N,N'-Bis(4-aminophenyl)piperazine
[CAS# 7479-12-1]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Piperazine
• Name: N,N'-Bis(4-aminophenyl)piperazine
• Synonyms: 4,4'-(1,4-Piperazinediyl)bis[benzenamine]; 1,4-Bis(4-aminophenyl)-1,4-diazacyclohexane; 1,4-Bis(p-aminophenyl)piperazine; N,N'-Bis(4-aminophenyl)piperazine; NSC 401585
• Molecular Formula: C₁₆H₂₀N₄
• Molecular Weight: 268.36
• CAS Registry Number: 7479-12-1
• SMILES: C1CN(CCN1C2=CC=C(C=C2)N)C3=CC=C(C=C3)N

Properties

• Density: 1.2±0.1 g/cm³ Calc.^*
• Boiling point: 540.9±50.0 °C 760 mmHg (Calc.)^*
• Flash point: 350.2±18.1 °C (Calc.)^*
• Solubility: Slightly soluble (7.2 g/L) (25 °C) (Calc.)
• Index of refraction: 1.672 (Calc.)^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302
• Safety Statements: P264-P270-P301+P317-P330-P501

Discovery and Applications

N,N'-Bis(4-aminophenyl)piperazine is an aromatic diamine with the molecular formula C₁₆H₂₀N₄. Structurally, it consists of a central piperazine ring substituted at both nitrogen atoms with 4-aminophenyl groups. This configuration results in two aromatic amino groups connected through a flexible, six-membered heterocyclic piperazine core, combining nucleophilic reactivity with a degree of conformational flexibility. The compound typically appears as a pale yellow to off-white solid, soluble in polar organic solvents such as dimethylformamide, dimethyl sulfoxide, and ethanol, while having limited solubility in water.

N,N'-Bis(4-aminophenyl)piperazine is primarily used as a monomer in high-performance polymer synthesis. The aromatic amino groups readily undergo condensation reactions with dianhydrides, diacid chlorides, or epoxides to form polyimides, polyamides, and epoxy networks. The aromatic rings provide rigidity and thermal stability, whereas the piperazine core introduces flexibility and can reduce polymer brittleness. This structural combination enables the formation of polymers with desirable mechanical properties, chemical resistance, and thermal stability suitable for coatings, adhesives, and electronic applications.

In addition to polymerization, the amino groups allow functionalization through acylation, sulfonation, or Schiff base formation, facilitating the synthesis of advanced materials with tailored chemical, mechanical, or optical properties. The piperazine ring also offers potential for modifying polymer chain packing and solubility characteristics.

Synthetically, N,N'-bis(4-aminophenyl)piperazine can be prepared via nucleophilic aromatic substitution of 4-nitrochlorobenzene with piperazine, followed by reduction of nitro groups to amines. Purification typically involves recrystallization or chromatographic techniques to achieve the required purity for polymerization or other chemical applications.

Overall, N,N'-bis(4-aminophenyl)piperazine is a versatile aromatic diamine featuring a rigid aromatic framework combined with a flexible piperazine core. Its dual amino functionality, reactivity, and structural properties make it a valuable intermediate for high-performance polymer synthesis, functionalized materials, and advanced chemical applications requiring a balance of thermal stability, mechanical flexibility, and chemical reactivity.

References

2012. 1,4-Diarylpiperazines and analogs as anti-tubercular agents: Synthesis and biological evaluation. European Journal of Medicinal Chemistry, 49.
DOI: 10.1016/j.ejmech.2011.12.035