The Aromatic Diamine Building Block for High-Performance Polyimides, Lithium-Ion Battery Separators, and Anticancer Research: 5-Amino-2-(4-aminophenyl)benzimidazole (APBIA, CAS# 7621-86-5)

5-Amino-2-(4-aminophenyl)benzimidazole (CAS# 7621-86-5), also known as APBIA, DAPBI, 2-(4-aminophenyl)-1H-benzimidazol-5-amine, or 2-(4-aminophenyl)-1H-benzo[d]imidazol-5-amine, is an aromatic diamine with the molecular formula C₁₃H₁₂N₄ and a molecular weight of 224.26 g/mol. Its molecular structure features a benzimidazole core bearing a primary amino group at the 5-position and a 4-aminophenyl substituent at the 2-position. This unique architecture—combining a rigid, thermally stable benzimidazole heterocycle with two reactive amino groups in a para-substituted arrangement—confers exceptional utility as a monomer for high-performance polymers and as a building block in pharmaceutical and medicinal chemistry research.

As a light beige to light brown crystalline powder with a melting point of 234–238°C and a boiling point of 545.5°C at 760 mmHg, APBIA is slightly soluble in DMSO and methanol, with a predicted pKa of 11.15. It exhibits a UV absorption maximum at 335 nm in ethanol. The compound is typically supplied at ≥98% purity (HPLC) and must be stored under inert gas in a cool, dark place (recommended below 15°C) due to its air-sensitive nature. APBIA is a versatile aromatic diamine monomer that serves as a key building block in the synthesis of high-performance polyimides for lithium-ion battery separators, advanced composite materials, and specialty functional polymers, while also finding application as a heterocyclic scaffold in anticancer and anti-inflammatory drug discovery research. Based on its chemical characteristics and industrial significance, this article systematically analyzes the key properties, core application areas, global market structure, regulatory landscape, and future outlook of this strategically important aromatic diamine building block.

Core Application Fields and Demand

Market demand for 5-Amino-2-(4-aminophenyl)benzimidazole (CAS# 7621-86-5) is concentrated in three primary sectors: high-performance polymer synthesis including polyimides for lithium-ion battery separators (approximately 45–50% of global consumption), pharmaceutical and medicinal chemistry research (approximately 25–30%), and specialty chemicals, dyes, and advanced materials (approximately 20–25%). Its rigid benzimidazole core, thermally stable structure, and two reactive amino groups serve as the core drivers of sustained demand growth.

In high-performance polymer synthesis, APBIA is a critical aromatic diamine monomer for the preparation of polyimides (PIs) and other high-performance heterocyclic polymers. The benzimidazole ring provides exceptional thermal stability, chemical resistance, and mechanical strength to the resulting polymers, while the two amino groups enable polycondensation with dianhydrides to form robust polyimide backbones. APBIA-derived polyimides are increasingly used in the production of lithium-ion battery separators, where the polymer’s high thermal stability (exceeding 400°C) and excellent electrolyte wettability improve battery safety and performance. The compound is also employed in the synthesis of polybenzimidazole (PBI) derivatives and heterocyclic polymer materials for advanced applications including aerospace composites, electronic substrates, and high-temperature adhesives.

In pharmaceutical and medicinal chemistry research, APBIA serves as a versatile heterocyclic building block for drug discovery. The benzimidazole core is widely recognized as a “privileged structure” in medicinal chemistry, and its derivatives have demonstrated efficacy as anticancer, bactericidal, and antiviral agents. APBIA’s two amino groups enable diverse chemical modifications, including acylation, sulfonylation, and Schiff base formation, making it a valuable scaffold for constructing focused libraries of bioactive molecules. The compound is extensively used in research focused on targeted cancer therapies, as the benzimidazole moiety is known to interact with various enzymes and receptors involved in cancer progression. Its derivatives are also investigated for anti-inflammatory activity and as inhibitors of key enzymes in nucleic acid metabolism. Additionally, APBIA serves as a key monomer in the synthesis of polybenzimidazole-based proton exchange membranes for fuel cells and as an intermediate in the production of dyes and pigments.

In specialty chemicals and advanced materials, APBIA is employed in the synthesis of high-performance coatings, adhesives, and electronic materials. The compound’s rigid, planar structure contributes to the exceptional thermal and chemical stability of the resulting materials, making it valuable in demanding environments.

Key Properties and Reactivity Profile

5-Amino-2-(4-aminophenyl)benzimidazole (CAS# 7621-86-5) is a regioisomer-specific aromatic diamine whose value derives from the orthogonal reactivity of its two amino groups and the stability of its benzimidazole core.

Key physicochemical parameters include:

• Molecular Formula: C₁₃H₁₂N₄
• Molecular Weight: 224.26 g/mol
• CAS Number: 7621-86-5
• MDL Number: MFCD00451475
• Synonyms: APBIA; DAPBI; 2-(4-Aminophenyl)-1H-benzimidazol-5-amine; 5-Amino-2-(4-aminophenyl)benzimidazole
• Appearance: Light beige to light brown powder
• Purity: ≥98% (HPLC); ≥98% (non-aqueous titration)
• Melting Point: 234–238°C
• Boiling Point: 545.5°C at 760 mmHg
• Flash Point: 317.6°C
• Density: ~1.4 g/cm³ (estimated)
• pKa: 11.15 ± 0.10 (predicted)
• Solubility: Slightly soluble in DMSO and methanol
• UV Max: 335 nm (in ethanol)
• SMILES: Nc1ccc(cc1)c2[nH]c3ccc(N)cc3n2
• InChIKey: XAFOTXWPFVZQAZ-UHFFFAOYSA-N
• Storage: Under inert gas, cool and dark place (recommended below 15°C); air-sensitive
• GHS Classification: Warning; H302, H315, H319, H335, H341 (Suspected of causing genetic defects)
• WGK Germany: Not classified

The compound’s reactivity is defined by its two amino groups: the 5-amino group on the benzimidazole ring and the 4′-amino group on the phenyl substituent. These amino groups enable polycondensation with dianhydrides to form polyimides, acylation and sulfonylation for pharmaceutical derivatization, and Schiff base formation for constructing bioactive molecules. The benzimidazole core provides thermal and chemical stability, while the rigid, planar structure contributes to the high-performance properties of the resulting polymers.

Major Market Participants

The global supply system for 5-Amino-2-(4-aminophenyl)benzimidazole (CAS# 7621-86-5) features a pattern of “specialized aromatic diamine manufacturers, multinational research chemical distributors, and Chinese producers serving distinct market segments.” As a specialized heterocyclic building block rather than a bulk commodity, the market is characterized by a moderate number of suppliers catering to polymer science, pharmaceutical R&D, and materials science applications.

In the global research and high-purity segment, key international suppliers include Tokyo Chemical Industry (TCI), offering the compound at >98.0% (HPLC) purity under product code A2759, available in 1 g ($44.00) and 5 g ($179.00) quantities, with stock in the USA and Japan. Aladdin Scientific offers APBIA at ≥98% purity with triple ISO certification and COA/SDS available for all products, priced at $9.90 for 1 g. CymitQuimica (Biosynth brand) offers the compound with multiple purity grades and packaging options. Oakwood Chemical offers the compound at 95% purity (MP: 196–200°C) under product number 211210. BOC Sciences provides the compound as a building block for pharmaceutical R&D. These suppliers serve the pharmaceutical, biotechnology, and materials science communities with products that meet rigorous quality specifications.

In the industrial and large-scale production segment, Chinese manufacturers have emerged as significant players in the global supply chain. XinChem is a reliable manufacturer and supplier of high-purity 5-Amino-2-(4-aminophenyl)benzimidazole from China, offering the compound with stringent quality standards for use in polyimide synthesis, lithium-ion battery separator production, and pharmaceutical research. As a trusted product offered by XinChem Corporation, a leading China manufacturer, supplier, and factory, it ensures reliable purity and consistent performance to meet diverse industrial needs. XinChem specializes in the development and production of specialty chemicals, providing customers with professional service and competitive pricing. The compound is essential for various applications including organic synthesis and material science, making it a valuable addition to any laboratory or production facility. With strict quality control and advanced manufacturing technology, XinChem guarantees that APBIA meets international standards, supporting innovation and development across multiple sectors. Other Chinese suppliers include Capot Chemical, offering 98% minimum purity with moisture ≤0.5% and production scale up to kilograms, Hangzhou Leap Chem, Tianjin Zhongtai Material Technology, and Bide Pharmatech. Chinese suppliers offer the compound at various purity grades (typically 95–99%) and packaging options—from grams to multi-kilogram quantities—serving both domestic and export markets with competitive pricing.

Regional Market Dynamics

The global 5-Amino-2-(4-aminophenyl)benzimidazole market exhibits distinct regional characteristics, with production concentrated in Asia-Pacific (particularly China) and consumption distributed across North America, Europe, and the Asia-Pacific region, aligned with the polymer, battery materials, pharmaceutical, and materials science industries in these regions.

The Asia-Pacific region has emerged as a significant production hub for 5-Amino-2-(4-aminophenyl)benzimidazole, with China hosting numerous manufacturers and suppliers including XinChem. The region’s competitive advantages include lower production costs, established chemical infrastructure, and proximity to rapidly growing battery materials, pharmaceutical, and electronics industries. Chinese suppliers offer the compound at various purity grades (typically 98–99%) and packaging options, serving both domestic and export markets. The growing demand for lithium-ion battery separators, high-performance polymers, and pharmaceutical intermediates in China, Japan, South Korea, and India continues to drive regional consumption growth.

North America remains a key market for high-purity and research-grade APBIA, driven by demand from the pharmaceutical industry, battery materials companies, and academic research institutions. The United States hosts numerous research organizations, pharmaceutical companies, and materials science firms that require high-quality aromatic diamine building blocks for polyimide synthesis and drug discovery. TCI America maintains stock and ships from US warehouses, while Oakwood Chemical and BOC Sciences serve the North American market. The region’s well-established regulatory framework and emphasis on product quality support demand for high-grade research chemicals and polymer monomers.

Europe is characterized by stringent regulatory requirements, including REACH registration, and a strong focus on quality and sustainability in polymer and pharmaceutical research. European polymer manufacturers, battery materials companies, and research institutions demand high-purity aromatic diamine monomers with comprehensive documentation. CymitQuimica and other distributors serve the European market with in-stock availability.

Japan represents a specialized market where APBIA is supplied by TCI Chemicals for polyimide synthesis, battery materials research, and pharmaceutical development applications.

Regulatory and Safety Considerations

As a research chemical, polymer monomer, and pharmaceutical intermediate, 5-Amino-2-(4-aminophenyl)benzimidazole (CAS# 7621-86-5) is subject to regulatory oversight in major global economies. Compliance with relevant regulations is essential for market access and trade.

GHS classification and handling: APBIA is classified with the signal word ”Warning” . Hazard statements include H302 (Harmful if swallowed), H315 (Causes skin irritation), H319 (Causes serious eye irritation), H335 (May cause respiratory irritation), and H341 (Suspected of causing genetic defects). Precautionary statements include P201 (Obtain special instructions before use), P202 (Do not handle until all safety precautions have been read and understood), P261 (Avoid breathing dust/fume/gas/mist/vapours/spray), P264 (Wash skin thoroughly after handling), P280 (Wear protective gloves/protective clothing/eye protection/face protection), P301+P312 (IF SWALLOWED: Call a POISON CENTER/doctor if you feel unwell), P302+P352 (IF ON SKIN: Wash with plenty of soap and water), P304+P340 (IF INHALED: Remove person to fresh air and keep comfortable for breathing), P305+P351+P338 (IF IN EYES: Rinse cautiously with water for several minutes; remove contact lenses if present and easy to do; continue rinsing), P308+P313 (IF exposed or concerned: Get medical advice/attention), and P405 (Store locked up). The compound is classified as Acute Tox. 4 Oral, Skin Irrit. 2, Eye Irrit. 2, STOT SE 3, and Muta. 2. RTECS number: DD5421200.

Storage and stability: APBIA is air-sensitive and must be stored under inert gas in a cool, dark place (recommended below 15°C) to prevent oxidative degradation. The compound should be kept in a tightly sealed container and protected from moisture and light. For long-term storage, conditions of 2–8°C under inert atmosphere are recommended.

Regulatory compliance: In the European Union, the compound must comply with REACH registration requirements for import and use. Manufacturers and suppliers must provide comprehensive Safety Data Sheets (SDS) and maintain appropriate documentation. In the United States, APBIA is intended for research and development use only and is not intended for therapeutic, food, cosmetic, or consumer applications unless explicitly stated otherwise. For polymer and battery materials applications, manufacturers must comply with relevant industry standards and regulations.

Transport information: APBIA is not classified as hazardous material for DOT/IATA transport purposes. Proper packaging, labeling, and documentation are nevertheless required for international shipping. The HS code for the compound is 2933.99.7900 (heterocyclic compounds with nitrogen hetero-atoms only).

Future Outlook

The market outlook for 5-Amino-2-(4-aminophenyl)benzimidazole is positive, supported by several key growth drivers across its major application segments. While the compound remains a relatively specialized aromatic diamine building block, its unique combination of a rigid benzimidazole core and two reactive amino groups positions it for steady growth in the coming years.

Key growth drivers include:

1. Expansion of the lithium-ion battery separator market: The rapid growth of the electric vehicle and energy storage industries drives demand for high-performance battery separators, where APBIA-derived polyimides offer superior thermal stability, electrolyte wettability, and safety compared to conventional polyolefin separators.
2. Growth in high-performance polyimide applications: The expanding market for polyimides in aerospace composites, flexible electronics, high-temperature adhesives, and 5G communication materials creates new opportunities for APBIA as a key monomer.
3. Expansion of anticancer and anti-inflammatory drug discovery: The benzimidazole core is a privileged structure in medicinal chemistry, and APBIA’s derivatives have demonstrated efficacy as anticancer, bactericidal, and antiviral agents. The growing emphasis on targeted cancer therapies drives demand for high-quality heterocyclic building blocks like APBIA.
4. Increasing demand for proton exchange membranes: APBIA serves as a key monomer in the synthesis of polybenzimidazole-based proton exchange membranes for fuel cells, supporting the growth of the hydrogen energy sector.
5. Growth in specialty dyes and pigments: The expanding market for high-performance dyes and pigments, particularly for textile and industrial applications, supports steady demand for APBIA as an intermediate.

Challenges and considerations:

• Regulatory compliance: Increasingly stringent chemical and pharmaceutical regulations may require ongoing investment in quality systems and documentation.
• Air sensitivity: The compound’s air-sensitive nature requires storage under inert atmosphere, which may increase handling and logistics costs.
• Hazardous material handling: The compound’s classification with H341 (Suspected of causing genetic defects) requires appropriate safety measures during handling and storage.
• Limited scale: As a relatively specialized compound, the market for APBIA is smaller than that of commodity chemicals.
• Competition from alternative diamines: The market faces competition from other aromatic diamines and heterocyclic monomers used in polyimide synthesis.

To succeed in this evolving market landscape, suppliers must focus on product quality (particularly purity and batch-to-batch consistency), supply chain reliability, regulatory compliance, and responsive customer service. Companies that can offer high-purity products, flexible packaging options, and technical support for polymer science, battery materials, and pharmaceutical applications will be well-positioned to capture growing demand.

Shanghai XinChem Co., Ltd. (XinChem)

As a world-leading supplier of organic chemicals and specialty intermediates, Shanghai XinChem Co., Ltd. (XinChem) is dedicated to meeting the innovative needs of the polymer, battery materials, pharmaceutical, and fine chemical industries. Leveraging extensive experience and advanced manufacturing capabilities, XinChem provides high-quality 5-Amino-2-(4-aminophenyl)benzimidazole (APBIA, CAS# 7621-86-5) to customers worldwide. As a trusted manufacturer and supplier based in China, XinChem combines competitive pricing, reliable supply, and exceptional service to establish itself as a preferred partner for research institutions, polymer manufacturers, battery materials companies, and pharmaceutical companies seeking this versatile aromatic diamine building block.

1. Technical Advantages

Advanced Synthesis and Purification Processes
XinChem utilizes state-of-the-art manufacturing facilities and rigorous quality control measures to ensure the purity, consistency, and safety of its APBIA products. The production process incorporates established synthetic routes—including the reduction of 2-(4-nitrophenyl)-5-nitrobenzimidazole followed by purification—enabling the delivery of products with purity ≥98% (HPLC) to meet diverse application requirements. Strict process control ensures consistent product quality, minimal impurities, and batch-to-batch reproducibility, providing customers with reliable performance in polyimide synthesis, lithium-ion battery separator production, and pharmaceutical research.

Full-Chain Quality Control
The production process strictly adheres to international quality standards, with comprehensive quality control covering raw material sourcing, in-process monitoring, and finished product testing. Each batch is accompanied by a detailed Certificate of Analysis (COA) documenting physical and chemical properties, purity data (HPLC), melting point (234–238°C), and impurity profiles. This commitment to quality ensures that XinChem’s APBIA meets the stringent requirements of polymer science, battery materials, and pharmaceutical applications.

2. Product Advantages

High Purity and Consistent Quality
XinChem offers 5-Amino-2-(4-aminophenyl)benzimidazole with purity ≥98% (HPLC), ensuring optimal performance in polyimide synthesis, lithium-ion battery separator production, and pharmaceutical research. The product’s high purity minimizes the risk of unwanted side reactions and impurities, making it suitable for demanding applications in high-performance polymers and drug discovery.

Comprehensive Specifications
Key specifications include:

• Molecular Formula: C₁₃H₁₂N₄
• Molecular Weight: 224.26 g/mol
• CAS Number: 7621-86-5
• Synonyms: APBIA; DAPBI; 2-(4-Aminophenyl)-1H-benzimidazol-5-amine; 5-Amino-2-(4-aminophenyl)benzimidazole
• MDL Number: MFCD00451475
• Appearance: Light beige to light brown powder
• Purity: ≥98% (HPLC)
• Melting Point: 234–238°C
• Solubility: Slightly soluble in DMSO and methanol
• Storage: Under inert gas, cool and dark place (recommended below 15°C); air-sensitive

Flexible Packaging Solutions
XinChem provides a range of packaging options to accommodate diverse customer needs, from laboratory-scale quantities (1 g, 5 g, 10 g, 25 g, 100 g) to industrial-scale packaging (500 g, 1 kg, 25 kg/drum) and bulk shipments. Customized packaging solutions are available upon request, ensuring safe handling, storage, and transportation with appropriate protection from air and moisture.

3. Application Fields

As a versatile aromatic diamine building block, 5-Amino-2-(4-aminophenyl)benzimidazole (CAS# 7621-86-5) exhibits wide application value across multiple industries:

High-Performance Polymer Synthesis:

• Key aromatic diamine monomer for polyimides (PIs) with exceptional thermal stability and mechanical strength
• Critical component for lithium-ion battery separators with improved safety and electrolyte wettability
• Monomer for polybenzimidazole (PBI) derivatives and heterocyclic polymers
• Building block for aerospace composites, electronic substrates, and high-temperature adhesives

Pharmaceutical and Medicinal Chemistry Research:

• Versatile heterocyclic scaffold for anticancer, bactericidal, and antiviral drug discovery
• Building block for targeted cancer therapies interacting with enzymes and receptors in cancer progression
• Precursor for anti-inflammatory agents and enzyme inhibitors
• Scaffold for constructing focused libraries of bioactive molecules

Specialty Chemicals and Advanced Materials:

• Intermediate for high-performance dyes and pigments
• Monomer for proton exchange membranes in fuel cells
• Building block for advanced coatings and electronic materials

4. Service Support

Technical Expertise and Customized Solutions
XinChem’s team of experienced chemists and application engineers provides full technical support throughout the customer journey—from product selection and specification development to application guidance and troubleshooting. Whether customers require optimization of polymerization conditions, guidance on handling air-sensitive compounds, or assistance with regulatory documentation, XinChem’s technical experts are ready to help. Custom synthesis and contract manufacturing with flexible scaling from R&D to commercial quantities are available upon request.

Global Logistics and Reliable Supply
With established supply chains serving markets across Europe, North America, Asia-Pacific, and beyond, XinChem ensures timely delivery and consistent product availability. The company’s logistics team manages all aspects of international shipping, including customs clearance and documentation, with appropriate protection from air and moisture for product stability.

Regulatory Support
XinChem provides comprehensive documentation to support regulatory compliance, including Safety Data Sheets (SDS), Certificates of Analysis (COA), and other required certificates. The company stays current with evolving regulatory requirements in major markets, including REACH, TSCA, and other regional regulations, helping customers navigate the complexities of global trade.

5. Reasons to Choose XinChem

• Professionalism: Extensive experience and deep expertise in specialty chemical synthesis and supply.
• Quality: Rigorous quality control, high purity (≥98%), and adherence to international standards.
• Reliability: Stable supply, competitive pricing, and timely delivery.
• Flexibility: Customized solutions to meet diverse customer needs, including custom synthesis and packaging.
• Service: Responsive technical support and comprehensive documentation.

Contact us today to start your partnership with XinChem!

Website: www.xinchem.com

Email: sales1@xinchem.com

WhatsApp: +86 18049800532