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

✍ Scribed by Yoshio Takeuchi; Noriaki Itoh; Toru Koizumi; Chisako Yamagami; Yoshito Takeuchi

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 533 KB
• Volume: 30
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.1260300111

✦ Synopsis

Abstract

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.