Abstract: A perfluoro unsaturated nitrile compound represented by the following general formula:CF.sub.2 .dbd.CFO(CF.sub.2)nOCF(CF.sub.3)CNis produced by reaction of chlorine or bromine to a perfluoro unsaturated carboxylic acid ester represented by the following general formula:CF.sub.2 .dbd.CFO(CF.sub.2)nOCF(CF.sub.3)COORfollowed by reaction with ammonia, thereby converting the ester group to an acid amide group, and then conducting a dehydration reaction and a dehalogenation reaction of the resulting perfluoro unsaturated carboxylic acid amide represented by the following general formula:CF.sub.2 .dbd.CFO(CF.sub.2)nOCF(CF.sub.3)CONH.sub.2in any desired sequence, and is effectively applied as a cross-linking site monomer for fluorine-containing elastomers.

Abstract: 2-Chloroacrylonitrile is prepared in a particularly advantageous and readily industrially practicable manner by chlorinating acrylonitrile and then thermally cleaving the 2,3-diehloropropionitrile formed, by chlorinating acrylonitrile in the presence of a catalyst system comprising dimethylformamide and pyridine and/or pyridine derivatives and subjecting the resulting crude 2,3-dichloropropionitrile to thermal cleavage in the presence of the same catalyst system without the addition of further catalysts.