METHOD OF SYNTHESIZING TETRAFLUOROPHTHALONITRILE

摘要

A process for the preparation of compounds of the general formula C6Fx(CN)y, wherein x and y are whole integers whose sum equals 6. The process is particularly useful for the synthesis of fluorinated nitriled containing at least two cyano groups (y=2). Among the preferred compounds prepared is tetrafluorophthalonitrile, a key intermediate used as a building block in the pharmaceutical industry. In the process described, tetrafluorophthalonitrile is prepared by the reaction of a chlorinated compound of general formula C6Clx(CN)y wherein x and y are whole integers whose sum equals 6. Specifically, tetrachlorophthalonitrile is reacted with potassium fluoride in an aprotic solvent to prepare tetrafluorophthalonitrile. The fluoronitrile is produced in at least 80 % yield and a minimum purity of 98.5 %. Only one additional recrystallization is required to produce a material of > 99.5 % purity. In another embodiment, the crude tetrafluorophthalonitrile is recrystallized from a hydrocarbon alkane solvent to produce a product of > 99.5 % purity which can be used directly as an intermediate. This process represents an economical means to produce tetrafluorophthalonitrile on an industrial scale.