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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