Tricarbon dioxide orCarbon suboxideis anoxideofcarbonThe linearoxocarbonhaving threecarbonatoms. Chemical formulaC3O2or O=C=C=C=O It is synthesized by warming a dry mixture ofphosphorus pentoxide(P4O10) andmalonic acidor theestersofmalonic acid. It is used as anauxiliary to improve the dye affinity of furs