Related Experiment Video
Updated: Jul 6, 2026

Facile Preparation of 4-Substituted Quinazoline Derivatives
Published on: February 15, 2016
Charge transfer interaction of 4-acetamidophenol (paracetamol) with 2,3-dichloro-1,4-naphthoquinone: a study in
Avijit Saha1, Amit S Tiwary, Asok K Mukherjee
1Department of Chemistry Jogesh Chandra Chaudhuri College, 30-Prince Anwar Shah Road, Kolkata 700033, India.
Abstract:
4-Acetamidophenol (paracetamol) is shown to form charge transfer complex with 2,3-dichloro1,4-naphthoquinone in aqueous ethanol media exhibiting the unusual 2:1 (paracetamol:quinone) stoichiometry. The complexation enthalpy and entropy have been estimated from the formation constant (K) determined spectrophotometrically at five different temperatures. In aqueous ethanol mixtures of varying composition K increases with increasing dielectric constant of the medium. This has been rationalized by calculating the electronic charge distribution in paracetamol molecule and its conjugate base at the DFT/B3LYP/6-31++G(d,p) level. The theoretically calculated vertical ionization potential of paracetamol also agrees with reported experimental value.
Related Concept Videos
IR and UV–Vis Spectroscopy of Carboxylic Acids
However, the stretching absorptions for the C=O bond vary depending on the structure of carboxylic acids. The C=O bond of the free carboxylic acids shows a higher stretching frequency, 1760 cm−1, while H-bonded carboxylic acids (dimers) exhibit stretching absorptions at a lower frequency, 1710 cm−1. The C=O bond of the...
IR and UV–Vis Spectroscopy of Aldehydes and Ketones
Acidity and Basicity of Alcohols and Phenols
¹H NMR Signal Integration: Overview
¹³C NMR: Distortionless Enhancement by Polarization Transfer (DEPT)
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

