),

291 M.A.Berchiesi,

C-La

Mesa,

B.Sesta,

J.Phys.Chem.

88