Sulfonation, selective

The ultimate in xylene separation is claimed, however, by Hetzner (10), who first distills the mixture to remove o-xylene by taking m-p-xylene and ethylbenzene overhead in a column having about 35 to 60 theoretical plates. It is reported that concentrates containing up to 97% o-xylene have been produced by this process. The m-xylene, p-xylene, and ethylbenzene mixture is selectively sulfonated to remove m-xylene. In this operation, 2 moles of Sulfuric acid (96 to 98%) are added per mole of m-xylene in the mixture to be treated. After separation, the aqueous layer is hydrolyzed at 250° to 300° F. to recover a concentrate containing 90% or more m-xylene. The hydrocarbon layer is cooled to produce p-xylene crystals, which are separated by filtration or centrifugation. The 85 to 90% p-xylene concentrate is reprocessed to recover a final product containing 96% p-xylene. The mother liquor from the p-xylene crystallization contains impure ethylbenzene and is rejected from the system. 

Crude naphthalene obtained from coal tar may contain up to 5% benzo[6]thiophene which is only partially removed by selective sulfonation.43-45 Several improvements45-51 make this process more efficient. Other chemical methods of separation include oxidation with peracetic acid, which converts benzo[6]thiophene into its readily separated 1,1-dioxide,52 and treatment with ozone, which selectively... 

Two novel reagents for the selective sulfonation of styrene to the (3-sultone (49) are reported (94ZOR948). The action of sulfur trioxide on the olefin CF2 CFS03SiMe3, yields the p-sultone (50) (94JFC89). 

Sulfonates (58) are obtained by reaction of a sulfonyl chloride with an alcohol or phenol in the presence of a base, e.g. pyridine, at low temperatures to avoid side reactions (Scheme 42). In the reaction, yields of the sulfonate (58) may be enhanced under anhydrous conditions or by the use of phase transfer catalysts, and it is found that primary alcohols react must faster than secondary alcohols and the primary sulfonates are more stable. Tertiary alcohols only form alkenes. The selective sulfonation of a primary hydroxy group in the presence of a secondary hydroxy group is therefore possible and is a useful procedure for the selective protection of a primary alcohol group (Scheme 43). 

Use Pharmaceutical intermediate, protective reagent for the guanidino group in peptide synthesis, selective sulfonating agent. 

Thiochemicals Mereapto Adds and Organosulfur (IV/VI) Compounds Table 4B Physical properties of selected sulfonic acids... 

Polvisoprene/Polybutadiene (IPB) Star-Block Copolymers. The obsen-ed selective sulfonating capabilities of acetyl sulfate was the basis for the first attempted variation of the synthetic strategy. Regardless of the exact nature... 

PS-fc-poly(4-f-butylstyrene)]n, (PS-fi-PfBuS) star-block copolymers were prepared by anionic polymerization and sequential addition of monomers with DVB as the linking agent for the formation of the star structure [156]. The functionality of the stars ranged between 10 and 20. Selective sulfonation of PS blocks was subsequently performed using the sulphur trioxide and triethyl phosphate complex in 1,2-dichloroethane, followed by neutralization with sodium methoxide. For this reason DVB was used for the linking reaction instead of chlorosilanes, where a better control could be achieved. DVB stars are more robust and the sulfonation reaction proceeds without cleavage of the arms from the star structure. 

Xylene. Pure xylene isomers are manufactured industrially in substantial quantity by selective sulfonation followed by selective desul-fonation, as discussed in a subsequent section the isomers are veiy difficult to separate physically. The sodium xylene sulfonates are used in steadily increasing quantity as solubilizing or hydrotroping agents. As in the case of toluene, the partial-pressure distillation procedure and the 80 method are both used industrially. 

The observation of Schollkopf and coworkers, that the mercury method is applicable to a-diazo- 8-carbonyl compounds, but not to diazomethane, is likely to be due to the same reason as the selective sulfonation of anthraquinone in the 1-position. The mercury ion approaches the reacting CH group via a complex with the O-atom of the neighboring carbonyl group. Mercuration of a-diazo- ff-carbonyl compounds and of anthraquinone are different, however, in another aspect, namely substitution by the metal takes place at the C-atom neighboring the carbonyl group... 

B. Paquette, H. Ali, R. Langlois, J.E. van Lier (1988). Biological activities of phthalocyanines-VIII. Cellular distribution in V-79 Chinese hamster cells and phototoxicity of selectively sulfonated aluminium phthalocyanines. Photochem. PhotobioL, 47, 215-220. 

Difficult to separate because solvent selectivity Sulfonic acids is too low... 

Analysis of polymer solubility in chloroform indicates that the solution of polymer XV shows a tendency toward precipitation. On the contrary, polymer XTV, bearing a more flexible diamine component, forms solutions up to a concentration of 0.2%, and polyimides xi-xm are soluble up to a concentration of 0.5%. Water-soluble polymer XVII was produced by the selective sulfonation of PPI XVI which is soluble in organic solvents. 

G. S. Gohil, R. K. Nagarale, V. V. Binsu, and V. K. Shahi. Preparation and characterization of monovalent cation selective sulfonated poly(ether ether... 

Brown, J. P Dietrich, P. S. Mutagenicity of selected sulfonated azo dyes in the Saknonella/microsome assay use of aerobic and anaerobic activation procedures. Mutat. Res. 1983,116, 305-315. 

Bae JM, Honma I, Murata M, Yamamoto T, Rikukawa M, Ogata N (2002) Properties of selected sulfonated polymers as proton-conducting electrolytes for polymer electrolyte fuel cells. Solid State Ionics 147 189... 

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