Provided is a process for preparing a heterocycle by catalytic reaction of an aromatic dinitrile with an amino alcohol, wherein the process includes: initially charging into a reaction vessel the amino alcohol and a catalyst to produce a reaction mixture; adding the aromatic dinitrile into the reaction mixture, which is maintained at a reaction temperature, wherein no solvent other than the amino alcohol of formula (III) is added to the reaction mixture prior to and/or during the catalytic reaction; and after completion of the catalytic reaction, completely replacing, or substantially completely replacing, unreacted amino alcohol with a nonpolar solvent to obtain the heterocycle, wherein the unreacted amino alcohol is present in an amount of not more than 20 wt. %, preferably 3-10 wt. % or less, based on a total weight of the heterocycle.