Reactions of perchlorofluoro compounds VI. Rearrangement of higher perchlorofluoroolefins and their reactions with nucleophiles and electrophiles

Abstract

The fluoride ion induced isomerization of CFCl 2CF 2CFClCF 2CFCF 2 ( 1 ) gave only trans isomer CFCl 2CF 2CFClCFCFCF 3, ( 2 ), then trans CFCl 2CF 2CClCFCF 2CF 3 ( 3 ) and trans CFCl 2CF 2CFCFCF 2CF 3 ( 4 ), with the latter in predominance, while AlCl 3-catalyzed isomerization of 1 gave only 2 and then 3 . No cis isomer could be detected. Such isomerization was terminated once a chlorine atom was linked to the double bond. Reactions of perchlorofluoroolefins 1 , 2 and 3 with various nucleophiles have been studied. With terminal olefin 1 , C-1 was exclusively attacked by nucleophiles with the formation of three kinds of products[1]. In 2 , merely C-2 was attacked and as a chlorine atom was just located at the allylic position, the reaction only proceeded through a S N2′ mechanism. In 3 , only C-4 was attacked and no protonation product could be found. Competitive reaction showed the reactivity of these three perchlorofluoroolefins decreased in this order: 1 > 3 > 2 , which was directly related to the polarity of double bond. Only 1 reacted with electrophiles under normal conditions.