Method of producing near-infrared absorbing dye compound

摘要

A method of producing a near-infrared absorbing dye compound, useful for image forming materials, infrared heat-sensitive recording devices, optical film materials, and the like, containing a process of reacting a compound represented by formula (I) with peroxomonosulfuric acid or its salt. wherein R¹¹¹, R¹¹², R¹²¹, R¹²², R¹³¹, R¹³², R¹⁴¹ and R¹⁴² each independently represent a hydrogen atom, an aliphatic group or an aromatic group; R¹⁰³, R¹¹³, R¹²³, R¹³³ and R¹⁴³ each independently represent a substituent; and n₁₀₃, n₁₁₃, n₁₂₃, n₁₃₃ and n₁₄₃ each independently denote an integer from 0 to 4.