Resins iminodiacetic acid

Theory. Conventional anion and cation exchange resins appear to be of limited use for concentrating trace metals from saline solutions such as sea water. The introduction of chelating resins, particularly those based on iminodiacetic acid, makes it possible to concentrate trace metals from brine solutions and separate them from the major components of the solution. Thus the elements cadmium, copper, cobalt, nickel and zinc are selectively retained by the resin Chelex-100 and can be recovered subsequently for determination by atomic absorption spectrophotometry.45 To enhance the sensitivity of the AAS procedure the eluate is evaporated to dryness and the residue dissolved in 90 per cent aqueous acetone. The use of the chelating resin offers the advantage over concentration by solvent extraction that, in principle, there is no limit to the volume of sample which can be used. 

A very useful, but difficult, case has been reported by Smith and Barclay (1992) for the recovery of Monsanto s highly successful herbicide, glyphosphate (N-phosphonomethyl-glycine, tradename Roundup), from an aqueous waste stream. This stream contains a lot of unwanted products like HCHO, HCOOH, aminomethylphosphoric acid, and N-phosphonomethyl iminodiacetic acid (PMIDA). The removal of PMIDA and HCOOH from glyphosphate is essential as HCOOH can react to give the formyl derivative. Amberlite IRA-93 and Amberlite IRA-68 (anionic resins) were chosen to separate glyphosphate from PMIDA and HCOOH, respectively (HCHO does not get adsorbed). 1500 recovery cycles were tried, and the resin has two years plant life scale-up with a factor of 90,000 was very successful. 

Resins can also be prepared with chelating functional groups which show selective affinities for certain metals. Iminodiacetic acid, vinylacetylacetone, glyoxal-thiophenol and 8-hydroxy quinoline have all been used to produce these so-called chelating resins. Their selectivities are similar to those of the free reagent. 

The preparative capacity of CLEC columns is reasonable. However, the presence of copper in the mobile phase is not convenient. Copper can be removed using a iminodiacetic acid-based resin column. ... 

Particulates consisting of porous, particulate ion exchange resins with various paramagnetic ions (Cu, Fe " , Fe " , Mn " ", and Gd " ") bound to their surface were investigated by Braybrook et al. (93,94). The resins used were sulfonated polystyrene, iminodiacetic acid substituted polystyrene and sepharose activated with l,4-bis(2,3-epoxypropoxy) butane and substituted with iminodiacetic acid. 

Aiming at easier workup conditions, immobilization of several transition metal catalysts, which show activity for the epoxidation of allylic alcohols, on polymer support has been investigated. For example, Suzuki and coworkers incorporated an oxo-vanadium ion into cross-linked polystyrene resins functionalized with iminodiacetic acid or diethylenetri-amine derivatives (Scheme 57), which afforded a heterogeneous catalyst that can promote... 

The reducing power of the MV formed in a solid phase can be transfered to liquid phase. Ru(bpy)3+ and MV2+ were adsorbed in water-swollen chelate resin beads containing iminodiacetic acid (IDA) groups. The irradiation of the beads induced rapid formation of MV in the solid phase through the electron relay of IDA -Z- Ru(bpy)2 MV2 49>.When the beads were irradiated in water contain-... 

In Figure 4.11, the formula of a chelating resin is shown with the iminodiacetic acid group as the chelating ligand, which is bonded onto a cross-linked polystyrene matrix. This type of resin shows a large affinity for alkaline-earth and transition metal ions. 

Figure 4.11 Chelating resin with the iminodiacetic acid group as the chelating ligand bonded onto a cross-linked polystyrene matrix.

Fig. IS. Adsorption of metal ions on iminodiacetic acid resin (a) and schematic representation of adsorption behavior of polymers (b), (c)...

PDA = partially diethylaminomethylated poly(styrene), DBQP-partially crosslinked PVP with 1,4-dibromobutane, IDA - chelating resin containing iminodiacetic acid group. 

Colloidal palladium or platinum supported on chelate resin beads were employed for the stereoselective hydrogenation of olefins 86). Colloidal palladium supported on iminodiacetic acid type chelate resin beads was prepared by refluxing the palladium chloride and the chelate resin beads in methanol-water. Using the resin-supported colloidal palladium as a catalyst, cyclopentadiene is hydrogenated to cyclopentene with 97.1% selectivity at 100 % conversion of cyclopentadiene under 1 atm of hydrogen in methanol at 30 °C. Finely dispersed metal particles ranging from 1 to 6 nm in diameter are the active species in the catalyst. 

Oxovanadium(V) and oxomolybdenum(VI) were incorporated into crosslinked polystyrene resins functionalized with iminodiacetic acid or diethylenetriamine derivatives 921 The polymer complexes were used as catalysts in the oxidation of olefins with f-butylhydroperoxide. Vanadium(V) complexes promote the epoxidation of allylic alcohols in a highly regioselective manner, e.g., 2,3-epoxide was obtained in 98 % selectivity from e-geraniol at 80 °C. The catalytic activity of the vanadium(V) complexes is generally higher than that of the molybdenium(VI) complexes in the oxidation of allylic alcohols, whereas an opposed trend holds for the epoxidation of cyclohexene. 

The [Ru(bpy)3]2+ photosensitized reduction of methyl viologen (MV2+) proceeds rapidly in water-swollen iminodiacetic acid type chelate resin beads which adsorb both [Ru(bpy)3]2+ and MV2+ (RM resin). The reduction takes place with the aid of polymer-bound iminodiacetate as a donor 102). Photosensitized formation of hydrogen peroxide occurs in an aqueous solution containing RM resin and oxygen molecules (Fig. 8)102 The some reaction also occurs using a polystyrene-coated filter paper, onto which both [Ru(bpy)3]2 + and MV2+ were adsorbed 103). 

Ordinary anion and cation ion-exchange resins are of limited use for the analytical concentration of trace elements from water, because of their lack of selectivity. This is especially so with strong electrolytes such as seawater. In this case the major ions sodium, magnesium, calcium and strontium, are retained preferentially. However, the recent advent of commercial chelating resins based mainly on iminodiacetic acid-substituted cross-linked polystyrene, makes it possible to concentrate trace elements from waters. In consequence, a number of researchers have used chelating resins for trace-metal preconcentration from seawater and natural waters. 

ANKB-33 resin is an iminodiacetic acid exchanger this multidentate chelating functionality is capable of forming metal coordination complexes with different stabilities [10,31]. 

The resemblance between metal ion complexation of the repeating chelate moiety constituting the reactive sites of a chelating resin, Dowex A-1, and the simple iminodiacetic acid molecule itself is also reasonably consistent with the above estimate of the situation [5]. 

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