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Pathirana, Navin Deepal. (1990) Chemistry and biological activity of iron quinoneoximic complexes. Doctoral thesis, Polytechnic of North London.
The synthesis and structure of 1,2-quinone mono-oximes have been reviewed. The reaction of 3-hydroxyphenol, 3-hydroxy-2-aethylphenol, 3-hydroxy-5-methylphenol and N-acetyl-3-aminophenol with amyl nitrite/M(OEt) (M - Na or K) has been systematically examined. It has been found that the complex formed depends on the reaction temperature and phenol/M(OEt) ratio. Infra-red spectroscopic studies have shown that in the solid state 5-hydroxy-l,2-benzoquinone 2-oxime (hqoH,), 5-hydroxy-3-methyl-l,2-benzoquinone 2-oxime (3-MehqoH2), 5-hydroxy-6-methyl-l,2-benzoquinone 2-oxime (e-MehqoH,) and H-acetyl-5-amino- 1,2-benzoquinone 2-oxime (N-AcqoH) and their sodium and potassium complexes exist in the oximic form rather than the nitroso form. Nuclear magnetic resonance studies have also shown that in d,-DHSO solution hqoH,, 3-MehqoH, and 6-MehqoH} and their sodium complexes exist in one form only which is oximic in character. However, in DjO the results for the sodium complexes of hqoH, and e-MeqoH, indicate the presence of at least two species. In the case of the sodium 5-hydroxy-6-methyl-l,2-benzoquinone 2-oximate these species are oximic in character. An X-ray crystallographic study of e-HehqoH, has shown that in the solid state this compound exists in the 1,4- rather than the 1,2-quinone 2-oxlmic form.
The synthesis of iron(II) complexes of hqoH,, 3-MehqoH] and 6-HehqoH] using the direct and the nitrosation methods was examined. The direct method gave rise to the complexes Fe(hqoH), OHjO, Fe(3-HehqoH), and Fe(6-MehqoH)2 '2H20 whereas the nitrosation method gave rise to ill-defined solids. Na[Fe(N-Acqo), ]-4H20 was obtained by nitrosation of N-acetyl-3-aminopnenol in the presence of Iron(II) ammonium sulphate. Hossbauer and magnetic studies indicate that Na[Fe(N-Acqo)j]-4H20 is a low spin iron(II) complex whereas the bischelates have properties indicative of the S - 1 spin state.
In-vlvo assesment of the iron chelating ability of hqoHj, 3-MehqoH2, 6-MehqoH2, N-AcqoH , N,N-dimethyl-5- amino-1,2-benzoquinone 2-oxime and violuric acid was carried out using a normal rat model. The chelators hqoH, and 6-HehqoH2were found to be effective in removing iron when administered intra-muscularly but they also caused the excretion of magnesium. Their activity was lower than that of desferrioxamine and neither was effective when administered orally.
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