Oxidation-reduction resins

Like other manganese lakes, P.R.63 2 may accelerate the drying process of oxidatively drying resin systems. Its full shade lightfastness, which matches step 6-7 on the Blue Scale, is good. The pigment reaches step 4-5 in white reductions (1/3 SD), which is considerably better than that of the corresponding calcium lake. 

Berry, K. L., and J. H. Peterson Tracer studies of oxidation-reduction polymerization and molecular weight of Teflon tetrafluoroethylene resin. J. Am. Chem. Soc. 73, 5195-5197 (1951). 

The oxidation-reduction method, developed initially by Mukaiyama et al. [133] and related to the previously described organophosphorus methods, has permitted a variety of important solid-phase applications. The mechanism of the activation is complex and involves the oxidation of the triaryl/ alkyl-phosphine to the oxide as well as reduction of the disulfide to the mercapto derivative. However, different active species, such as 81 (Fig. 11), the 2-pyridyl thioester, or even the symmetrical anhydride, have been postulated to form. For the intermediate 81, the peptide bond formation may proceed through a (cyclic transition state. The method has been used for conventional stepwise synthesis [134], acylation of the first protected amino acid to a hydroxymethyl resin, and to achieve segment condensation on a solid support in the opposite direction (N C) [135,136]. Lastly, it has been used for efficient grafting of a polyethylene glycol (molecular weight 2000) derivative to an aminomethyl resin to prepare PEG-PS resins [137]. 

In addition to ion exchange resins, polymer reagents also include what are called redox or oxidation-reduction polymers which also represent electron transfer agents. Polymer reagents are also used in the Merrifield synthesis of peptides and proteins (see Chapter 30). Other polymer reagents, together with their applications, are... 

The chemical reactivity of resin acids is determined hy the presence of hoth the double- bond system and the COOH group [5], The carboxylic group is mainly involved in esterification, salt formation, decarboxylation, nitrile and anhydrides formation, etc. These reactions are obviously relevant to both abietic- and pimaric-type acids (Rgs 4.1 and 4.3, respectively). The olefinic system can be involved in oxidation, reduction, hydrogenation and dehydrogenation reactions. Given the conjugated character of this system in the abietic-type acids, and the enhanced reactivity associated with it, much more attention has been devoted to these stractures. In terms of industrial applications, salt formation, esterification, and Diels-Alder additions are the most relevant reactions of resin acids. 

Chemical separation methods deployed in solution utilize the very slight difference in the tendency of the two isotopes to undergo oxidation reduction reactions or their affinity toward an ion-exchange resin. 

In 1949 Harold Cassidy of Yale University took the next step from ion-exchange resins as catalysts, to resins which could function as reagents by accepting or donating electrons. He essentially created the field of redox pol3rmers and was quickly joined by the efforts of Manecke in Germany (1953). While this concept has remained dormant since Cassidy and Kun s book, "Oxidation Reduction Polymers" was published in 1965, it has gained new currency since... 

Sansoni prepared several samples of polycondensates of resorcinol, formaldehyde and Methylene Blue and tested their redox properties by repeated oxidation reduction cycles,9 with ammoniacal sodium dithionite as the reductant and acidic hydrogen peroxide as the oxidant. The best resins had a redox capacity of. 5 5 8 meq of Fe(lll) per gram. This novolac type of condensation was later used th azo dyes to give thermosetting colored coating compositions. When dye molecules are available with two condensable... 

Oxidation-reduction carrier resin Ethylene, isobutylene United States 4,065,435 1977 Fuji Photo Film ... 

The presence of the ortho-riiXro group allowed nucleophilic cleavage to liberate the desired amine [6]. An amidine linker [7,8] provided a resin bound amine that was stable to oxidative, reductive, and alkylative conditions. The use of 2-chlorotrityl resin proved to be useful for the preparation of a secondary amine library [9] as well as hydroxamic acids [10]. Tertiary amines were prepared by 1,4 addition to a resin bound acrylate followed quatemization and a retro-Michael reaction [11]. The p-nitrophenyl carbonate linker has been shown to be useful for the inunobilization of ben-zamidines [12] and for the synthesis of sulfonamides [13]. Sulfonamides and amides were also prepared using a halogenated Wang resin [14]. 

Catalyst Selection. The low resin viscosity and ambient temperature cure systems developed from peroxides have faciUtated the expansion of polyester resins on a commercial scale, using relatively simple fabrication techniques in open molds at ambient temperatures. The dominant catalyst systems used for ambient fabrication processes are based on metal (redox) promoters used in combination with hydroperoxides and peroxides commonly found in commercial MEKP and related perketones (13). Promoters such as styrene-soluble cobalt octoate undergo controlled reduction—oxidation (redox) reactions with MEKP that generate peroxy free radicals to initiate a controlled cross-linking reaction. 

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