Benzenesulfonic acid

May 29, 2023
I’m almost as corrosive as the mineral acids.
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Benzenesulfonic acid is the simplest aromatic sulfonic acid. It is highly water-soluble and a strong acid with a pKa of –2.8. It has been known since at least the 1880s; its synthesis, which goes back to 1916, is via the reaction of benzene with hot concentrated sulfuric acid.

Benzenesulfonic acid is used to produce phenol by fusing it with sodium hydroxide or hydrolyzing one of its salts, usually sodium. Other uses include surfactants made with its metal or amine salts and as a counterion for cationic pharmaceuticals.

For additional information on benzenesulfonic acid’s properties and uses, see articles curated by ScienceDirect.

Benzenesulfonic acid hazard information*

Hazard class**GHS code and hazard statement
Corrosive to metals, category 1H290—May be corrosive to metalsChemical Safety Warning
Acute toxicity, oral, category 4H302—Harmful if swallowedChemical Safety Warning
Skin corrosion/irritation, category 1CH314—Causes severe skin burns and eye damageChemical Safety Warning
Serious eye damage/eye irritation, category 1H318—Causes serious eye damageChemical Safety Warning
Specific target organ toxicity, single exposure, respiratory tract irritation, category 3H335—May cause respiratory irritationChemical Safety Warning

*Compilation of multiple safety data sheets.
**Globally Harmonized System (GHS) of Classification and Labeling of Chemicals. Explanation of pictograms.

Molecules from the journals

Cerium(IV) oxide1 (CeO2), also called ceric oxide or ceria, is a rare earth oxide that appears as pale yellow crystals or powder. It occurs in nature mixed with other cerium oxides and as oxides of other rare earth. Its several uses include polishing and decolorizing glass, inclusion in various types of coatings, and catalyzing organic reactions.

This past March, Pinxian Xi and co-workers at Lanzhou University (China) reported a new catalytic application of CeO2. They used it in combination with bismuth trisulfide2 (Bi2S3) to promote the electrochemical reduction of carbon dioxide to the formate anion. Bi2S3 and CeO2 combine to form a Bi–O–Ce structure, which promotes electron transfer between the two compounds and increases the selectivity of the reaction in favor of formate.

Wickerol A3 and wickerol B4 are triterpenes produced by the soil fungus Trichoderma atroviride that is found worldwide. In 2012, Satoshi Ōmura, Kazuro Shiomi, and co-workers at Kitasato University (Tokyo) reported that the wickerols show potent activity against an influenza virus strain, with the A compound having greater activity than B. In March, Christopher D. Vanderwal and co-workers at the University of California, Irvine, described the enantioselective total syntheses of the two wickerols starting from 2-cyclohexen-1-one5.

1. CAS Reg. No. 1306-38-3.
2. CAS Reg. No. 1345-07-9.
3. CAS Reg. No. 1187951-84-3.
4. CAS Reg. No. 1355394-77-2.
5. CAS Reg. No. 930-68-7.

Molecules from the Journals

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Benzenesulfonic acid 
fast facts

CAS Reg. No.98-11-3
SciFinder nomenclatureBenzenesulfonic acid
Empirical formulaC6H6O3S
Molar mass158.18 g/mol
AppearanceDeliquescent white crystals or waxy solid
Melting point65 °Ca
Water solubility930 g/L (25 °C)

a. Uncertain; also reported as low as 43 °C.

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