Telescopic synthesis of azo compounds via stable arenediazonium bis(trifluoromethane)sulfonimide salts by using tert-butyl nitrite

Azo compounds were synthesized in a multi-step catalyst-free reaction by using tert-butyl nitrite as a diazotization reagent and a mixture of bis(trifluoromethane)-sulfonimide (CF3SO2)2NH, (TFSI-H) and glacial acetic acid as a mild acidic agent in ethanol/water mixed solvent followed by azo coupling reaction with 4-hydroxybenzaldehyde was investigated. The stable arenediazonium bis(trifluoromethane)-sulfonimide salts were stored for long periods of time and then were used without any loss of activity and ascertained threads. The current method has the advantages such as reduce waste by avoiding solvent for the purification of products in diazotization step; no nitrous acid was produced during the diazotization; save energy, time and cost; simple experimental procedure, environmentally benign conditions, and good yield of the products with potential use as azo-dyes, pigments and therapeutic agents.