Analytical Application of 1, 1'-(Sulfonyldibenzene-4,1-diyl)bis(3-hydroxy-3-phenyltriaz-1-en) (BHDPT) in the Spectrophotometric Determination of Iron (III)

 

Sharad Sharma, Ashok K. Patidar, Krishna K. Rathore, Ram C. Senwar Anita Mehta,

Ajay K. Goswami

Synthetic Organic Chemistry Laboratory, ML Sukhadia University, Udaipur, India. 313001

*Corresponding Author E-mail: sharadsharma.chem@gmail.com

Bis hydroxytriazenes (1,1'-(sulfonyldibenzene-4,1-diyl)bis(3-hydroxy-3-phenyltriaz-1-en)) has been proposed as a sensitive and selective reagent for the spectrophotometric determination of Iron(III). The method is based on the formation of green coloured 1:1 complex by the reaction of Iron (III) with Bis hydroxytriazenes. Beer’s law is valid over the concentration range of 1×10^-4 to 4.5×10^-4. The coloured complex exhibit an absorption maximum at 410 nm with molar absorptivity of 45606.2 L mol^-1cm^-1and sendell sensitivity of 1.22 ng cm^-2 the absorbance is found to increase linearly with increase in concentration of iron which are corroborated by the calculated correlation coefficient.

 

 

INTRODUCTION:

Iron serves as a key component in industries and play vital role in biological system. Biologically iron is used in various processes such as an oxygen carrier in blood of mammals, electron carrier in plant, animal and bacteria (Cytochrome), oxygen storage in muscle tissue (myoglobin) etc. Excess intake of iron causes siderosis while its deficiency causes anemia¹. Iron also used in agriculture as pesticides and textile as dyes and pigment. Colourimetry and atomic absorption spectroscopy method are most commonly used in determination of iron^2,3. Atomic absorption spectroscopy method is quite costly and cumebersome for routine measurement. Consequently, there is a need for the development of a rapid, sensitive and low-cost analytical method for determination of iron. Hence we attempt to develop a simple and sensitive spectrophotometric method for determination of iron.

 

Hydroxytriazenes are well known class of compounds which contain three linear nitrogen with hydroxyl group, have been studied for their biological and pharmacological activities. They have been shown to exhibit a broad range of activities including antibacterial, antifungal, insecticidal, analgesic, wound healing and anti-inflammatory properties^4-8. They are also used as a chelating ligand for spectrophotometric and complexometric determination of metal^9-13.

 

In the present study a new reagent bishydroxytriazene has been used first time for the spectrophotometric determination of Iron (III). The reagent (BHDPT) has been synthesized by using standard methods, duly characterized by IR, 1H NMR, elemental analysis (CHN) and m.p. determination etc. proving that compound was obtained in pure form. It was used for the spectrophotometric determination of Iron (III).

 

MATERIAL AND METHODS:

1. Synthesis of bis hydroxytriazenes:

Materials and Methods- For the synthesis of BHDPT, AR grade chemicals were used. The process is completed in three steps. The general method of synthesis has been given by the following three step reaction procedure

 

1.1. Preparation of hydroxylamine:

In the preparation of aryl hydroxylamine, 0.1 moles of nitro benzene, 0.1 mole of NH₄Cl and 75 (50 mL water + 25 mL sprit) mL of solvant were mixed and stirred mechanically at 40^oC and then 21 g of Zn dust was added in the small lots at maintain temperature of the reaction between 45-60^oC. After one hour the reaction mixture was filtered and the solution obtained was kept in refrigerator at about 0^oC which were used for coupling.

 

1.2. Preparation of diazonium salts:

Dapsone (4,4'-sulfonyldianiline) (0.05 mole) was dissolved in mixture containing 25 mL of HCl and 25 mL of water. In other beaker 0.1 moles sodium nitrite was dissolved in minimum quantity of water. The temperature of the reaction mixture was maintained between 0-5^o C. To this solution, sodium nitrite solution was added drop by drop with stirring. The diazotized product so obtained was directly used for coupling.

 

1.3. Coupling:

The temperature of aryl hydroxylamine prepared in step-1 and diazotised product obtained from step-2 were maintain between 0-5^oC. Step-2 solution was added drop-by-drop to solution obtained in step 1 and pH of solution was maintained between 5 and 6 by adding sodium acetate solution. The resultant product was filtered, washed with cold water and dried. The crude compounds were purified and recrystallized. The purity of bishydroxytriazene was checked by I.R., ¹H NMR and Melting Point analysis. Their compositions were verified by elemental analysis.

 

 

Synthetic Route:

Step-1 Reduction of Nitro benzene

 

Step-2 Diazzotization of Dapsone

 

Step- 3 Coupling

 

 

1,1'-(sulfonyldibenzene-4,1-diyl)bis(3-hydroxy-3-phenyltriaz-1-en) (BHDPT)- Yellow crystal, M.P. 123˚C, Solubility ꞊ Acetone, FTIR (KBr) cm^-1: 3402 (ν^O-H), 3029 (Ar-H), 1523 (ν^N=N), 1215 (ν^C-N). 1H NMR (DMSO-D6) δ: 12.25 (s, 1, O-H), 7.11-7.75 (m, 18, Ar-H), Anal. Found for CHN: C; 59.21, H; 4.09, N; 17.15%. calcd: C; 59.01, H; 4.13, N; 17.20%.

Resultant compound was subjected to four spot tests detection as described by Purohit^14-17. This compound gave positive test with all the four reagents proving that the synthesized compound is a bishydroxytriazene.

 

2. Spectrophotometric Study of the Complex-

(A) Preparation of Solutions

(i)Reagent solution- A fresh stock solution of 1.0*10^-4 M of the reagent 1,1'-(sulfonyldibenzene-4,1-diyl)bis(3-phenyltriaz-1-en-3-ol)  was prepared by dissolving requisite quantity of the reagent in ethanol. Dilute solution were prepared from this stock solution when required.

 

(ii)Standard solution of Fe(III)- A 1.0*10^-4 M stock solution of Fe (III) was prepared by dissolving the requisite quantity of A.R. grade Ferric nitrate and making it up to the required volume with double distilled water. It was standardized with standard1.0*10^-4 EDTA solutions at pH 2.5-3.0 using sulpha salicylic acid as an indicator. Dilute solution of different concentration were prepared from stock solution by proper dilution with double distilled water.

 

(iii) Solutions for pH adjustment:

(a) Tris buffer solution- A 1.0% of tris buffer solution was prepared by dissolving 1.0 gm of the tris buffer in minimum quantity of double distilled water and then making it up to 100 ml with distilled water.

 

(b) Perchloric acid solution- A 1.0% Perchloric acid solution was prepared by dissolving1.0 ml of the Perchloric acid in minimum quantity of double distilled water and then making up to 100 ml with distilled water.

 

(iv) Instruments- The spectrophotometric studies have been carried out on Systronic-108 UV-VIS spectrophotometer and Systronic-324 was used for pH measurement.

 

(B) Selection of suitable working wavelength- 3ml (1*10^-4M) Fe(III)solution and 3ml (1*10^-4M) reagent solution was taken in 10ml volumetric flask and then makeup to the mark with alcohol. Absorbance of solution against its reagent blank was measured selected in a region where the absorption of Fe (III) complex was maximum. For working wavelength, maximum absorbance was found at 410 nm.

 

(C) Effect of pH on absorbance-Absorbance of the solutions at various pH values containing Fe (III) and reagent solutions in the ratio of 1:10 was taken at working wavelength 510 nm against reagent blank. The optimum pH range for constant maximum absorption was selected.

 

(D) Composition of the Fe (III)complex- The composition of the Fe(III) complex was determined using Job’s method, mole ratio method of Yoe and Jone’s and slope ratio method.

 

(a) Job’s method- The composition of Fe (III) complex was determined at two different concentrations with Job’s method. For each concentration, set of solution was prepared by varying the volume of equimolar Fe (III) and reagent solution from 0 to6 ml. After pH adjustment, the solutions were marked (10ml) with ethanol. The absorbance of solution was measured at suitable working wavelength against reagent blank. The second set of this method differed from the first set only in the concentration used. By this method the composition was found to be 1: 1[Fe: R].

 

(b) Mole ratio method of Yoe and Jone’s-In this method Fe(III)concentration was kept constant and reagent concentration was varied. A series of solutions having Fe(III)to regent ratio 1:1 to 1:10 were prepared with maintaining the pH of constant absorbance. Absorbance of each solution of a set was measured at working wavelength against the reagent blank. By this method the composition was found 1:1[Fe: R].

 

(E) Beer’s Law- A set of solution, having to ligand ratio 1:10 was prepared. The studies were performed under optimum condition of pH, concentration and solvent at corresponding working wavelength. The absorbance was measured for the complex against the reagent blank. The results are shown in Table 2.

 

(F) Sandell’s sensitivity- The molar absorptivity of the Fe (III) complex was calculated from the Beer’s law graph and it was found to be €= 45,606.2 L mol^-1cm^-1. The value thus obtained was used for determining Sandell’s sensitivity of the complex that is obtained 1.22 ng cm^-2. This value shows that the method used is quite sensitive and satisfactory for the determination of Fe(III).

 

 

Table. 1: Spectrophotometric determination of Fe(III)with BHDPT

Fe(III)complex with reagent	Composition of the complex [Fe (III): R]	Working Wavelength (nm)	Optimum pH range	Beer’s Law range (M)	Molar absorptivity [L mol-1 cm-1]	Sendell’s Sensitivity ng cm-2
1,1'-(sulfonyldibenzene-4,1-diyl)bis(3-hydroxy-3-phenyltriaz-1-en)	1:1	410	4.2-5.0	1.0 x10-4to 4.5 x10-4	45606.2	1.22

 

 

RESULT AND DISCUSSION:

As described in the Table-1, 1,1'-(sulfonyldibenzene-4,1-diyl)bis(3-hydroxy-3-phenyltriaz-1-en) forms complex in the ratio of 1:1. The conditional stability constants have also been given in the table, determined by two different methods. Bisydroxytriazenes act as, tetradentateligand and in the present case, the reagent has been found to form a 1:1 complex with 1,1'-(sulfonyldibenzene-4,1-diyl)bis(3-hydroxy-3-phenyltriaz -1-en), which indicates hexa coordinated Fe (III) complex with a probable geometry being Octahehral.

 

ACKNOWLEDGMENT:

The authors are thankful to the Head, Department of Chemistry, M.L. Sukhadia University, Udaipur (Rajasthan) for providing requisite laboratory facilities.

 

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Received on 31.03.2015         Modified on 22.04.2015

Accepted on 27.04.2015         © AJRC All right reserved