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Electrophilic Substitution at Saturated Carbon. XXIX. Relationships between Position of Protonation of Allylic Anions and the Kinetic and Thermodynamic Stabilities of the Olefinic Products’ Stephen W. Ela2and Donald J. Cram Contribution No. 1953from the Department of Chemistry, The University of California at Los Angeles, Los Angeles, California 90024. Received August 15, 1966 Abstract: The relationship between the kinetic and thermodynamic stabilities of proton-tautomeric olefins and the
position of protonation of their derived allylic anions has been examined. The four 1,3-diphenylbutenes were synthesized, characterized, and interconverted in t-butyl alcohol-potassium t-butoxide. At 40 ” the equilibrium proportions were 32 trans-1,3-diphenyl-l-butene (I), 52 cis-1,3-diphenyl-2-butene(11), 15 trans-1,Zdiphenyl2-butene (111), and 1 cis-1,3-diphenyl-l-butene (IV). The second-order rate constants (l./mole sec) for isomIII,1.8 X and IV, 7.5 X lo-*. erization of the olefins at 40” were as follows: I, 5.1 X lo+; 11,3.2 X The ratio of rate constants for isotopic exchange and isomerization (k,/ki) was estimated for each olefin in t-butyl alcohol-0-d: 1,
