C H A P T E R - III

GRAVIMETRIC DETERMINATION AND SEPARATION OF COPPER(II)

AND NICKEL(II) USING N-HYDROXY-N-(0-CHLORO)PHENYL-N'

(3-METHYL) PHENYL p-TOLUAMIDINE HYDROCHLORIDE

CHAPTER - I II

GRAVIMETRIC DETERMINATION AND SEPARATION OF COPPER(II)

AND NICKEL(II) USING N-HYDROXY-N-(0-CHLORO)PHENYL-N'

(3-METHYL)PHENYL-p-TOLUAMIDINE HYDROCHLORIDE.

SUMMARY

A newly synthesised Hydroxyamidine N-Hydroxy­

N-(0-chloro)phenyl N'-(3-Methyl)phenyl-p-toluamidine

hydrochloride has been employed for gravimetric deter­

mination of copper(!!) and Nickel(II) and their

separation in binary mixture. The reagent reacts with

copper(II) giving a buff coloured precipitate in the

pH range 1. 8 - 11.3 but the reaction is quantitative

in the pH range 3.0 to 10.5 only. This reagent preci­

pitates Nickel(II) ion in the pH range 7.5 - 10.5 and

the reaction is quantitative. On this basis new methods

have been developed for gravimetric determinations of

copper(II) and nickel(II) and their separation in binary

mixture. Copper was precipitated first at pH 3.0 + 0.5

from the solution using HCPMPTH. The buff coloured

precipitate was dried at 110 - 120° and weighed as

(c21H1

aN 20C1) 2cu. The conversion factor of copper/

copper complex is Q.0833. The filtrate of the copper

estimation containing Nickel(!!) was concentrated and

59

pH was adjusted to 7.5 ~ 0.5 using dilute ammonia solu­

tion. Yellow Nickel-HCPMPTH complex was precipitated.

It was dried and weighed as (c21H18N20C1) 2Ni. The

conversion factor Nickel/Nickel complex is 0.07747.

Iron interferes in the determination and was masked

with Tartaric acid. The solid coaplexes have been

characterised on the basis of m.p., elemental analysis

and I.R. spectra. Thermal and magnetic properties of

copper complex have been studied.

DTA and TGA studies suggest that Copper-HCP~~H

complex is stable upto 210°C. Paramagnetic nature of

the complex is confirmed from magnetic measurements.

60

introduction:

Copper(!!) ions form buff, insoluble precipitate

with N-Hydroxy-N-(o-chloro)phenyl N'-(3-Methyl)phenyl­

p-toluamidine hydrochloride 1n the pH range 1.8 - 11.3

but the reaction is quantitative in the pH range

3.0 - 10.5 only. The precipitate has the composition

(C2 1H1aN 20Cl) 2cu, It is insoluble in alcohol, chloroform,

carbontetrachloride and many organic solvents.

Cu(II)-HCPMPTH has a constant weight between 70 - 210°

and its composition is strictly that expressed by the

formula. When heated organic material decomposes at

370- 480° and above 540°, Copper(!!) oxide remains.

The precipitate can be weighed after drying at 105-110°,

The greatest advantage of the method is that it achieves

a fairly good separation from a number of ions. After

precipitation of Copper(II)-HCPMPTH complex, Nickel(II)

can be determined in the filterate by its precipitation

with the reagent (HC?MPTH) at PH 7.5 - 10,5. The yeliow

Nicke-HCPMPTH complex is stable at 202° and has the

stoichiometry 1 : 2, The complex having the composition

(c21H1

aN20Cl) 2Ni can be weighed directly after drying

at 100-110°. The conversion factor Ni/Nickel complex is

very small {0.07747). This makes possible the determi­

nation of small amount of Nickel(II) ion.

61

62

A comparative account of

other . 2-54 well known methods for

the proposed method with

gravimetric determination

of Copper(!!) suggest that method is superior both in

selectivity as well as sensitivity. The method has been

successfully applied for the determination of copper

content in alloys.

The complexes have been characterised on the

basis of m.p., elemental analysis and I.R. spectra.

Thermogravimetric and Differential thermal analysis

of Copper-HCP~~H complex were carried out to evaluate

the thermal stability of the complex. No weight loss is

observed upto 210° which indicates that complex is non-

hydrated in nature. Paramagnetic nature of the complex

was confirmed by magnetic measurements.

EXPERIMENTAL:

Apparatus: A single pan semimicro balance DONA CR-X

(maximum load 200 g, sensitivity 0.01 mg) was used for

weighing purposes. The pH of the solution was measured

with a systronic pH meter type 321,

Chemicals: All the chemicals used were of A.R. grade.

A stock solution of copper(!!) was prepared by

dissolving BDH Analar copper metal in dilute nitric acid

and the solution was boiled to expel oxides of nitrogen,

This solution was standardised gravimetrically using

Salicyladoxime1 and volumetrically by iodometric method 1 •

BDH Analar ammonium nickel-sulphate was dissolved

in double distilled water to get stock solution of

Nickel(I1). It was standardised gravimetrically using

dimethyl glyoxime1 •

A 1% (w/v) solution of HCPMPTH in alcohol was

used for precipitation purpose.

Recommended Procedure:

Respective metal ion solution containing 10,0 to

15.0 mg of the metal was diluted to 100 ml with distilled

water and the pH was adjusted in between 3.0 to 5.0 by

adding acetic acid in case of copper and 7.5 to 10.0 by

dilute ammonia solution in case of Nickel. The solution

63

was heated at 40-60°. Then added 1~ (w/v) solution o!

reagent in alcohol with constant stirring, A buff

coloured precipitate of Copper-HCPMPTH complex was

precipitated. In case of Nickel yellow precipitate of

Nickel-HCPMPTH complex was obtained, The solid mass was

digested on water bath at 60-70° for 30 minutes. The

precipitate was filtered in a G-4 sintered crucible,

washed repeatedly with distilled water and 40% alcohol.

The precipitate was dried at 110-120° and weighed as

M(C21H1aN20Cl)2'

Properties of Copper and Nickel complexes with HCPMPTH:

Copper complex is precipitated instantaneously

when reagent solution is added to cupric ion in the pH

range 3.0 to 10.5. The complex is heavy, buff coloured

and readily filterable. It is insoluble in water and

many organic solvents like ethanol, chloroform, carbon­

tetrachloride, etc. The complex is thermally stable

upto 210°. The results of elemental analysis are given

in Table 3.1. The TGA and DTA curves are shown in

Fig. 3.1 and 3.2 and l.R. spectra in Fig. 3.3.

Table - 3.1

ELEMENTAL ANALYSIS OF COPPER(II) CO~lfl.J!;X

------------------------------------------------------Element Calculated for Found

------------------------------------------------------c H

N

Cu

66.09

4, 72

7.34

8.33

66.23

4. 78

7.40

8.29

------------------------------------------------------Nickel-HCPMP'l'H complex is heavy yellow coloured

and is readily filterable. The reaction is quantitative

in the pH range 7.~ - 10.5. The yellow complex is

insoluble in water, alcohol, carbontetrachloride,

chloroform and many other organic solvents, The m,p, 0 of the complex is 202 C. 'l'he results of elemental

analysis are given in Table 3,2,

65

Table - 3.2

~Lt.MENTAL ANALYSIS OF Ni(II) COMPLEX WITH HCPMPTH

------------------------------------------------------l!:lement Calculated for

(C21H 1aN20Cl) 2Ni Found

------------------------------------------------------c

H

N

Ni

66.51

4. 75

7.39

7.615

66.58

4.79

7.28

7.58

------------------------------------------------------

OPTIMUM EXPERIMENTAL CONDITIONS

Influence of pH:

The precipitation of copper complex commenced

at pH 1.8 but it was quantitative at pH 3.0- 10.5.

For solutions containing pure copper ion any value

from 3.0 to 10.5 can be employed. Acetic acid, dilute

ammonia and ammonium acetate were used for adjustment

of pH of the solution 3.0 - 5.0 pH range is

recomrnended,as selective precipitation of copper

complex.

66

Table - 3.3

Determination of copper at different pH

Copper taken 15.276 mg

------------------------------------------------------Weight of

copper complex mg

Copper found

mg

Error %

------------------------------------------------------I II III IV ------------------------------------------------------1. 8 122. 18 10. 178 - 33.37

2.0 152.05 12,660 - 17.12

2.5 162.81 13.560 - 11,23

2,8 178.64 14,880 - 2.59

3.0 183.30 15.270 - 0.039

3.5 183.34 15.272 - 0,026

4.0 183.40 15,2 77 + 0.006

4.5 183.38 15.275 - 0,003

5.0 183.30 15.270 - 0.039

6.0 183.42 15.279 + 0.019

7.0 183.40 15.277 + 0.006

8.0 183.42 15.2 79 + 0.019

------------------------------------------------------

6i

68

Table - 3.3 (contd)

------------------------------------------------------I II III IV

------------------------------------------------------9.0 183.52 15.287 + 0.072

10.0 183.40 15.277 + 0.006

10.2 183.40 15.277 + o.oo6

10.5 183.44 15.280 + 0.029

11.0 178.34 14.855 - 2. 755

11.5 158.94 13.239 -13.33

------------------------------------------------------

Nickel complex was precipitated instantaneously

at pH 6,8 but it was quantitative in the ~ range

7.2 - 10.5. Dilute ammonia was used for the adjustment

of the pH of the solution. The results of the gravi­

metric determination of copper(II) and nickel(II) at

different pH are shown in Table 3.3 and Table 3.4,

respectively.

Amount of reagent: To study the effect of amount of

reagent on gravimetric determination of copper and

nickel, varying amounts of reagent solution were added

to 15.276 mg of copper(II) and 15,0 mg of Nickel(II)

ions after adjusting the pH of the solution to required

value. The final volume of the solution was made to

100 ml. It was found that 15 mg of reagent per mg of

Copper/Nickel was sufficient for complete precipita-

tion. In practice for 15 mg copper or nickel, 25 ml

of 1% (w/v) reagent solution in alcohol was used, An

excess of reagent could easily be washed with 40~

alcohol, therefore it caused no adverse effect in the

determination of copper(II) and nickel(II),

Digestion: The digestion of the precipitated complex

was done on boiling water bath for about 20 min. This

time was sufficient to increase the particle size suit­

able for filteration. A prolonged digestion of one

hour was found to have no adverse effect on the

determination.

69

Table - 3.4

Determination of Nickel at different PH

Nickel taken - 15.0 mg

------------------------------------------------------Weight of Nickel found

mg

Nickel found

mg

Error "

------------------------------------------------------I II III IV

------------------------------------------------------6.2 115.94 8.978 - 40.1466

6.5 120.34 9. 3227 - 37.24

6,8 183.90 14.246 - 5.026

7.0 190.90 14.789 - 1.406

7.2 194.56 15.07 + 0.466

7.3 193.70 15.005 o.oo

7.5 193.58 14.996 - 0.023

7.8 193.60 14.998 - 0.013

8.0 193.70 15.005 + 0.033

9.0 193.82 15.0152 + 0.100

------------------------------------------------------

70

Table - 3.4 (contd)

------------------------------------------------------I II III IV

------------------------------------------------------10.0 193.70 15.005 + 0.033

10. 1 193.50 14.998 - 0.013

10.2 193.20 14.967 - 0.221

10.3 193.25 14.981 - 0.126

10.5 193.30 14.969 - 0.246

10.8 172.060 13.329 - 11.14

11.0 160.420 12.423 - 17.18

------------------------------------------------------

Filteration and Washing: Filteration was done imme-

diately after digestion as hot filteration saves time

and reduces number of washings given to the precipitate.

The precipitate was washed with 40~ hot aqueous

alcohol till the washings did not give blue colour with

ferric chloride solution confirming the absence o!

reagent.

Drying the precipitate: The precipitate can be dried

to constand weight at 110-180° without decomposition.

The m.p. of copper complex is 210° and that of Nickel­

HCPMPTH complex is 202°.

Quantitative determination using varying

amounts of copper and nickel were made following the

procedure described above. The results are summarised

in Table 3.5 and Table 3.6. The results show that as

little as 1.75 mg copper and 3.0 mg nickel can be

determined with fair accuracy.

Accuracy and Precision:

Precise and accurate results are obtained in

the determination of copper and nickel using the proposed

method. The standard deviation for ten independent -4 determination with 15.276 mg copper is 7.85x10 while

relative standard deviation is 5.139x10-3 per cent.

For 15.0 mg of pure nickel solution these values are

6.12x1o- 3 and 4.083x10-2 per cent respectively

(Table '.7 and 3.8).

72

73

Table - 3.5

Determination of Copper

I*!= 3.5.:!: 0.1

------------------------------------------------------Copper taken Weight of Copper Error " mg copper complex found

obtained ------------------------------------------------------0.9016 10.3200 0.8596 - 4.66

1. 7524 21.0042 1. 7496 - 0.1597

2,2032 26.4492 2.2032 o.ooo

2. 7048 32.4700 2. 7047 o.ooo

3.6064 43.3002 3.6069 ... 0.013

4.508 54.1204 4. 5082 o.ooo

6.2604 75.1604 6.2608 ... 0.006

6. 7620 81.1808 6. 7624 + 0.0059

9.016 108.2410 9.0164 + 0.004

15.2 76 183.385 15.2759 0.000

------------------------------------------------------

Table - 3.6

Determination of Nickel

pH • 7.5 .± 0.1

------------------------------------------------------Nickel taken Weight of Nickel Error %

Nickel complex found

------------------------------------------------------1 • 5 13.68 1.059 - 29.4

3.0 38.62 2. 992 - 0.266

4.5 58,22 4.510 + o.266

6,0 77.50 6.004 + 0.067

7.5 96.74 7.4944 - 0.075

9.0 116.20 9.0020 + 0,022

10.5 135.62 10.5065 + 0.061

12.0 154.94 12.0032 + 0,026

13.5 174.34 13.5061 + 0,045

15.0 193.66 15.0028 + o.o186

16.5 212.92 16.4949 + 0.0309

18.0 232.40 18.0319 + 0.177

21.0 2 71.16 21.0067 + 0.0390

------------------------------------------------------

Table - 3. 7

Determination of Copper

Copper taken = 15.276 mg rH - 3.5 ..:!: 0.1

-------------------------------------------------------No. of determi­nations

Weight of copper complex

Copper found Standard Relative deviation standard

deviation

-------------------------------------------------------183.39 15.2760

183.38 15.2755

183.40 15.2772

183.38 15.2755

183.38 15.2755

10 183.40 15.2772 7.85x10 -4 5.139x10-3

183.39 15.2760

183.38 15.2755

183.40 15.2772

183.38 15,2 755

-------------------------------------------------------

75

Table - 3.8

Determination of Nickel

Nickel taken ~ 15.0 mg P-1 = 7.5.:!:,0.1

-------------------------------------------------------No. of weight of Nickel found determi- Nickel nations complex

Standard Relative deviation standard

deviation

-------------------------------------------------------193.60 14.9980

193.70 15.0000

193.52 14.990

193.66 15.000

193.60 14.998

10 193.82 15.0150 6 ,12x1o-3 4.083x10 -2

193.66 15.000

193.62 14.9990

193.66 15.0000

193.60 14.998

-------------------------------------------------------

76

DETERMINATION OF COPPER AND NICKEL IN PRESENCE OF

DIVERSE. IONS

Definite amount of copper was estimated in

presence of varying amounts of foreign ions at

pH 3.5 - 5.5. The pH of the solution was adjusted

after addition of foreign ion, Iron(III) interferes

in the determination of copper ion and was masked with

tartaric acid (2 g). It is evident from Table 3.9

that copper can be separated from almost all common

ions like Pb(II), Cr(III), Ni(II), Bi(III), etc.

thus the method is selective,

The resUlts of the estimation of Nickel(II)

in presence of various anions and cations are listed in

Table 3.10. The results suggest that the method suffers

from interference of many ions and needs preseparation.

77

Table - 3.9

Determination of copper in presence of Diverse Ions

Copper taken ~ 15.276 mg pH - 3.5 .± 0.1

-------------------------------------------------------Ion Amount of

diverse ion added

Weight of copper complex

Copper found

Error %

-------------------------------------------------------I II III IV v

-------------------------------------------------------* Fe (III) 25 183.40 15.277 + 0.006

* Fe (II) 25 183.42 15.279 + 0.019

Co (II) 100 183.30 15.270 - 0.039

Ni(II) 100 183.44 15.280 + 0.029

Cr(III) 100 183.30 15.270 - 0.039

Mn(II) 100 183.42 15.279 + 0.019

Zn(II) 150 183.40 15.277 + 0.006

Cd(II) 150 183.52 15.287 + 0.072

Mg(II) 100 183.40 15.277 + 0.006

Na 200 183.38 15.275 - 0.003

K 200 183.40 15.277 + 0.006

-------------------------------------------------------

78

79

Table - 3.9 ( contd)

-------------------------------------------------------I II III IV v

-------------------------------------------------------Vanadate 25 183.24 15.264 + 0.078

Phosphate 100 183.42 15.279 + 0.019

Chloride 200 183.30 15.270 - 0.039

Bromide 100 183.40 15.277 + 0.006

Nitrate 200 183.44 15,280 + 0.029

Citrate 2000 183.44 15.280 + 0,029

'l'artarate 3000 183.30 15.270 - 0.039

Sulphate 2000 183.38 15.2755 - 0,003

-------------------------------------------------------* In presence of tartaric acid.

so

Table - 3.10

Determination of Nickel in presence of Diverse Ions

+------------------------------------------------------Ion Amount of Weight of Nickel Error %

diverse ion Nickel found added complex

-------------------------------------------------------I II III IV v -------------------------------------------------------

* Fe (III) 25 193.92 15.020 + 0.133

Fe*(II) 25 193.82 15.015 + 0.100

Co (II) 25 193.70 15.005 + 0.033

Mn(II) 50 193.70 15.005 + 0.033

* Bi (III) 25 193.72 15.007 + 0.046

" Ti (1 V) 25 193.82 15.015 + 0.100

Zr( IV) 25 193.80 15.013 + 0,087

Al (III) 25 193.88 15.019 + 0.126

Na(I) 1000 193.70 15.005 + 0.033

K(I) 1000 193.70 15.005 + 0.033

Vanadate 10 193.60 14.998 + 0.013

-------------------------------------------------------

81

Table- 3.10 (contd)

-------------------------------------------------------I II III IV v

-------------------------------------------------------Molyboate interferes

Phosphate 25 193.88 15.019 + 0,126

Tartarate 3000 193.70 15.005 + 0.033

Sulphate 2000 193.72 15.007 + 0.046

Citrate 2000 193.82 15.015 + 0.100

Chloride 1000 193.78 15.012 + 0.080

*-------------------------------------------------------In presence of tartaric acid.

&2

SEPA.RAT fl,:~ A!'JD DETERMINATION OF COPPER (II) AND NICKEL (II)

Nickel ( li) was separated

N - Hydro~ - N - (O - Chloro)

from Copper (II) using 1

Phenyl N ( 3 - Methyl) Phenyl -

P - Tolyamidine hydrochloride.Copper (II) was precipitated first

at pH 3.0! 0.1 with the reagent HCPt-lPTH.

The mixture of the two ions was taken in a beaker and

diluted to 10) ml. The pH of the solution was adjusted

between 3.0 to 4.0 with acetic acid or dilute ammonia. It was

warmed to 60 - 65° C and two fold excess of the reagent was

added with constant stirring in hot state. The buff coloured

precipitate wc;s digested on a water bath at a temperature

70 - so 0 for about twenty minutes and then filtered through

a G - 4 Sinlered crucible of known weight. The complex was

washed with 4:'.' hot alcohol. Then it was dried at 110 - 120°

and weighed as ( c21

H18

N2

0 Cl >2

Cu. The conversion

factor Cu/Cop;>er complex is o. 0833.

Now the ~ilterate containing Nickel was evaporated to

about 100 ml. Its pH was adjusted to 7.5 = 0.2 with dilute

ammonia. The nickel was precipitated and determined as

described abovce. The results are given below 1

S3

DST<':R MIN AT ION ,\:JD 3SPARATION 0 F COPPSR AND NICKEL USING

HCP:1PTH AS A GRAVIM8TRIC REAGENT

-------------------------------------------------------

Metal Taken (mg)

Cu Ni

12.8 15.0

16.0 16.5

6.40 6,0

3. 84 3,0

Complex (mg)

Cu Ni

153.70 193.60

192.14 212,92

76.76 77,50

46,22 38.62

Metal Found (mg)

Error %

Cu Ni Cu Ni

12.8 14,99 o.o -0.13

16,0 16,49 o.o -0.06

6,39 6.004 -.0.15 + 0,006

3.85 2.69 + 0.26 -10.3

COMPARISON WITH OTHER REAGENTS

Several methods have been proposed for gravi­

metric determination of copper(!!) but all these suffer

from experimental limitations such as instability of the

complex, temperature conditioning, solubility of the

complex, etc.

Rubeanic acid2 •3 is one of the most sensitive

reagent known for the determination of copper(!!) but the

method lacks selectivity. Co, Zn, Ni and many other ions

interfere in the determination. Olive green to black

complex is precipitated in alkaline pH which can not be

directly weighed due to the presence of some of the

adhering impurities.

8-Hydroxy quinoline 4 ' 5 , Salicyldoxime6- 15,

-Benzoin oxime16- 22 , Quinaldinic acid23-26 , pyridine­

thiocyanate27, N-Benzoyl-phenyl hydroxylamine28 ,

3-Hydroxy-1,3 diphenyl triazine, etc. are used as preci-29-46 pitants but all lack selectivity •

N-Hydroxy-N-(o-chloro) phenyl N '-(3-M ethyl) phenyl­

p-toluamidine hydrochloride has been proposed as a highly

selective reagent for the gravimetric determination of

copper(II). The conversion factor copper/copper complex

is very small (0.0833) hence very small quantity of

copper upto 2,0 mg can be determined with the proposed

method, Copper-HCPMPTH complex is insoluble in alcohol

while reagent is freely soluble in it, Hence excess of

reagent can be easily removed by washing the complex with

alcohol. The greatest advantage of the method is that it

achieves fairly good separation from a number of ions.

After precipitation of Copper-HCPMPTH complex, Nickel(II)

can be determined in the filterate by its precipitation

with the reagent at pH 7.5 - 10.5. The yellow complex

having the composition (c21H18N20C1) 2 Ni can be weighed

directly after drying at 100-110°, The conversion factor

Nickel/Nickel complex is very small. This makes possible

the determination of very small amount of Nickel. Since

Nickel-HCPMPTH complex is precipitated in alkaline medium,

preseparation of copper(II), Mo(VI) is necessary. Fe(III)

can be masked with tartaric acid.

Some important forms of the determination of

copper and nickel47- 64 are given in Table 3.11 and Table

3.12. The discussion of the other reagents has been

deliberately avoided for the sake of brevity, The

proposed method does not suffer from many experimental

limitations such as solubility of the copper and nickel

complexes, instability of the reagent and the complexes,

temperature conditioning, etc. Hence the method is rapid

and precise for the separation and determination of copper

and nickel in binary mixture.

85

----------------------R

eag

en

t

TAB

LE -

3.1

1

FOR

MS

OF

GR

AV

IMETR

IC

DETER

MIN

ATIO

N

OF

(X)PPER

----------------------------------------

\ -----

I*!/ acid

ity

Weig

hitlg

form

C

On

versio

n

facto

r

-----------------------In

terfe

ren

ce

-----------------------------------------------------------------------------------------------I

II III

IV

v -----------------------------------------------------------------------------------------------8

-Hy

dro

xy

qu

ino

line 4

•5

Salic

yld

ox

ime 6

-1

5

16

-22

-B

en

zo

ino

xim

e

(Cu

pro

n)

Qu

inald

inic acid

23

-26

2.7

-14

,6

2.6

7.8

1.5

-6.9

(Crji6

0N

)2 cu

0.1

80

59

(Cfi602N

}2CU

0.18922

(C1

4H

11

02

N)2

Cu

0

.22

00

2

0.1

40

9

Mn,

Fe(II),

Fe(III)

Fe(II}

V

(V)

Pd

(II), A

u(IIIj,

Zn

(h),

Cd

(II), N

i(II)

W(V

I)t V

(V),

Fe(III),

Zn

(IIJ an

d

amm

onium

salts

.

Fe(III),

Zn

(II) an

d

amm

onium salts

.

-------------------------------------------------------------------------------C

ontd

. • •

. .

Qr)

C7

)

Tab

le-

3.1

1

(co

ntd

.)

-----------------------------------------------------------------------------------------------I

II

III IV

v

--------------------------------------------------------------------------------------2

7

Py

ridin

e-th

iocy

an

ate

6

.8-

7.0

C

u(SC

N)

2(c

5 H5 N

)2

N-B

en

zo

yl-N

-Ph

en

yl

3.6

-

6.0

(c

13 H10 o

2 N)

2C

u 2

8

Hy

dro

xy

lam

ine

HC

PMPTH

3

.0

-1

0.5

(c

21H

1 aN2

0C

l)2

Cu

0.1

88

03

0. 1

30

3

0.0

83

_3

Cd

(II), N

i(II), C

o(II),

Zn

(II), M

n(II)

V(V

), M

o(VI)

W(V

I) S

n(IV),

Ti(IV

), Z

r(fv).

Inte

rfere

nce

du

e to

F

e(III)

can

be elim

ina­

ted

by

m

askin

g w

ith

tarta

ric acid

.

-----------------------------------------------------------------------------------------------

oro ~

TA

BL

E-

3.1

2

FOR

MS

OF

GR

AV

IME

TR

IC

DE

TE

RM

INA

TIO

N

OF

NIC

KE

L

-----------------------------------------------------------------------------------------------R

eag

en

t rR

/ acid

ity

Weig

hin

g

form

C

on

versio

n

facto

r H

eat

treatm

en

t

-----------------------------------------------------------------------------------------------l

II

III

IV

v -----------------------------------------------------------------------------------------------1 •

Dim

eth

ylg

lyo

x1

me 4

7-

50

4

.5-1

0.0

C

1ali1

4N

40

4N

i 0

,20

31

1

10

-13

0°

2,

Dim

eth

ylg

lyo

x1

me 5

1• 5

2

4.5

-10

.0

NiO

0

.78

58

9

00

°C

3.

NH

4SC

N

+ P

yrid

ine

53• 5

4

7.0

N

i(Py)4

(sCN

)2 0

.11

95

R

oom

tem

p,

4.

NaO

H

+ K

S o

55

• 56

2

2 7

.5

NiO

0

.78

58

9

00

°

or

NaO

H

+ Br~?-Go

------------------------------------------------------------------------------co

ntd

. . .

. .

00

0

0

Tab

le-

3.1

2

co

ntd

.

-----------------------------------------------------------------------------------------------I

II

III IV

v

-----------------------------------------------------------------------------------------------5

.

6.

7.

8-H

yd

rox

yq

uin

olin

e5

7-6

0

HzS

61

-63

PB

HA

64

8.

HC

PM

PTH

4.6

-10

.0

Ni(C~60N)z

7.0

-

10

.0

NiO

7.5

-6.5

N

i(c1

3 H1

0 o2 N

)

or

NiO

7.5

-10

.5

( c21 H 1 aN 2 o C

l) 2 N1

0. 1

69

18

2

00

-30

0°C

0.7

85

8

90

0°

0. 1

21

6

11

0-1

20

°

0.7

85

8

85

0-9

00

°

0.0

77

47

110-120°

--------------------------------------------------------------------------

Qr)

co

SPECTRAL, THERMAL AND MAGNETIC ANALYSIS OF

CXlPPER COMPLEXES

Infra-red spectra of the ligand and copper

complex were studied in KBr in the region 4000-400 -1 em •

The vibrations which occur in high frequency

originate in the ligand itself while the vibrations which

occur in low frequency region originate in the metal

ligand bond65 • studies of the low frequency spectra

provide direct information about the metal ligand bond

but little work is available in low frequency region

because far infra-red spectrophotometers are not very

common.

According to Bellamy66 since the metal ligand bond

is stronger all the fundamental frequencies of the ligand

should be shifted to higher or lower frequencies depending

on modes of vibrations. The magnitude of band shifts are

used to determine the strength of the metal ligand bond.

According to Nakamoto67 in coordination compounds the

asymmetric frequencies increase while symmetric frequen-

ci es decrease.

In the present investigation the infre-red spectra

of Copper-P.CPMPTH has been compared with that of free

ligand to establish its structure.

90

Instrumental

I.R. spectra was recorded using Perkin-Elmer

grating l.R. spectrophotometer Model 377 by KBr disc

technique. I.R. spectra of the ligand and complex are

given in iigs. 3.3.

The ligand molecule consists of a weak band at -1 2550 em This confirms the presence of protonated

azomethene nitrogen in the reagent68-7°. This band is

absent in the i.r. spectra of the complex, which is a

proof of involvement of the group in complexation.

+ A strong band at 1610 cm-1 due to C • NH in the

free ligand appears at 1580 cm-1 in the spectra of the

complex. This band shift to lower frequency by 30 cm-1

on complexation. It is due to reduction of electron

density in the azomethine linkage. The formation of

C m N ..• Cu coordinate bond is confirmed,

The N - 0 stretching mode appears at 960 cm-1 in

copper complex which was at 930 cm-1 in the free ligand.

The shift to higher frequency supports replacement of

proton of - N - 0 - H group by copper.

According to

appears around 400 -

Nakamoto, -1 500 em •

II - N stretching band

In the present complex

a band at 460 cm-1 is observed which is in support of

cu - N bonding in the complex. Cu - 0 band absorbs in

low frequency region due to low bond order and relatively

91

120

ISJ

110

105 I

1QQ~

'l5

go

85

80

75

70

65

60

55

~I so

z ;:;I 4

5

a: Sii

40

"' <l:i 35

30

25 2

0 40

00

F19 J.a

j

lv

3500 3000

25

00

2000

c m-: 1 -----..

I.R.

SPEC

TR

A

OF

CO

PPER

(II)

CO

MPLEX

W

ITH

N-H

YD

RO

XY

-N-(0-C

HL

OR

O)

PHE

NY

L

N'-(3

-ME

TH

YL

) P

HE

NY

L-p-T

OL

UA

MID

INE

H

YD

RO

CH

LO

RID

E

ISU

) 1000

50

0.

CD

N

heavy ma<.s of copper71 . In the present complex this

band appears at 420 cm-1 .

The comparison of the infra-red spectra of free

ligand and copper complex suggest that CU - N and CU - 0

bonding are present in the complex.

THERMAL ANALYSIS OF OOPPER-HCPMPTH COMPLEX

Thermal analysis of the newly synthesised Copper­

HCPMPTH complex were carried out in order to evaluate

their thermal stabilities. The techniques employed are

thermogravimetry and differential thermal analysis.

Thermogravimetry was carried out on TGA Model

TGs-2 Thermogravimetric analyser Perkin-Elmer USA of long

sensitivity in static nitrogen, The TG curves of the

comple~ and ligand under investigation are shown in

F'ig. 3.i-3·2.The thermograms give percentage weight loss

at di!'ferent temperatures. These indicate that the

complex is thermally stable than the ligand. Wendlandt72

indicated relationship between thermal stability of the

metal chelate and structure of the chelating agent.

Liptay73 showed that thermal stability depends on the

structurf of chelate. 74

Sheshagiri and Rao showed that

tnermal stability can be increased by the introduction

of an exr ra electron releasing group in the reagent.

93

The thermogravimetric curve of Copper-HCPMPTH

shows three stage decomposition. F' rom the graph it is

clear that there is no weight loss upto 210°. This

confirms that water molecule is absent in the chelate.

This is furtner confirmed by the absence of a peak

around 3600 cm-1 in the I.R. spectra of the complex75 •

Thus the initial decomposition temperature is 210° and

inflexion temperature is 480°. The initial decomposi­

tion temperature is used to define thermal stability of

the complex76 •

A sharp exothermic peak is observed in D.T.A.

Curve of the complex in the temperature range 210-220°

which is due to phase transition from one state to

another. The complex gets ox1d1sed during melting

(Melting with decomposition). Broad exothermic peak is

present in the temperature range 450-480°C corresponding

to rapid mass loss in TG curve, Similar exothermic peaks

are present in chelates of oxime77 • 78 due to oxidation

reduction,

~he exothermic peaks are proceeded by broad endo-

thermic peaks (Fig, 3.~). According to Dollimore and

Griffiths79 exothermic break down of the copper complex

makes the endothermic decomposition of the copper complex.

The exothermic nature of the decomposition in air is the

result of the oxidation-reduction reactions.

ol-----.

20

40

60

eo

Fig.3.l

toe

600'1-----...

400

200

TGA CURVE OF COPPER COMPLEX WITH N-HYDROXY-N-(0-CHLORO)

PHENYL N'-(3-METHYL) PHENYL P-TOLUAMIDINE HYDROCHLORIDE

·L---------------------------------------~ rTJ\ rt·p·;r f'f rr'l'rrfl 0'"1'1 FX WITH N-HYDROXY-

'i '"-rll!f'Pr'\1 f'HFNYl '/'- 13-METHYt.)

r "' •;y 1 r F111'fi~ID:'If IIYOROCHLORIOF.

95

1"1AGNETIC PROPERTY Of THE. COPPER OOMPLEX

vihen an object is placed in a magnetic field, a

magnetic moment is induced in it. Substance is called

Paramagnetic or Ferromagnetic depending on whether the

field due to the induced moment is small or large in

comparison with the external field. If the induced

moment is antiparallel to the external field, the material

is called diamagnetic. The moment in this case is always

small.

The volume magnetic susceptibility X is defined

by the equation

I = X.H

I is magnetic moment per unit volume induced by

the field H.

96

For a paramagnetic substance X is positive and

for a diamagnetic substance it is negative. It is a

dimensionless number, generally very small in comparison

with unity except in case of ferromagnetism and essentially

independent of H for small fields readily available in

the Laboratory.

~, d I f 1 80-82 1 1 Applying r ara ay s ormu a , on y vo ume

susceptibility measurements were done, due to experi-

mental limitations.

Method: At first weight of empty ignition tube was taken

in presence and absence of magnetic field. Then it was

filled with the complex and again weighed in presence and

absence of magnetic field. A.R. grade Mohr's salt was

used to determine apparatus constant (Fig. 3.5).

Observations

Weight of empty ignition tube

--------------------------------------------------------Distance

em

Weight of tube (g)

-------------------------------without field with field

--------------------------------------------------------39

40

41

42

0.1892

0.1890

0.1890

0.1890

0.1892

0.1890

0.1890

0.1890

--------------------------------------------------------

97

98

Observation for Ferrous ammonium sulphate

Volume of the tube • 3.4329 cm3

X for Ferrous ammonium sulphate • 70 X 10-6 units

Distance Weight Weight Difference em without with field

field

36 1.2790 1. 3286 0.0496

37 1.2782 1. 3317 0.0535

38 1.2848 1.3488 0.0640

39 1.2840 1. 3572 0.0732

40 1.2834 1.3572 0.0738

41 1.2834 1.3572 0.0738

42 1.2832 1.3572 0.0740

43 1.2816 1. 3486 0.0670

44 1.2810 1.3422 0.0612

99

Calculation:

wf - wNo --------------v.x

Distance dH H --a:r-

36 206.4

37 222,6

38 266.3

39 304.6

40 307.1

41 307.1

42 307.9

43 278.8

44 254.6

Mean H dH 304,6 + 307. 1 + 307.1 + 307.9

--~-- = -----------------------------4

= 306.675

320

310

3100

290

28

0

270

260

:z=!'~ '"0

-o

250 . :r

240

230

22

0

21

0

36

37

FIg

. 3

.5

38 39

40 41

42

1,+3

__

Jil,t

em

_.

dH

GR

APH

SH

OW

ING

V

AR

IAT

ION

O

F H

.----W

ITH

D

ISTA

NC

E

dZ

-C

)

Q

Observation for Copper-HCPMPTII Complex

--------------------------------------------------------Distance

em

Weight without field

Weight with field

Difference

--------------------------------------------------------39

40

41

42

1.2672

1.2670

1.2670

1. 2668

1 .2 743

1.2740

1.2743

1. 2738

0.0071

0.0070

0.0073

0.0070

--------------------------------------------------------Calculation

X = ------------V Mean H

1 • X 0.0071

= ---------------- = 3.4329 X 306.675

0.0070 2. X = ---------------- "

3.4 329 X 306.675

3. X = 0.0073 ---------------- =

3.4 32 9 X 306.675

4. 0.0070 ----------------3.4329 X 306.675 X = •

r. ean value ,. o.7 x 10-6

-6 6.7 X 10

-6 6,6 X 10

-6 6 • 9 X 10

-6 6,6 X 10

:onclusion: The positive value of X indicates that

complex is para magnetic.

101

CONCLUSION

Simple, rapid and selective methods have been

developed for gravimetric determination of Copper( II)

and Nickel(II) using N-Hydroxy-N-(o-chloro)-N'­

(3-Methyl)phenyl-p-toluamidine hydrochloride. Copper­

HCP!'JPTH complex is precipitated quantitatively in the

pH range 3.0 - 10.5 while Nickel complex is precipitated

above 7.0 pH. This makes the separation of Copper and

Nickel from the solution of binary mixture. Both the

complexes are thermally stable and can be directly 0 weighed as (c21H18N20cl) 2M after drying at 100-110 •

102

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109