4-Amino-1-naphthalenesulfonic Acid: FAQs & Lab Guide
4-Amino-1-naphthalenesulfonic Acid: FAQs & Lab Guide
4-Amino-1-naphthalenesulfonic Acid is an aromatic amino sulfonic acid compound widely used as a key intermediate in the synthesis of azo dyes and as a reagent in various analytical chemistry applications.
- CAS Number
- 84-86-6
- Molecular Formula
- C₁₀H₉NO₃S
- Molecular Weight
- 223.25 g/mol
- Appearance
- Off-white to light beige crystalline powder
- Solubility
- Sparingly soluble in cold water; more soluble in hot water; soluble in dilute alkali solutions
- Aladdin SKU
- A151594
- Common Synonym
- Naphthionic acid; 4-aminonaphthalene-1-sulfonic acid
What Is 4-Amino-1-naphthalenesulfonic Acid?
4-Amino-1-naphthalenesulfonic Acid (CAS 84-86-6), also known as naphthionic acid or 4-aminonaphthalene-1-sulfonic acid, is an aromatic compound bearing both a primary amino group (–NH₂) and a sulfonic acid group (–SO₃H) on a naphthalene ring system. Its molecular formula is C₁₀H₉NO₃S, with a molecular weight of 223.25 g/mol.
The compound belongs to the broader class of aminonaphthalenesulfonic acids and exists as a zwitterion at neutral pH due to the contrasting acid–base characters of its functional groups. This amphoteric nature influences its solubility profile and reactivity in synthetic pathways.
In the laboratory, it is supplied as an off-white to light beige crystalline powder. Researchers commonly refer to it by its trivial name, naphthionic acid, particularly in older dye-chemistry literature.
Key Applications in Research and Industry
4-Amino-1-naphthalenesulfonic Acid is most prominently used as an intermediate in the synthesis of azo dyes. The free amino group can be diazotized under acidic conditions to form a diazonium salt, which then couples with phenols, naphthols, or other aromatic amines to produce a wide variety of colored azo compounds used in textile dyeing, biological staining, and indicator chemistry.
Beyond dye synthesis, the compound finds use in analytical chemistry as a reagent for the detection of nitrous acid and nitrites via the Griess reaction (when combined with an appropriate coupling agent). Its sulfonic acid group imparts water solubility in alkaline media, making it amenable to aqueous analytical protocols.
In biochemical research, aminonaphthalenesulfonic acid derivatives serve as fluorescent probes and reporters in studies of protein folding and membrane dynamics, though 4-amino-1-naphthalenesulfonic acid itself is primarily a synthetic building block rather than a direct fluorophore in most contemporary assays.
Handling, Storage, and Safety Considerations
When handling 4-Amino-1-naphthalenesulfonic Acid, standard laboratory precautions for organic aromatic amines should be observed. Researchers should wear appropriate personal protective equipment (PPE) including nitrile gloves, safety goggles, and a lab coat. Work should be conducted in a well-ventilated area or under a fume hood to avoid inhalation of dust particles.
The compound should be stored in a tightly sealed container, away from strong oxidizing agents, strong acids, and strong bases. Storage at room temperature in a cool, dry location, protected from light and moisture, is generally recommended to maintain stability and prevent degradation over time.
Disposal must comply with local regulations for chemical waste. As an aromatic amine derivative, it should not be discharged directly into drains or waterways. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific (SKU A151594) for full hazard classification, first-aid measures, and disposal guidance before use.
Purity, Grades, and Quality Specifications
For most synthetic and analytical research applications, 4-Amino-1-naphthalenesulfonic Acid is required at high purity to ensure reproducible results. Impurities such as residual inorganic salts, isomeric aminonaphthalenesulfonic acids, or unreacted starting materials from its manufacture can interfere with diazotization efficiency and coupling reactions.
Aladdin Scientific supplies 4-Amino-1-naphthalenesulfonic Acid under SKU A151594. Researchers and procurement personnel should consult the current Certificate of Analysis (CoA) for the specific lot they are purchasing, as it provides purity assay results, appearance confirmation, and any additional quality parameters determined by Aladdin's quality control process.
When comparing suppliers, key quality parameters to verify include: purity by titration or HPLC, water content (Karl Fischer), heavy metals content, and visual appearance (freedom from discoloration that may indicate oxidative degradation). Selecting the appropriate grade for the intended application ensures experimental reliability and cost-effectiveness.
Ordering, Availability, and Technical Support
4-Amino-1-naphthalenesulfonic Acid is available from Aladdin Scientific under SKU A151594. Researchers can place orders directly through the Aladdin Scientific website, where current stock levels, pack sizes, and pricing are listed. Bulk quantity inquiries can be directed to Aladdin's sales team for custom quotations.
For technical questions regarding application suitability, solubility protocols in specific buffer systems, or compatibility with downstream assays, Aladdin Scientific's technical support team is available to assist. Customers are encouraged to reference the SKU (A151594) when contacting support to facilitate efficient service.
The product is shipped in accordance with applicable regulations for chemical reagents. Upon receipt, customers should inspect the packaging for integrity and verify the lot number against the CoA provided. Any concerns regarding product quality or shipment condition should be reported to Aladdin's customer service team promptly for resolution.
Frequently asked questions
What is 4-Amino-1-naphthalenesulfonic Acid used for in the laboratory?
4-Amino-1-naphthalenesulfonic Acid is primarily used as an intermediate in the synthesis of azo dyes, where its amino group is diazotized and coupled with other aromatic compounds to produce colored products. It is also employed in analytical chemistry, notably in nitrite detection via Griess-type reactions, and serves as a building block for specialty chemical synthesis.
How should I dissolve 4-Amino-1-naphthalenesulfonic Acid for my experiment?
4-Amino-1-naphthalenesulfonic Acid is sparingly soluble in cold water but dissolves more readily in hot water. It is more soluble in dilute aqueous alkali solutions (e.g., dilute sodium hydroxide or sodium carbonate), which is the preferred dissolution method for many analytical and synthetic protocols. Avoid strongly acidic or strongly basic conditions unless specifically required by your protocol, as extreme pH may affect compound stability.
What safety precautions are needed when handling 4-Amino-1-naphthalenesulfonic Acid?
As with other aromatic amine compounds, appropriate PPE including gloves, eye protection, and a lab coat should be worn at all times. Handling should be performed in a well-ventilated area or fume hood to minimize dust inhalation. Always consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for SKU A151594 before use for complete hazard, first-aid, and disposal information.
What purity grade of 4-Amino-1-naphthalenesulfonic Acid does Aladdin Scientific offer?
Aladdin Scientific offers 4-Amino-1-naphthalenesulfonic Acid under SKU A151594. For specific purity assay values and quality parameters for a given lot, customers should refer to the Certificate of Analysis (CoA) available for their purchased batch, as specifications may be updated over time. Contact Aladdin's technical support team for guidance on grade suitability for your specific application.
How should 4-Amino-1-naphthalenesulfonic Acid be stored to maintain its stability?
The compound should be stored in a tightly sealed container at room temperature in a cool, dry place, protected from light and moisture. It should be kept away from strong oxidizing agents, strong acids, and strong bases. Under these conditions, the reagent is expected to remain stable for an extended period; refer to the product label and CoA for specific shelf-life information.
Can 4-Amino-1-naphthalenesulfonic Acid be used in the Griess reaction for nitrite detection?
Yes, 4-Amino-1-naphthalenesulfonic Acid has been used as the diazotizable aromatic amine component in Griess-type reagent systems for the colorimetric detection of nitrite ions. In this reaction, the compound is diazotized by nitrous acid generated from the nitrite analyte, and the resulting diazonium salt couples with a second aromatic amine or naphthol to produce a detectable colored azo product. Researchers should verify the specific Griess reagent formulation required for their assay conditions.
References
- March, J. Advanced Organic Chemistry: Reactions, Mechanisms, and Structure. 4th ed. Wiley-Interscience, 1992. (General reference for diazotization and azo coupling reactions.)
- Griess, P. Bemerkungen zu der Abhandlung der HH. Weselsky und Benedikt 'Ueber einige Azoverbindungen'. Ber. Dtsch. Chem. Ges. 1879, 12, 426–428. (Historical reference for Griess reaction chemistry.)
- Aladdin Scientific. Product Page: 4-Amino-1-naphthalenesulfonic Acid, SKU A151594. (Accessed via Aladdin Scientific website; consult for current specifications, CoA, and SDS.)
Products are supplied for research and development use only. Not for use in humans, animals, diagnosis, or therapy.
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