2-(2-Hydroxyphenyl)-2H-benzotriazoles

2-(2-Hydroxyphenyl)-2H-benzotriazoles, also referred to as phenolic benzotriazoles, are an important class of UV absorbers^[1] comprising the benzotriazole building block.

General structural formula of 2-(2-hydroxyphenyl)-2H-benzotriazoles

Structure

The molecules are composed of substituted benzotriazoles with a phenyl group in the 2-position, which carries a hydroxy group in the ortho-position.^[2]

Examples of 2-(2-hydroxyphenyl)-2H-benzotriazoles

Name	Acronym	Structural formula	R1	R2	R3
2-(2H-Benzotriazol-2-yl)-4-methylphenol	UV-P		–	methyl	–
2-(2H-Benzotriazol-2-yl)-4-tert-butylphenol	UV-PS		–	tert-butyl	–
2-(2H-Benzotriazol-2-yl)-4,6-bis(2-phenyl-2-propanyl)phenol	UV-234		(2-propanyl)phenol	(2-propanyl)phenol	–
2-(2H-Benzotriazol-2-yl)-4,6-di-tert-butylphenol	UV-320		tert-butyl	tert-butyl	–
2-(5-Chloro-2H-benzotriazol-2-yl)-4-methyl-6-di-tert-butylphenol	UV-326		tert-butyl	methyl	chlorine
2-(5-Chloro-2H-benzotriazol-2-yl)-4,6-di-tert-butylphenol	UV-327		tert-butyl	tert-butyl	chlorine
2-(2H-Benzotriazol-2-yl)-4,6-di-tert-pentylphenol	UV-328		tert-pentyl	tert-pentyl	–
2-(2H-Benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol	UV-329		–	1,1,3,3-tetramethylbutyl	–
2-(2H-Benzotriazol-2-yl)-6-(sec-butyl)-4-(tert-butyl)phenol	UV-350		sec-butyl	tert-butyl	–
2,2′-Methylenbis[6-(2H-benzotriazol-2-yl)-4-(2,4,4-trimethyl-2-pentanyl)phenol]	UV-360		[dimer linked via methylene group]	1,1,3,3-tetramethylbutyl	–
2-(2H-Benzotriazol-2-yl)-6-(2-phenyl-2-propanyl)-4-(2,4,4-trimethyl-2-pentanyl)phenol	UV-928		(2-propanyl)phenol	1,1,3,3-tetramethylbutyl	–

Use

2-(2-hydroxyphenyl)-2H-benzotriazoles are used as UV stabilizers in lacquers and plastics.^[2]