Xylene sulfate-reduction

The catalyst commonly used in this method is 5 wt % palladium supported on barium sulfate inhibited with quinoline—sulfur, thiourea, or thiophene to prevent reduction of the product aldehyde. A procedure is found in the Hterature (57). Suitable solvents are toluene, benzene, and xylene used under reflux conditions. Interestingly, it is now thought that Rosenmund s method (59) originally was successful because of the presence of sulfur compounds in the xylene used, since the need for an inhibitor to reduce catalyst activity was not described until three years later (60). 

As with nitrate, the anaerobic biodegradation of m- and /-xylene could also be linked with the reduction of sulfate at a rate of about 1 /M/day. Edwards et al. (1992) demonstrated the sulfate-dependent degradation of all three xylene isomers. Interestingly, the xylenes were not degraded until toluene was almost depleted. 

To synthesize alcohol with the reversed configuration at C-2, we started with the reduction of levoglucosenone to form the well-known alcohol (4) (Scheme 11.8). It was reacted with mesyl chloride to produce mesylate (28). The nucleophilic substitution was performed in refluxing toluene (or xylene) using sodium benzoate as a nucleophile and a nonnucleophilic phase transfer catalyst (tetrabutylammonium hydrogen sulfate) to give a very good yield of the expected benzoate (29). The hydrolysis of the... 

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