Extraction Of Some Transtion Metal Ions Of Oxidation States (Ii) ,(Iv) ,(V) And (Vi) By Differen Hydroxamic Acids

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Awad Elseed Elshiekh Awad, Elkarim
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Hydroxamic acids form stable chelates with some metal ions; therefore, they are used as extractant for these metal ions. Three new hydroxamic acids, namely, N-p-Tolyl-N-Phenylaceto-hydroxamic acid, N-p-Chlorophenyl-N-Phenylacetohydroxamic acid and N-p-Tolyl-N-1-Naphthylacetohydroxamic acid, were prepared. Preparation of these hydroxamic acids was carried out by the reactions of p-Tolylhydroxylamine and p-Chlorophenylhydroxylamine with phenyl-acetyl chloride and 1-N-Naphthylacetyl chloride in 1:1 ratio in alkaline medium at 0 0 C. The three hydroxamic acids were characterized by determination of their melting points, nitrogen contents, characteristic infrared functional groups absorption and determination of their molecular weights by titration of their ethanolic solutions against standard sodium hydroxide solution, as well as the reaction of their chloroform solutions towards acidic solutions of vanadium (V) and iron (III) which gave characteristic violet and blood-red colored complexes in the chloroform layer respectively. The three hydroxamic acids were used as analytical reagents for the extraction of chromium (VI), titanium (IV) vanadium (V), molybdenum (VI), uranium (VI) and copper (II) ions in aqueous solutions of 1M to 4M acid and pH 1 to pH 6. With equal volumes of organic and aqueous phase and only one extraction, the extractabilities of these metals were studied. N-p-Tolyl-N-Phenylacetohydroxamic acid has a maximum extr-action for chromium (VI) 100% in 1M H2SO4, titanium (IV) 37.50% in pH 1, vanadium (V) 81.25% in 4M HCl, uranium (VI) 65.11% in pH 6, molybdenum (VI) 94.33% in 4M HCl and copper (II) 70.40% in pH 6. N-p-Chlorophenyl-N-Phenylacetohydroxamic acid has a maximum extraction for chromium (VI) 98.60% in 1M H2SO4, titanium (IV) 44.44% in pH 1, vanadium (V) 85.42% in 4M HCl, uranium (VI) 74.47% in pH 6, molybdenum (VI) 97.16% in 4M HCl and copper (II) 78.25% in pH 6. N-p-Tolyl-N-1-Naphthylacetohydroxamic acid has a maximum extraction for chromium (VI) 97.22% in 1M H2SO4, titanium (IV) 29.17% in pH 1, vanadium (V) 82.64% in 4M HCl, uranium (VI) 72.22% in pH 6, molybdenum (VI) 90.07% in 4M HCl and copper (II) 66.25% in pH 6. The complexation ratios of the three hydroxamic acids with chromium (VI), vanadium (V), uranium (VI) and copper (II) were determined by the continuous variation method. The metal : hydroxamic acid were found to be 1:2 for chromium (VI), uranium (VI) and copper (II) and 1:1 for vanadium (V
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Extraction,Transtion,Metal,Ions,Oxidation States,Differen,Hydroxamic,Acids