Tiotropium Bromide Impurity 18 CAS 51-56-9
| CAS No. | 51-56-9 |
| Molecular Formula | C16H21NO3 |
| Molecular Weight | N/A |
| Category | Pharmacopoeial Impurity Standards / EP Impurities |
| Availability | In Stock |
Chemical Structure
Description
This reference standard supports related-substances testing and method development in line with ICH Q3A/Q3B guidance on impurity control, and is suitable for system suitability testing and forced-degradation studies.
As a process- or degradation-related impurity, Tiotropium Bromide Impurity 18 (CAS 51-56-9, C16H21NO3HBr) is essential for impurity profiling, related-substances testing, and forced-degradation studies in pharmaceutical development.
Owing to a nitrogen-containing heterocyclic scaffold, an amide group, a hydroxyl group, an ether linkage, bromine substitution, Tiotropium Bromide Impurity 18 is typically off-white to pale yellow crystalline powder. Its solid-state physicochemical attributes — including a molecular weight of 356.26 g/mol — guide the selection of appropriate sample preparation and analytical techniques. Halogen substitution (F/Cl/Br/I) produces a distinctive isotope pattern in mass spectrometry, a valuable aid for qualitative confirmation.
The assigned purity is verified by mass-balance and quantitative NMR (qNMR) approaches, with the expanded uncertainty reported at a 95% confidence level (k=2). Batch homogeneity and stability are independently assessed for every lot.
Physical & Chemical Properties
| Molecular Formula | C16H21NO3 HBr |
| Molecular Weight | 356.26 g/mol |
| Appearance | Off-white to pale yellow crystalline powder. (slight halide-like odor) |
| Purity | >95% |
| Storage | Store at 2-8°C, protect from light, keep sealed and dry |
| Solubility (reference) | Soluble in chloroform, dichloromethane, ethyl acetate, DMSO |
| Stability | May oxidize slowly on prolonged air exposure; Light-sensitive; avoid direct strong light; Contains ester bond; hydrolyzes under strong alkaline conditions |
| Degree of Unsaturation (DBE) | 6.0 |
| UV Absorption | UV-absorbing |
| Structural Features | Aromatic ring present |
| CAS Registry Year (est.) | 1957 |
| Halogen Content | Br-containing |
| Nitrogen Atoms | 1 |
Related Tiotropium Standards
- Tiotropium Impurity 26 (CAS 10299-90-8)
- Tiotropium Bromide Impurity 8 Potassium Salt (CAS 10304-09-3)
- Tiotropium Bromide EP Impurity H (Mixture of Enantiomers) (CAS 1044148-31-3)
- Tiotropium Bromide EP Impurity H-d3 Bromide (Mixture of Enantiomers) (CAS 1044148-31-3（unlabeled）)
- Tiotropium-d6 (CAS 1126775-44-7)
- Tiotropium-D3 Bromide (CAS 1127226-56-5)
- Tiotropium Bromide EP Impurity B (CAS 136310-64-0)
- Tiotropium EP Impurity D (CAS 136310-66-2)
Recommended Standards
- Doxepin impurity 17 (CAS 22684-91-9)
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- 3,4-Dimethyl 1h-pyrrole-3,4-dicarboxylate (CAS 2818-06-6)
- Hydroxychloroquine Impurity 31 (CAS CATO-C4X-183531)
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- N-phenyl-5-(1-tosylpyrrolidin-2-yl)pyridin-2-amine (CAS 1352499-74-1)
- Chondroitin disaccharide 6S sodium salt (CAS CATO-C4X-32818)
- 1-(3-Bromopropyl)-3-chlorobenzene (CAS 91085-89-1)
- Endo-38a-Pro-Exenatide trifluoroacetate salt (CAS 1678416-95-9)
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