Premium
Acidity constants of benzimidazolium ketone and pyridinium aldehyde hydrates
Author(s) -
Owen Terence C.
Publication year - 1990
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570270431
Subject(s) - chemistry , pyridinium , pyridine , aldehyde , ketone , hydrate , medicinal chemistry , salt (chemistry) , inorganic chemistry , organic chemistry , catalysis
Acidity constants (p K a) of the hydroxyl groups of the quaternary heterocyclonium carbinols 2‐hydroxy‐methyl‐1‐methylpyridinium and 2‐(1‐hydroxyethyl)‐1,3‐dimethylbenzimidazolium ions are 11.5 ± 0.5. Acidity constants of the corresponding gem diols, the hydrates of 2‐formyl‐1‐methyl‐pyridinium and 2‐acetyl‐1,3‐dimethylbenzimidazolium ions hence are estimated to be 9 ± 0.5. Accordingly, acidity constants of the hydroxyl groups of pyridine aldehyde salt hydrates are 12–13, not 4–5 as previously reported; and conversely, acidity constants of the pyridinium groups are 4–5, not 12–13.