Spectrophotometric determination of the acidity dissociation constants of symmetric Schiff base derivatives

Authors : Gülşen TÜRKOĞLU, Halil BERBER, Müjgan ÖZKÜTÜK

Pages : 771-783

View : 20 | Download : 13

Publication Date : 2014-06-27

Article Type : Other Papers

Abstract :800x600 In this study, the acidity constants of series symmetric Schiff base derivatives have been determined using the UV-visible spectrophotometric method at a temperature of 25insert ignore into journalissuearticles values(±0.1); °C. The deprotonated acidity constants insert ignore into journalissuearticles values( p K a ); have been found to be associated with the deprotonation of phenolate oxygen. The first and the second protonated acidity constants insert ignore into journalissuearticles values( p K a1 and p K a2 ); have been found to cause the protonation of the imine nitrogen atom for all molecules. The deprotonated acidity constants insert ignore into journalissuearticles values( p K a ); were found for molecules 5 insert ignore into journalissuearticles values( 9.088);, 8 insert ignore into journalissuearticles values( 9.848);, 6 insert ignore into journalissuearticles values( 10.243);, 2 insert ignore into journalissuearticles values( 10.2569);, 3 insert ignore into journalissuearticles values(10.297);, 1 insert ignore into journalissuearticles values(10.587);, 7 insert ignore into journalissuearticles values( 10.692); and 4 insert ignore into journalissuearticles values(10.804);. The first protonation insert ignore into journalissuearticles values( pK a1 ); was found for molecules 2 insert ignore into journalissuearticles values( 3.432);, 5 insert ignore into journalissuearticles values( 4.207);, 8 insert ignore into journalissuearticles values( 4.612);, 7 insert ignore into journalissuearticles values( 4.758);, 4 insert ignore into journalissuearticles values(4.995);, 1 insert ignore into journalissuearticles values(5.288);, 6 insert ignore into journalissuearticles values( 5.606); and 3 insert ignore into journalissuearticles values(6.452);. The second protonation insert ignore into journalissuearticles values( pK a2 ); was found for molecules 2 insert ignore into journalissuearticles values( -5.384);, 8 insert ignore into journalissuearticles values( -5.165);, 5 insert ignore into journalissuearticles values( -5.028);, 7 insert ignore into journalissuearticles values( -4.775);, 4 insert ignore into journalissuearticles values(-4.518);, 1 insert ignore into journalissuearticles values(-4.111);, 6 insert ignore into journalissuearticles values( -3.866); and 3 insert ignore into journalissuearticles values(-3.212);. Normal 0 21 false false false TR X-NONE X-NONE MicrosoftInternetExplorer4
Keywords : Spectrophotometric determination, Symmetric Schiff base, Acidity Dissociation Constants, UV spectroscopy