The Schiff base,
N-n-butylsalicylideneimine, extracts more than 99.8% beryllium into toluene
from dilute aqueous solution. The distribution of beryllium has been studied in
the pH range 5-13 and is discussed in terms of the several complex equilibria in
aqueous solution. The stability constants of the complexes formed between
beryllium and the Schiff base are log β1 11.1 and log β2
20.4, and the distribution coefficient of the bis complex is 550. Over most of
the pH range, hydrolysis of the Be2+
ion competes with complex formation and provides a means of measuring the
hydrolysis constants. They are for the reactions: Be(H2O)42+
↔ 2H+ + Be(H2O)2(OH)2, log*β2
- 13.65; Be(H2O)42+ ↔ 3H+ + Be(H2O)(OH)3-,
log*β3 -24.11.
A fluorescent pH probe for an aqueous solution composed of 7-hydroxycoumarin, Schiff base and phenanthro[9,10-d]imidazole moieties (PICO)