Reducing agents polymer-bound

Polymer-bound reducing agents have received significantly less attention, presumably because main group metal hydride complexes predominate as reducing... 

Application of Polymer-Bound Reducing Agents for Silver Recovery from Photographic Fixer. Several 10-mL aliquots of a spent photographic fixer solution containing 0.55% silver were diluted to 100 mL and adjusted to 5 different pH levels 4.5, 5.5, 6.5, 7.5, and 8.5. One gram of borohydride-form A-26 anion-exchange resin was added to each sample. The samples were stirred and allowed to stand at 20 °C for 30 min. 

Secondary amines, such as pyrrolidine, must be alkylated with care too polar a solvent leads to participation of a second nearby polymer-bound alkylant in the formation of a quaternary ammonium salt, along with the desired immobilized trialkyl amine. The exception, as seen above, is diisopropylamine, which refuses to displace tosylate even in the refluxing pure amine, or in hot dimethyl-formamide or other polar solvent, while metal diisopropylamide is notorious as a powerful non-nucleophilic base. However, carboxamide is not difficult to form from (carboxymethyl)polystyrene, again using toluenesulfonyl chloride as condensing agent this can then be reduced to (diisopropyl-ethylaminoethyl)polystyrene, which is of interest as a polymer-bound non-nucleophilic base. ... 

Devaky and Rajasree have reported the production of a polymer-bound ethylenediamine-borane reagent (63) (Fig. 41) for use as a reducing agent for the reduction of aldehydes.87 The polymeric reagent was derived from a Merrifield resin and a 1,6-hexanediol diacrylate-cross-linked polystyrene resin (HDODA-PS). The borane reagent was incorporated in the polymer support by complexation with sodium borohydride. When this reducing agent was used in the competitive reduction of a 1 1 molar mixture of benzaldehyde and acetophenone, benzaldehyde was found to be selectively reduced to benzyl alcohol. 

Figure 41 The polymer-bound ethylenediamine-borane reagent (63) for use as a reducing agent for the reduction of aldehydes. (Adapted from ref. 87.)...

Gorecki, M., and Patchornik, A. (1973) Polymer-bound dihydrolipoic acid a new insoluble reducing agent for disulfides. Biochim. Biophys. Acta 303, 36-43. 

SMANCS (Styrere-co-maleic acid/anhydride polymer bound to neocarzinostatin Neocarzinostatin (an antitumor protein) Amide bond between polymer carboxyl and protein amino None N/A SMANCS showed anticancer activity against many tumor cell lines, and had lower IC50 values than five other anticancer agents tested Liver tumors reduced more than 50% after 6 months in human subjects 15, 56, 57... 

Polymer-bound reagent. Reaction of a quaternary ammonium anion-exchange resin (Amberlites) wth NaBH4 results in an immobilized borohydride reducing agent (1), which is somewhat less reactive than NaBH4.4... 

In nonpolar solvents such as hexane, the macroreticular styrene-DVB (A-26) polymer-bound borohydride was substantially more effective in aldehyde reduction than the other reducing agents. 

Based on the stability and aldehyde and hydroperoxide reduction studies, the macroreticular borohydride-form styrene-DVB resin (A-26) appears to be the most reactive reducing agent of those investigated. This polymer-bound borohydride reagent was thus selected for investigation of several application areas of interest. 

Generation of Volatile Hydrides (11). The use of commercial sodium borohydride as a reducing agent for the generation of volatile arsine (AsH3) in trace arsenic analysis is often complicated by trace (ppb) arsenic impurities in the borohydride. The following procedure using polymer-bound borohydride has eliminated these problems ... 

---