4,4'-(9-Fluorenylidene)dianiline
[CAS# 15499-84-0]

Identification

• Classification: Chemical reagent >> Organic reagent >> Polyamine
• Name: 4,4'-(9-Fluorenylidene)dianiline
• Synonyms: 9,9-Bis(4-aminophenyl)fluorene; Bisaminophenylfluorene
• Molecular Formula: C₂₅H₂₀N₂
• Molecular Weight: 348.44
• CAS Registry Number: 15499-84-0
• EC Number: 628-740-5
• SMILES: C1=CC=C2C(=C1)C3=CC=CC=C3C2(C4=CC=C(C=C4)N)C5=CC=C(C=C5)N

Properties

• Density: 1.2±0.1 g/cm³, Calc.^*
• Melting point: 237-239 °C (Expl.)
• Index of Refraction: 1.725, Calc.^*
• Boiling Point: 535.2±50.0 °C (760 mmHg), Calc.^*
• Flash Point: 334.1±29.6 °C, Calc.^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H312-H319-H332-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P317-P319-P321-P330-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Acute toxicity	Acute Tox.	4	H302
Acute toxicity	Acute Tox.	4	H312
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315

Discovery and Applications

4,4'-(9-Fluorenylidene)dianiline is an aromatic diamine compound characterized by a central fluorene core bearing two para-substituted aniline groups at the 9-position. The molecular structure includes a rigid fluorenylidene backbone with two amino-substituted phenyl rings, providing a symmetrical and planar geometry. This compound is also known by its abbreviated name, FDA or FDN, and is widely recognized for its role in the synthesis of high-performance polymers.

The synthesis of 4,4'-(9-fluorenylidene)dianiline is generally accomplished through a condensation reaction involving fluorene derivatives, particularly 9-fluorenone, and aniline derivatives under reducing conditions. The resulting product possesses two primary amine groups, which are reactive functional sites for subsequent polymerization processes.

One of the most important applications of this compound is in the production of polyimides and polyamides, where it serves as a diamine monomer. The presence of the bulky and rigid fluorene moiety contributes to the enhanced thermal and mechanical properties of the resulting polymers. These high-performance materials are utilized in demanding environments such as aerospace, microelectronics, and advanced coatings, where thermal stability, chemical resistance, and mechanical strength are critical.

In polyimide synthesis, 4,4'-(9-fluorenylidene)dianiline is often reacted with dianhydrides, such as pyromellitic dianhydride (PMDA), to form polyamic acids, which are then thermally imidized to yield the final polyimide product. The introduction of the fluorenylidene group reduces chain flexibility, resulting in materials with high glass transition temperatures and low dielectric constants, making them suitable for insulating layers in electronic devices.

Additionally, this compound is used in liquid crystal alignment materials and photoresists, benefiting from its aromatic structure and electronic properties. It has also found use in the formulation of thermosetting resins and epoxy networks where its diamine structure enables cross-linking reactions.

The stability of 4,4'-(9-fluorenylidene)dianiline under thermal and oxidative conditions further supports its incorporation in polymers intended for harsh environments. It is typically handled in the form of a crystalline solid and requires standard chemical handling procedures to ensure safety, including avoidance of prolonged skin or respiratory exposure.

In summary, 4,4'-(9-fluorenylidene)dianiline is a well-established diamine used extensively in the development of high-performance polymeric materials. Its structural features contribute to the desirable mechanical, thermal, and electrical properties of advanced engineering plastics and electronic materials.

References

2024. Synthesis of UV-resistant and colorless polyimide films for optoelectrical applications. npj Materials Degradation, 8, Article 1.
DOI: 10.1038/s41529-023-00422-w

2020. High-Performance Polyimides with Pendant Fluorenylidene Groups: Synthesis, Characterization and Adsorption Behaviour. Journal of Polymers and the Environment, 28(8), 2186-2197.
DOI: 10.1007/s10924-020-01777-w

2022. Structure and Properties of Nanocomposites Based on Polyimides with Different Chemical Structures and Metalloalkoxysiloxanes. Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques, 16(4), 685-690.
DOI: 10.1134/s1027451022040218