Hydroxyethylethylenediaminetriacetic acid

The lanthanides form many compounds with organic ligands. Some of these compounds ate water-soluble, others oil-soluble. Water-soluble compounds have been used extensively for rare-earth separation by ion exchange (qv), for example, complexes form with citric acid, ethylenediaminetetraacetic acid (EDTA), and hydroxyethylethylenediaminetriacetic acid (HEEDTA) (see Chelating agents). The complex formation is pH-dependent. Oil-soluble compounds ate used extensively in the industrial separation of rate earths by tiquid—tiquid extraction. The preferred extractants ate catboxyhc acids, otganophosphoms acids and esters, and tetraaLkylammonium salts. 

Wood and Higginson " have made a detailed study of the kinetics of oxidation of Fe(ll) by a number of complexes of Co(IIl) with ethylenediaminetetraacetic acid (H4Y = EDTA) and hydroxyethylethylenediaminetriacetic acid (H3YOH = HEDTA). Rate data and activation parameters are quoted (Table 21) for the... 

The reaction between two polydentate complexes of Cu(II), CuY (YjH4 = ethylenediaminetetraacetic acid, Y2H4 = hydroxyethylethylenediaminetriacetic acid) and thiourea to give a Cu(I) complex of thiourea (this product was not identified), follows kinetics ... 

Versenol 120 [Dow], TM for the trisodium salt of IV-hydroxyethylethylenediaminetriacetic acid (C10H15O7N2Na3). 

The most important ferrous developers, however, are the complexes with ethylenediaminetetraacetic acid (EDTA) and related ligands, such as diethylenetriaminepentaacetic acid (DTPA), nitrilotriacetic acid (NTA) and A-hydroxyethylethylenediaminetriacetic acid (HETA). Complexes... 

N-Hydroxyethyl-1,2-ethanediamine. See Aminoethylethanolamine Hydroxyethyl ether cellulose. See Hydroxyethylcellulose N-(2-Hydroxyethyl)-N-ethylaniline. See Phenylethylethanolamine Hydroxyethyl ethylcellulose (INCI). See Ethyl hydroxyethyl cellulose Hydroxyethylethylenediamine N-(2-Hydroxyethyl) ethylenediamine N-(P-Hydroxyethyl) ethylenediamine. See Aminoethylethanolamine Hydroxyethyl ethylenediamine triacetic acid N-(2-Hydroxyethyl) ethylenediamine triacetic acid N-(P-Hydroxyethylethylenediamine)-N,N, N -triacetic acid. See HEDTA Hydroxyethylethylenediaminetriacetic acid, trisodium salt. See Trisodium HEDTA (N-Hydroxyethylethylenedinitrilo) triacetic acid. See HEDTA... 

Fig. 8.9 Correlation of stability constants with number of available coordination sites 1, iminodiacetic acid 2, N-hydroxyethyliminodiacetic add 3, nitrilotriacetic acid 4, N-hydroxyethylethylenediaminetriacetic acid 5, ethylenediaminetetracetic acid 6, diethylene-triaminepentaacetic acid 7, triethylenetetraaminehexaacetic acid 8, diaminocyclohexcme-tetraacetic acid [3].

The electrochemical properties of the W /V -NTA (nitrilotriacetic acid) system have been studied [1]. From the Ei/j value and Nernst equation, Meier et al. evaluated the formation constant for V(II)NTA(H20). Kato et al. [2] studied the polarographic behaviour of V(III)-HEDTA (N-hydroxyethylethylenediaminetriacetic acid). They proposed the electrode mechanisms for V(III)-HEDTA and calculated the equilibrium constants by a curve fitting method. Jung et al. [3] studied reduction mechanism of VO" -DTPA (diethylenetrlaminepentaacetlc acid) at a mercury electrode in aqueous solution. They proposed that reduction reactions of the VO " -DTPA system occurred through an ECE reaction sequence. 

HsiHEDTA), hydroxyethylethylenediaminetriacetic acid, and the lighter Ln(HEDTA) chelate species are more soluble in water than H4(EDTA) and the HLa(EDTA)-7H20, HLa(EDTA) H20, HCe(EDTA) H20 and HPr(EDTA) H20 species. This permits ammonium HEDTA to be used as the eluant with H -ion retaining beds at all temperatures and greatly simplifies reagent recovery. Even the effluent water can be reused. Table 22.6 lists the separation factors available with HEDTA at 92°C, as well as at 25°C. 

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