Cellulose sulfate: An efficient heterogeneous catalyst for the ring-opening of epoxides with alcohols and anilines

Abstract

Cellulose sulfate was synthesized by esterification of α-cellulose with concentrated sulfuric acid at −10°C in ethanol. Cellulose is mainly sulfated on 3-, 6- and 3, 6-positions of the cellulose. It acts as a heterogeneous catalyst for the ring-opening of epoxides with alcohols or anilines and the Friedel-Crafts reaction between N-benzylindole and crotonaldehyde at room temperature. Methanolysis of cyclic epoxides, styrene oxide, terminal aliphatic epoxides, and glycidyl ethers were carried out using the catalyst (0.4–6.8 mg/mmol of epoxide) and afforded the corresponding products in 53–97% isolated yields after 10 min–24 h. Cellulose sulfate was successfully recycled and reused up to 3 catalytic cycles for the ring-opening of styrene oxide with methanol.

Graphical Abstract

Keywords:

• Alcoholysis
• cellulose sulfate
• Friedel–Crafts reaction
• heterogeneous catalyst
• methanolysis

Acknowledgments

PC and Deepa are thankful to CSIR and UGC, respectively for the Senior Research Fellowship (SRF). We are also thankful to Synthesis with Catalyst Pvt. Ltd., India for gifting the (S)-styrene oxide.

Additional information

Funding

SS acknowledges the CSIR, DST-PURSE, and DST-SERB, India for funding. We are thankful to USIC, University of Delhi, Delhi, India for the instrumentation facility and DST-FIST for funding for the NMR spectrometer.