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Abstract

Reaction of diethylamine with 3-chlorononafluoro-1,5-hexadieae (I) in molar ratio of 1.5 : 1 to 2 : 1 at -30 to -17 °C gives N,N-diethyl-1,1,2,3,4,4,5,6,6-nonafluoro-2,5-hexadienylamine (II) which is easily hydrolyzed to N,N-diethyl-2,3,4,4,5,6,6-heptafluoro-2,5-hexadienamide (III). The same reaction with the molar ratio 4 : 1 at 0-6 °C and at 40 °C produces a mixture of N,N,N',N'-tetraethyl-1,1,2,3,4,5,6,6-octafluoro-2,4-hexadiene-1,6-diamine (IV), N,N,N',N'-tetraethyl-1,1,2,3,4,4,5,6,6-nonafluoro-2-hexene-1,6-diamine (V), and N,N,N',N'-tetraethyl-1,2,3,3,4,5,6,6-octafluoro-1,4-hexadiene-1,6-diamine (VI), which on hydrolysis gives N,N,N',N'-tetraethyl-2,3,4,5-tetrafluoro-2,4-hexadienediamide (VII) and N,N,N',N'-tetraethyl-2,3,4,4,5-pentafluoro-2-hexenediamide (VIII). Reaction of the mixture of diamines IV-VI with methanol or 1-propanol gives dimethyl or dipropyl 2,3,4,5-tetrafluoro-2,4-hexadienedioate (Xa,b), respectively. Stereospecificity of the chlorine substitution in perfluoroallyl grouping and the reaction mechanism are discussed. Conformation of the butadiene skeleton of these compounds is also discussed on the basis of calculation of ¹⁹F NMR spectra of trans,trans-2,3,4,5-tetrafluoro-2,4-hexadienedioic acid (IX) and its dimethyl ester Xa.