Schiff base equilibria. VIII. Aqueous equilibria between salicylaldehyde and aliphatic diamines

1973 ◽  
Vol 26 (8) ◽  
pp. 1653 ◽  
Author(s):  
RW Green ◽  
PW Alexander ◽  
RJ Sleet
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Equilibrium Constants ◽  
Large Excess ◽  
Acid Base ◽  
Aliphatic Diamines

Equilibria between salicylaldehyde and three aliphatic diamines, ethylenediamine, trimethylenediamine, and 1,3-diaminopropan-2-ol, have been measured in aqueous solution containing a large excess of diamine to suppress hydrolysis. Equilibrium constants are reported for the formation and acid-base reactions of the mono-salicylideneimines formed from the three diamines. It is demonstrated that there are no conditions under which detectable concentrations of bis- salicylideneimines exist in aqueous solution.

scholarly journals Sensing Zn2+ in Aqueous Solution with a Fluorescent Scorpiand Macrocyclic Ligand Decorated with an Anthracene Bearing Tail

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1355 ◽  
Author(s):  
Matteo Savastano ◽  
Matteo Fiaschi ◽  
Giovanni Ferraro ◽  
Paola Gratteri ◽  
Palma Mariani ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Complex Formation ◽  
Metal Ion ◽  
Equilibrium Constants ◽  
Macrocyclic Ligand ◽  
Fluorescence Emission ◽  
Zinc Complexes ◽  
Large Excess ◽  
Macrocyclic Ring ◽  
Ph Range

Synthesis of the new scorpiand ligand L composed of a [9]aneN3 macrocyclic ring bearing a CH2CH2NHCH2-anthracene tail is reported. L forms both cation (Zn2+) and anion (phosphate, benzoate) complexes. In addition, the zinc complexes of L bind these anions. The equilibrium constants for ligand protonation and complex formation were determined in 0.1 M NaCl aqueous solution at 298.1 ± 0.1 K by means of potentiometric (pH-metric) titrations. pH Controlled coordination/detachment of the ligand tail to Zn2+ switch on and off the fluorescence emission from the anthracene fluorophore. Accordingly, L is able to sense Zn2+ in the pH range 6–10 down to nM concentrations of the metal ion. L can efficiently sense Zn2+ even in the presence of large excess of coordinating anions, such as cyanide, sulphide, phosphate and benzoate, despite their ability to bind the metal ion.

scholarly journals Schiff base equilibria. VII. Formation and distribution of N-(β-Hydroxyethyl)salicylideneimine

1969 ◽  
Vol 22 (5) ◽  
pp. 917 ◽  
Author(s):  
RW Green ◽  
RJ Sleet
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Formation Constant ◽  
Equilibrium Constants

The formation constant and pK of the Schiff base N-(8- hydroxyethyl)salicylideneimine in aqueous solution at 25� have been determined spectrophotometrically to be 5.01 x 103 and 11.4 respectively. These equilibrium constants have been used to account for the distribution of the imine between water and chloroform.

Spectrophotometric study of the acid-base and optical properties of the 5-bromo and 5-chloro derivatives of 2-(2-pyridylazo)-5-(diethylamino)phenol (BrPADAP, ClPADAP) and their complexation equilibria with zinc(II) ions

1982 ◽  
Vol 47 (10) ◽  
pp. 2676-2691 ◽  
Author(s):  
Miroslav Macka ◽  
Vlastimil Kubáň
Keyword(s):  
Equilibrium Constants ◽  
Spectrophotometric Study ◽  
Graphical Analysis ◽  
Alkaline Media ◽  
Acid Base ◽  
Ethanol Medium ◽  
Triton X ◽  
Mixed Water ◽  
Derivatives Of

The optical and acid-base characteristics of BrPADAP and ClPADAP were studied in mixed water-ethanol and water-DMF media and in 10% ethanol medium in the presence of cationic, anionic and nonionic tensides. The composition, optical characteristics, molar absorption coefficients and equilibrium constants of the ML and ML2 complexes with zinc(II) ions were found by graphical analysis and numerical interpretation of the absorbance curves by the modified SQUAD-G program. Optimal conditions were found for the spectrophotometric determination of Zn(II) in the presence of 0.1% Triton X-100 or 1% Brij 35 in alkaline media with pH = 6.5-10. BrPADAP and ClPADAP are the most sensitive reagents (ε = 1.3-1.6 . 105 mmol-1 cm2 at 557 and 560 nm, respectively) for the determination of zinc with high colour contrast of the reaction (Δλ = 104 nm) and selectivity similar to that for the other N-heterocyclic azodyes (PAN, PAR, etc.).

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

1965 ◽  
Vol 18 (5) ◽  
pp. 651 ◽  
Author(s):  
RW Green ◽  
PW Alexander
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Complex Formation ◽  
Distribution Coefficient ◽  
Dilute Aqueous Solution ◽  
The Stability ◽  
Ph Range ◽  
Hydrolysis Of ◽  
Beryllium Complexes ◽  
Equilibria In Aqueous Solution

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.

The influence of β-cyclodextrin on acid–base and tautomeric equilibrium of fluorescein dyes in aqueous solution

2010 ◽  
Vol 345 (13) ◽  
pp. 1882-1890 ◽  
Author(s):  
Larisa N. Bogdanova ◽  
Nikolay O. Mchedlov-Petrossyan ◽  
Natalya A. Vodolazkaya ◽  
Alexander V. Lebed
Keyword(s):  
Aqueous Solution ◽  
Tautomeric Equilibrium ◽  
Acid Base ◽  
Fluorescein Dyes
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