Molekula
Cresol Red
Supplying 4,500+ customers in over 80 countries
ISO 9001:2015 & ISO 14001:2015 certified · Supplying laboratories and industry since 2000 · Listed pack sizes are a starting point — we manufacture, source and repack to the quantity you need
Cresol Red is a synthetic pH indicator dye used in analytical chemistry for titrations, particularly in determining the pH range of 7.2–8.8, and in biological buffers. It appears yellow in acidic solutions and red in alkaline conditions, making it ideal for precise pH monitoring. Catalogue details include CAS 1733-12-6, molecular formula C21H18O5S, and a molecular weight of 382.43. Store at ambient conditions, with a signal word of Warning. Molekula supplies Cresol Red from research to bulk quantities with full documentation and ISO 9001:2015 traceability.
Example image for illustration only. Other packaging and pack sizes are available.
Pricing & pack sizes
These pack sizes aren't a limit. Molekula manufactures, sources and repacks to order — if you need 500 kg and only see 1 kg listed, . We quote from grams to multi-tonne.
Need a different size? Add the nearest pack and change the size in your basket — we price it at the same rate per unit.
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25 g — £49.20 per pack ex VAT · £59.04 inc. VAT
Need a different quantity or pack?
Tell us how much you need and when — drums, IBCs, sacks or a one-off bulk lot. We'll manufacture or source it and come back with a price.
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Specifications
| Property | Value |
|---|---|
| Appearance | Dark Red Powder |
| Solubility at 0.1% (95% Ethanol) | Clear Yellow Solution |
| Loss on drying (110 °C) | (Max.) 3.00% |
| pH Transition - Colour Change | pH6.5 (Yellow) - pH8.8 (Purple) |
| Wavelength of Maximum Absorption (pH6.5) λmax1 | 432.0-436.0 nm |
| Wavelength of Maximum Absorption (pH 8.8) λ max2 | 571.0-574.0 nm |
| Specific Absorption (E 1%/1cm) at λ max1 | (Min.) 490 |
| Specific Absorption (E 1%/1cm) at λ max2 | (Min.) 1000 |
Storage & handling
| Property | Value |
|---|---|
| Storage Temperature | Ambient |
| Acidity | Neutral |
Identification
| Property | Value |
|---|---|
| SKU | 32608392 |
| CAS Number | 1733-12-6 |
| IUPAC Name | 4-[3-(4-hydroxy-3-methylphenyl)-1,1-dioxo-2,1lambda6-benzoxathiol-3-yl]-2-methylphenol |
| EC Number | 217-064-2 |
| Molecular Formula | C21H18O5S |
| Molecular Weight | 382.43 |
| Exact Mass | 382.0875 |
| SMILES | CC1=C(C=CC(=C1)C2(C3=CC=CC=C3S(=O)(=O)O2)C4=CC(=C(C=C4)O)C)O |
| InChIKey | OBRMNDMBJQTZHV-UHFFFAOYSA-N |
| InChI | InChI=1S/C21H18O5S/c1-13-11-15(7-9-18(13)22)21(16-8-10-19(23)14(2)12-16)17-5-3-4-6-20(17)27(24,25)26-21/h3-12,22-23H,1-2H3 |
| PubChem CID | 73013 |
| REACH Code | Y113 |
| TSCA Listed | Yes |
| HTS Code | 2934.99.4400 |
| Tariff Code | 2934999090 |
Safety & GHS
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Health Hazard
GHS07
Hazard statements
- H315 Causes skin irritation
- H319 Causes serious eye irritation
- H335 May cause respiratory irritation
Precautionary statements
- P261 Avoid breathing dust/fume/gas/mist/vapours/spray
- P264 Wash thoroughly after handling
- P280 Wear protective gloves/protective clothing/eye protection/face protection
- P302+P352 IF ON SKIN: Wash with soap and water
- P304+P340 IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
- P305+351+338 IF IN EYES: Rinse with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing
Documents
Safety Data Sheets (SDS)
Available in English, French, German, Italian, Portuguese, Spanish.
Certificate of Analysis (CoA) by batch
Enter a lot or batch number to retrieve the CoA for that specific batch. We can generate one from spec data if no PDF is on file.
Synonyms
- 3,3-bis(4-hydroxy-3-methylphenyl)-3H-benzo[c][1,2]oxathiole 1,1-dioxide
- 3',3''-Dimethylphenolsulfonephthalein
- 4,4'-(1,1-Dioxido-3H-2,1-benzoxathiol-3-ylidene)bis[2-methylphenol]
- Cresol red indicator
- Cresolsulfophthalein
- o-Cresol Red
- o-Cresol, 4,4'-(3H-2,1-benzoxathiol-3-ylidene)di-, S,S-dioxide
- o-Cresolsulfonephthalein
- o-Cresolsulfonphthalein
- Phenol, 4,4'-(1,1-dioxido-3H-2,1-benzoxathiol-3-ylidene)bis[2-methyl-
Frequently asked questions
What is Cresol Red commonly used for?
Cresol Red is primarily used as a pH indicator in laboratories, with a transition range of pH 7.2–8.8 (yellow to purple-red). It is also employed in some biochemical assays and as a dye in certain analytical applications.
What is the chemical formula and molecular weight of Cresol Red?
The chemical formula is **C₂₁H₁₈O₅S**, and the molecular weight is **382.43 g/mol**.
How should Cresol Red be stored?
Store Cresol Red at **ambient temperature** in a tightly sealed container, away from direct sunlight and moisture.
What grade or purity is available for Cresol Red from Molekula?
Molekula supplies Cresol Red in **analytical reagent (AR) grade** for laboratory applications, ensuring high purity and consistency.
Can Molekula supply Cresol Red in bulk quantities?
Yes, Molekula can provide Cresol Red in bulk, with quantities tailored to meet your specific research or industrial requirements—please contact us for pricing and availability.
What documentation comes with an order of Cresol Red?
Each order includes a **Certificate of Analysis (CoA)** detailing purity, batch-specific data, and safety information, along with a **Material Safety Data Sheet (MSDS)** for handling and storage guidelines.
Ready to order or need a custom pack?
Tell us the product, grade, and quantity — Molekula usually responds within one working day with pricing and lead time.