preparation, characterization and use of sulfonylbis(1,4-phenylene)bis(sulfamic acid) as an eco-benign, efficient, reusable and heterogeneous catalyst for the synthesis of mono- and bis-chromenes

Sulfonylbis(1,4-phenylene)bis(sulfamic acid) (spsa) is easily prepared and recognized as a new heterogeneous catalyst by the reaction of 4,4′-sulfonyldianiline with chlorosulfonic acid. this reagent was used for the synthesis of the mono- and bis-chromene derivatives. all reactions were performed under mild reaction conditions in high to excellent yields. the advantages of using the spsa as a heterogeneous catalyst in these reactions are: being environmentally friendly, low cost, commercially availability and easy to separate from the mixture of the reaction and high reusable catalyst. using this catalyst, results in acceptable reaction time and high yields with high purity of the obtained products without utilizing any organic solvents. the catalyst was characterized by ft-ir, 1h nmr, 13c nmr, mass and tga studies. all the products were characterized by ft-ir, 1h, 13c nmr, hrms, melting point and elemental analyses.