Hydrolysis of Certain 5-Aminodibenzo[a, d]cycloheptanes

Labilization of C—N Linkages by Dibenzocyclohepten-5-yl Ring System

“…Relative Reactivities-Removal of two hydrogen atoms and subsequent aromatization of the dibenzocycloheptane nucleus bring about almost a 100-fold enhancement of the rate constants, k cycioheptene/k cycioheptane, for the molecules with the same amino substituents a t position 5 of the ring. The kene/kane values are 79, 87, and 204 for the diethylamino, pyrrolidino, and piperidino analogs, respectively, within the rate constant data for the 10.11-dihydro congeners taken from previously published results (7). That 1000 100 L 1 i the fully aromatic structures (11) react so rapidly is not as disconcerting as the fact that the hydrogenated analogs (I) react at all, because the opportunity for formation of the tropylium ion is not afforded in these molecules.…”

“…Several 5-aminodibenzo[a.d]cycloheptanes were recently reported to undergo cleavage a t the C-N bond in aqueous acid by a route that may be visualized as proceeding uia a carbonium ion or a kinetically equivalent mechanism (7). From the standpoint of resonance-stabilized structures, these 5-aminodibenzocycloheptanes (I) allow spreading of the positive charge over seven carbon atoms, presumably leading to the observed high reactivity.…”

“…Evaluation of R a t e Constants-Decomposition of the various 5-aminodibenzocycloheptenes (11) in aqueous solution (pH 7 and below) was monitored by colorimetry using the acid-dye method with methyl orange as the anionic component (7,13). Complexes were of the amines (Tables I and 11) and methyl orange (1:l).…”

“…Complexes were of the amines (Tables I and 11) and methyl orange (1:l). The molecularity was determined by extraction of a fixed quantity of amine in p H 3.44 buffer with increasing amounts of methyl orange indicator (7). Small discrepancies from the equimolar ratio were the result of volatile impurities-likely water-in the methyl orange indicator.…”

“…renes (Tables I a n d 11)-The compounds in Table I Solution Preparation a n d Solvents-The pH 3.44 citrate buffer and methyl orange solution were prepared as previously stated (7).…”