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AZERBAIJAN CHEMICAL JOURNAL No 3 2020
ISSN 2522-1841 (Online) ISSN 0005-2531 (Print)
UDK 546.732, 541.49. 543/546
SYNTHESIS OF AZODERIVATIVES OF CHROMOTROPIC ACID AND INVESTIGATION OF ITS COMPLEXFORMATION WITH COBALT(II) IN THE
PRESENCE OF THIRD COMPOUNDES
V.I.Mardanova
Baku State University
Received 08.10.2019 Accepted 09.06.2020
Complex formation of cobalt(II) with 2-[2-dihydroxy-3,5-disulphenyla3o]naphthalene-1,8-dihydroxy-3,6-disulphosodium has been investigated in the presence and absence of surfactants-cetylpyridinium chloride, cetylpyridinium bromide, cetylpyridiniumtrimethylammonium bromide. Molar absorbtivities and stability constants of complexes have been determined. The determined concentration interval obeys to Beer's law. The developed technique was applied to determine cobalt(II) in the Akstafa and Jogaz rivers of the Kazakh region of the Azerbaijan Republic.
Keywords: cobalt(II), surfactants, cetylpyridinium chloride, cetylpyridinium bromide, cetyltrimethylam-monium bromide, complexes of cobalt(II).
doi.org/10.32737/0005-2531-2020-3-56-61
Introduction
Cobalt is an important element not only for industry but also for biological systems. In rapidly developinganalytical fields such as environmental, biological and material monitoring of trace metals, there is an increasing need to develop simple, sensitive and selective analytical techniques which do not use expensive or complicated test equipment. Many sensitive techniques, such as spectrofluorimetry, X-ray fluorescence, spec-trometry, neutron activation analysis, atomic absorption spectrometry and chemiluminescence have been widely applied to the determination of cobalt [1-7]. However, the spectrophotometry method still has the advantages of being simple and not requiring expensive or complicated test equipment. For this reason, a wide variety of spectrophotometric methods for the determination of cobalt have been developed. The main chromogenic reagents are pyridylazo reagents, thiazolylazo reagents, benzothiazalylazo reagents, 8-aminoquinoline derivatives, porphyrins, nitroso dyes etc [8-12]. Each chromogenic system has its advantages and disadvantages with res-
pect to sensitivity, selectivity and rapidity. However, very often a direct definition cannot be applied due to the low concentration of the analyzed or matrix noise.
In the present work, the complexfor-mation of cobalt(II) with 2-[2-dihydroxy-3,5-disulphenyla3o]naphthalene-1,8-dihydroxy-3,6-disulphosodium (R) has been investigated in the presence and absence of surfactants- cetylpyri-dinium chloride (CPCl), cetylpyridinium bromide (SAC)-(CPBr), cetyltrimethylammonium bromide (CMABr).
Materials and methods
Solutions and reagent. Reagent is synthesized by known methods [13].
OH OH
HO
NaOjS
N = N-
SO3Na
SO3H
SO3H
The synthesis of other derivatives of chromotropic acid was carried out in a similar manner.
OH3S.
HO3S
OH
. + NaNO2+ 2HCl
OH3S
HO3S
OH
N=N
Cl + NaCl +2H2O
+
OH OH
NaO3S
SO3Na
HO3S
HO3S
OH OH
N=N Cl
NaO3S
N=N-SO3Na
SO3H
SO3H
+ HCl
Reagent is dissolved well in water. A aqueous reagent solution was used in
the work.
A solution of cetylpyridinium bromide (CPBr) (1-10"2M), cetyl pyridinium chloride (CPCl) (1-10-2M) and cetyltrimethylammonium bromide (CMABr) (1-10M) is prepared by dissolving 0.3845 g of CPBr, 0.3395 g of CPCl and 0.3646 g of CMABr of a water-ethanol mixture [3:1].
Initial solution of cobalt(II) 1-10- M was prepared by dissolving of precise hinge of Co(NO3)2 in distillate water. the worked solutions of Co(II) were prepared by dissolving of an initial solution with distillate water. For making of needed acidity we used phycsanal HCl (pH 1-2) and ammonium-acetate buffer solution (pH 3-11).
Apparatus. pH of solutions we measured by ionometer PHS-25 with glass electrode. Optical density of solutions we measured by using of photocolorimeter KFK-2 (/=1 cm). Spec-
trums of absorbance were registered by spectrophotometer Lambda 40 (Perkin Elmer).
The calculation. The correlation of components was determined by method of Starik-Barbanel installed, shift of the equilibrium and isomolar series. Molar coefficients and stability constants of absorption of complexes were calculated [14].
Reagents dissociation coefficients have been determined and take the following values: (pK1=4.14±0.03, pK2=8.21±0.03, pK3=10.19± 0.07). According to their values molar parts were calculated (Table 1) and distribution diagram has been built (Figure 1). As is seen in Figure 1, complex exists in a reactive form of H2R- at pH 4, aH2R- = 41.98. By Astakhov method [15] it has
been determined in the pH 3-4 interval angular coefficient for CoR lg AA(AAmax - AA) is equal to
2, for H3R form of complex, aHR = 93.25 at pH
2-3 interval and angular coefficient for CoR-CPCl, CoR-CPBr. lg AA(AAmax - AA) is equal to 2.
Table 1. Mole parts of molecular and ionic forms of reagent dipending on pH
pH 1 2 3 4 5 6 7 8 9 10 11
«h3r 100 99.28 93.25 58 12.13 1.28 0 0 0 0 0
%2r- 0 0.72 6.75 41.98 87.4 92.98 61.79 13.94 1.58 0.15 0
«hr^- 0 0 0 0.03 0.54 5.74 38.21 86 97.8 93.8 60.7
0 0 0 0 0 0 0 0.06 0.64 6.06 39.3
100 80 60 40 20 0
3
5
7
9
13 pH
Fig. 1. Distribution diagram of the reagent in the solution.
+
+
1
This shows that when a reagent reacts with metal, a proton is separated. When reactive form is H2R- , aH R = 99.28 at pH 2 Astaxov's method [15] shows that in the range of pH 1-2, angular coefficient for CoR-CMABr complex lg AA(AAmax -AA) is equal to 2, what indicates to the separation of proton.
Results and discussion Influence of pH. We found that water solution R at pH 4 has an absorption band with a maximum À=477 nm. Under these conditions, it forms a complex with Co(II) (absorption maximum at 497 nm). In the presence of cation-ic SAB the optimal condition of complex formation shifts to acid medium. The complexes have a maximal light absorption at pH 3-512 nm
A
0,8 0,7 0,6 0,5 0,4 -0,3 0,2 0,1 0
(CoR-CPCl), pH 3 523 nm (CoR-CPBr) and pH 2-542 nm (CoR-CPMABr) (Figure 2, 3).
During the complexformation of co-balt(II) with R in the presence of third component the dependence of A=f(C) is expressed by following linear equations: ^=(0.14±0.02)C+(7.1 ±0.12)10"2 for CoR ^=(0.21±0.01)C+(5.4±0.12)10"2 for CoR-CPCl ^=(0.22±0.01)C+(5.2±0.12)10"2 for CoR-CPBr ^=(0.24±0.01)C+(3.5±0.12)10"2 for CoR-CMABr
The composition and constants of stability of complexes. The correlation of components is installed by methods of Starik-Barbanel, shift of the equilibrium and isomolar series. The ratio of components of binary system is as 1:2 (CoR) and the ratio of components of triple complexes is as 1:2:1 (CoR-CPCl, CoR-CPBr and CoR-CPMABr,) (Table 2).
Fig. 2. Absorption spectra of solutions of complexes with cobalt(II): 1 - CoR, 2 - CoR-CPCl, 3 - CoR-CPBr, 4 -
CoR-CMABr, CCo = 4 -10" 1-10~4M.
M ; CR =
440
490
540
590
À, nm
5
A
0,9 0,8 -0,7 0,6 0,5 -0,4 0,3 -0,2 " 0,1 0
Fig. 3. Dependence of the optical density of a solution of cobalt(II) complexes on pH in the presence and in the absence of third components at Xopt. on the background of control experience: 1 - CoR, 2 - CoR-CPCl, 3 - CoR-CPBr, 4 - CoR-CPMABr.
0
PH
1
2
3
4
5
6
7
As it follows from Table 2 mixed ligand complexes are formed in more acidic medium, than binary complexe of the cobalt(II).
The constants stability of binary- and mixed ligand complexes of cobalt(II) were calculated. For calculation of the stability constants of the complex the method of the intersection crooked was used [14]. According to calculation: lgP(CoR)=8.27±0.04, lgp(CoR-CPCl)=9.68+0.03, lgP(CoR-CPBr)=9.83±0.05, lgP(CoR-CPMABr)= 10.22+0.04.
Under optimal conditions for complexa-tion R-SAC (SAC=CPCl, CPBr and CMABr)
Table 2. Spectrophotometry characteristics of the complexes cobalt(II)
was titrated with a solution of cobalt(II) using the conductometric method [16] (Table 3).
The results demonstrate that the lower the electrical conductivity, the greater the stability of the complexes.
The influence of foreign ions. The influence of foreign ions by photometric determination of the cobalt(II) of mono- and different ligand complexes was studied. The effect of interfering ions and masking agents has been learned. The determination of cobalt(II) is not interfered by alkali metals and ions of Ca(II), Ba(II), Mn(II), Cr(III) (Table 4).
Complexes pHopt ^max, nm e M:R Sybjekting to Bace's low, mkg/ml lgP
Co-R 4 497 11250 1:2 0.236-2.36 8.27+0.04
CoR-CPCl 3 512 13250 1:2:1 0.19-2.36 9.68+0.03
CoR-CPBr 3 523 16500 1:2:1 0.19-2.83 9.83+0.05
CoR-CPMABr 2 542 19500 1:2:1 0.12-2.83 10.22+0.05
Table 3. The results of conductometric titration of a solution of R and R-SAC with a solution of cobalt(II) (mx-104 Om-1 sm-1)
^^^^Co, ml Systems 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
R- 1.78 1.74 1.71 1.69 1.65 1.62 1.61 1.61 1.61 1.61
R-CPCl 1.70 1.68 1.65 1.62 1.58 1.55 1.51 1.51 1.51 1.51
R-CPBr 1.61 1.58 1.53 1.50 1.47 1.45 1.42 1.42 1.42 1.42
R-CMABr 1.65 1.63 1.60 1.58 1.51 1.48 1.46 1.46 1.46 1.46
Table 4. Admissible ratios of foreign ions to cobalt(II) at determination in the form of mono-and mixed ligand complexes (CCo=2 10-5 , 5% error)_
Foreign ions R R-CPCl R-CPBr R-CMABr 4-(6-Nitro-2-benzothiazolylazo) resorcinol [12]
Na(I) * * * *
K(I) * * * *
Mg(II) 81 81 244 407
Ca(II) 135 407 407 678
Ba(II) 464 1393 2322 2322 100
Zn(II) 110 661 1101 1101 18
Cd(II) 190 190 380 380
Ni(II) 197 197 589 983 5
Cu(II) 217 217 217 651 5
Mn(II) 93 186 559 932
Al(III) 275 275 458 641 200
Fe(III) 10 57 95 95 20
Cr(III) 88 88 176 529
Pb(II) 35 70 351 351 3.6
V(V) 519 519 1504 1504 25
W(VI) 312 312 624 1871
Mo(VI) 325 976 976 1627
F- 627 627 1254 3762 500
C2O42- 1281 1281 2136 2136 1000
HPO42- 607 1214 3641 6067
Vine acid 259 1525 1525 2542
Tiocirbomid 129 258 772 1288
* does not interfere
The developed methodology has been applied to determine cobalt(II) in the Akstafa and Jogaz rivers of the Kazakh region of the Azerbaijan Republic.
Determination of cobalt(II) in the Ak-stafa and Jogaz rivers of the Kazakh region of the Azerbaijan Republic
For the analysis took 1 liter of water from the coast of the river was taken. Water was evaporated without boiling and a precipitate was formed. The resulting precipitate was dissolved in 5 ml of HNO3 and transferred to a 50 ml flask and diluted to the mark with distilled water. Under determining cobalt(II) by the photometric method, an aliquot part of the obtained solution is placed in a 25 ml flask, 2 ml of 1-10-3 M R and 2 ml of 1-10-2M CMABr are added and diluted to the mark with pH 2. The optical density of the solutions is measured at X = 490 nm in a cuvette with l = 1 cm on KFK-2 relative to the test solution. The correctness of the procedure was checked using the "ICP-OES thermo ICAP 7400 Duo" instrument. The results are presented in Table 5.
Table 5. The results of the determination of cobalt(II) in river waters («=5, P=0.95)_
Water sample Found by photometric method, Co, mg/l Found Co, mg/l (ICP-OES thermo ICAP 7400 Duo)
I sample river water 0.390±0.005 0.400±0.004
II sample river water 0.187±0.004 0.191±0.003
These methods can be applied to the determination of cobalt(II) in different natural and artificial objects.
Conclusion
1. To determine cobalt by spectrophotometry method, the azo derivative of chromotropic acid was used in the presence of third components.
2. The complex compounds of cobalt with a reagent in the presence of third components were studied spectrophotometrically, the optimal conditions for complex formation and characteristics of the complexes (pHopt, XOpt, molar absorption coefficients, composition of complexes, interval of obedience to
Beer's law, stability constant) were determined. It was determined that in the presence of the third component, some analytical reaction parameters are improved. The least squares method determines the coefficients in the equations of the calibration graphs.
3. Under optimal complexation conditions, CoR was titrated with a solution of the third components (CPCl, CPBr and CMABr) by the conductometric method. The results show that the lower the electrical conductivity, the higher the stability of the complexes.
4. The effect of foreign ions and masking substances on complexation reactions was studied. It was found that reactions with modified forms of the reagents are characterized by higher selectivity. These methods are highly sensitive and selective. It is a very rapid and a simple technique. The developed technique was applied to determine cobalt(II) in the waters of the Akstaf and Jogaz rivers of the Kazakh region of the Azerbaijan Republic.
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XROMOTROP TURSUSUNUN azotoromolorínín síntezí уэ ücüncü komponentlor ͧTÍRAKINDA KOBALTIN (II) KOMPLEKOMOLOGOTÍRMOSÍNÍN TODQÍQÍ
V.LMardanova
Kobaltm(II) 2-[2-dihidroksi-3,5-disulfenilazo]naftalin-1,8-dihidroksi-3,6-disulfanatrium ila sathi aktiv maddalar -setilpiridin xlorid, setilpiridin bromid, setiltrimetilammonium bromid. Sathi-aktiv maddalar i§tirakinda va i§tiraki olmadan kompleksamalagalmasi tadqiq edilmi§dir. Komplekslarin molar udma amsali va davamliliq sabiti tayin edilmi§dir. On kigik kvadratlar metodundan istifada edarak daracali qrafikin tanliklari qurulmu§dur. Ber qanununa tabegilik intervali tayin edilmi§dir. Bu metodikadan istifada edarak Azarbaycan Respublikasinin Qazax rayonunun Akstafa va Cogaz gaylarinda kobaltin (II) tayini aparilmi§dir.
Agar sözlzr: kobalt(II), sathi aktiv madd3hr, selilpiridin xlorid, selilpiridin bromid, seliltrimetilamonium bromid, kobalt(II) kompleksbri.
СИНТЕЗ АЗОПРОИЗВОДНЫХ ХРОМОТРОПОВОЙ КИСЛОТЫ И ИССЛЕДОВАНИЕ ИХ КОМПЛЕКСООБРАЗОВАНИЕ С КОБАЛЬТОМ (II) В ПРИСУТСТВИИ ТРЕТЬИХ КОМПОНЕНТОВ
В.И.Марданова
Комплексообразование кобальта(П) с 2-[2-дигидрокси-3,5-дисульфенилазо]нафталин-1,8-дигидрокси-3,6-дисуль-фонатрием исследовано в присутствии и в отсутствие поверхностно -активных веществ - хлорида цетилпириди-ния, бромида цетилпиридиния, бромида цетилпиридинийтриметиламмония. Определены молярный коэффициент поглощения и константы устойчивости комплексов. Установлен интервал концентрации, подчиняющихся закону Бера. Разработанная методика применена для определения кобальта(П) в водах рек Акстафа и Джогаз Казахского района Азербайджанской республики.
Ключевые слова: кобальт(П), поверхностно-активные вещества, хлорид цетилпиридиния, бромид цетилпиридиния, бромид цетилтриметиламмония, комплексы кобальта (II).
