Azulenesquaric acid dyes that contain urethane groups

摘要

Azulenesquaric acid dyes of the formula <IMAGE> where L is substituted or unsubstituted C1-C12-alkylene, R1 is C1-C20-alkyl, C5-C7-cycloalkyl or substituted or unsubstituted phenyl and R2, R3, R4 and R5 are each independently of the others hydrogen or substituted or unsubstituted C1-C12-alkyl, with the proviso that when R5 is hydrogen the positions of the substituents CH2-L-O-CO-NHR1 and R4 on an azulene ring may also be interchanged within a ring in either or both of the azulene rings, derived from azulene intermediates that contain urethane groups, are suitable for use in an optical recording medium.