Chlorobenzene, sulfonation

Sulfonation—Desulfonation of Chlorobenzenes. Sulfonation of chlorobenzenes can also be used to produce chlorophenols. Sulfonation is carried out at 60—80°C using oleum at 15—20%. The subsequent desulfonation usually calls on aqueous alkaU solutions at 15—20% at temperatures between 170 and 230°C. 

This is converted by methyl iodide to the quaternary salt which is converted to the p-chlorobenzene sulfonate salt (73) for pharmacological purposes. 

The Stringfellow Superfund site in California poses analytical problems similar to those encountered with most waste sites across the United States and that may be best addressed via LC/MS based methods. Most of the organic compounds in aqueous leachates from this site cannot be characterized by GC/MS based methods. Analysis of Stringfellow bedrock groundwater shows that only 0.78% of the total dissolved organic materials are identifiable via purge and trap analysis (IQ). These are compounds such as acetone, trichloroethylene etc, whose physical properties are ideally suited for GC/MS separation and confirmation. Another 33% of the dissolved organic matter is characterized as "unknown", i.e., not extractable from the aqueous samples under any pH conditions and thus not analyzed via GC. Another 66% is 4-chlorobenzene sulfonic acid (PCBSA), an extremely polar and water soluble compound that is also not suitable for GC analysis. This compound, a waste product from DDT manufacture, is known to occur at this site because of the history of disposal of "sulfuric acid waste from industrial DDT synthesis. 

Chlorobenzene-sulfonic Acid Aqueous solution or pure 95... 

N,N-Dimethyl-N-(2-phenoxyethyl)-2-thiophehmethanaminium salt with 4-chlorobenzene-sulfonic acid (1 1). 

In addition to the solubility behaviour, the selection of solvents is also important since solvents can change the solubilities of the enantiomers under consideration. Shiraiwa et al. (3) reported that the control of the solvent composition could eliminate the purity drop by the preferential crystallization for the racemic compound forming system of (R -Tyiosinc 4-chlorobenzenesulfonate (Figure 5) in which the solvents examined were mixtures of ethanol and 4-chlorobenzene sulfonic acid (CBA). 

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