1,3-Dipolar cycloadditions. XXXII. Kinetics of the addition of organic azides to carbon-carbon multiple bonds

Abstract

cf. preceding abstr. The ir spectrophotometrically-detd. addn. consts. of phenyl azide to 27 olefinic and 4 acetylenic dipolarophiles at 25 Deg are of the 107 order of magnitude. The interaction between electronic and steric substitution effects on the dipolarophiles is discussed. The addn. rates of the ring-substituted phenyl azides obeyed the Hammett equation; the r values depended on the dipolarophile, and are as follows: maleic anhydride -1.1, N-phenylmaleimide -0.8, norbornene 0.88, cyclopentene 0.9, 1-pyrrolidinocyclohexene 2.5. The activation entropies for cycloaddn. of the 4 azides are -26 to -36 cal./mole degree. The addn. const. of phenyl azide to pyrrolidinocyclopentane depends only slightly on the polarity of the solvent. The cycloaddn. of azides seems to be a multicenter reaction. [on SciFinder (R)]