About the reaction of aryl fluorides with sodium sulfide: investigation into the selectivity of substitution of fluorobenzonitriles to yield mercaptobenzonitriles via SNAr displacement of fluorine

In this report we describe a simple synthesis of mercaptobenzonitriles from the reaction of fluorobenzonitriles with Na2S in DMF at room temperature and following direct treatment with Zn/HCl. Significantly, 2- and 4-fluorobenzonitriles substituted with chlorine or bromine, but not iodine, undergo selective substitution of fluorine at room temperature to yield synthetically useful halo-substituted mercaptobenzonitriles.