Room temperature diazotization and coupling reaction using a DES-ethanol system: a green approach towards the synthesis of monoazo pigments.

An environmentally benign, one-pot diazotization and coupling reaction using ChCl:tartaric acid DES at room temperature is described. The bulky tartrate ion renders stability to the diazonium salt at room temperature, also evidenced by 1H NMR. The isolated diazonium salt is stable and active even after 192 h at room temperature.