Sulfonated amorphous carbons

This acid-catalyzed cleavage of the glycosidic bonds is rather complex and often suffers from a lack of selectivity mainly due to side dehydration or recombination reactions of monosaccharides. In the existing literature, four different classes of solid catalysts are reported (1) cation-exchange resins, (2) siliceous-based materials, (3) metal oxides, and (4) sulfonated amorphous carbons. 

Stepwise degradation of sugars under catalytic conditions leads to shorter-chain sugars and such by-products as CO, C02, and H20 depending on the conditions (see also next section).348 Sucrose or other carbohydrates have been used for the preparation of new solid acidic catalysts by partial carbonization followed by sulfonation. This leads to sheets of amorphous carbon bearing hydroxyl, carboxyl, and sulfonic groups. These have been used for the production of biodiesel fuel.349... 

These carbonaceous catalysts can be obtained by the sulfonation of incompletely carbonized organic compounds [42]. Note that starch and cellulose can be used as carbon precursor [43, 44]. After the incomplete pyrolysis of the carbon precursor, the SO3H groups have been introduced by sulfonation with sulfuric acid (Scheme 3). After this treatment, the presence of phenolic hydroxyl, carboxylic acid, and sulfonic groups at the surface of these amorphous carbonaceous materials has been demonstrated. 

Studies of carbonate-sulfonate RMs in engine oil on the antiwear performance of ZDDP, using reflectance-absorbance infrared spectroscopy RAIR, X-ray photoelectron spectroscopy XPS and Auger electron spectroscopy AES, showed that the tribofilms were inorganic amorphous phosphates, mainly orthophosphate (P043 ) and pyrophosphate (P2074 ) associated with zinc and magnesium (from the hard-core RMs) (Willermet et al., 1991 and 1992). 

The Chinese patented polyetherketone and polyethersulfone (PEK-C PES-C) are amorphous polymers with high glass transition temperatures (Tj,=228°Cand 260 C respectively)("7-i. They were synthesized by nucleophilic polycondensation of phenolphthalein (PPH) and dichlorobenzophenone or dichlorodiphenylsulfone in sulfolane in the presence of potassium carbonate. They were found to be good membrane materials for ultrafiltration and microfiltration( and could also be used as charged membranes (after sulfonation or chloromethylation/quaternization) for nanofiltration and electrodialysis processes. 

This reaction is carried at temperatures of about 300 °C in the presence of Si02 or K2CO3 catalysts, using diphenyl sulfone as solvent. In addition to the polymeric products, carbon dioxide and KF by-products are formed. The amorphicity of these poIy(ether ketones) is caused by the non-syirunetric dibenzofuran species being formed along the aromatic polymer chain [483-485] ... 

Highly hindered biphenols 1 (R= CH3, Ph, Cl) were synthesized by oxidative coupling of the corresponding phenols. High molecular weight poly(aryl ether)s 3 were prepared from these biphenols by reaction with bis(4-fluorophenyl)sulfone or 4,4 -difluorobenzophenone in polar, aprotic solvents in the presence of potassium carbonate. The polymerization reactions were very slow because of the steric hindrance provided by the pendant phenyl groups in these biphenols. The polymers are amorphous and very thermooxidatively stable. They are very soluble in methylene chloride at room temperature and they can be cast into tough, flexible films. ... 

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