A Convenient Protocol for the Synthesis of 2‐(2′‐Hydroxy‐5′‐carboxyphenyl)‐2H‐benzotriazole to Avoid Decarboxylation When Using p‐Hydroxybenzoic Acid as Coupling Component

In the study of the synthesis of 2‐(2′‐hydroxy‐5′‐carboxyphenyl)‐2 H ‐benzotriazole, we found that decarboxy intermediate‐4‐((2‐nitrophenyl)diazenyl)phenol was obtained when using p ‐hydroxybenzoic acid as coupling component. A convenient protocol for the synthesis of 2‐(2′‐hydroxy‐5′‐carboxyphenyl)‐2 H ‐benzotriazole is reported with methyl‐ p ‐hydroxybenzoate as coupling component. Different dizao components and different coupling components were also used for further investigation of decarboxylation.