4-methylbenzene-1-sulfonic acid

4-Methylbenzenesulfonic acid: Overview and chemical identifiers

4-Methylbenzenesulfonic acid is an aromatic sulfonic acid with methyl and sulfonic acid groups in para positions on a benzene ring. The 4-methylbenzenesulfonic acid CAS identifier is 104-15-4. Common names include p-toluenesulfonic acid, p-TsOH, and TsOH. The systematic name 4-methylbenzene-1-sulfonic acid describes the same structure.

Names, synonyms and CAS 104-15-4

CAS 104-15-4 identifies 4-methylbenzenesulfonic acid, while the commonly encountered monohydrate is separately identified as CAS 6192-52-5. The hydration state should be confirmed from the specific product documentation. 4-Amino-3-methylbenzenesulfonic acid contains an additional amino group and is a separate compound with CAS 98-33-9. The term 4-methylbenzenesulfonic acid methyl ester refers to methyl p-toluenesulfonate, or methyl tosylate, with CAS 80-48-8. Neither related compound is a synonym for CAS 104-15-4.

Molecular structure and chemical properties

The 4-methylbenzenesulfonic acid structure comprises a benzene ring bearing CH3 and SO3H groups para to each other. The anhydrous formula is C7H8O3S, and its average molecular weight is 172.20 g/mol. A valid SMILES representation is Cc1ccc(S(=O)(=O)O)cc1. The standard InChI is InChI=1S/C7H8O3S/c1-6-2-4-7(5-3-6)11(8,9)10/h2-5H,1H3,(H,8,9,10), and the InChIKey is JOXIMZWYDAKGHI-UHFFFAOYSA-N. Hydration changes the formula and molecular weight and must be considered in calculations. Physical form, water content, storage requirements, and hazard information should be taken from the SDS for the exact product.

Applications and research use

4-Methylbenzenesulfonic acid is used as a Brønsted acid catalyst in organic synthesis. Published procedures document its use in esterification and acid-mediated deprotection, including removal of Boc groups under substrate-specific conditions. It may also provide the tosylate counterion when basic compounds are isolated as salts. Reaction suitability depends on the substrate, solvent, temperature, water content, and acid loading; these examples are not universal protocols. No biological, pharmacological, or therapeutic activity should be inferred from these synthetic uses.

Sourcing and supplier selection on ChemSpace

ChemSpace presents offers from independent suppliers rather than manufacturing the compound. When sourcing 4-methylbenzenesulfonic acid under CAS 104-15-4, users should confirm whether an offer represents the anhydrous acid, a hydrate, a solution, or another form. The formula, molecular weight, structure, and identifiers should agree with the supplier documentation. Selection should be based on the current offer, analytical specification, batch-specific CoA, SDS, and laboratory requirements. Handling and storage should follow product-specific documentation.