Sulfone linkages

The isopropylidene linkage imparts chemical resistance, the ether linkage imparts temperature resistance, and the sulfone linkage imparts impact strength. The brittleness temperature of polysulfones is — 100°C. Polysulfones are clear, strong, nontoxic, and virtually unbreakable. They do not hydrolyze during autoclaving and are resistant to acids, bases, aqueous solutions, aliphatic hydrocarbons, and alcohols. 

A weight loss of 20-30% was observed for all of the systems over 200 h. There is little difference between the various products since the controlling factor of the thermoxldative stability, the sulfone linkage, is common to each of them. 

The commercial products contain one chlorine atom per 2-3 repeat units and about one chlorosulfonyl group per 70 repeat units. The chlorosulfonyl groups allow the elastomer to be vulcanized with metal oxides such as lead or magnesium oxide by the formation of metal sulfonate linkages ... 

Intermolecular alkyl-alkyl couplings have been performed with a complex molecule, e g., a fragment of vitamin D, attached to a sohd support via a sulfonate linkage, and an alkyl Grignard reagent such as (89) [207]. The Cu-catalyzed reaction was designed to attach various alkyl chains at the 22-position of atom Tl of vitamin D3 analogs (88) (Scheme 20). 

Whereas high molar mass polyether sulfones are expected to show phase separation, the low molar mass versions can be miscible and can alter the T of the cyanurate network. A recent kinetic study on the reaction of BACY with a low molar mass, cyanated polyether sulfone showed an unexpected S shape for the Tg-composition curve [269]. Studies on model compounds using UV and IR spectroscopy suggested the possible polar interaction between the lone pair of electrons on the N-atoms of the triazine ring and the n orbital of the phenylene rings neighboring the sulfone linkage to be responsible for the miscibility and the peculiar shape of the Tg-composition curve. 

The melt viscosity is regarded as still too high for injection molding of these materials. However, an additional option for adjusting their processing conditions is their plastification. An effective means for attenuating ionic association within the clusters is the incorporation of various metal acetates, particularly Zn acetate, which supposedly breaks-up divalent sulfonate linkages ... 

Phthalocyanlnes. Gebler (18) has reported the attachment of a variety of metal phthalocyanines to both 8% and 20% dlvlnylbenzene polystyrene copolymer beads. The attachment of the phthalocyanine unit was either ly a sulfonamide or a sulfone linkage. Nickel, vanadyl, cobalt, iron and manganese complexes were formed in this way. Since solution aggregation accounts for a diminution of the catalytic activity, it was anticipated that polymer immobilization would Increase reactivity. Such an effect was not observed and little advantage over the homogeneous catalysts could be observed in the oxidation of cyclohexene. Oxidations of thiols by immobilized phthalocyanines have been reported (19-20) by both Schutten and Brouwer. 

It is well-documented that aromatic polymers containing aryl ether or sulfone linkages have excellent thermal and mechanical properties [107]. Analysis of the TGA traces for 15-18 revealed that they all exhibit good thermal stability. They retained more than 95% of their mass in the range of 335 to 363 °C. Their onset decomposition temperatures appeared higher than that in tra s-[-Pt(PBu3)2C = C (p-C H )jC = C-] (-300°C) [116]. Thus, the introduction of a heteroatom can enhance the thermal stability of this class of metal polyynes. We observed a sharp... 

Hsiao SH, Chiou JH (2001) Aromatic poly(l,3.4-oxadiazole)s and poly(amide-l,3,4-oxadiazole) s containing ether sulfone linkages. J Polym Sci A Polym Chem 39 2271-2286... 

Generally speaking, polymers containing e.g., ether and sulfone linkages exhibit lowered thermooxidative stability but increased solubility and flexibility, which facilitates the further processing, modification (cross-linking and... 

Urea Derivatives. Sun et al. have developed a strategy to synthesize substituted ureas 102 from sodium benzenesulhnate resin 43 (Scheme 12.24). 2-Chloroethanol was hrst coupled with the resin 43 to afford resin 100, which can easily react with carboxylic acid to form ester linkages that can be cleaved under basic or acidic conditions. Treatment of resin 100 with Boc-protected glycine using DCC/DMAP afforded resin 101 whose sulfone linkage was cleaved using HCl in dioxane to yield the cyclized urea derivatives 102. 

Synthesis of 2-Substituted-4-piperidones Involving -Elimination of Sulfone. /3-Elimination of sulfone linkage was first described by Schwyzer et al. using a 2-(4-carboxyphenylsulfonyl)ethanol linker for the synthesis of peptides and oligonucleo-... 

Figure 5.8 Structure of the aromatic PA bearing sulfone linkages (from [28]).

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