Description

m-Methyl Red CAS NO 20691-84-3 is a high-purity azo dye indicator widely recognized for its sharp and reliable color change in analytical chemistry. Its primary value lies in providing precise pH endpoint detection, which is critical for accurate titrations and quality control procedures in various industrial and research settings. This product is essential for laboratories and manufacturers in the chemical, pharmaceutical, and educational sectors requiring dependable analytical reagents.

Application

• pH Indicator in Titrations: Primarily used as an acid-base indicator in volumetric analysis, offering a clear visual transition.
• Microbiological Media: Employed as a colorimetric pH indicator in selective culture media for microbial identification.
• Educational & Research Laboratories: A standard reagent for teaching and demonstrating acid-base chemistry and titration principles.
• Chemical Synthesis: Serves as an intermediate or a model compound in the synthesis of more complex azo dyes and related chemicals.
• Quality Control Testing: Utilized in standardized test methods within pharmaceutical and chemical manufacturing for process verification.

Basic Information

Product Name	m-Methyl Red
CAS No.	20691-84-3
Molecular Formula	C15H15N3O2
Molecular Weight	269.30 g/mol
Synonyms	3-[[4-(Dimethylamino)phenyl]azo]benzoic acid; Acid Red 2; C.I. 13020; 2-(4-Dimethylaminophenylazo)benzoic acid; m-Methyl Red Indicator; Methyl Red (meta-); Benzoic acid, 2-[(4-(dimethylamino)phenyl)azo]-
EINECS	243-934-0

Quality Control

Our m-Methyl Red is manufactured under a strict quality management system to ensure batch-to-batch consistency and high purity. Each lot is tested against rigorous in-house specifications, which typically include identity confirmation, purity assay, and loss on drying. A Certificate of Analysis (COA) detailing these results is provided with every shipment to support your quality assurance protocols.

Storage

Preserve in a tightly closed container, protected from light. Store in a cool, dry, and well-ventilated area at room temperature (15-25°C). Keep away from incompatible materials.

Specification

Item	Specification
Appearance	Dark red to violet crystalline powder
Identification (IR)	Conforms to structure
Assay (HPLC)	≥ 98.0%
Loss on Drying	≤ 1.0 %
pH Transition Range	4.4 - 6.2
Color Change	Red to Yellow
Solubility (Ethanol)	Clear solution

Note: Specifications can be tailored. Please contact us for the detailed technical data sheet of a specific grade.