UV-vis and IR spectroscopic studies of some 4-arylhydrazo-2-phenyl-2-oxazoline-5-one derivatives

The absorption spectra of some 4-arylhydrazo-2-phenyl-2-oxazoline-5-one derivatives, have been studied in organic solvents of different polarity. The diagnostic IR spectral bands are assigned and discussed in relation to molecular structure and hydrogen bond existing in the stable compounds in the hydrazo form. The presence of electron withdrawing group in the phenyl ring facilitates the charge migration and hence the proton transfer, thus the azohydrazo form may appear in these compounds, but the major compounds were in the hydrazo form. The fact that these compounds show evidence for intramolecular hydrogen bonding is in favor of the hydrazone structure, this fact excludes the possibility of azo structure. The electronic absorption bands are assigned to the corresponding electronic transitions and the effect of solvent parameters on the charge transfer energy [ECT] is investigated. Four absorbance bands appeared for hydrazones in the range 443-221 nm, the first band has Amax within the range 222-237 nm corresponding to the medium energy transition of the phenyl group e [1]La-[1]A]. The second band with [lambda]max at 243-257 nm is attributed to the low energy mm transition of the phenyl rings representing the [[1]Lb-[1]A] electronic state. The third band at 278-314 nm lies within the energy region for the mm excitation of the electrons of the hydrazo groups. The last band in the visible which has [lambda]max within the range 422-443 nm is considered as being due to an intramolecular charge transfer involving the whole molecule. Finally, the substitution effect was also studied

determination of phenylpropanolamine hydrochloride

The present review summarizes the different methods suggested for the analysis and assay of the important pharmaceutical compound phenylpropanolamine hydrochloride. The methods are classified according to the technique applied in order to simplify and make it easy for the reader. The following methods have been used for the determination of phenylpropanolamine and reported in this review viz. chromatographic methods, high performance liquid chromatography [HPLC], liquid chromatography-mass spectrometry [LC-MS], capillary gas chromatography [CGC], capillary electro-phoresis [CE], spectrophotometric methods, raman spectroscopy, and electrometric methods

Spectrophotometric determination of thulium [lll] and dioxouranium ions using 8- [arylazo] -6,7 dihydroxy - 4 - methylcoumarin derivatives

The complexes of Tm [III] and UO2 [VI] with 8-[arylazo] -6,7-dihydroxy-4-methylcoumarin derivatives were investigated spectrophotometrically. The optimum conditions for chelation, pH, sequence of addition, time, solvents and stoichiometry were critically evaluated. The studies revealed that 1: 1 and 1: 2 [M: L] complexes were formed. The higher stability constants for Tm [III] complexes compared to those of UO2+ 2 complexes were explained in terms of the hydrolysis, steric effect and nature of bonding of both metal ions. Beer's Law was valid up to 16.89 mug/cm3 for Tm3+ complexes and 23.28 mug/cm3 for UO2+ 2 complexes. Spectrophotometric methods for the determination of Tm [III] and UO2+ 2 were presented. The methods were precise as shown by low standard deviations ranging from 0.0011 to 0.0146 and high correlation coefficient [r] ranging from 0.9965 to 0.9994. The values of molar absorptivity, epsilon [LM-1 cm-1] specific absorptivity, a [ml g-1 cm-1] and Sandell sensitivity and S [mug cm-1] indicated the method to be quite sensitive compared to recommended methods using arsenazo I and thoron. A photometric titration method using EDTA as titrant was given

Spectrophotometometric and potentiometric studies on cr [lll], Mn [ll], Fe[III], Co [ll] and Ni [ll] complexes with 5,7-dinitroso-6-hydroxy-4-methylcoumarin

The composition, stability constants and optimal formation conditions of the complexes of Cr3+, Mn2+, Fe3+, Co2+ and Ni2+ with 5, 7-dinitroso-6-hydroxy-4-methylcoumarin have been studied spectrophotometrically. The stoichiometries of the complexes showed that 1: 1 and 1: 2 [M: L] species were formed and the influence of foreign ions was investigated. The ionization constants [pKa] of the investigated ligand and stability constants of the metal ions complexes were determined, potentiometrically, in 40% ethanolic solution

Spectrophotometric determination of tannins in tea samples using alpha and alpha'-dipyridyl and tiron

Tannins are determined spectrophotometrically in Indian, Kenyan and Ceylon tea samples using direct and indirect methods In the direct method excess amount of Fe[III] is added to tea sample followed by alpha, alpha ['] -bipyridyl at pH 4.4 and the absorbance of Fe [II]- alpha, alpha ['] -bipyridyl complex is measured at 522 mm. In the indirect method an excess amount of Fe[III] is added to the sample followed by Tiron reagent and the absorbance of the formed Fe[III]-Tiron complex is measured at 620 nm

Chelation behaviour of some lanthanide [III], scandium [III], yttrium [III], thorium [IV] and uranium [VI] complexes with some hydroxy nitrosocoumarins

The stability constants of the lanthanide ions [La, Ce, Pr, Nd, Sm, Gd, Dy, Er and Yb]; Sc, Y, Th and UO22+ ions with some hydroxy nitrosocoumarins were determined in 40% ethanol-water mixture at 25 degree and 0.1 ionic strength. It was found that the stability constants of the complexes increased with increasing ionic radii, from Y to Sm. The so called Gadolinium break was observed with heavier lanthanides. Sc and Th complexes possessed the highest stability constants. The potentiometric measurements and conductimetric titrations showed that 1: 1 and 1: 2 [M: L] complexes were invariably formed

Conductimetric studies of charge transfer complexes of some benzylidene aniline Schiff bases with substituted p-benzoquinones

The charge transfer complexes formed between some benzylidine aniline derivatives and p-benzoquinones have been investigated conductimetrically. The results indicate the formation of 1:1 and 1:2 [D: A] complexes. The stoichiometric conductance sigma p and molar conductance of the complexes have been calculated at 22 degree. The effects of electron affinity of the acceptor, ionization potential of the donor and temperature have been investigated and discussed

Spectrophotometric studies on some hydroxy nitrosocoumarins

The UV and visible absorption spectra of some hydroxy nitrosocoumarins have been studied in organic solvents of varying polarities. The dependence of the band shift on the nature of substituent, dielectric effect and specific solvation was studied. The acid dissociation constants of the different ionizable groups were determined using the half- height and the modified limiting absorbance methods. The observed transition energy and oscillator strengths were correlated with those calculated from the SCF PPP CI method for molecular orbitals

Spectrophotometric studies on 5- [P-nitrophen-Ylazo] -J-acid and its complexe with trivalent Sc, Y and la ions

An organic dye, 5-[p- nitrophenylazo]-1-hydroxy-6-aminonaphthalene-3-sulfonic acid was prepared, chemically analyzed and subjected to IR spectra. The absorption spectra of this dye was investigated in aqueous solution of varying pH values. The pKp and pKa values were determined from the absorbance wavelength relations at various pH values. The complexes formed between Sc, Y and La and the active ligand were studied spectrophotometrically and by conductimetric titrations. The stability constants of the formed complexes were calculated and the effect of diverse ions was investigated. A spectrophotometric method for the precise determination of the three metal ions was proposed

Effect of solvents on the electronic absorption spectra of some thioschiff bases

The electronic absorption spectra of substituted benzylidene-O- amino- thiophenol in some organic solvents of different polarities have been investigated. The spectra obtained in ethanol comprised mainly 4 bands, assigned to corresponding electronic transitions. The results indicated that the spectral shifts were governed by the dielectric constants of the solvents. UV-visible spectra of the thioschiff bases were correlated with the calculated data from theoretical treatment by applying Pariser-Parr-Pople Self-Consistent Field approach [SGF PPP CI]

Spectrophotometric studies of Al [III] complexes with 4- [arylazo] -1-hydroxy-2-naphtoic acid dyes

The optimum conditions favoring the formation of Al [III] complexes with 4-arylazo-1-hydroxy-2-naphthoic acid dyes [Ia-h] are extensively investigated. The molecular structure of the complexes and their obedience to Beer's law and Ringbom ranges, as well as, their stabilities are studied. Methods for the spectrophotometric determination of Al [III] and spectrophotometric titration using EDTA and CDTA were reported. The interference effect of several ions was checked. The stoichiometry of Al [III] with [Ia-h] dyes was investigated by conductometric titrations. The study was extended to the determination of Al in pure Al metal and in Si-Al master alloy. A new rapid and accurate method for the spectrophotometric microdetermination of Al [III] using 4-[arylazo]-1-hydroxy-2-naphthoic acid dyes [Ia-h] is given

Spectrophotometric microdetermination of ampicillin and cloxacillin in pure form, mixtures and in pharmaceutical preparations using bromothymol blue

A simple, accurate and highly-sensitive spectrophotometric method for the rapid determination of ampicillin trihydrate and cloxacillin sodium in the pure state, their mixtures and pharmaceutical preparations was described. The method is based on the formation of deep color complexes by the reaction of ampicillin trihydrate [amp.] or cloxacillin sodium [clox.] with bromothymol blue [BTB] at 25 and 50C +/- 2C, respectively, in basic solution containing 30% [v/v] acetone. The effect of pH, time, temperatures, solvent and amount of BTB have also been studied. Beer's law is obeyed within the concentration range 0.4-18 and 0.4-20 mug/ml of amp. and clox., respectively, whereas the optimum concentration ranges as evaluated by Ringbom's method are 1-16 and 1-17 mug/ml, respectively. The specific absorptivity, molar absorptivity, Sandell sensitivity, standard deviation and recovery% are evaluated. The method has been used to determine each of amp. and clox. in pure form, synthetic binary mixtures and pharmaceutical preparations [capsules, vials, syrup and drops] containing both of them

Spectrophotometric determination of tetracycline by coupling with diazonium salts

A simple, rapid and accurate spectrophotometric method for the determination of tetracycline [TC] in aqueous solution was developed. The method was based on the coupling reaction between TC and diazontized p-nitroaniline [I], sulfanilic acid [II], and sulfanilamide [III] to form stable dyes. The variables affecting development of the color were investigated and the conditions optimized. The Beer's law was obeyed for up to 19, 70 and 40 ppm on using I, II and III, respectively. Their absorptivities [L mol-1 cm-1] and Sandell's sensitivities [mug cm-2] are 125 x 104, 4.0 x 104 and 0.13 x 104 and 38.4 x 10-3, 175 x 10-3 and 148.0 x 10-3, respectively, for I, II and III. The recoveries of the method for I, II and III were 100.07 +/- 0.24, 98.97 +/- 0.64 and 99.95 +/- 0.45 for TC, while the recoveries for the dosage forms were 100.2 +/- 0.277, 100.0075 +/- 0.227 and 99.075 +/- 0.297, respectively. The proposed methods were applied for the quantitation of TC in pharmaceutical preparations with high precision and accuracy. The nature of the dye formation and the structure of mono azo dye was suggested

Spectrophotometric determination of oxytetracycline by coupling with diazonium salts

Diazotized p-nitroaniline [I], sulfanilic acid [II] and sulfanilamide [III] were used for the spectrophotometric determination of oxytetracycline [OTC]. The procedure is based on the observation of that in slightly alkaline medium OTC reacts with I, II and III. A stable azo dye is formed and show maximum absorption at 550, 560, and 575 nm, respectively. The variable affecting development of the color have been investigated and the conditions optimized. Beer's law is obeyed for up to 25, 90 and 90 mug/ml on using I, II and III, respectively. Molar absorptivities [L mol-1 cm-1] and Sandell's sensitivities [mug cm-2 per 0.001 absorbance unit] are respectively; 0.83 x 104 and 57.8 x 10-3, 0.14 x 104 and 200 x 10-3 and 0.12 x 104 and 176.5 x 10-3. The mean percentage accuracies were 99.9 +/- 1.75, 99.95 +/- 0.71. The results obtained either in pure form or in pharmaceutical formulations are accurate and precise. The nature of the dye was discussed and the structure of a mono azo dye was suggested

Spectrophotometric studies on some azo compounds derived from tetracycline and oxytetracydine

The absorption spectra of some azo compounds derived from aniline, p- nitroaniline, sulfanilic acid and sulphanilamide coupled with tetracycline [TC] and oxytetracycline [OTC] in organic solvents and buffer solutions of different pH values have been investigated. The results have been utilized for the determination of pKa. The spectra of the compounds were discussed in relation to molecular structure

Mixed ligand complexes of Al [III], In [III] and Ti [I] with 6, 7 dihydroxy-4-methylcoumarin as primary ligand and some amino acids as secondary ligand

Formation constants [log KMA MAL] of the mixed ligand complexes of the type MAL [where M = Al[3], In[3] and Tl[1], A = 6,7-dihydroxy-4-methylcoumarin and L = threonine, phenylalanine, glutamic acid, aspartic acid, glycine and alanine] were determined pH metrically in ethanol-water mixture [30% v/v] at 25C and mu = 0.1 [mol dm-3 NaClO4] by using the extension of Irving-Rossotti technique to ternary systems. The formation of 1: 1: 1 [M: A: L] species was evidenced. The stability sequence with respect to metal ions were found to be Al[3] > In[3] > Tl[1]

Charge transfer complexes of pyrimidine, pyrazine and their 2-amino derivatives with nitrobenzenes

The solid complexes of pyrimidine, pyrazine and their 2-amino derivatives with nitro-compounds have been prepared and investigated by IR, electronic absorption and proton magnetic resonance spectroscopy. Nonacidic acceptors yield complexes through pi-pi[*] electronic interaction with the possibility for n-pi[*] bonding whenever the orientation of the molecules permits its formation .Strongly acidic acceptors from complexes with pi - pi[*] and proton transfer interactions. In the case of weak acidic acceptors the two types are formed depending on both acidity of acceptor and basicity of donor. The reaction of pyrimidine and pyrazine with p-nitrophenol takes plase through pi- pi [*] CT and intermolecular hydrogen bonding