13 C and 19 F nuclear magnetic resonance spectra of multisubstituted methanes

The 13 C and 19 F (when appropriate) chemical shifts of a variety of di‐, tri‐ and tetrasubstituted methanes of the type CH 2 XCOOEt (I), CHXYCOOEt (II) and CXYZCOOEt (III), where the substituents X, Y and Z are F, Br, OEt, OPh, SEt, SPh and NO 2 , were determined. The prediction of the observed C‐α chemical shifts of I, II and III based on the simple additivity of substituent effects in monosubstituted methanes [MeX; SCS(IV)] is not satisfactory, although those of I are well correlated with SCS (IV). The C‐α chemical shifts of II and III can be correlated in terms of the multi‐parameter analysis of individual SCS (I), the difference between δ (CH 2 XCOOEt) and δ (CH 3 COOEt). The origin of the chemical shifts is discussed. The 19 F chemical shifts of I, II and III were also satisfactorily analysed in terms of σ I and σ   R 0 .