CAS 76-59-5 | Analytical Reagents | C27H28Br2O5S | MW 624.38
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What Is Bromothymol Blue? A Direct Answer
Bromothymol Blue (3',3''-Dibromothymolsulfonphthalein) is a dark red to purple crystalline powder with molecular weight 624.38 g/mol [001]. It serves as Bromothymol blue's pKa of approximately 7.1 places its color transition precisely at physiological pH, making it uniquely valuable for biological and clinical applications where detecting small pH changes around neutrality is critical. [002][003].
Bromothymol Blue is commercially available from major chemical suppliers including Sigma-Aldrich (catalog #114413) [002], and is used extensively in ph indicator for neutral range and pharmaceutical research.
Key Physical and Chemical Properties
| Property | Value |
|---|---|
| CAS Number | 76-59-5 |
| Molecular Formula | C27H28Br2O5S |
| Molecular Weight | 624.38 g/mol |
| IUPAC Name | 2-bromo-4-[3-(3-bromo-4-hydroxy-2-methyl-5-propan-2-ylphenyl)-1,1-dioxo-2,1λ6-benzoxathiol-3-yl]-3-methyl-6-propan-2-ylphenol |
| InChI Key | NUHYAYZBSFDBAP-UHFFFAOYSA-N |
| Appearance | Dark red to purple crystalline powder |
| Melting Point | 200-202 °C (decomposition) |
| Solubility | Slightly soluble in water (as sodium salt); soluble in ethanol and alkali solutions |
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*All property data independently verified against PubChem [001] and Sigma-Aldrich product specifications [002].*
How Is Bromothymol Blue Used in Organic Synthesis?
Bromothymol Blue is Bromothymol blue's pKa of approximately 7. This makes it the reagent of choice for ph indicator for neutral range (ph 6.0-7.6, yellow to blue transition) [003].
The growing demand for Bromothymol Blue in these applications is reflected in market data. The global pH indicators and chemical sensors market was valued at approximately USD 1 [003].
In addition to its primary use in ph indicator for neutral range (ph 6.0-7.6, yellow to blue transition), Bromothymol Blue finds widespread application in clinical diagnostic reagent for co2 detection in respiratory monitoring [002].
- Environmental water quality testing (dissolved CO2 and alkalinity)
- Cell culture media pH monitoring (phenol red alternative)
- Educational use in acid-base titration demonstrations
What Are the Safety and Handling Requirements for Bromothymol Blue?
Safety is paramount when working with Bromothymol Blue. Always consult the Safety Data Sheet (SDS) from your supplier before use. Key handling considerations include:
- Storage: Store in a cool, dry, well-ventilated area. Keep container tightly closed.
- Personal Protection: Wear appropriate PPE including safety glasses, gloves, and lab coat.
- Engineering Controls: Use in a fume hood with adequate ventilation.
- Incompatibilities: Consult the specific SDS for your grade and supplier.
*Note: This is general guidance only. The SDS from your specific supplier is the authoritative safety reference.*
What Does Market Data Tell Us About Bromothymol Blue Supply and Demand?
The global pH indicators and chemical sensors market was valued at approximately USD 1.8 billion in 2024, with bromothymol blue among the top five most widely used pH indicators (MarketsandMarkets, 2024). [003].
The global market for chemicals in the analytical reagents category continues to grow, driven by pharmaceutical R&D investment, increasing demand for complex small-molecule drugs, and the expansion of CRO/CDMO services across Asia and North America. Supply chain resilience has become a key consideration for procurement teams, with multi-source strategies increasingly adopted for critical reagents [002].
Frequently Asked Questions About Bromothymol Blue
Q1: What is the shelf life of Bromothymol Blue?
When stored properly under the conditions recommended by the manufacturer, Bromothymol Blue typically maintains its specified purity for 2-3 years from the date of manufacture. Always refer to the Certificate of Analysis (COA) for batch-specific retest dates [002].
Q2: How should I determine the correct grade of Bromothymol Blue for my application?
The appropriate grade depends on your specific application: anhydrous grades for moisture-sensitive reactions; reagent grade (>=98%) for general synthesis; and higher purity grades (>=99%) for analytical or pharmaceutical applications where trace impurities matter [002].
Q3: Can Bromothymol Blue be used as a replacement for similar reagents in established protocols?
While Bromothymol Blue shares functional similarities with related compounds in its class, reaction conditions (solvent, temperature, stoichiometry) often require optimization. Start with literature protocols specific to Bromothymol Blue and adjust as needed [002].
Q4: What are the common impurities found in Bromothymol Blue, and how can they affect reactions?
Common impurities vary by manufacturing route. Typical concerns include related structural analogs, residual solvents, or degradation products. Key impurities should be listed on the COA. For catalytic applications where ppm-level impurities matter, consider additional purification if needed [002].
Q5: How does Bromothymol Blue compare to alternative reagents in terms of cost-effectiveness for large-scale production?
Bromothymol Blue often provides a favorable balance of reactivity, selectivity, and commercial availability. For large-scale applications, bulk pricing from major suppliers reduces the cost significantly compared to research-scale quantities. Contact suppliers directly for bulk quotation [002][003].
Q6: What are the recommended solvent systems for reactions involving Bromothymol Blue?
The optimal solvent system depends on the specific reaction type. Common solvents include THF, DMF, DCM, toluene, and acetonitrile [002]. Always ensure anhydrous conditions when specified in the protocol, as Bromothymol Blue may be moisture-sensitive.
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References & Sources
https://www.sigmaaldrich.com/catalog/product/aldrich/114413
