Method for marking hydrocarbons with substituted anthraquinones

摘要

A method for marking a liquid petroleum hydrocarbon. The method comprises adding to the liquid petroleum hydrocarbon at least one substituted anthraquinone dye having formula (I) wherein R¹ and R² independently are hydrogen, hydroxy, OR¹¹, amino or NR¹¹R¹²; R³ and R⁵ independently are alkyl, aryl, aralkyl, heteroalkyl or heterocyclic; R⁴ and R⁶ independently are hydrogen or alkyl; R⁷, R⁸, R⁹ and R¹⁰ independently are cyano, nitro or hydrogen, provided that at least two of R⁷, R⁸, R⁹ and R¹⁰ are cyano or nitro; R¹¹ is alkyl, aryl, aralkyl, heteroalkyl, heterocyclic or alkanoyl; R¹² is hydrogen or alkyl; and wherein the substituted anthraquinone dye(s) has an absorption maximum in the range from 690 nm to 1000 nm.