Carbon bonding resin bond

Oxidation. Ketones are oxidized with powerful oxidizing agents such as chromic or nitric acid. During oxidation, carbon—carbon bond cleavage occurs to produce carboxyHc acids. Ketone oxidation with hydrogen peroxide, or prolonged exposure to air and heat, can produce peroxides. Concentrated solutions of ketone peroxides (>30%) may explode, but dilute solutions are useful in curing unsaturated polyester resin mixtures (see... 

Degree of unsaturation. Unsaturation accounts for the existence of carbon-carbon double bonds in resins. It is generally indicated by the bromine or iodine number. Both methods are based on the halogen addition to the double carbon-carbon bonds. Because the different reactivity of bromine and iodine, both numbers cannot be compared. The bromine or iodine number does not necessarily correlate with the reactivity of the resin, for instance in the ageing process. However, within a given resin series of the same structure, relative comparisons can be made. 

Group of plastics composed of resins derived principally from polymeric esters that have recurring polyester groups in the main polymer chain. These polyester groups are crosslinked by carbon/carbon bonds. 

Diels-Alder reactions provide one of the few general methods of forming two carbon-carbon bonds simultaneously. The main features of these reactions are described in Box 1.3. The reaction finds widespread industrial use for example hardeners for epoxy resins are made by reaction of maleic anhydride with dienes such as 2-methyl-1,4-butadiene. 

An example in which cleavage from the resin was achieved using a carbon electrophile demonstrated the ability of these polymer-bound metathesis products to act as substrates for carbon-carbon bond formation (Eq. 19). 

Furfiirylthiol is a key flavour especially for coffee, beef and roast-like food aromas. It was synthesised in concentrations of up to 1 g L using /1-lyase activity of whole bacterial cells, e.g. Enterobacter cloacae or Eubacterium limosum [256] (Scheme 23.21). Resting cells were used to cleave the sulfur-carbon bond of a furfural-cysteine conjugate and an XAD-4 resin connected to the gas outlet... 

The first example of l,4-benzodiazepin-5-one that incorporates an unsubstituted 2,3-carbon-bond was obtained by hydrolyzing the acetal 69 in THF in the presence of Amberlyst-15 resin <2000S265>. Subsequent heating of the product in toluene with azeotropic removal of water gave the HA>cnTo[e][, 4]dixLcpin-5(4H)-ox e 70 (Scheme 31). 

The Suzuki coupling reaction is a powerful tool for carbon-carbon bond formation in combinatorial library production.23 Many different reaction conditions and catalyst systems have been reported for the cross-coupling of aryl triflates and aromatic halides with boronic acids in solution. After some experimentation, we found that the Suzuki cleavage of the resin-bound perfluoroalkylsulfonates proceeded smoothly by using [l,l -bis (diphenylphosphino)ferrocene]dichloropalladium(II), triethylamine, and boronic acids in dimethylformamide at 80° within 8 h afforded the desired biaryl compounds in good yields.24 The desired products are easily isolated by a simple two-phase extraction process and purified by preparative TLC to give the biaryl compounds in high purity, as determined by HPLC, GC-MS, and LC-MS analysis. 

A quite useful resin in nucleophilic carbon-carbon bond formation reactions is the carboxylic resin (5). The soft metal from the nucleophile is... 

Screening the encoded library produced interesting structures to build an SAR and to design focused libraries of binders for the artificial receptor, but some limitations of these linkers for applications different from peptide chemistry are clearly evident. The carbonate bond connecting the electrophone tag and the photocleavable linker (Figure 9.8) is sensitive to many organic reaction conditions, and the carboxylate requires an amino- or hydroxy function to be linked to the resin after each synthetic step to be encoded. 

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