Bromothymol Blue CAS 76-59-5
Chemical Name: Bromothymol Blue
Synonymous Names: Bromthymol Blue; 3′,3″-Dibromothymolsulfonphthalein; 3′,3″-Dibromothymolsulfophthalein; BTB; Dibromothymolsulfonphthalein
CAS No.: 76-59-5
Molecular Formula: C₂₇H₂₈Br₂O₅S
Molecular Weight: 624.38 g/mol
EINECS No.: 200-971-2
Bromothymol blue is a crystalline powder ranging in color from pale pink to brown or purple. It belongs to the sulfonphthalein class of dyes and is widely used as a pH indicator.
Structural formula: 
Product Specification
| Item | Specification |
| Product Name | Bromothymol Blue |
| CAS Number | 76-59-5 |
| Appearance | Light pink to brown to purple crystalline powder |
| Molecular Formula | C27H28Br2O5S |
| Molecular Weight | 624.38 g/mol |
| Purity / Dye Content | ≥95% for representative ACS reagent grade |
| Solubility | Slightly soluble in water; soluble in alcohol and alkaline solution |
| Visual Transition Interval | pH 6.0–7.6, yellow to blue |
| Melting Point | About 200–204°C |
Bromothymol Blue Applications
1.pH Indicator
Bromothymol Blue is widely used as a visual pH indicator. Its transition range near neutral pH is useful for laboratory tests where a visible color change is required.
2.Laboratory Analysis
It is used as a reagent in chemical and biological laboratory work. It can help indicate changes in acidity and alkalinity during testing and analytical procedures.
3.Biological Staining
Bromothymol Blue can be used as a biological slide stain in microscopy. It is applied in certain staining procedures to help observe biological structures such as cell walls or nuclei.
Packaging & Storage
Packaging: Our products are packaged in 1 kg bags and 25 kg drums.
Storage: Please store the product in a sealed container in a cool, dry place.
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