5-Amino-2-(4-aminophenyl)benzimidazole APBIA(CAS#7621-86-5)

1. Properties:

• Appearance and Physical Form: 5-Amino-2-(4-aminophenyl)benzimidazole (APBIA) is supplied as a white to light orange to yellow powder to crystal . It is available in research-grade purity (≥98.0% by HPLC) and polymer-monomer grade (≥99.5%) for advanced materials applications .
• Solubility: The compound is slightly soluble in methanol . Its rigid-rod molecular architecture provides excellent solubility in polar aprotic solvents commonly used in polyimide synthesis, such as N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc).
• Chemical Properties: 5-Amino-2-(4-aminophenyl)benzimidazole (C₁₃H₁₂N₄) is a heterocyclic aromatic diamine belonging to the benzimidazole family . The compound features two primary amino groups—one at the 5-position of the benzimidazole core and one at the 4′-position of the pendant phenyl ring—conferring dual-site reactivity for polymerization and derivatization .
  • Rigid-Rod Architecture: The rigid benzimidazole structure, combined with hydrogen-bond-donating N–H and dual reactive amines, distinguishes it structurally from conventional non-heterocyclic diamines such as 4,4′-oxydianiline (ODA) and p-phenylenediamine .
  • High-Temperature Performance: Polyimide films derived from APBIA achieve a glass transition temperature (Tg) of 370°C and a coefficient of thermal expansion (CTE) of 19 ppm/K, precisely matching copper .
  • Enhanced Mechanical Properties: APBIA-based polyimide foams exhibit a 35.8% compressive strength enhancement and a thermal conductivity of 0.05 W/(m·K), making them suitable for EV battery fire barriers .
  • Oxidative Stability: Cross-linked sulfonated polyimide membranes incorporating APBIA demonstrate nearly 4× improvement in anti-free-oxidative stability for fuel cell applications .

2. Applications:

High-Performance Polymers & Advanced Materials (Primary Application):

• Polyimide (PI) Films: APBIA is a key monomer for the synthesis of high-temperature polyimide films used in flexible printed circuit boards (FPCBs) and aerospace applications. Its rigid structure delivers a CTE of 19 ppm/K, precisely matching copper and eliminating curl in flexible electronics .
• Polybenzimidazole (PBI) and Polybenzoxazole (PBO) Copolymers: The compound serves as a building block for PBI and PBO copolymers, which exhibit exceptional thermal stability and mechanical strength .
• Polyimide Foams: APBIA-based polyimide foams provide enhanced compressive strength and thermal insulation for EV battery fire barriers and lightweight structural composites .
• Fuel Cell Membranes: Cross-linked sulfonated polyimide membranes incorporating APBIA offer improved oxidative stability for proton exchange membrane fuel cells .

Chemical Synthesis & Polymer Research:

• Polymer Monomer: Used as a diamine monomer in the synthesis of various high-performance polymers and copolymers .
• Cross-Coupling Reactions: The compound serves as a substrate for palladium-catalyzed cross-coupling reactions and other organic transformations.
• Materials Science Research: APBIA is cited in over 19 peer-reviewed publications across chromatography, organic synthesis, and cross-coupling reactions .

Other Applications:

• Aerospace Materials: High-Tg polyimides derived from APBIA are used in aerospace composites and structural components.
• Flexible Electronics: Low-CTE polyimide films enable the production of dimensionally stable flexible printed circuit boards .

3. Preparation Method:

• Synthetic Route: 2-(4-Aminophenyl)-1H-benzimidazol-5-amine can be synthesized via the condensation of 4-aminobenzaldehyde with 4-nitro-1,2-phenylenediamine, followed by reduction of the nitro group to amine. The synthesis has been described in patent literature (e.g., CN107474016, CN108558770) . Alternatively, it can be prepared through the cyclization of appropriate diamine precursors under acidic conditions. Purification via recrystallization yields material of ≥99.5% purity for polymer-grade applications .

4. Safety Information:

• Hazard Classification: 5-Amino-2-(4-aminophenyl)benzimidazole is classified as a hazardous substance. Under GHS, it carries the following hazard statements:
  • H302: Harmful if swallowed
  • H315: Causes skin irritation
  • H319: Causes serious eye irritation
  • H335: May cause respiratory irritation
  • H341: Suspected of causing genetic defects
• Hazard pictogram: GHS07
• Signal word: Warning
• RTECS#: DD5421200
• Health Hazards:
  • Inhalation: May cause respiratory irritation (H335). If inhaled, remove person to fresh air and keep comfortable for breathing .
  • Skin Contact: Causes skin irritation (H315). Wash with plenty of soap and water .
  • Eye Contact: Causes serious eye irritation (H319). Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing .
  • Ingestion: Harmful if swallowed (H302). Rinse mouth. Do NOT induce vomiting .
  • Genetic Defects: Suspected of causing genetic defects (H341). Obtain special instructions before use .
• First Aid Measures:
  • Eye Contact: IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. If eye irritation persists: Get medical advice/attention .
  • Skin Contact: IF ON SKIN: Wash with plenty of soap and water. If skin irritation occurs: Get medical advice/attention .
  • Inhalation: IF INHALED: Remove person to fresh air and keep comfortable for breathing .
  • Ingestion: IF SWALLOWED: Rinse mouth. Do NOT induce vomiting. Immediately call a POISON CENTER/doctor .
• Personal Protective Equipment (PPE):
  • Respiratory protection: Do not breathe dust/fume/gas/mist/vapours/spray .
  • Eye protection: Wear protective gloves/protective clothing and eye/face protection .
  • Skin protection: Wear protective gloves and protective clothing .
  • General hygiene: Wash hands thoroughly after handling . Do not eat, drink or smoke when using this product . Use only outdoors or in a well-ventilated area .
• Storage & Stability: Store in a cool, dark place at room temperature (<15°C recommended) . Store under inert gas as the compound is air-sensitive . Keep container tightly closed and store locked up . Under recommended storage conditions, APBIA has a shelf life of 12 to 24 months from the date of manufacture in sealed original containers.
• Regulatory Compliance: 5-Amino-2-(4-aminophenyl)benzimidazole (CAS#7621-86-5) is listed on EINECS (231-538-6), TSCA, DSL, and other regional chemical inventories. It is classified under HS code 2933.99.7900 . This product is for R&D use only and is not intended for medicinal, household, or other uses. Always consult the Safety Data Sheet (SDS) and local regulations for complete safety, environmental, and regulatory information specific to each product grade and application jurisdiction.