Schiff base equilibria. II. Beryllium complexes of N-n-butylsalicylideneimine and the hydrolysis of the Be²⁺ ion

Abstract

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.