Application of a Schiff base derived from sulfanilamide as an acid-base indicator

Abstract

The present paper firstly announces the possibility of using a Schiff base as an acid-base indicator. This surprising phenomenon can be considered as an interest due to the fact that Schiff bases are usually unstable in solutions and definitely undergo hydrolysis. It was found that such a specific observation depends merely upon the chemical structure and type of the substitute of amine that reacts with aldehyde to give the Schiff base. The latter reagent 4[(4-dimethylamino-benzylidene)-amino]-benzene sulfonamide was synthesized from the condensation of sulfanilamide with p-dimethylaminobenzaldehyde. The reagent solution shows a reproducible change in its color due to the addition of acid and base. A UV-Vis spectroscopic characterization and acid-base equilibrium study of the reagent for its possible use as an indicator were investigated. The results show that the reagent is an amphoteric which possesses four ionization constants K a1 , K a2 , K b1 and K b2 of weak dibasic and diacidic properties. The value of pK a2 (9.80) is parallel to the observed transition interval pH 9.5 (yellow) and pH 10.5 (colorless), which is considered to be the indicator exponents pK i . It was concluded that the benzyl sulfonamide group plays a key role in the stability of the reagent towards hydrolysis and also for indicator characteristics through breaking the conjugation.

Application of N,N′-ethylenebis(acetylacetoneiminato) Nickel (II) and Copper (II) Schiff Base Complexes as Acid–Base Sensing Materials and Indicators in Volumetric Titrations : Qualitative, Spectroscopic and Titrimetric Analyses

“…Many studies, describing the synthesis of similar Schiff base complexes and their applications for both ion sensing [2][3][4] and catalysis [5][6][7][8][9][10][11][12], have been reported. However, no studies are reported concerning the applications of transition metal Schiff base complexes as acid-base indicators, except a report on the application of a Schiff base as an acid-base indicator [13]. In this paper, we report spectroscopic and titrimetric evidence for possible applications of square planar Ni(II) and Cu(II) Schiff base complexes of N,N 0 -ethylenebis(acetylacetoniminate) ligand (L) as acid-base sensing materials and indicators.…”

Theoretical and experimental investigation of 4-[(2-hydroxy-3-methylbenzylidene)amino]benzenesulfonamide: Structural and spectroscopic properties, NBO, NLO and NPA analysis

“…The derivatives of sulfonamide are very important because of their varied structures and biological activities [1]. These types of derivatives display interesting enzymatic inhibition towards the carbonic anhydrase (CA) isozymes CA I, II, IV, IX, and XII [2][3][4][5] and the cyclo-oxogenase (COX) enzymes COX-1 and COX-2 [6] still widely used for conditions such as antimicrobial drugs, antithyroid agents, antibacterial, antifungal, antitumor, antibiotics, acid-base indicator, potential anticancer agents [7][8][9][10][11].…”

Multiresponsive Photo-, Solvato-, Acido-, and Ionochromic Schiff Base Probe

“…The pK a value for the deprotonation of P1 resulted to be 11.03 ± 0.02, while the first protonation, on the N imine atom, is 6.36 ± 0.01 (pK b = 7.64) and the second protonation, on the N amine atom, is 4.27 ± 0.05 (pK b = 9.73), where the later pK a value is in agreement with other N,N′-dimethylaniline derivatives and Schiff bases. 58,59 On the other hand, the pK a values were also obtained by spectrophotometric technique to corroborate the assignment of the protonation events of individual functional groups (N imine and N amine ), 60 see Figure S3, Supporting Information. The pK a values were in good agreement with potentiometric titrations, being in fact that N imine is the first protonation with a pK a = 6.28 ± 0.02 (pK b = 7.72) and N amine is the second protonation, pK a = 4.31 ± 0.06 (pK b = 9.69).…”