Acid orange II

Name: Acid orange II
Brand: Vaqora Chemicals
SKU: VQ-000447

About Acid orange II

Listed under CAS 633-96-5, Acid orange II is a biological stain available from Vaqora Chemicals in Microscopy grade. Formula C16H11N2NaO4S, molecular weight 350.3 g/mol. The IUPAC name is sodium 4-[(2-hydroxynaphthalen-1-yl)diazenyl]benzenesulfonate. Common synonyms include Acid Orange A and Acid Orange 7.

The material typically appears as an orange powder. Key physical data: a melting point of 164 °C. Keep the container tightly sealed and store it in a cool, dry area. It carries the GHS signal word “Warning” with 3 hazard statements. Review the Safety Data Sheet before use.

Key uses span histology and cytology staining, microscopy, clinical laboratories and biological staining. Typical end-use sectors are academic and industrial research, diagnostics and biotechnology and textiles and dyeing.

Vaqora Chemicals supplies Acid orange II in 25 g, 100 g, 5 kg and 4 x 25 kg packs, each shipped with a Certificate of Analysis (COA), and exports worldwide.

Typical applications

Histology & cytology staining
Microscopy
Clinical laboratories
Biological staining

Industries

Specifications & identifiers

Chemical identifiers
Product name	Acid orange II
Catalogue No.	VQ-000447
CAS Number	633-96-5
IUPAC name	sodium 4-[(2-hydroxynaphthalen-1-yl)diazenyl]benzenesulfonate
Molecular formula	C₁₆H₁₁N₂NaO₄S
Molecular weight	350.3 g/mol
Exact mass	350.0337
Grade	Microscopy
HSN code	32129090
InChIKey	CQPFMGBJSMSXLP-UHFFFAOYSA-M
SMILES	C1=CC=C2C(=C1)C=CC(=C2N=NC3=CC=C(C=C3)S(=O)(=O)[O-])O.[Na+]
PubChem CID	135442941

Physical properties
Physical form	Powder
Appearance	Orange powder
Melting point	164 °C
H-bond donors / acceptors	1 / 6
TPSA	111 Å²
Synonyms	4-(2-Hydroxy-1-naphthylazo)benzenesulfonic acid sodium salt, Acid Orange A, Acid Orange 7, Orange II, Tropaeolin 000 No. 2, C.I. Acid Orange 7, 2-naphthol orange, 4-((2-Hydroxy-1-naphthalenyl)azo)benzenesulfonic acid monosodium salt, beta-naphthol orange, AO-7 dye, Acid Orange, Orange II sodium salt

Safety & hazard information (GHS)

Harmful / irritant

Signal word: Warning

Hazard statements

H315Causes skin irritation
H319Causes serious eye irritation
H335May cause respiratory irritation

Precautionary statements: P261, P305 + P351 + P338

Classification is indicative (aggregated GHS notifications) and may vary by grade and concentration. Always refer to the SDS supplied with your lot.

Documents

Safety Data Sheet (SDS)16-section GHS · on request Certificate of AnalysisTypical / batch COA · on request Specification sheetTDS / MOA · on request

Other grades of CAS 633-96-5

Tropeolin OOO (Certified by the Biological Stain Commission), Dye content ≥90%

CAS: 633-96-5
Formula: C₁₆H₁₁N₂NaO₄S
MW: 350.3 g/mol

VQ-000422

Tropeolin OOO, indicator

CAS: 633-96-5
Formula: C₁₆H₁₁N₂NaO₄S
MW: 350.3 g/mol

VQ-000423

Frequently asked questions

What is the CAS number of Acid orange II?

The CAS Registry Number of Acid orange II is 633-96-5. It is also known as 4-(2-Hydroxy-1-naphthylazo)benzenesulfonic acid sodium salt, Acid Orange A, Acid Orange 7.

What is the molecular formula and molecular weight of Acid orange II?

Acid orange II has the molecular formula C16H11N2NaO4S and a molecular weight of 350.3 g/mol. Its IUPAC name is sodium 4-[(2-hydroxynaphthalen-1-yl)diazenyl]benzenesulfonate.

Which grade and pack sizes of Acid orange II can I order?

We supply Acid orange II in Microscopy grade, in 25 g, 100 g, 5 kg, 4 x 25 kg packs. Larger bulk quantities and custom packing are quoted on request.

Do you provide a COA and SDS with Acid orange II?

Yes. Every lot of Acid orange II is shipped with a batch-specific Certificate of Analysis, and a 16-section GHS Safety Data Sheet is provided with the quotation and the shipment.

Can Acid orange II be shipped internationally?

Yes. Acid orange II is classified as hazardous, so it is packed in UN-approved packaging and shipped as dangerous goods under IATA/IMDG rules. We export worldwide on EXW, FOB, CIF and DAP terms.