3(2H)-Benzoxazolepropanesulfonic acid, 2-(4-(1,3-dibutyltetrahydro-2,4,6-trioxo-5(2H)-pyrimidinylidene)-2-butenylidene)-, sodium salt 58823-12-4 MC 540 Merocyanine 540 Merocyanine dye Sodium 2-(4-(1,3-dibutyltetrahydro-2,4,6-trioxo-5(2H)-pyrimidinylidene)-2-butenylidene)-3(2H)-benzoxazolepropanesulfonate