- Facile and Selective Conversion of Ethylenediaminetetraacetate to Ethylenediamine-N,N,N'-triacetate on a Cobalt Complex
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Ethylenediaminetetraacetatocobaltate(III) is converted to aqua(ethylenediamine-N,N,N'-triacetato)cobalt(III) selectively in a 1 mol dm-3 K2CO3 aqueous solution at room temperature in the presence of PbO2.This reaction could be a simple and versatile procedure to obtain ed3a-type ligands.
- Yashiro, Morio,Mori, Tomonori,Yoshikawa, Sadao,Shiraishi, Shinsaku
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- Efficient Photoreduction of Methylviologen Sensitized by Chlorophyll Derivatives and Hydrogen Evolution by Visible Light
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The photoreduction of methylviologen sensitized by chlorophyll derivatives and porphines was investigated using EDTA as a reducing agent.The quantum yield of the photoreduction depends greatly on the kind of central metal ion of chlorophyll derivatives and porphines.Zn-chlorophyll-a and Zn-tetraphyenylporphine show a high quantum efficiency amounting 0.4, which is higher than that of chlorophyll-a.
- Koiso, Takashi,Okuyama, Masataka,Sakata, Tadayoshi,Kawai, Tomoji
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p. 2659 - 2660
(2007/10/02)
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- The iron(III)-catalyzed oxidation of EDTA in aqueous solution
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At temperatures above 100 deg C iron(III) oxidizes coordinated EDTA to ethylenediaminetriacetic acid in aqueous solution in the absence of molecular oxygen.The reaction proceeds with an activation energy of 28.6 kcal/mol, and its rate is directly proportional to the concentration of Fe(III) and inversely proportional to pH.At 125 deg C, the halflife of Fe(III) in the presence of excess EDTA is about 3 h at pH 9.3, but increases to >70 h at pH 5.4.The reaction is stoichiometric and no other reaction products or by-products were detected by nmr, gc, and gc - mass spectroscopy.In the presence of oxygen iron catalyzes quantitative oxidation of ethylenediamine-N,N,N',N'-tetraacetic acid (EDTA) to ethylenediaminetriacetic acid.The copper(II)-EDTA chelate undergoes a similar reaction but higher temperatures (>/=170 deg C) are required.Iron(III) also oxidizes nitrilotriacetic acid (NTA) to iminodiacetic acid (IDA) and glycine.The hydrolyzed species Fe(OH)EDTA is shown to be the reactive intermediate, and the well-known (Fe-EDTA)2O(4-) μ-oxo dimer is shown not to exist at elevated temperatures (above 100 deg C).Probable mechanisms are proposed for these reactions and comparisons are made with earlier work.
- Motekaitis, Ramunas J.,Martell, Arthur E.,Hayes, David,Frenier, Wayne W.
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p. 1999 - 2005
(2007/10/02)
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