Synthesis Of Noval Water-soluble Triazene And Its Analytical Application

Triazene reagent which has the analytical functional group"–N=N–NH–"is one of the good sensitivity organic chromogenic agents in determination of transition metal ions such as Cd²⁺, Cu²⁺, Ag⁺, Hg²⁺, Zn²⁺, Co²⁺, Ni²⁺ and so on. In order to further probe their spectroscopic qualities and find more sensitive and selective reaction systems, a novel water-soluble triazene reagent 2,6-dibromo-4-nitrophenyl-4′-(β- sulfateshyl)sulfonylbenzenediazoaminoazo- benzene(DBNSESDAA) was designed and synthesized in this paper on the basis of the relation of organic reagent structure and the function. The general structure of DBNSESDAA is as follows:By the way of brominating, amino protecting, diazotization, coupling, hydrolysis and so on reactions, DBNSESDAA crude product was synthesized in the process. The purified product was coincidental with the design after characterized by ultraviolet spectrum, infrared spectrum and mass spectrum. While preliminary study was put on its physicochemical property. The hydrolysis constant of hydrogen of"–N=N–NH–"was tested as pKa=9.87.In this paper, the color reactions of DBNSESDAA with Cd²⁺, Hg²⁺, Ni²⁺, Co²⁺, Cu²⁺, Zn²⁺, Ag⁺ and so on had been studied. From the experimental results we found: the reagent reacted sensibly only with Cd²⁺, Cu²⁺, Ag⁺ and Hg²⁺, and the common co-existed interference ions could be tolerated in a large mounts. And the optimization of the reactions′conditions had been studied separately in detail. The results are as follows: In the presence of TritonX- 100, four ions can reacted with DBNSESDAA to get their optimal absorbancy in the medium of Borax-HCl buffer of pH8.0. To cadmium, form a red complex with a molar ratio of 4:1. Its apparent molar absorptivity was 1.5×10⁵ L·mol^-1·cm^-1 at 509nm. Beer′s law was obeyed in the concentration range of 0～20μg/25mL for cadmium. To copper, form a red complex with a molar ratio of 2:1. Its apparent molar absorptivity was 1.2×10⁵ L·mol^-1·cm^-1 at 518nm. Beer′s law was obeyed in the concentration range of 0～10μg/25mL for copper. To silver, form a red complex with a molar ratio of 2:1. Its apparent molar absorptivity was 1.0×10⁵ L·mol^-1·cm^-1 at 539nm. Beer′s law was obeyed in the concentration range of 0～15μg/25mL for silver. To mercury, form a red complex with a molar ratio of 3:1. Its apparent molar absorptivity was 1.2×10⁵ L·mol^-1·cm^-1 at 504nm. Beer′s law was obeyed in the concentration range of 0～15μg/25mL for mercury. All the complex compounds′stability constant and the maximal permit amount of co-existed interference ions had been determination in this paper.After studing the absorption spectrum and the optimal condition of the color reaction of Cd²⁺, Cu²⁺, Ag⁺ and Hg²⁺, we found: the four ions had the same optimal condition of the color reaction, but their absorption spectrum overlapped seriously. The absorbancy and the density of the mixed-ion were not appeared linearity. So they could not be determined simultaneously by general spectrophotometry. The Radial basis function neural network associated with the triazene to determine four ions simultaneously in this paper. First, prepare the four ions′compounds that had different mixture ratio to react with DBNSESDAA in the same optimal condition. Second, input the data of spectrum and density to the program of radial basis function neural network. The network model would be established after taining. Finally, input the spectral data of four ions′compounds which had unknown density to the established network model, then the four ions′data of density would output. Cd²⁺, Cu²⁺, Ag⁺ and Hg²⁺ could be directly determined simultaneously in the water solution by the new method. The results were satisfied.