Synthesis of Azobenzenes via direct oxidation of Aryl amines using aqueous tert-Butyl HydroPeroxide

Tanveer Mahmadalli Shaikh

doi:10.5267/j.ccl.2020.10.001

Abstract

A new method for the direct oxidation of aromatic amines to azobenzenes employing aqueous tertiary-butyl hydrogen peroxide and potassium tertiary butoxide as an oxidant and base, respectively is described. The desired products are obtained in good yields. The developed protocol is associated with certain advantages for example free from any metal oxidants.

Highlights

The azo compounds have been extensively investigated, due to their versatile structural features and unique –N=N– bonds.[1-2]
We have reported one-pot direct oxidation of diols to carboxylic acids using TBHP as metal-free oxidant.[51]
AReaction conditions aniline (1 mmol), aq. 70% TBHP (3 mmol), KtOBu (1 mmol), acetonitrile (2 mL), 60 oC, 6 h; bIsolated yield; cThe formation of products were confirmed by FTIR, 1H-NMR and 13C-NMR; dThe formation of product was confirmed by FTIR due to reaction highly exothermic; eCorresponding hydrolysis product was observed along with starting compound

Summary

Introduction

The azo compounds have been extensively investigated, due to their versatile structural features and unique –N=N– bonds.[1-2]. The azobenzenes has been thoroughly exploited in dyes,[4-5] pigments,[6] textiles,[7] polymers, 89 electronics,[10-12] and bioactive molecules.[13-15]. In this context, numerous transformations have been described to accomplish direct oxidation of aromatic amines to azobenzene.[16]. Numerous transformations have been described to accomplish direct oxidation of aromatic amines to azobenzene.[16] Such as BaMnO4,17 Pb(OAc)[4,18-19] HgO/I2,20 KMnO4,21-22 MnO2,23 Cu2Cl2-O2,24-26 CuBr,[27] Ag2O,28 Ag2CO3,29-30 AgMnO4,31 Ag-nanoparticles,[32-33] Ni peroxide,[34] Ce(OH3)O2H,35 Co3O4-O2,36 B(OH)[3,37-39] has been depicted in literature. The metal-free oxidative process employing PhI(OAc)[2,40] O2-t-BuOK,[41] KO2,42 BBCP,[43] Ozone,[44-45] t-BuOCl/NaI,[46-48] CH3ONO,[49] NCS/DBU,[50] have been reported. Despite all these developments, a mild protocol with metal-free oxidants is of practical and environmental concern, such methods have been received a great attention.

Results and Discussion

Conclusions

Materials and Methods

General procedure for the synthesis of azobenzenes

Findings

Spectral Data