Processes are described which comprise: (a) providing a mixture comprising a cyclic formal and water, wherein the mixture has a cyclic formal concentration and a water concentration; (b) bringing the mixture into contact with an organically selective membrane; (c) creating a pressure differential across the membrane; and (d) obtaining a permeate having a lower water concentration and a higher cyclic formal concentration than the mixture, and a retentate having a higher water concentration and a lower cyclic formal concentration than the mixture.