Charge transfer interaction of 4-acetamidophenol (paracetamol) with 2,3-dichloro-1,4-naphthoquinone: a study in aqueous ethanol medium by UV-vis spectroscopic and DFT methods.
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.
Saha
Avijit
A
Department of Chemistry Jogesh Chandra Chaudhuri College, 30-Prince Anwar Shah Road, Kolkata 700033, India.
Tiwary
Amit S
AS
Mukherjee
Asok K
AK
D000082:Acetaminophen / Q000737:chemistry*; D004563:Electrochemistry; D000431:Ethanol; D015394:Molecular Structure; D009285:Naphthoquinones / Q000737:chemistry*; D012996:Solutions; D013053:Spectrophotometry; D013056:Spectrophotometry, Ultraviolet; D013816:Thermodynamics; D014867:Water
D009285:Naphthoquinones; D012996:Solutions; D014867:Water; D000082:Acetaminophen; D000431:Ethanol; C007332:dichlone