@article{Azimi_Kefayati_2024, title={Cellulose sulfuric acid: an efficient biopolymer-based catalyst for the synthesis of 5H-dibenzo[b,i]xanthene-tetraones and spiro[dibenzo[b,i]xanthene-13,3′-indoline]-pentaones under solvent free conditions}, volume={3}, url={https://oiccpress.com/iranian-journal-of-catalysis/article/cellulose-sulfuric-acid-an-efficient-biopolymer-based-catalyst-for-the-synthesis-of-5h-dibenzobixanthene-tetraones-and-spirodibenzobixanthene-133-indoline-pentaones-under-solvent-free-condi/}, abstractNote={A practical and green method for the synthesis of 5H-dibenzo[b,i]xanthene-tetraones and spiro[dibenzo[b,i]xanthene-13,3’-indoline]-pentaones by the condensation of 2-hydroxynaphthalene-1,4-dione with aldehydes or isatins, respectively, in the presence of a catalytic amount of cellulose sulfuric acid (CSA) under solvent-free conditions at 100 °C is described. The significant features of this procedure are high yields of the products, simple work-up, solvent-free conditions, operational simplicity and non-toxicity of the catalyst. Moreover, cellulose sulfuric acid is successfully reused for four cycles without significant loss of activity.}, number={3}, journal={Iranian Journal of Catalysis}, publisher={OICC Press}, author={Azimi, Seyyedeh Cobra and Kefayati, Hassan}, year={2024}, month={Feb.}, keywords={Solvent-free, Xanthenes, 2-Hydroxynaphthalene-1, 4-dione, Cellulose sulfuric acid} }