Related Experiment Video
Updated: Jul 23, 2026

Defining Substrate Specificities for Lipase and Phospholipase Candidates
Published on: November 23, 2016
Lipophilicity of the nitrophenols
1Department of Chemistry, University College London, 20 Gordon Street, London, UK WC1HOAJ, and Department of Chemistry, Cardiff University, Cardiff, U.K. CF1 3TB.
Abstract:
The lipophilicity of the nitrophenols, expressed as a water-solvent partition coefficient, P, has been investigated using the solvation equation, log P = c + eE + sS + aA + bB + vV. It is shown that this equation accounts quantitatively for lipophilicity in a selection of water-solvent systems, viz: octanol, 1,2-dichloroethane, and cyclohexane. In the latter two systems, the major factor in the increased lipophilicity of 2-nitrophenol over 3- and 4-nitrophenol is the lack of hydrogen bond acidity of 2-nitrophenol. The water-octanol system differs in that the a coefficient is effectively zero, so that hydrogen bond acidity of solutes plays no part, and the three mononitrophenols then have similar lipophilicities. The dinitrophenols and picric acid are similarly discussed. The hydrogen bond acidity of 2,3-dinitrophenol (0.67) is very much larger than that of 2,4- or 2,5-dinitrophenol (0.09 and 0. 11), indicating a very much reduced internal hydrogen bonding. A similar but much smaller effect occurs with 2,6-dinitrophenol (A = 0. 17). Picric acid has a moderate hydrogen bond acidity (0.46) so that the phenolic OH is still available for external hydrogen bonding. These results are confirmed by ab initio calculations which show that 2,3- and 2,6-dinitrophenol and picric acid are significantly distorted away from planarity, which apparently disrupts their internal hydrogen bonding.
More Related Videos
09:32A New Straightforward Method for Lipophilicity (logP) Measurement using 19F NMR Spectroscopy
Published on: January 30, 2019
07:30A Direct, Regioselective and Atom-Economical Synthesis of 3-Aroyl-N-hydroxy-5-nitroindoles by Cycloaddition of 4-Nitronitrosobenzene with Alkynones
Published on: January 21, 2020
Related Concept Videos
Nucleophiles
Physical Properties of Alcohols and Phenols
Alcohols possess a higher boiling point than aliphatic hydrocarbons of similar...
Acidity and Basicity of Alcohols and Phenols
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3
Basicity of Aromatic Amines
Factors Affecting Dissolution: Drug pKa, Lipophilicity and GI pH
A drug's pKa and the pH of the gastrointestinal (GI) tract play crucial roles in drug...