Biography:

One of their most recent publications is AnnotationOn the condensation of salicylaldehyde with hydrazine. Which was published in journal Talanta.

More information about Emmanuel Chukwuemeka Okafor research including statistics on their citations can be found on their Copernicus Academic profile page.

Emmanuel Chukwuemeka Okafor's Articles: (5)

AnnotationOn the condensation of salicylaldehyde with hydrazine

AbstractA simple procedure for preparing uncontaminated salicylaldehyde hydrazone is outlined. The condensation reaction of salicylaldehyde and hydrazine in 2:1 molar ratio usually gives initially a mixture of the three geometrical isomers of salicylaldazine: one isomer is bright yellow, another is cream, the third is light pink. The earlier reports of Feigl and of Terentev et al. on the use of salicylaldehyde in the detection of hydrazine have been found to be misleading and the later report of Jain et al. incomplete. A detailed account is now given and improved salicylaldehyde tests for hydrazine are recommended. The structure given by Jain et al. for the copper(II) complex of salicylaldehyde hydrazone is confirmed by means of infrared spectroscopy and microanalysis. Preliminary studies on the copper(II) complex of salicylaldazine are reported.

Observations on 1-phenyl-3-methyl-4-trifluoroacetylpyrazolone-5, a promising extracting agent

AbstractA simple procedure for obtaining 1-phenyl-3-methyl-4-trifluoroacetyl-pyrazolone-5 (HPMTFP), a promising metal extractant, is described. Recrystallization studies reveal that only one tautomer can be isolated, sometimes with one molecule of water of crystallization, contrary to reports that a yellow enol and a white keto tautomer can be obtained from n-hexane and aqueous ethanol respectively. The melting points and colours of some of the metal chelates of HPMTFP are tabulated and in the case of Hg(II) and Cu(II) chelates, differ from those reported by others. Solubility data for some of the metal chelates of HPMTFP are also given.

The metal complexes of heterocyclic β-diketones and their derivatives—VI. The synthesis, structure and i.r. spectral studies of some new metal(II) complexes of 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP)

AbstractThe monovalent metal complex of Na and the divalent metal complexes of Be, Mn, Co, Ni, Cu, Zn, Mg, Ba, Hg and Pb with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP), have been synthesized. It is shown that HPMBP behaves like a bidentate enol forming neutral metal chelates through the carbonyl and enolic hydroxyl groups. Characterization of the complexes were by means of elemental analyses, conductivity measurements, i.r. and proton NMR spectroscopy. The i.r. spectra were recorded between 4000 and 200 cm−1 and assignments are proposed for the observed frequencies. Replacement of the methyl group of the 4-acetyl moiety by the phenyl group in the metal chelates of 1-phenyl-3-methyl-4-acetyl-pyrazolone-5 (HPMAP), is found to decrease the CO, CC and MO stretching frequencies of the chelate ring. The magnitudes of the MO stretching frequencies for the transition metals show good agreement with the Irving—Williams stability order Cu>Ni>Co>Zn>Mn.

The metal complexes of heterocyclic β-diketones and their derivatives—IX. Lanthanon chelates of 3-methyl-1-phenyl-4-trifluoroacetylpyrazol-5-one (HPMTFP). 1H, 13C and 19F NMR, i.r. and u.v.-visible spectral studies

AbstractLanthanon chelates of 3-methyl-1-phenyl-4-trifluoroacetylpyrazol-5-one (HPMTFP) have been synthesized and investigated. Characterization was by elemental analysis, conductivity measurements, Karl Fischer titrations, i.r. and proton magnetic resonance spectra. The complexes are shown to be neutral chelates with the empirical formula Ln(PMTFP)3 · xH2O · yC2H5OH where for Ln = La, Nd, Eu, Dy, Er, Pr and Lu, x = 2 and y = 0 while for Ln = Y and Gd, x = 2 and y = 12. 1H, 13C and 19F NMR, i.r. and u.v.—visible spectral data together with assignments are presented. Sinha's parameters have been calculated and discussed for Nd and Er.

The metal complexes of heterocyclic (β-diketones and their derivatives—II : Lanthanide chelates of 1-phenyl-3-methyl-4-acetylpyrazolone-5, (HPMAP)

AbstractSome lanthanide chelates of l-phenyl-3-methyl-4-acetyl-pyrazolone-5, HPMAP, have been synthesized and investigated. Characterisation involved elemental analysis, conductivity measurements, IR and proton magnetic resonance spectra, melting points and Karl-Fischer titrations. The complexes are shown to be neutral chelates with the empirical formula Ln(PMAP)3·xH2O·yC2H5OH were for Ln = La, Ce and Nd, x = 2 and y = 1, and for Ln = Y, Eu, Gd, Dy, Er and Lu, x = 2 and y = 0. IR, PMR and electronic spectral data together with band assignments are presented. The Nd chelate was found to exhibit positive nephelauxetic effect and Sinha's parameters were calculated and discussed for Nd and Er.

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