Ionization equilibria of harmol and harmalol in concentrated hydroxide solutions
Abstract
The deprotonation equilibria of the β-carboline alkaloids harmol (1-methyl-9H-pyrido[3,4-b]indol-7-ol) and harmalol (4,9-dihydro-1-methyl-3H-pyrido[3,4-b]indol-7-ol) in concentrated potassium hydroxide have been examined by u.v. spectrophotometry at 25 °C. The pKavalues obtained using the Hammett and the Excess Acidity Functions are reported and compared with those of related compounds.