4711-72-2Relevant articles and documents
Substituent Effects on Carbon-13 NMR Chemical Shifts of Side-chain Carbons in 5-Aryl-2E,4E-pentadienoic Acid Derivatives
Banerji, Avijit,Ghosal, Tapasree,Acharyya, Aditi K.
, p. 546 - 549 (2007/10/02)
The 13C NMR spectra of two series of 5-aryl-2E,4E-pentadienoic acid derivatives, viz. the methyl esters and piperidides have been determined.The chemical shifts of C-2 and C-4 show very good correlations with the Hammett ?+-constants for all the substituents investigated, except for the para-nitro group which is capable of excerting a strong -R effect.A possible explanation for this has been advanced.Hammett correlations between substituents and the chemical shifts of both C-3 and C-5 carbons using ?0 parameters are less satisfactory.A reverse chemical shift effect has been observed for these two centres.