Pulse radiolysis of trans-1,2-bis(4-pyridyl)ethylene in aqueous solution

Journal Article · Thu May 16 04:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100163a021· OSTI ID:5889597

Goerner, H; Koltzenburg, G; Schulte-Frohlinde, D ^[1]

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1. Max-Planck-Inst. fuer Strahlenchemie, Muelheim an der Ruhr (West Germany)

Pulse radiolysis with optical and conductometric detection techniques was used to study the reactions of hydrated electrons (e{sub aq}{sup {minus}}), H atoms, 2-hydroxy-2-propyl radicals, and OH radicals with trans-1,2-bis(4-pyridyl)ethylene (neutral form: M) and its conjugate acids HM{sup +} and H{sub 2}M{sup 2+} in aqueous solution. Electron attachment to M leads to a transient with {lambda}{sub max} = 455 nm ({epsilon} = 4.0 {times} 10{sup 4} dm{sup 3} mol{sup {minus}1} cm{sup {minus}1}) at pH 11-12 and to another transient ({lambda}{sub max} = 500 nm, {epsilon} = 5.2 {times} 10{sup 4} dm{sup 3} mol{sup {minus}1} cm{sup {minus}1}) at pH 6-9. The 455-nm transient is assigned to a neutral H-adduct radical (HM{sup {sm bullet}}, H attached to an N atom), formed via reaction of water with the radical anion. The 500-nm transient is assigned to H{sub 2}M{sup {sm bullet}+}, the conjugate acid of HM{sup {sm bullet}}, with both H's at the N's; pK{sub a} = 9.8. At pH 4-6 H{sub 2}M{sup {sm bullet}+} is also formed by reactions of e{sub aq}{sup {minus}} or H atoms with HM{sup +} and H{sub 2}M{sup 2+} (at pH 1-5) quantitatively to H{sub 2}M{sup {sm bullet}+} but does not react with neutral M. Three OH-adduct radicals were observed in different pH regions. M{sup {sm bullet}}OH, a neutral radical ({lambda}{sub max} = 392 nm), and its conjugate acid (HM{sup {sm bullet}+}OH, {lambda}{sub max} = 410 nm) have a pK{sub a} of about 6; at pH {le} 4.5 the latter radical is converted by acid catalysis into an isomer with {lambda}{sub max} = 510 nm. Structural assignments are presented for all radicals observed. Some results with trans-1,2-bis(n-pyridyl)ethylene (n = 2 or 3) are also reported.

• OSTI ID: 5889597
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 95:10; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400600* -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
ACCELERATORS
ALKENES
ALKYL RADICALS
AQUEOUS SOLUTIONS
ATOMS
AZINES
CATALYSIS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTIONS
DATA
DECOMPOSITION
DISPERSIONS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELECTRON ATTACHMENT
ELECTRONS
ELECTROSTATIC ACCELERATORS
ELEMENTARY PARTICLES
ELEMENTS
ENERGY RANGE
EXPERIMENTAL DATA
FERMIONS
HETEROCYCLIC COMPOUNDS
HOMOGENEOUS CATALYSIS
HYDROCARBONS
HYDROGEN
HYDROXYL RADICALS
INFORMATION
LEPTONS
MEV RANGE
MIXTURES
MOLECULAR STRUCTURE
NONMETALS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PH VALUE
PHYSICAL PROPERTIES
PYRIDINES
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION INTERMEDIATES
REDUCTION
SOLUTIONS
SOLVATED ELECTRONS
SPECTRA
SPECTROSCOPY
TRANSIENTS
VAN DE GRAAFF ACCELERATORS
VISIBLE SPECTRA