Process for producing N,N′-carbonyldiimidazole

123 The present invention provides a process for producing N,N′-carbonyldiimidazole, comprising: reacting phosgene, diphosgene, or triphosgene with imidazole in an inert solvent to produce N,N′-carbonyldiimidazole; to imidazole hydrochloride yielded as a by-product in the above step, adding a gaseous or liquid basic compound represented by the below-shown general formula (1) in an inert solvent to conduct neutralization reaction; and circulating the imidazole thus generated to use it as a starting material for N,N′-carbonyldiimidazole production.In the general formula (1), R, R, and Reach independently represents a hydrogen atom, a methyl group, or an ethyl group. The CDI produced by the production process of the invention is a compound useful in the fields of synthesis of pharmaceutical agents, synthesis of agricultural chemicals, peptide synthesis, and the like, e.g., intermolecular condensation reactions, intramolecular condensation reactions for synthesizing N-carboxylic anhydrides, production of activated esters, and the like. The compound is especially suitable for use in applications where colorlessness is required.