Graphite methanesulfonic acid

Table 5.4 Promotion of acylation of phenols with carboxylic acids by graphite-methanesulfonic acid...

Graphite combined with methanesulfonic acid represents an effective catalyst for the acylation of phenols and naphthols, wifh carboxylic acids giving a good yield of ortho-hydroxy aryl ketones (Table 5.4). The reactions seem to be faster with activated aromatic carboxylic acids. It must be emphasized that, in the absence of graphite, in the model reaction between mefa-cresol and BAC, the product is isolated in lower yield (20% versus 81%). 

The recovered graphite shows good catalytic activity on recycling the yields of the ortho-product in the model reaction in the second, third, and fourth cycles are almost the same as the yield in the first run. Because methanesulfonic acid is not adsorbed onto graphite, it is necessary to add it again in the successive cycle after having washed the catalyst with methylene chloride. 

Sharghi, H., Hosseini-Sarvari, M., and Eskandari, R. 2006. Direct acylation of phenol derivatives in a mixture of graphite and methanesulfonic acid. Synthesis 2047-2052. 

Also obtained by Filedel-Crafts acylation of o-cresol with benzoic acid in a mixture of graphite and methanesulfonic acid at 120° for 3 h (90%) [1598]. 

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