| prov:value
| - The catalyst can be any strong mineral acid such as sulfuric, hydrochloric, perchloric, hydrobromic, hydrofluoric, chlorosulfonic and ethanesulfonic acid; an acid regenerated cation exchange resin; various salts of mercury, silver, cobalt, nickel and cerium; or aromatic sulfonic acids such as benzenesulfonic, p-toluenesulfonic, or ??-naphthalenesulfonic acid.
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