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Sigma-Aldrich

α-Naphtholbenzein

indicator grade

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Synonym(s):
4,4′-(α-Hydroxybenzylidene)di-1-naphthol, p-naphtholbenzein
Empirical Formula (Hill Notation):
C27H18O2
CAS Number:
145-50-6
Molecular Weight:
374.43
Beilstein:
2628063
EC Number:
205-656-3
UNSPSC Code:
12171500
PubChem Substance ID:
24857510
NACRES:
NA.47

grade

indicator grade

Quality Level

100

form

powder

color

faintly Faint Brown to Very Dark Brown to Very Dark Red and Black

pH

0.0, green
0.8, yellow
10.0, blue-green
8.2, yellow

mp

230-235 °C (lit.)

ε (extinction coefficient)

≥50000 at 207-213 nm in methanol at 0.01 g/L

application(s)

diagnostic assay manufacturing
hematology
histology

storage temp.

room temp

SMILES string

Oc1ccc(\C(c2ccccc2)=C3\C=CC(=O)c4ccccc34)c5ccccc15

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-

InChI key

VDDWRTZCUJCDJM-PNHLSOANSA-N

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General description

α-Naphtholbenzein is a dye belonging to the Benzein family insoluble in water and soluble in alcohol. α-Naphtholbenzein is primarily used as an indicator for pH range 8.2-10.0 (mostly in acid-base titrations), causing a color change for the neutral solutions turning alkaline. Its applications include detection of bacterial growth in packed food, viable cells, enzymes, ammonia odors in patients with bacterial infection, and many more.

Application

α-Naphtholbenzein has been used as an indicator during sequential injection analysis technique done for acid-base titrations.

Hazard Statements

H413

Precautionary Statements

P273 - P501

Hazard Classifications

Aquatic Chronic 4

WGK

WGK 2

Flash Point(F)

Not applicable

Flash Point(C)

Not applicable

Personal Protective Equipment

dust mask type N95 (US), Eyeshields, Gloves

Certificates of Analysis (COA)

Search for Certificates of Analysis (COA) by entering the products Lot/Batch Number. Lot and Batch Numbers can be found on a product’s label following the words ‘Lot’ or ‘Batch’.

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