Efficient combination of ionic liquids and microwave irradiation as a green protocol for polycondensation of 4-(3-hydroxynaphthalene)-1,2,4-triazolidine-3,5-dione with diisocyanates

In this investigation, a novel urazole containing 3-hydroxynaphthalene group, 4-(3-hydroxynaphthalene)-1,2,4-triazolidine-3,5-dione (3HNTD) was synthesized in six steps starting from 3-hydroxy-2-naphthalene carboxylic acid. The reaction of 3HNTD with n-propylisocyanate was performed in N,N-dimethylacetamide solution at different molar ratios, and the resulting monosubstituted as well as disubstituted urea derivatives were obtained in high yields and were used as model compounds for polymerization studies. An efficient, fast and easy method for the preparation of new soluble poly(urea-urethane)s (PUU)s containing heterocyclic and chromophoric moieties from 3HNTD and various diisocyanates are employed using room temperature ionic liquids and molten tetrabutylammonium bromide under microwave irradiation as well as conventional heating. The polymerization reactions occurred rapidly under microwave and produced a series of PUUs with good yields and moderate inherent viscosities of 0.21–0.46 dL/g. All of the new PUUs showed good solubility and were readily dissolved in organic solvents.