Synthesis, Characterization and Biological Activity Evaluation of Some New Azo Derivatives from 2- Amino Benzothiazole and Their Derivatives

This study includes synthesis 2-amino benzothiazole and its substitutes (M1-M14) by the reaction of aniline derivatives with KSCN in presence of Br2 and glacial acetic acid then neutralize by concentrated ammonia solution or (by 50% NaOH). The prepared compounds (M3-M5-M6-M11) were used for preparation diazonium salts through reaction with NaNO2 and HCl, at that point diazonium salts were utilized specifically interaction with 4-amino antipyrine and 4-amino-3-hydroxy-1-naphthalene sulphonic acid (in alkaline medium) to produce azo dyes (M15-M22). These compounds were characterized by their physical properties, spectroscopic information (FT-IR, 1H-NMR, 13C-NMR and CHNS elemental analysis), and also to systematically defining of a few active functional groups for these prepared compounds. The biological activity evaluated for four of prepared compounds towards four kinds of bacteria .


1-Introduction:
Benzothiazole is un-homogenized a cyclic system due to sulfur atom on position (1) and nitrogen on position (3) on thiazole that attached to benzene ring. It is important because of multi applications, which attracted chemistry and pharmaceutical people because of biological activities [1]. When the benzothiazole discovered, they helped in reducing the death percent due to many diseases that could not cure before or a kind of high cost treatment [2]. From the literatures, the benzothiazole and its derivatives used as virus inhibitors for (1-HIV), and protein activities inhibitors [3]. They contain two un homogenized atoms of (N, S), in which they give anti-inflammable activities [4], anti-tumors [5], anti-convulsant [6], anti-microbial [7], anti-malaria [8], anti-infection bacterial [9], anti-fungi [10], tuber clauses, anti-parasitic worms [11], and anti-diabetes [12]. The benzothiazole derivatives used as painkiller and reduce the muscle spasms and it interact with nerve transfer of glutamate in biochemical and electro-physiological experiments [13].
While the paints Azo, they are organic compounds that were prepared for the first time by scientist (Peter) on 1858. They are prepared by coupling reactions in which Amine group (NH2) is attached to the compound (2-ABT) and its derivatives with organic reagents in acidic environment to give colorful organic compounds that absorbed at UV and visible length [14]. These compounds are characterized by high stability because they contain azo group (-N=N-) with double bond, accordingly it is classified as aliphatic and aromatic homogenized and heterocyclic compounds. It was found that the aliphatic compounds are limited in their distribution compared to aromatic compounds because of their low stability and breaking down to nitrogen and hydrocarbons [15]. While the un-homogenized aromatic azo compounds are distributed widely for their industrial, pharmaceutical, and medicinal importance as they are prepared by the reaction of amine group with different aromatic reagents [16]. thiocyanate were added to (350 ml) of (97%) glacial acetic acid, the mixture was cooled between (0-5) 0 C then (0.1 mol, 5.1 ml) of bromine dissolved in (50 ml) glacial acetic acid, which was added slowly with stirring, temperature was kept between (0-5) 0 C, then the mixture was stirred for (2 hours) at (0-5) 0 C .

2-Experimental Section
The mixture was filtered off and the precipitate dissolved in warm water, then the mixture was heated at (80) 0 C for (15 min). The produced solution neutralized with (50%) NaOH .The precipitate was filtered off and collected on a filter paper and dried, recrystallization from ethanol. The physical properties of the synthesized compounds are given in Table (1)   (2) and (3) and scheme (1) shows the synthesis of some new 2-amino benzothiazole derivatives with diazonium salt.

Evaluation Biological [19]:
The biological evaluation was carried out on four different types of bacteria for a number of compounds prepared (4 compounds) against four types of pathogenic bacteria were used in this study one of them (gram positive) is Staphylococcus aurea, and the rest (gram negative) is Esheriechia Coli, Enterobacter Cloaca's and Bacillus subtilis. All these species are very important in the medical field because of their resistance to antibiotics then incubated at
FT-IR spectral data of the prepared compounds (M 1 -M 14 ) are listed in Table (

Biological Activity:
The The results showed that most of the tested compounds possessed good antibacterial activity as shown in Table (6).

Conclusion
In this study used substituted 2-Amino benzothiazoles have different groups to prepare a substituted diazonium salt and coupling new reagents, 4-amino antipyrine and 4-amino -3hydroxy-1-naphthalene sulphonic acid and prepare derivatives sulphonamide.
One step process for synthesis of 2-aminobenzothiazole by using substituted aniline, potassium thiocyanate and bromine in acidic condition at low temperature (0-5 o C). For the acidic media, acetic acid as solvent. Based on previous results, the study concluded the followings: 1-Purity and characterization of the synthesized compounds were confirmed by determination of physical properties (melting points, FT IR spectroscopy, elemental microanalysis, 1 H NMR spectra and 13 C-NMR).
2-From the antimicrobial and cytotoxic activity studies, compound (M 11 ) showed the best activity that may be a potential candidate for a new drug discovery.