title: Proton transfer from 2-naphthol to aliphatic amines in supercritical CO2.
abstract: The proton transfer from 2-naphthol to aliphatic amines was studied in supercritical CO(2) (scCO(2)) and in cyclohexane as reference solvent, by absorption and fluorescence spectroscopy and by time-resolved emission. Irradiation of 2-naphthol in scCO(2) in the presence of ethyldiisopropylamine shows dynamic fluorescence quenching of the acidic form of 2-naphthol and emission from the basic form. Fluorescence excitation spectra show that the emission of the basic form is originated upon excitation of the acidic form. The interaction between 2-naphthol and the amines is described by the formation of a complex with proton donor-acceptor character in the ground and excited states of 2-naphthol. The acidity increase of 2-naphthol upon electronic excitation to the first excited singlet in scCO(2) is as high as in water. Proton transfer quantum yields of 0.6 can be easily achieved in scCO(2). The results have implications for carrying out acid-base catalyzed reactions in scCO(2).
authors.affiliation: INQUIMAE and Departamento de Química Inorgánica, Analítica y Química Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Simoncelli
authors.forename: Pablo A
authors.initials: PA
authors.lastname: Hoijemberg
authors.forename: M Laura
authors.initials: ML
authors.lastname: Japas
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Aramendía
mesh_terms: D000143:Acids / Q000737:chemistry; D000473:Alkanes / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D002245:Carbon Dioxide / Q000737:chemistry*; D002384:Catalysis; D002627:Chemistry, Physical; D003080:Cold Temperature; D003510:Cyclohexanes / Q000737:chemistry; D005453:Fluorescence; D006860:Hydrogen Bonding; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D015394:Molecular Structure; D009284:Naphthols / Q000737:chemistry*; D011312:Pressure; D011522:Protons; D012997:Solvents / Q000737:chemistry; D013050:Spectrometry, Fluorescence; D014867:Water
chemical_list: D000143:Acids; D000473:Alkanes; D000588:Amines; D003510:Cyclohexanes; D009284:Naphthols; D011522:Protons; D012997:Solvents; D014867:Water; D002245:Carbon Dioxide; C506365:Cyclohexane; C028405:2-naphthol