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Oxygen‐atom transfer chemistry of α‐AZO hydroperoxides: Effect of competitive intramolecular hydrogen bonding and α‐methyl substitution
Author(s) -
Baumstark Alfons L.,
Vasquez Pedro C.
Publication year - 1988
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610010503
Subject(s) - chemistry , medicinal chemistry , intramolecular force , reactivity (psychology) , yield (engineering) , benzene , hydrogen atom , photochemistry , sulfoxide , oxygen , organic chemistry , medicine , materials science , alternative medicine , alkyl , pathology , metallurgy
1‐(Phenylazo)‐1‐(2‐pyridyl)ethyl hydroperoxide, 1 , 1‐(phenylazo)‐1‐(2‐furyl)ethyl hydroperoxide, 2 , phenylazo(2‐furyl)methyl hydroperoxide, 3 , 1‐(phenylazo)‐1‐(4‐anisyl)ethyl hydroperoxide, 4 , were synthesized in moderate yield by autoxidation of the phenylhydrazones in benzene. The ionic oxidation of benzyl methyl sulfide in benzene by 1‐4 yielded the sulfoxide and the metastable α‐azo hydroxides in essentially quantitative yield. The reaction was of the first order in α‐azo hydroperoxide and sulfide, respectively. The relative reactivity series found was: 1 (1.0) < 4 (1.4) < phenylazo(4‐anisyl)methyl hydroperoxide 5 (2·9) < 2 (3·8) < 3 (9·6). α‐Methyl substitution was found to slow the rate of oxygen‐atom trasfer by a factor of 2 to 2.5. The low relative reactivity of 1 was opposite that expected based on electronic effects. Competitive intramolecular hydrogen bonding of the hydroperoxy proton to the pyridyl nitrogen in 1 accounted for the observed result.