68059-83-6Relevant academic research and scientific papers
Effects of neutral and charged substituents on the infrared carbonyl stretching frequencies in phenyl and alkyl benzoates in DMSO
Nummert, Vilve,Piirsalu, Mare,Vahur, Signe,Toom, Lauri,Leito, Ivo,Koppel, Ilmar A.
supporting information, (2017/02/23)
The carbonyl infrared stretching frequencies for 57 meta-, para- and ortho-substituted phenyl benzoates, C6H5CO2C6H4-X and alkylbenzoates, C6H5CO2R, containing besides neutral substituents the charged substituents in phenoxy and alkoxy part in dimethyl sulfoxide (DMSO) have been recorded. The carbonyl stretching frequencies, νCO, for meta- and para-substituted phenyl esters of benzoic acids in the case of neutral substituents were found to correlate well with the substituent constants, σ°. The νCO values for ortho derivatives correlated with the inductive substituent constants, σI, only. The values of constants for charged substituents, σ°±, calculated on the basis of the νCO and the 13C NMR chemical shifts, δCO, in DMSO agree well with the σ°± values for the corresponding ion pairs reported by Hoefnagel and Wepster and those determined from the log k values of the alkaline hydrolysis in 4.4 M NaCl solution at 50 °C. Thus, the values of substituent constants for ion pairs of charged substituents estimated on the basis of aqueous data could be successfully used in non-aqueous solution (DMSO) simultaneously with neutral substituents in case the charged substituents were not completely ionized and are in ion pair form. Copyright
