Online article for Non-subscribers

Pay per view

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact:

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

Paper | Regular issue | Vol 32, No. 6, 1991, pp.1123-1130
Published online, 1st January, 1970
DOI: 10.3987/COM-91-5697
Acid-Base Properties of 4-Substituted Indoles

Manuel Balón,* Carmen Carmona, Jose Hidalgo, Maria A. Muñoz, and Pilar Guardado

*Departmento de Química Física, Facultad de Farmacia, Universidad de Sevilla, 41012 Sevilla, Spain


The protonation and deprotonation equilibria of a set of 4-substituted indoles have been studied spectrophotometrically at 25 °C. Ionization data have been analyzed by the Hammett acidity function and the excess acidity methods. The existence of close relationships between the Hammett’s σM constants of the substituents and the ionization constants for both types of aicd-base equilibria is reported.