1. Molecular Design and Key Characteristics 2,2-Bis(3-amino-4-hydroxyphenyl)propane, commonly abbreviated as BAP, is an organic compound with CAS 1220-78-6. It is a diamine monomer widely recognized for its critical role in synthesis of high-performance polyimides and other functional polymers. The compound is also known by several synonyms, including 4,4'-(Propane-2,2-diyl)bis(2-aminophenol) and 2,2-Bis(3-amino-4-hydroxylphenyl)propane. BAP is a hydroxyl-containing aromatic diamine monomer with the molecular formula C₁₅H₁₈N₂O₂ and a molecular weight of 258.32 g/mol. Its molecular architecture consists of two ortho-aminophenol groups bridged by an isopropylidene (–C(CH₃)₂–) linker. This unique structure endows BAP with dual amine (–NH₂) and hydroxyl (–OH) functionality—a feature that distinguishes it from generic diamines such as ODA or MDA. Key characteristics that make BAP valuable in polymer design include: --Aromatic backbone contributing to molecular rigidity, thermal resistance, and mechanical performance --Hydroxyl groups that influence polarity, hydrogen bonding, interfacial compatibility, and post-reaction behavior --Isopropylidene bridge providing a balance between rigidity and processability --Ortho-hydroxyl-diamine architecture essential for polybenzoxazole (PBO) cyclization BAP is typically supplied as an off-white to white crystalline powder with a purity of ≥99.5% (HPLC), a melting point of 248–254 °C, and solubility in alcohols, ketones, ammonia, and DMF, but is insoluble in water. 2.Synthesis: BAP is commonly synthesized via the catalytic hydrogenation of its dinitro precursor, 4-[2-(4-hydroxy-3-nitrophenyl)propan-2-yl]-2-nitrophenol. In a typical procedure, the dinitro compound is dissolved in anhydrous ethanol in presence of a wet 10% Pd/C catalyst and heated to reflux. Hydrazine hydrate is then added dropwise, and the reaction is maintained under reflux for approximately 24 hours. Following filtration to remove the catalyst and concentration under reduced pressure, the crude product is precipitated in cold distilled water, collected, washed, and dried. Recrystallization from methanol yields BAP as white powder with reported yield of 88%.
3.Core Applications in High-Performance Polymers ---Polyimide Synthesis – The Primary Application BAP serves as a structural building block in the synthesis of high-performance polyimides (PIs).When polymerized with various dianhydrides—such as rigid aromatic BPDA or BTDA, or fluorinated dianhydrides like 6FDA—BAP-based polyimides exhibit: -Exceptional thermal stability: weight loss temperatures (T5%) exceeding 538 °C- -High glass transition temperatures (Tg): depending on the co-monomer and formulation -Good mechanical properties: tensile strengths in the range of 41–64 MPa- -Excellent chemical and flame resistance The hydroxyl groups in BAP also enable post-polymerization crosslinking and thermal rearrangement reactions, offering additional routes to tailor material properties. --Photosensitive Polyimides and Polyimide Films BAP is a key intermediate for synthesizing photosensitive polyimides and polyimide films. The hydroxyl functionality allows the introduction of photosensitive groups, enabling the fabrication of positive-tone photosensitive polybenzoxazole (PBO) precursors for applications such as integrated circuit passivation and interlayer dielectrics. --Low Dielectric Constant and Low CTE Polyimides for 5G/Advanced Packaging With the rapid development of microelectronic devices toward higher frequency, higher speed, and higher integration, there is a growing demand for interlayer dielectric materials with low dielectric constant (ε) and low coefficient of thermal expansion (CTE). Traditional aromatic polyimides with ε of 3.2–3.6 and CTEs exceeding 60 ppm/K are insufficient for modern 5G communications and advanced packaging. BAP addresses this challenge. Through thermal polycondensation with diamines such as ODA and dianhydrides like PMDA, followed by thermal rearrangement to form oxazole ring structures in the main chain, BAP-derived polyimides achieve: -Dielectric constants as low as 2.79 at 200 kHz -CTE values reduced to 19.6–25.4 ppm/K—a significant improvement over conventional PIs -Water absorption rates as low as 2.47%- These properties make BAP-based polyimides strong candidates for interlayer dielectric materials in integrated circuits and advanced packaging 4.Versatility in Copolymer Design BAP’s utility extends to copolymerization with other diamines and dianhydrides, allowing fine-tuning of material properties: Co-polymerization with ODA/ODPA elevates Tg, tensile strength, and modulus in copolyimide films; Pairing with rigid aromatic dianhydrides (BPDA, BTDA) enhances thermal resistance and dimensional stability Pairing with fluorinated dianhydrides (6FDA) can further reduce dielectric constant and improve solubility Product manager: Joy Wu Email address: Joy@coreychem.com
