Synthetic approaches to some new fluorescent dyestuffs for synthetic polymer fibres: Synthesis of new 2‐(4′‐Hetarylphenyl)‐1, 2, 3‐triazolo (4, 5‐b) pyrido (1′, 2′‐a)‐benzimidazoles

Since Victor Meyer's first report on coupling of diazonium salts with activated carbon compounds, a growing interest has appeared in literature for synthesis and use of different isolated and/or fused nitrogen‐containing heterocyclic dyestuffs as fluorescent whitening agents. A technically important class of these products is those embodying pyrido (1,2‐a) benzimidazole residue in their structure. The parent pyrido (1, 2‐a) benzi‐midazole itself has been previously used in the synthesis of a variety of dyes and pigments.