Molekula
alpha-Naphtholbenzein
Supplying 4,500+ customers in over 80 countries
ISO 9001:2015 & ISO 14001:2015 certified · Supplying laboratories and industry since 1999 · Listed pack sizes are a starting point — we manufacture, source and repack to the quantity you need
Alpha-Naphtholbenzein (C27H18O2) is a triarylmethane-type acid-base (pH) indicator used primarily in non-aqueous acid-base titrations, such as acid and base number determination by ASTM D974, where it changes colour from orange to green. It appears as a crystalline solid with a molecular weight of 374.43 g/mol. CAS number: 145-50-6. Store at ambient temperature. Signal word: Warning.
Molekula supplies alpha-Naphtholbenzein in 5 g and 25 g packs, from £37.08 inc. VAT. It is in stock for same-day dispatch. Every batch ships with a certificate of analysis, and safety data sheets are available in 8 languages. Larger quantities, up to multi-tonne, are quoted on request.
Example image for illustration only. Other packaging and pack sizes are available.
Often bought together
Pricing & pack sizes
In stock — same-day dispatch
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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5 g — £30.90 per pack ex VAT · £37.08 inc. VAT
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25 g — £71.60 per pack ex VAT · £85.92 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.
Prices exclude VAT/sales tax and shipping.
Specifications
| Property | Value |
|---|---|
| Appearance | Red/ blue black powder |
| Loss on Drying | max 7% |
| Absorptivity (1%/1cm at 625.6nm) | min 640 |
Storage & handling
| Property | Value |
|---|---|
| Storage Temperature | Ambient |
| Acidity | Neutral |
Identification
| Property | Value |
|---|---|
| SKU | 90027782 |
| CAS Number | 145-50-6 |
| IUPAC Name | (4E)-4-[(4-hydroxynaphthalen-1-yl)-phenylmethylidene]naphthalen-1-one |
| EC Number | 205-656-3 |
| Molecular Formula | C27H18O2 |
| Molecular Weight | 374.43 |
| Exact Mass | 374.1307 |
| SMILES | C1=CC=C(C=C1)/C(=C\2/C=CC(=O)C3=CC=CC=C23)/C4=CC=C(C5=CC=CC=C54)O |
| InChIKey | VDDWRTZCUJCDJM-SOYKGTTHSA-N |
| InChI | InChI=1S/C27H18O2/c28-25-16-14-23(19-10-4-6-12-21(19)25)27(18-8-2-1-3-9-18)24-15-17-26(29)22-13-7-5-11-20(22)24/h1-17,28H/b27-24+ |
| PubChem CID | 3033966 |
| REACH Code | Y113 |
| TSCA Listed | Yes |
| HTS Code | 2914.50.3000 |
| Tariff Code | 2914500090 |
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+P351+P338 IF IN EYES: Rinse continuously with water for several minutes. Remove contact lenses if present and easy to do, continue rinsing
Documents
Safety Data Sheets (SDS)
Available in English, German, Spanish, French, Italian, Portuguese, Arabic, Dutch.
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.
Quality certificates
Molekula Group is certified to ISO 9001:2015 (quality) and ISO 14001:2015 (environmental management), audited by a UKAS-accredited body. Both certificates are valid to 17 May 2028.
Synonyms
- (4E)-4-[(4-hydroxynaphthalen-1-yl)-phenylmethylidene]naphthalen-1-one
- 1-Naphtholbenzein
- 1(4H)-Naphthalenone, 4-[(4-hydroxy-1-naphthalenyl)phenylmethylene]-
- 1(4H)Naphthalenone, 4(alpha(4hydroxy1naphthyl)benzylidene)
- 4-[(4-Hydroxy-1-naphthalenyl)phenylmethylene]-1(4H)-naphthalenone
- 4-[(4-hydroxynaphthyl)phenylmethylene]naphthalen-1-one
- 4(alpha(4Hydroxy1naphthyl)benzylidene)naphthalen1(4H)one
- Naphtholbenzein
- p-Naphtholbenzein
- VDDWRTZCUJCDJM-SOYKGTTHSA-N
Frequently asked questions
What is alpha-Naphtholbenzein used for?
It is primarily used as a pH and titration indicator, notably in non-aqueous acid-base titrations such as acid and base number determination by ASTM D974, where it changes colour from orange to green.
What is the chemical formula and molecular weight of alpha-Naphtholbenzein?
The formula is C27H18O2 with a molecular weight of 374.43 g/mol.
How should alpha-Naphtholbenzein be stored?
It should be stored at ambient temperature, protected from light and moisture.
What grade of alpha-Naphtholbenzein does Molekula supply?
We supply alpha-Naphtholbenzein to a specification covering appearance (red/blue black powder), loss on drying (max 7%) and absorptivity (1%/1cm at 625.6 nm, min 640); custom grades available upon request.
Can Molekula supply alpha-Naphtholbenzein in bulk?
Yes, we can supply alpha-Naphtholbenzein in bulk quantities; please contact us for pricing and availability.
What documentation comes with an order of alpha-Naphtholbenzein?
Each order includes a Certificate of Analysis (CoA) and Safety Data Sheet (SDS) with the shipment.
Where can I buy alpha-Naphtholbenzein?
Directly from Molekula, which lists alpha-Naphtholbenzein in 5 g and 25 g packs from £37.08 inc. VAT, with a certificate of analysis for every batch. Larger quantities are quoted on request. Molekula's offices: United Kingdom, France, Spain, Germany, Italy, United States and China.
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.