Controlling factors in the synthesis of cucurbituril and its homologues

The acid-catalyzed synthesis of cucurbit[n]urils from formaldehyde and glyc oluril is poorly understood. In this paper, we examine a wide range of reac tion conditions that include the effects of acid type, acid concentration, reactant concentrations, and temperature to both probe the mechanism and op timize the yields of isolated cucurbit[n]urils, where n = 5-10. A mechanism for the formation of these cucurbit[n]urils is presented. Individual cucur bit[n]urils were unambiguously identified in reaction mixtures using ESMS a nd C-13 NMR.