Chelator resins derivation

In contrast to the above resins, the chelating resin Amberlite IRC-718 is based upon a macroreticular matrix. It is claimed to exhibit superior physical durability and adsorption kinetics when compared to chelating resins derived from gel polymers and should also be superior for use in non-aqueous solvent systems. 

Shrinking core model The shrinking core model has been derived for noncatalytic solid-fluid reactions (Levenspiel, 1972). However, it has been successfully used for specific ion-exchange systems—those using synthetic ion exchangers, mainly chelating resins (Cortina et al, 1998 Juang, 1999). 

The A -Boc-protected diamino acids are prepared via the copper(II) complexes of lysine or ornithine,b l or by using suitable N -protected derivatives obtained by the benzylidene route under conventional Schotten-Baumann conditionsJ l Since previous reports differ in yields and are not completely reproducible, the procedures have been optimizedJ l Thereby, the chelating resin Chelex 100 can efficiently be used for decomposition of the Cu[Lys(Boc)]2 complex. However, as this resin is expensive, an alternative procedure has been proposed for large-scale synthesis that is based on the use of the inexpensive quinolin-8-ol to quantitatively remove the copper(II) ions.P l The resulting H-Lys(Boc)-OH intermediate is then converted into the desired N -protected form by the classical procedures reported in Section 2.1.1. For cleavage of the A -Boc protection by various acidic reaction conditions, see Section 2.1.1.1.3.1.3. 

Pb was sorbed on a resin [27] and polyurethane foam [28] modified with the crown ether, 18-crown-6, and its derivatives. The sorption of Pb (and other metals) on a chelating resin containing Arsenazo I was studied in water-organic solvent media [29]. A silica gel, modified with 2-mercaptobenzothiazole [30] or 2-mercaptobenzimidazole [31 ] was used for concentration of Pb and other heavy metals from aqueous solutions. Pb was selectively separated from Al, Mg, and Fe(III) on a cation exchanger modified with tin(IV) antimonate [32]. 

For our publication in this subject [14], we focused on elucidating the structure of cellulose acetate (CA)-U02[VI), because despite the importance of using cellulose derivatives as chelating resins for removing rare metal ions in waste- and sea-water, before year of publishing of this study, there was a lack of Information regarding the structure of cellulose acetate-U02 (VI) complexes. We had prepared cellulose acetate-U02[VI] complex samples from three degrees of substitution of viscose pulp with uranyl acetate. The role of acetyl content of CA on the amount of chelated uranium was also evaluated [Table 7.6]. 

Chitosan, a biopolymer, has attracted considerable attention due to its many physical and chemical properties and due to its many applications inclnding its usage as a material for medical applications, such as artificial skin and immnnosnppressarrt. In addition, resins derived from chitosan have been synthesized and characterized. The chelation and sorption properties of these chitosan-based polymers towards heavy metal ions in aqueous solutions have been investigated by several research groups. Therefore, the aim of this article will be to shed some light on some of these chitosan-derived resins and their application to sorption of heavy metal ions and some anions. 

Ahuja M, Rai AK. Adsorption studies with some chelating ion exchange resins derived from guaran. Carbohydr Polym 1997 33 57-62. 

Depending on the mechanism, chelation reactions can be considered as additions or substitutions (for instance ion is replaced by one or several ions The amino resins derived from the copolymers of styrene, chlorostyrene and divinyl benzene can be modified by halogenoacetic acid to form structures which are able to complex metal ions (reaction 12). Kaeriyama and Shimura prepared polystyrenes (6) substituted by ethylenediaminetetraacetic acid, which are able to absorb heavy metal ions from solutions. 

Platinum-group metals (qv) form complexes with chelating polymers with various 8-mercaptoquinoline [491-33-8] derivatives (83) (see Chelating agents). Hydroxy-substituted quinolines have been incorporated in phenol—formaldehyde resins (84). Stannic chloride catalyzes the condensation of bis(chloromethyl)benzene with quinoline (85). 

In addition to phosphine ligands, a variety of other monodentate and chelating ligands have been introduced to functionalized polymers [1-5]. For example, cyclo-pentadiene was immobilized to Merrifield resins to obtain titanocene complexes (Fig. 42.13) [102]. The immobilization of anionic cyclopentadiene ligands represents a transition between chemisorption and the presently discussed coordinative attachment of ligands. The depicted immobilization method can also be adopted for other metallocenes. The titanocene derivatives are mostly known for their high hydrogenation and isomerization activity (see also Section 42.3.6.1) [103]. 

At present, soil derived humic matter and fulvic acids extracted from freshwater are available commercially and are commonly used to test techniques for DOM detection and also used as model compounds for trace metal chelation studies. The results obtained using these model compounds are frequently extrapolated to the natural environment and measurements on "real" samples provide evidence that this DOM is a good model compound. In the past, some investigators also made available organic matter isolated from marine environments using C18 resins. While these compounds come from aquatic sources, this isolation technique is chemically selective and isolates only a small percentage of oceanic DOM. Reference materials are not currently available for these compounds, which inhibits study of the role they play in a variety of oceanographic processes. 

Allyl chloride is used to make intermediates for downstream derivatives such as resins and polymers. Approximately 90% of allyl chloride production is used to synthesize epichlorohydrin, which is used as a basic building block for epoxy resins and in glycerol synthesis. Allyl chloride is also a starting material for allyl ethers of phenols, bisphenol A and phenolic resins, and for some allyl esters. Other compounds made from allyl chloride are quaternary amines used in chelating agents and quaternary ammonium salts, which are used in water clarification and sewage sludge flocculation (Kneupper Saathoff, 1993). 

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