There is a large collection of substituent constant data measured in polar protic and polar aprotic solvents, but a lack of information on substituent effects in nonpolar aprotic solvents. In this study, substituent effects on the acidities of phenol derivatives were examined in CCl4 using infrared (IR) spectroscopy. The IR peak of the free phenolic -OH appears at approximately 3600 cm-1 which is red shifted in the presence of a hydrogen bond acceptor. The magnitude of the shift between the free and the hydrogen-bonded -OH peak is related to the acidity of the protic hydrogen. Deuterated acetonitrile was used as the hydrogen-bond acceptor to probe the relative acidities of 21 phenol derivatives in CCl4. While most phenol derivatives exhibited similar acidity trends in CCl4 as in DMSO and the gas phase, several demonstrated a reduction in acidity which indicates a solvent dependence on substituent effects. This study offers a facile method to examine substituent effects on the acidity of alcohols and has identified several solvent-dependent substituents.

Substituent and solvent effects: Examining acidity via infrared spectroscopy

249th National Meeting (2015)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.