3-Methylisothiazole-4-sulfonic acid CAS 933-85-7
| CAS No. | 933-85-7 |
| Molecular Formula | C4H5NO3S2 |
| Molecular Weight | 179.22 g/mol |
| Category | Pharmaceutical Standards / API Standards |
| Availability | In Stock |
Chemical Structure
Description
3-Methylisothiazole-4-sulfonic acid (CAS 933-85-7), molecular formula C4H5NO3S2 and molecular weight 179.22 g/mol, is a CATO reference standard with documented purity and traceability.
3-Methylisothiazole-4-sulfonic acid (C4H5NO3S2) contains an amide group, a sulfone group, a carboxylic acid group, a hydroxyl group, an ether linkage. It is notably hygroscopic, the carboxyl group imparts weak acidity; these physicochemical properties determine the optimal preparation and storage of its standard solutions. Nitrogen-containing functional groups confer excellent ionization efficiency in positive-ion electrospray (ESI) mode, making the compound well suited to LC-MS/MS analysis.
This reference standard is suitable for quantitative analysis on major chromatographic platforms including HPLC, GC, LC-MS/MS, and GC-MS, serving as an external calibration standard or a system suitability test reference material.
As a certified reference material (CRM), 3-Methylisothiazole-4-sulfonic acid meets the metrological traceability requirements of ISO/IEC 17025 laboratories. Batch-to-batch consistency is monitored via control charts to guarantee comparable assigned values across lots.
Physical & Chemical Properties
| Molecular Formula | C4H5NO3S2 |
| Molecular Weight | 179.22 g/mol |
| Purity | 97%+ |
| Storage | Store at 2-8°C, protect from light, keep sealed and dry |
| Solubility (reference) | Soluble in methanol, ethanol, DMSO, water |
| Stability | May oxidize slowly on prolonged air exposure; Light-sensitive; avoid direct strong light; Hygroscopic; reseal immediately after opening |
| Degree of Unsaturation (DBE) | 3.0 |
| UV Absorption | UV-absorbing |
| CAS Registry Year (est.) | 1957 |
| Nitrogen Atoms | 1 |
| Sulfur Atoms | 2 |
Related Methylisothiazole Standards
- 3-Methylisothiazole-5-sulfonamide (CAS 1022128-99-9)
- 3-Methylisothiazole-4,5-dicarboxylic acid (CAS 67048-61-7)
- Ethyl 3-methylisothiazole-4-carboxylate (CAS 15901-51-6)
- 3-Methylisothiazole-5-sulfonyl chloride (CAS 1355334-86-9)
- (3-Methylisothiazole-4-carbonyl)glycine (CAS 1239754-56-3)
- Methyl 3-methylisothiazole-5-carboxylate (CAS 15901-54-9)
- Methyl 5-methylisothiazole-4-carboxylate (CAS 15901-70-9)
- 3-Methylisothiazole-4-carbohydrazide (CAS 89179-69-1)
Recommended Standards
- 3-Methyl-3,4,7,8-tetrahydroquinoline-2,6(1H,5H)-dione (CAS 77903-18-5)
- 3-Morpholinophenol (CAS 27292-49-5)
- 3-Methyl-2-(pyridin-3-yl)butanoic acid (CAS 699527-72-5)
- 3-p-Tolylamino-propionic acid (CAS 27418-59-3)
- 4-Formylphenyl 4-acetamidobenzenesulfonate (CAS 432000-22-1)
- 1-(Bromomethyl)-2,5-dichloro-3-nitrobenzene (CAS 1009349-32-9)
- 5-Amino-1-(4-fluorophenyl)-1h-1,2,3-triazole-4-carboxamide (CAS 606135-57-3)
- 2-(4-Amino-1h-pyrazol-1-yl)-N-(2,2,2-trifluoroethyl)acetamide (CAS 1153735-51-3)
- Methylethenyl Sulfoxide (CAS 10258-86-3)
- 2,2-DIMETHYLTETRAHYDRO-2H-THIOPYRAN-4-CARBONITRILE (CAS 74376-76-4)
- 2-Amino-1-(2,3-dihydro-benzofuran-5-yl)-ethanolHydrochloride (CAS 1332886-38-0)
- 4-(2-Ethoxybenzyl)-3-phenylisoxazol-5(2H)-one (CAS 89114-12-5)
- Ethyl N-(1-{[3-chloro-5-(trifluoromethyl)pyridin-2-yl](methyl)amino}-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carbonyl)carbamate (CAS 338770-26-6)
- Liraglutide Impurity 25 (CAS CATO-C4X-199225)
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