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p-Toluenesulfonic acid (PTSA or pTsOH) or tosylic acid (TsOH) is an organic compound with the formula CH3C6H4SO3H.
T 1897 (OTTO) p-Toluene sulphonic acid, GR 99%+ Cas 6192-52-5 - used as alkylating agents because the tosyl group is electron-withdrawing, which makes the tosylate anion a good leaving group.