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Oxidation of phenolates and phenylenediamines by 2-alkanonyl radicals produced from 1,2-dihydroxy- and 1-hydroxy-2-alkoxyalkyl radicals. [Pulsed irradiation]

Journal Article · · J. Phys. Chem.; (United States)
DOI:https://doi.org/10.1021/j100468a008· OSTI ID:6478438
Using pulse radiolysis with optical detection it is shown that the formylmethyl radical CH/sub 2/CHO reacts with phenolated XC/sub 6/H/sub 4//sup -/(X = H, alkyl, OCH/sub 3/, OH) by one electron oxidation to yield XC/sub 6/H/sub 4/O. With parasubstituted phenolates the rate constants for formation of XC/sub 6/H/sub 4/O increase with increasing electron-donating power of X (Hammett p=7.9). For X = OH (hydroquinone anion) the rate constant for the electron transfer reaction is 2.2 x 110/sup 9/M/sup -1/s/sup -1/. Replacement of H in CH/sub 2/CHO by alkyl or hydroxyalkyl groups leads to a decrease in the rate constants for oxidation of the hydroquinone anion. CH/sub 2/CHO is also able to oxidize o- and p- phenylenediamine and N,N'-tetramethyl-p-phenylenediamine (k = 7.3 x 10/sup 7/, 4.0 x 10/sup 8/, and 2.0 x 10/sup 9/M/sup -1/s/sup -1/, respectively). The 2-alkanonyl radicals were produced by elimination of OH/sup -/ or alkoxide from ionized 1,2-dihydroxyalkyl or 1-hydroxy-2-alkoxyalkyl radicals, respectively. For cyclic 1-hydroxy-2-alkoxyalkyl radicals elimination of alkoxide results in ring opening. The rate constants for elimination of OH/sup -/ from ionized 1,2-dihydroxyalkyl radicals R/sub 1/C(O/sup -/)CH(OH)R/sub 2/ are between 3 x 10/sup 6/s/sup -1/ (for R/sub 1/ = R/sub 2/ = H and R/sub 1/, R/sub 2/ = H, hydroxyalkyl) and greater than or equal to 8 x 10/sup 6/s/sup -1/ (for R/sub 1/ = R/sub 2/ = CH/sub 3/). 1 figure, 3 tables.
Research Organization:
Univ. of Notre Dame, Indiana
OSTI ID:
6478438
Journal Information:
J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 83:5; ISSN JPCHA
Country of Publication:
United States
Language:
English