244064-79-7Relevant academic research and scientific papers
Correlation analysis of carbonyl carbon 13C NMR chemical shifts, IR absorption frequencies and rate coefficients of nucleophilic acyl substitutions. A novel explanation for the substituent dependence of reactivity
Neuvonen, Helmi,Neuvonen, Kari
, p. 1497 - 1502 (1999)
Rate coefficients of nucleophilic acyl substitutions, carboxylate carbon 13C NMR chemical shift values and v(C=O) frequencies of several series of aryl and acyl substituted aryl acetates or alkyl benzoates have been investigated. An increasing electron-withdrawal by the acyl or aryl substituents results in higher reaction rates, upfield 13C NMR chemical shifts and higher frequencies of the C=O stretching. Good correlations are observed for the log k versus δC(C=O) plots. The increase of the reaction rate with increased electron density at the C=O carbon (as proved by 13C NMR shifts) contradicts the previous concept of increased electrophilicity of the carbonyl carbon by electron-withdrawing substituents. The rate increase is now attributed to the decrease of the ester ground state resonance stabilization caused by electron-withdrawing substituents. The use of log k versus δc(C=O) correlations is presented as a practical method to evaluate rate coefficients especially for compounds for which Hammett type correlations cannot be used.
"Naked" Hydrogencarbonate Ion as a Bifunctional Catalyst toward Amide Substrates. Nucleophilic Ion Pairs. 9.
Shinkai, Seiji,Nakashima, Naotoshi,Kunitake, Toyoki
, p. 840 - 845 (2007/10/02)
The cleavage of amide substrates(p-nitro-N-methyltrifluoroacetanilide and p-nitro-N-methyldichloroacetanilide) with anionic nucleophiles was studied at 30 deg C in aprotic (acetonitrile and N,N-dimethylformamide) and protic (ethanol) media.Hydrogencarbona
