281
6.2.2 Estimation of 19 F Chemical Shifts of Substituted Fluoroethylenes
(δ in ppm relative to CFCl 3 ) [3]
δ C=CF = -133.9 + Z cis + Z trans + Z gem + S cis/trans + S cis/gem + S trans/gem
Substituent R
Z cis
Z trans
Z gem
–H
-7.4
-31.3
49.9
–CH 3
-6.0
-43.0
9.5
–CF 3
-25.3
-40.7
54.3
–CH=CH 2
–
–
47.7
–CF=CF 2
-23.8
-38.9
44.7
–phenyl
-15.7
-35.1
38.7
–F
0.0
0.0
0.0
–Cl
-16.5
-29.4
–
–Br
-17.7
-40.0
–
–I
-21.3
-46.3
17.4
–OC 2 H 5
-77.5
–
84.2
–SCH 3
-25.1
-43.7
16.6
–COF
-46.5
-56.8
54.1
Substituent
Substituent
S cis/trans
S cis/gem
S trans/gem
–H
–H
-26.6
–
2.8
–H
–CF 3
-21.3
–
–
–H
–CH 3
–
11.4
–
–H
–OCH 2 CH 3
-47.0
–
–
–H
–phenyl
-4.8
–
5.2
–CF 3
–H
-7.5
-10.6
12.5
–CF 3
–CF 3
-5.9
-5.3
-4.7
–CF 3
–CH 3
17.0
–
–
–CF 3
–phenyl
-15.6
–
-23.4
–CH 3
–H
–
-12.2
–
–CH 3
–CF 3
–
-13.8
-8.9
–CH 3
–phenyl
–
-19.5
-19.5
–OCH 2 CH 3
–H
-5.1
–
–
–phenyl
–H
–
–
20.1
–phenyl
–CF 3
-23.2
–
–
R trans
F
R gem
R cis
6.2 19 F NMR Spectroscopy