Schiff base equilibria. IV. N-Methylimines of m- and p-hydroxybenzaldehydes

1966 ◽  
Vol 19 (2) ◽  
pp. 233 ◽  
Author(s):  
RW Green ◽  
RJ Sleet
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Schiff Bases ◽  
Formation Constants ◽  
Dilute Solution

The formation of Schiff bases between methylamine and m- and p-hydroxybenzaldehydes has been studied by spectrophotometry. Because of overlapping equilibria and ionic strength effects, the formation constants, KF, of the neutral Schiff bases are determined with less precision than for the ortho compound. In dilute solution they are estimated by extrapolation to be 1.0 x 103 and 1.0 x 104, respectively. The formation constants, KA, of the anionic forms of the Schiff bases have been more precisely measured as 1.45 x 102 and 5.52, respectively. The equilibria are compared with those for salicylaldehyde.

scholarly journals Metallation of tetradentate N2O2 Schiff base with Mn(II), Co(II), Cu(II) and Zn(II): synthesis, characterization and formation constants measurement

2010 ◽  
Vol 8 (2) ◽  
pp. 291-299 ◽  
Author(s):  
Mozaffar Asadi ◽  
Maryam Mohammadikish ◽  
Khosro Mohammadi
Keyword(s):  
Mass Spectrometry ◽  
Schiff Base ◽  
Ionic Strength ◽  
Nmr Spectroscopy ◽  
Elemental Analysis ◽  
1H Nmr Spectroscopy ◽  
Formation Constants ◽  
Free Energies ◽  
Schiff Base Ligands ◽  
Ft Ir

AbstractFour Schiff base ligands, salabza-H2 = N,N′-bis(salicylidene)-2-aminobenzylamine, were synthesized by condensation of one mole of 2-aminobenzylamine and two moles of salicylaldehyde and/or two moles of substituted salicylaldehyde (5-OMe, 5-Br, 5-NO2). All the four Schiff bases and their Mn(II), Co(II), Cu(II) and Zn(II) complexes are characterized by UV-Vis, FT-IR, 1H NMR spectroscopy, mass spectrometry and elemental analysis. The formation constants and the Gibbs free energies were measured spectrophotometrically for 1:1 complexes in methanol in constant ionic strength (I = 0.1 mol dm−3 NaClO4) and at 25°C. The data refinement was carried out with the SQUAD program. The trend of formation constants of H2L1 with M(II) follows the order: Mn(II) (3.97) Also, the trend of formation constants of ligand toward a given metal (for example Mn) is as follows: H2L1 (p-OMe) (3.97) > H2L2 (p-H) (3.65) > H2L3 (p-Br) (3.37) > H2L4 (p-NO2) (3.04)

Equilibrium constants of pyridoxal 5'-phosphate Schiff bases - A polarographic study

1983 ◽  
Vol 48 (7) ◽  
pp. 1950-1955 ◽  
Author(s):  
Juan Llor ◽  
Javier Bonal ◽  
Manuel Cortijo
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Equilibrium Constant ◽  
Schiff Bases ◽  
Ph Dependence ◽  
Equilibrium Constants ◽  
Constant Ionic Strength ◽  
Polarographic Study ◽  
Ionic Forms

The equilibrium constant for the formation of the Schiff base between pyridoxal 5'-phosphate and n-hexylamine has been evaluated from polarographic measurements. The pH dependence of the equilibrium constant has been investigated at constant ionic strength. The values thus obtained for the equilibrium constant compare well with those computed from the pK of the several ionic forms of pyridoxal 5'-phosphate, its Schiff base and the amine present in the solution.

scholarly journals Tetradentate schiff base ligands of 3,4- diaminobenzophenone: Synthesis, characterization and thermodynamics of complex formation with Ni(II), Cu(II) and Zn(II) metal ions

2011 ◽  
Vol 76 (1) ◽  
pp. 63-74 ◽  
Author(s):  
Mozaffar Asadi ◽  
Hajar Sepehrpour ◽  
Khosro Mohammadi
Keyword(s):  
Schiff Base ◽  
Ionic Strength ◽  
Nmr Spectroscopy ◽  
Complex Formation ◽  
1H Nmr Spectroscopy ◽  
Formation Constants ◽  
Schiff Base Ligands ◽  
Tetradentate Schiff Base ◽  
Salicylaldehyde Derivatives ◽  
Thermodynamics Of Complex Formation

Some new symmetrical diimino tetradentate Schiff base ligands were synthesized by the reaction of 3,4-diaminobenzophenone with salicylaldehyde derivatives, such as [N,N?-bis(4-methoxysalicylaldehyde)- 3,4-diaminobenzophenone] (L1), [N,N?-bis(5-methoxysalicylaldehyde)- 3,4-diaminobenzophenone] (L2), [N,N?-bis(5-bromosalicylaldehyde)-3,4- diaminobenzophenone] (L3), [N,N?-bis(5-nitrosalicylaldehyde)-3,4- diaminobenzophenone] (L4). Additionally, a tetradentate Schiff base ligand [N,N?-bis(3-methoxysalicylaldehyde)-3,4-diaminobenzophenone] (L5), was synthesized. All the Schiff bases and their Ni(II), Cu(II) and Zn(II) complexes were characterized using elemental analysis and infrared, electronic, mass and 1H-NMR spectroscopy. The formation constants of the complexes were measured using UV-Vis spectroscopic titration at constant ionic strength 0.1 M (NaClO4), at 25?C in dimethylformamide (DMF) as solvent.

scholarly journals Synthesis and Evaluation of Schiff Bases of 4-Amino-5-(chlorine substituted phenyl)-4H-1,2,4-triazole-3-thione as Antimicrobial Agents

2020 ◽  
Vol 41 (1) ◽  
pp. 26-35
Author(s):  
Kishor Devkota ◽  
Govinda Pathak ◽  
Bhushan Shakya
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Antimicrobial Agents ◽  
Triazole Ring ◽  
Antimicrobial Activities ◽  
Biologically Active ◽  
Spectral Techniques ◽  
Schiff Base Derivatives ◽  
Bacteria And Fungi ◽  
Different Strains

Triazole ring system has attracted a continuously growing interest of synthetic organic chemists and those dealing with the medicinal compounds due to its versatile potential to interact with biological systems. Schiff bases are also considered as one of the most biologically active compounds.  The aim of the present study was to synthesize new Schiff bases bearing triazole nucleus and to assess their antimicrobial activities. Four new Schiff base derivatives of 1,2,4-triazole-3-thione were synthesized by combining two different pharmacophores viz. triazole nucleus and Schiff base moiety and were characterized by spectral techniques (UV, FT-IR, and NMR). The Schiff bases were evaluated for antibacterial (Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae) and antifungal (Candida albicans) activities. The synthesized compounds exhibited good to moderate activities against different strains of bacteria and fungi tested.

Syntheses, Spectroscopy And Crystal Structures Of (R)-N-(1-Aryl-Ethyl)Salicylaldimines And [Rh{(R)-N-(1-Aryl-Ethyl)Salicylaldiminato}(η4-Cod)] Complexes

2007 ◽  
Vol 62 (6) ◽  
pp. 807-817 ◽  
Author(s):  
Mohammed Enamullah ◽  
A.K.M. Royhan Uddin ◽  
Anne-Christine Chamayou ◽  
Christoph Janiak
Keyword(s):  
Mass Spectrometry ◽  
Schiff Base ◽  
Schiff Bases ◽  
Structure Determination ◽  
Chelate Ring ◽  
Optical Rotation ◽  
X Ray ◽  
Mononuclear Complexes ◽  
Chiral Schiff Base ◽  
C Nmr

Condensation of salicylaldehyde with enantiopure (R)-(1-aryl-ethyl)amines yields the enantiopure Schiff bases (R)-N-(1-aryl-ethyl)salicylaldimine (HSB*; aryl = phenyl, 2-methoxyphenyl, 3- methoxyphenyl, 4-methoxyphenyl (4), 4-bromophenyl (5), 2-naphthyl). These Schiff bases readily react with dinuclear (acetato)(η4-cycloocta-1,5-diene)rhodium(I), [Rh(μ-O2CMe)(η4-cod)]2, to afford the mononuclear complexes, cyclooctadiene-((R)-N-(1-aryl-ethyl)salicylaldiminato-κ2N,O)- rhodium(I), [Rh(SB∗)(η4-cod)] (SB* = deprotonated chiral Schiff base = salicylaldiminate; aryl = phenyl (7), 2-methoxyphenyl, 4-methoxyphenyl, 4-bromophenyl, 2-naphthyl). The complexes have been characterized by IR, UV/vis, 1H/13C NMR and mass spectrometry, optical rotation as well as by single-crystal X-ray structure determination for 4, 5 and 7. The structure of 5 shows C-Br· · ·π contacts. Compound 7 is only the second example of a Rh(η4-cod) complex with a six-membered Rh-N,O-chelate ring

Notizen: Magnetic Studies on Schiff Base Complexes of Al(III) and Si(IV)

1974 ◽  
Vol 29 (7-8) ◽  
pp. 565-566 ◽  
Author(s):  
R. N. Prasad ◽  
J. P. Tandon
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Schiff Base Complexes ◽  
Magnetic Studies ◽  
Magnetic Susceptibilities

The magnetic susceptibilities of some newly syntesized Al(III) and Si(IV) complexes of Schiff bases derived from the condensation of o-hydroxyacetophenone or 2-dydroxy-1-naphthaldehyde with hydroxyalkylamines or diamines have been measured and the data indicate their diamagnetic character.

Schiff Bases and Related Substances. III. Acetylation of a Schiff Base-Thiol Adduct1

1958 ◽  
Vol 80 (13) ◽  
pp. 3475-3478 ◽  
Author(s):  
Gardner W. Stacy ◽  
Richard I. Day ◽  
Richard J. Morath
Keyword(s):  
Schiff Base ◽  
Schiff Bases ◽  
Related Substances

Electronic Structure of Pseudotetrahedral Copper(II) Schiff Base Complexes

1977 ◽  
Vol 32 (5) ◽  
pp. 551-561 ◽  
Author(s):  
John R. Wasson ◽  
H. Wayne Richardson ◽  
William E. Hatfield
Keyword(s):  
Electronic Structure ◽  
Schiff Base ◽  
Schiff Bases ◽  
Opposite Direction ◽  
Hyperfine Coupling ◽  
Coupling Constants ◽  
Schiff Base Complexes ◽  
Hyperfine Coupling Constants ◽  
Structure Correlations

Copper(II) complexes with the Schiff bases formed by condensing t-butyl-, isopropyl-, cyclohexyl- and diphenylmethylamines with salicylaldehyde and 3-methoxy- and 5-nitrosalicyl-aldehyde have been prepared and characterized. The isotropic nuclear hyperfine coupling constants increase in the order t-butyl < isopropyl < cyclohexyl < diphenylmethyl for the N-substituents in the three series of complexes while isotropic g-values increased in the opposite direction. Spectra structure correlations were examined and discussed.

scholarly journals A novel approach toward the synthesis of some new tridentate Schiff bases from anil-like compounds

2016 ◽  
Vol 81 (10) ◽  
pp. 1111-1119 ◽  
Author(s):  
Fatemeh Bagheri ◽  
Abolfazl Olyaei
Keyword(s):  
Schiff Base ◽  
Formic Acid ◽  
Schiff Bases ◽  
Condensation Product ◽  
Reaction Times ◽  
Acid Catalyst ◽  
Schiff Base Ligands ◽  
Novel Approach ◽  
Solvent Free Conditions ◽  
Novel Method

A novel method was developed for synthesizing a series of new three dentate Schiff base ligands starting from hydroxynaphthalidene pyrimidinyl amines with o-phenylenediamines or o-aminophenol or 2-amino-3-hydroxy-pyri-dine in the presence of formic acid catalyst under solvent-free conditions. In these reactions [1+1] condensation product as half-unit ligand was obtained. Moreover, the reaction of hydroxynaphthalidene pyrimidinyl amines with 3,4-diamino-pyridine and 1,8-naphthalenediamine lead to the formation of C2-naphthylated imidazopyridine and dihydropyrimidine, respectively. The attractive features of this protocol are: use of inexpensive catalyst, operationally simple, short reaction times, easy handling, and good yields.

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