novel addition products of isocyanates with oxyalkylene - substituted aminophenol compounds as intermediates for the production of urethane - substituted xanthene colorants , particularly triphenylmethane derivatives such as rhodamines , are provided . the xanthene colorants exhibit improved wax and / or oil solubility and high purity . the urethane - substituted xanthene colorant features very good wax and / or oil solubility , and is believed to be relatively nontoxic . a method for producing this novel colorant is also provided .