130778-81-3Relevant academic research and scientific papers
Kinetic and thermodynamic control of pseudobase formation from C-3 substituted 1-methylquinolinium cations
Bunting, John W.,Fitzgerald, Norman P.
, p. 1301 - 1307 (2007/10/02)
The kinetic and thermodynamic control of pseudobase formation from 3-W-1-methylquinolinium cations has been studied for a variety of substituents (W).Spectral data indicate that, in both aqueous and methanolic solution, the C-2 pseudobases predominate at equilibrium for W=H and Br, while the C-4 pseudobases are thermodynamically preferred species for W=CONH2, CO2CH3, CN, and NO2.Stopped-flow studies indicate that in all cases the C-2 pseudobases are the kinetically-controlled products upon basification of the aqueous solutions of these cations.Equilibrium constants (pKR+) have been measured for pseudobase formation at both C-2 and C-4 for each W in all cases where they are experimentally accessible.Substituent effects upon pK2R+ correlate with ?m for W, while pK4R+ depends upon ?-p.These substituent effects allow the prediction of pK2R+ = 15.4 and pK4R+ = 17.4 for the 1-methylquinolinium cation.Rates of C-2 to C-4 pseudobase equilibration have been measured in all cases where the latter species is thermodinamically more stable.These kinetic data allow the evaluation of rate constants for C-4 pseudobase equilibration with each cation.In all cases except W=CN, C-2 pseudobase formation is complete within the mixing time of the stopped-flow instrument.
