Cucurbit[n]uril synthesis using ethan-1, 2-diyl bis (hydrogen sulfate): A greener reaction medium

[Display omitted] •EDSA used as a greener acid for the synthesis of cucurbit[n]urils replacing the conventional corrosive acids.•High yield for synthesized Cucurbit[7]uril CB[7].•One-pot-two-step synthesis using urea and glyoxal as a starting material.•Recyclability up to three cycles for EDSA. Inevitable use of strong mineral acids and limitations to their reusability is one of the major challenges associated with Cucurbit[n]uril (CB[n]) synthesis. Cucurbituril formation does not take place at acid concentrations less than 5 M [1]. Herein, we report an environmentally benign synthesis of cucurbit[n]urils using [ethan-1,2-diyl bis(hydrogen sulfate)] (EDSA) as a green reaction media. The merits of this protocol highlight easy method of catalyst preparation, safe handling and ready recyclability for at least three times and high purity of cucurbituril can be obtained. The reaction can also be carried out in kg scale. These advantages may rank ethane-1,2-diyl bis(hydrogen sulfate) as a catalyst of first choice for cucurbituril synthesis.