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Hydrogen transfer from 9,10‐dihydrophenanthrene to anthracene
Author(s) -
Billmers R.,
Brown R. L.,
Stein S. E.
Publication year - 1989
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550210602
Subject(s) - anthracene , chemistry , phenanthrene , hydrogen atom , reaction rate constant , radical , photochemistry , electron transfer , autocatalysis , hydrogen , kinetics , organic chemistry , catalysis , alkyl , physics , quantum mechanics
Kinetic studies of the transfer of hydrogen from 9,10‐dihydrophenanthrene to anthracene were done at 350°C in the liquid phase. Principal products were phenanthrene and 9,10‐dihydroanthracene. Autocatalysis occurred at low extents of reaction, where H‐transfer from 9,10‐dihydroanthracene to anthracene caused an increase in free radical concentrations. At higher extents of reaction, 9,10‐dihydroanthracene inhibited rates by diverting intermediate 9‐hydrophenanthryl radicals back to reactants. A quantitative kinetic model based on literature rate and thermodynamic data fits the observations well. A key net reaction is the transfer of an H‐atom from a radical (9‐hydrophenanthryl) to a molecule (anthracene). It is shown that this process does not involve a free H‐atom intermediate. The derived rate constant for this exothermic process (7.5 × 10 3 M −1 s −1 ) is considerably greater than that for the related, but thermoneutral H‐transfer between anthracene moieties (120 M −1 s −1 ).