New Method for Spectrophotometric Determination of Lisinopril in Pure Form and in Pharmaceutical Formulations

Synthesis new organic azo dye as reagent 3-((4-acetyl-3-hydroxyphenyl) diazenyl)-4-amino-N-(5-methylisoxazol3-yl)benzene sulfonamide (SDA) and Analytical Study of Co(II), Ni(II) and Cu(II), metals complexes. The reagent and its complexes were characterized by elemental analysis, UV-Vis, and molar conductivity measurements. The data show that the complexes have the composition of [MR]X2 type. The conductivity data for all complexes are consistent with those expected for an electrolyte. Octahedral environment is suggested for metal complexes. *Corresponding author: Mohauman Mohammad Al-Rufaie, Department of Chemistry, College of Science, Kufa University, Iraq, Tel: 07809086646; E-mail: mohaumanmajeed@yahoo.com Received January 23, 2016; Accepted February 12, 2016; Published February 16, 2016 Citation: Al-Rufaie MM (2016) Synthesis and Analytical Studies of 3-(4-Acetyl3-Hydroxyphenyl) Diazenyl)-4-Amino-N-(5-Methylisoxazol-3-Yl)Benzene Sulfonamide with Some Metals. Mod Chem appl 4: 175. doi:10.4172/2329-6798.1000175 Copyright: © 2016 Al-Rufaie MM. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Introduction
Azo compounds are compounds bearing the functional group (R─N═N─R * ), in which R and R * can be either alkyl or aryl [1]. Aryl azo compounds are more stable than alkyl azo compounds (R and R * aliphatic) [2]. One example is diethyldiazene (Et─N═N─Et). At elevated temperatures, the carbon-nitrogen (C-N) bonds in certain alkyl azo compounds cleave with loss of nitrogen gas to generate radicals like azo bisisobutyl nitrile (AIBN) (Scheme 1) [3].
Aryl azo compounds are stable and have a broad range of colors [4], including yellow, orange, red, brown, and blue. The colors differences are caused by different substituents on the aromatic rings which lead to differences in the extent of conjugation of the π-system in the azo compound. In general, the less extensive the conjugated π-system of a molecule, the shorter the wavelength of visible light it will absorb as shown below: Colorless → yellow → orange → red → green → blue (Shortest wavelength) (Longest wavelength) Azo compounds constitute one of the largest classes of industrially synthesized organic compounds, for their widespread applications in many areas of dye-stuff industry, pharmacy and dissymmetry due to the presence of azo (-N=N-) linkage 1-3 [1,2]. It can simply be defined as any class of artificial dyes that contains the azo group (-N=N-). Describing a dye molecule as nucleophiles will be known as auxochromes, while the aromatic groups are called chromospheres. The dye molecule is often described as a chromogen [3]. Azo compounds are highly colored and have been used as dyes and pigments for a long time. A large number of (N,N΄)-donor reagent azo compounds have been prepared in the last years [4]. These are the largest group of organic dyes [5]. A number of these azo dyes have been used as chelating reagents in addition of the uses as reagents in analytical chemistry [6]. The present study reports the preparation, spectral characterization and analytical study of new azo reagent (SDA) and metal complexes. Synthesis of most azo dyes involves diazotization of primary aromatic amines, followed by coupling with one or more nucleophiles [7] (Scheme 2).
Azo compounds are important structures in the medicinal and pharmaceutical fields. Furthermore, azo dye compounds also have a lot of applications in industry and photodynamic therapy as well as photosensitive species in photographic or electro photographic systems and they are dominant organic photoconductive materials [8].

Experimental Apparatus and materials
All reagents and solvents were obtained from Fluke, The Merck and BDH. The melting points were determined on an Electro thermal, melting point 9300. Elemental analyses were carried out by means of Micro analytical unit of 1108 C.H.N.S Elemental analyzer while the UV-Vis. Spectra recorded in ethanol on Shimaduz model 1650PC. Molar conductance measurements were determined in DMF by using an Alpha Digital conductivity meter model 800. pH measurements were carried out using pH-meter Hanna. The metal content of the complex was measured by using atomic absorption technique by Perkin-Elmer model 2280.

Preparation of the reagent (SDA)
The reagent (SDA) was prepared according to the following general procedure [9,10] 4-amino-2-Hydroxy acetophenone (0.01 mol) (1.511 g) was dissolved in (3 ml) concentrated hydrochloric acid and (15 ml) distilled water. The mixture was cooled at (0-5°C) in ice-water bath. Then a solution of sodium nitrite (0.01 mol) dissolved in (5 ml) of distilled water was cooled at (0-5°C). This solution was added a drop wise to the mixture with stirring at the same temperature. The resulting diazonium chloride solution was mixed with Sulfamethoxazole (2.5 g, 0.01 mol) dissolved in (200 ml) alkaline ethanol cooled below 0°C. After leaving in the refrigerator for 24 hr, the mixture was acidified with dilute hydrochloric acid until pH=5. The precipitate was filtered off, and re-crystallized twice from hot ethanol, and dried in a vacuum desiccator and shown in the following Scheme 3 [11].

Preparation of metal complexes
The metal complexes were prepared by the mixing of 50 ml ethanolic solution of (CoCl 2 .6H 2 O, NiCl 2 .6H 2 O and CuCl 2 .2H 2 O) with the 50 ml of ethanolic solution of reagent in (1:1) (metal:reagent) ratio. The resulting mixture was refluxed for 2 h. Colored product appeared on standing and cooling the above solution. The precipitated complexes were filtered, washed and re-crystallized with ethanol several times and dried over anhydrous CaCl 2 in desiccators [12,13].

Results and Discussion
The analytical data for the reagent and complexes together with some physical properties are summarized in Table 1 [14]. The analytical data of the complexes correspond well with the general formula [MR] X 2 where M= Co(II), Ni(II), and Cu(II), R=(SDA).

Absorption spectra
The absorption spectra in aqueous ethanolic solution 50% (V/V) were studied for the prepared complexes showed a bath chromic shift ranging about (84-207) nm. The absorption spectra of reagent (SDA) and Co(II), Ni(II) and Cu(II) chelat complexes is shown in Figures 1-4 [15].

Effect of pH
The effect of acidity of the absorbance values of the complexes was studied in the 50%(v/v) ethanolic by changing the pH value of the solution and the results is shown in Figures 5-7, where demonstrated that the best absorbance of Co(II), Ni(II) and Cu(II) (SDA) system is in the range (6.5-8). The reagent formed stable complexes with metal ions at same pH.

Effect of time
Also the reaction is complete in 5 min at room temperature and remains stable for about 180 min. This show the reagent (SDA) strong coordination with metal ions in this time. The results are shown in Figure 8.

Metal: Reagent ratio
The (metal: reagent) ratios of complexes were determined by molar ratio method at fixed concentration and pH at wavelengths of maximum absorption. The results are given in Table 2, the reagent was found to form (2: 1) chelates with all metal ions.

Calculation of the metal complexes stability constant
Stability constants are obtained spectrophotometrically by measuring the absorbance of solutions of ligand and metal mixture at fixed wavelength λ max and pH values. The degree of formation of the complexes is obtained according to the relationship [16], β=(1-α)/ (4α3c2), and α=(Am-As)/Am, where As and Am are the absorbance's of the partially and fully formed complex respectively at optimum concentration. The calculated β and Log β values for the prepared complexes are recorded in Table 2.

Conclusions
In this present study we report the preparation characterization       and spectroscopy study of new azo reagent derived from imidazole and its complex with Cu(II) metal ion. The isolated complex was characterized by available techniques. The aryl azo reagent (SDA) behaves as a bidentate chelating agent and coordinating through the N 2 atom of imidazole and another nitrogen atom of azo group which is the farthest of imidazole ring to form five-member metalo ring and oxygen atom for cobalt and nickel complexes. The coordination of the metal ion Cu(II) with reagent(SDA) are to give hexa coordinated show octahedral stereochemistry.