Acid Red 94
[CAS# 632-69-9]

Identification

• Classification: Dyes and pigments >> Dyes >> Acid dyestuff
• Name: Acid Red 94
• Synonyms: C.I. 45440; Rose Bengal sodium salt; Disodium 3,4,5,6-tetrachloro-2-(2,4,5,7-tetraiodo-6-oxido-3-oxoxanthen-9-yl)benzoate; Xantryl
• Molecular Formula: C₂₀H₂Cl₄I₄Na₂O₅
• Molecular Weight: 1017.64
• CAS Registry Number: 632-69-9
• EC Number: 211-183-3
• SMILES: C1=C2C(=C(C(=C1I)[O-])I)OC3=C(C(=C(C=C3C24C5=C(C(=C(C(=C5Cl)Cl)Cl)Cl)C(=O)O4)I)[O-])I.[Na+].[Na+]

Properties

• Water solubility: soluble

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H302-H315-H319-H335
• Precautionary Statements: P261-P301+P312-P302+P352-P304+P340-P305+P351+P338

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Skin irritation	Skin Irrit.	2	H315
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2A	H319
Chronic hazardous to the aquatic environment	Aquatic Chronic	3	H412

Discovory and Applicatios

Acid Red 94, commonly known as Brilliant Scarlet 3R, is a synthetic azo dye widely utilized in textile, paper, and biological staining applications. The discovery of Acid Red 94 dates back to the late 19th century when synthetic dyes were extensively developed to replace natural colorants. This dye is characterized by its bright red hue and high solubility in water, making it particularly useful for various industrial and scientific purposes.

The synthesis of Acid Red 94 follows the classical diazotization and coupling reaction pathway, typical of azo dyes. It is derived from diazonium salts of substituted aromatic amines, which are coupled with an appropriate naphthol derivative to yield the final dye. This process allows for large-scale production with high purity and stability. Due to its strong anionic nature, Acid Red 94 exhibits excellent affinity for proteinaceous and cellulosic materials, making it a valuable dye for textiles and histological staining.

One of the major applications of Acid Red 94 is in the textile industry, where it is used to dye wool, silk, and nylon fabrics. Its vibrant red shade, coupled with its good fastness properties, makes it a popular choice for producing bright and durable textiles. In the paper industry, Acid Red 94 is employed as a colorant for specialty papers, ensuring uniform coloration and high print contrast. Additionally, its application in ink formulations has been explored for producing water-based red inks with excellent dispersibility and stability.

Beyond industrial uses, Acid Red 94 has found applications in biomedical and analytical fields. In histology and microbiology, it is used as a staining agent for tissues and microorganisms, facilitating microscopic examination and diagnosis. Its ability to bind selectively to specific cellular components allows researchers to distinguish between different cell types and structures. In biochemical research, Acid Red 94 has been investigated as a marker dye for electrophoresis and chromatography techniques, aiding in the visualization of separated biomolecules.

Despite its widespread utility, concerns regarding the environmental impact of Acid Red 94 have emerged. Like many azo dyes, its degradation in wastewater can lead to the formation of potentially toxic aromatic amines. Various treatment methods, including advanced oxidation processes and microbial biodegradation, have been studied to mitigate these effects and ensure the safe disposal of dye-contaminated wastewater. Regulatory measures have been implemented in several countries to monitor and control its use, especially in consumer products with potential dermal or oral exposure.

Recent advancements in dye chemistry have explored modifications to Acid Red 94 to enhance its environmental compatibility while retaining its desirable properties. Researchers are investigating alternative synthesis routes utilizing greener reagents and catalysts to reduce waste generation. Additionally, the development of biodegradable dye formulations aims to address concerns related to dye accumulation in ecosystems.

Acid Red 94 remains an important dye in both industrial and scientific domains due to its vivid coloration, stability, and versatility. Ongoing research and regulatory oversight continue to shape its applications, balancing its utility with environmental sustainability.