Pyridoxine and Pyridoxal Analogs. V. Syntheses and Infrared Spectra of Schiff Bases

1962 ◽  
Vol 84 (17) ◽  
pp. 3257-3263 ◽  
Author(s):  
Dietrich. Heinert ◽  
Arthur E. Martell
Keyword(s):  
Schiff Bases ◽  
Infrared Spectra

Studies in the stereochemistry of zinc(II). VI. Zinc complexes with quadridentate Schiff bases

1967 ◽  
Vol 20 (5) ◽  
pp. 885 ◽  
Author(s):  
GE Batley ◽  
DP Graddon
Keyword(s):  
Schiff Bases ◽  
Infrared Spectra ◽  
Zinc Complexes ◽  
Steric Effects ◽  
Pyridine Solution ◽  
Carbon Chains ◽  
Tetrahedral Environment ◽  
Oxygen Atoms

Zinc complexes have been prepared with Schiff bases formed from salicylaldehyde and polymethylenediamines with chains of 2-9 carbon atoms. The anhydrous zinc complexes of ligands with 2-3 carbon chains readily form 1 : 1 adducts with water or bases such as pyridine; the ultraviolet and infrared spectra of these anhydrous compounds indicate that they are polymeric with bridging oxygen atoms, the zinc being 5-coordinate. The zinc complexes of ligands with carbon chains of four or more atoms do not form adducts, even in pyridine solution, and their spectra show that none of the oxygen atoms is bridging, the zinc being 4-coordinate. The stereochemistry of the zinc appears to be determined solely by steric effects: when the ligand is such that 4-coordination can produce a tetrahedral environment, further coordination does not occur; when 4-coordination cannot produce a tetrahedral environment, 5- coordination always occurs.

scholarly journals Fabrication of Novel Ball-Like Polystyrene Films Containing Schiff Base Microspheres as Photostabilizers

Polymers ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1185 ◽  
Author(s):  
Emad Yousif ◽  
Dina Ahmed ◽  
Gamal El-Hiti ◽  
Mohammad Alotaibi ◽  
Hassan Hashim ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Schiff Base ◽  
Surface Morphology ◽  
Ultraviolet Light ◽  
Schiff Bases ◽  
Infrared Spectra ◽  
Ultraviolet Irradiation ◽  
Weight Reduction ◽  
Casting Method

Polystyrene films containing a low concentration of three highly aromatic Schiff bases were prepared using the casting method. The polystyrene films were irradiated with ultraviolet light (300 h). The polystyrene infrared spectra, weight loss, molecular weight reduction and the surface morphology were examined upon irradiation. The Schiff bases acted as photostabilizers and reduced the photodegradation of polystyrene films to a significant level in comparison to the blank film. The images recorded of the surface of the miscible polystyrene/Schiff base blends showed novel ball-like microspheres with a diameter of 3.4–4.3 µm. The Schiff bases were able to endow excellent protection to polystyrene against ultraviolet irradiation.

scholarly journals Effect of Ultraviolet Irradiation on Polystyrene Containing Cephalexin Schiff Bases

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2982
Author(s):  
Anaheed A. Yaseen ◽  
Emaad T. B. Al‐Tikrity ◽  
Emad Yousif ◽  
Dina S. Ahmed ◽  
Benson M. Kariuki ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Weight Loss ◽  
Surface Morphology ◽  
Carbonyl Group ◽  
Schiff Bases ◽  
Infrared Spectra ◽  
Ultraviolet Irradiation ◽  
Recent Past ◽  
Polystyrene Waste ◽  
High Yields

The scale of production of polystyrene has escalated in the recent past in order to meet growing demand. As a result, a large quantity of polystyrene waste continues to be generated along with associated health and environmental problems. One way to tackle such problems is to lengthen the lifetime of polystyrene, especially for outdoor applications. Our approach is the synthesis and application of new ultraviolet photostabilizers for polystyrene and this research is focused on four cephalexin Schiff bases. The reaction of cephalexin and 3-hydroxybenzaldehyde, 4-dimethylaminobenzaldehyde, 4-methoxybenzaldehyde, and 4-bromobanzaldehyde under acidic condition afforded the corresponding Schiff bases in high yields. The Schiff bases were characterized and their surfaces were examined. The Schiff bases were mixed with polystyrene to form homogenous blends and their effectiveness as photostabilizers was explored using different methods. The methods included monitoring the changes in the infrared spectra, weight loss, depression in molecular weight, and surface morphology on irradiation. In the presence of the Schiff bases, the formation of carbonyl group fragments, weight loss, and decrease in molecular weight of polystyrene were lower when compared with pure polystyrene. In addition, undesirable changes in the surface such as the appearance of dark spots, cracks, and roughness were minimal for irradiated polystyrene containing cephalexin Schiff bases. Mechanisms by which cephalexin Schiff bases stabilize polystyrene against photodegradation have also been suggested.

Infrared spectra of 15N-substituted Schiff bases

1967 ◽  
Vol 32 (3) ◽  
pp. 822-823 ◽  
Author(s):  
Gerald O. Dudek
Keyword(s):  
Schiff Bases ◽  
Infrared Spectra

Carboxylic Esters as Ligands. II. Transition metal complexes of Diethyl Acetonedicarboxylate, Ethyl Acetoacetate, and Diethyl oxaloacetate

1967 ◽  
Vol 20 (9) ◽  
pp. 1829 ◽  
Author(s):  
RW Hay ◽  
BP Caughley
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Schiff Bases ◽  
Transition Metal Complexes ◽  
Infrared Spectra ◽  
Ethyl Acetoacetate ◽  
Magnetic Moments ◽  
Magnetic Data ◽  
Keto Esters ◽  
Metal Metal

The preparation, infrared spectra, magnetic data, and reactions of a variety of transition metal complexes of diethyl acetonedicarboxylate are described. The infrared spectra indicate chelate ring formation with a metal-oxygen bond with the carbonyl group of the ester. Transesterification reactions with alcohols occur much less readily with these complexes than with the corresponding metal oxaloacetates. Bis(ethyl acetoacetato)copper(II) undergoes methanolysis rather than trans-esterification on refluxing with methanol to give a bright blue methoxy-bridged polymer with an abnormally low magnetic moment (μeff 1.14 B.M. at 17�), presumably indicating metal-metal interaction. The magnetic moments of various transition metal complexes of ethyl acetoacetate and diethyl oxaloacetate have also been determined. The β-keto esters have been condensed with 1,2-diaminoethane to give N,N?-bis Schiff bases which exist predominantly as the enamine tautomer in the solid state and in solution. Attempts to prepare copper(II) complexes of these Schiff bases in aqueous ethanol have been unsuccessful as the ligands rapidly hydrolyse in the presence of copper(II) ions.

An Evaluation of Hammett Relationships Derived from Infrared C=N Stretching Data for Aromatic Schiff Bases

1985 ◽  
Vol 39 (6) ◽  
pp. 1065-1069 ◽  
Author(s):  
J. J. Rafalko ◽  
E. W. Choe
Keyword(s):  
Aromatic Ring ◽  
Schiff Bases ◽  
Infrared Spectra ◽  
Normal Modes ◽  
Intensity Data ◽  
Isotopic Data ◽  
Internal Coordinates

Infrared spectra of benzylidene aniline, p-nitrobenzylidene aniline, p-N-dimethylaminobenzylidene aniline, and their 15N-labelled azomethine analogs were obtained to assess the reliability of C=N stretching assignments and Hammett relationships based on these results. The isotopic data indicate that there is extensive mixing of internal coordinates in bands near 1600 cm−1. Bands possessing the greatest C=N stretching character are not always readily distinguishable from aromatic ring breathing modes due to variations in relative intensities and band overlap. Problems related to the use of frequency and intensity data of highly coupled normal modes in Hammett correlations are discussed.

Aluminium Derivatives of Tridentate Bifunctional Schiff Bases Derived from Salicylaldehyde and Benzoylacetone

1972 ◽  
Vol 27 (1) ◽  
pp. 25-29 ◽  
Author(s):  
J. Dayal ◽  
R. C. Mehrotra
Keyword(s):  
Schiff Bases ◽  
Infrared Spectra ◽  
Thermogravimetric Analyses ◽  
Stoichiometric Ratios ◽  
Derivatives Of

S = salicylaldehyde and benzoylacetone and B = (CH2-)2, -CH2-CH -CH3 and C6H5) in different stoichiometric ratios have been synthesised. The products Al (OPri) (SB) are soluble in benzene. The tertiary butoxy products have been prepared by the alcohol interchange technique. Infrared spectra of the new derivatives are reported. Thermogravimetric analyses have also been carried out.

THE EFFECT OF ACIDS ON THE INFRARED SPECTRA OF SCHIFF BASES—II. IMINES CONTAINING THE C=C-C=N AND C=C-C=C-C=N UNITS

1987 ◽  
Vol 45 (s1) ◽  
pp. 801-808 ◽  
Author(s):  
L. S. Lussier ◽  
C. Sandorfy ◽  
H. OA L E-Thanh ◽  
D. Vocelle
Keyword(s):  
Schiff Bases ◽  
Infrared Spectra

THE EFFECT OF ACIDS ON THE INFRARED SPECTRA OF SCHIFF BASES—I. NON-CONJUGATED IMINES

1986 ◽  
Vol 44 (5) ◽  
pp. 629-639 ◽  
Author(s):  
L. S. Lussier ◽  
A. Dion ◽  
C. Sandorfy ◽  
Hoa Le-Thanh ◽  
D. Vocelle
Keyword(s):  
Schiff Bases ◽  
Infrared Spectra
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