Telescopic Synthesis of Azo Compounds via Stable Arenediazonium Tosylates by Using n-Butyl Nitrite as Diazotization Reagent

ABSTRACT

A multi-step catalyst-free synthesis of azo compounds by using n-butyl nitrite as a diazotization reagent and p-toluene sulfonic acid as a mild acidic agent in ethanol/water mixed solvent was investigated. In the combined one-pot synthesis process, no nitrous acid was produced during the diazotization. By controlling the conditions in a continuous process, a 62–88% yield was obtained. The current method has the following advantages: reduce waste by avoiding solvent for the purification of products in the diazotization step; save energy, time, and cost; work under environmentally benign conditions, and produce a good amount of products with potential use as azo-dyes, pigments, and therapeutic agents.

KEYWORDS:

• Azo coupling reaction
• enviromentally benign
• Knoevenagel's method
• stable arenediazonium salt
• telescopic reaction

Acknowledgment

The authors are grateful to staff members in the Analytical and Testing Center of Research House of Professor Reza for partial support.

Funding

This work was supported by a High Impact Research Grant (No. H-21001-F0032) for Scientific Research from University of Malaya, Malaysia.