4,4'-Difluorobenzophenone
[CAS# 345-92-6]

Identification

• Classification: Chemical reagent >> Organic reagent >> Aromatic ketone
• Name: 4,4'-Difluorobenzophenone
• Synonyms: Bis(4-fluorophenyl)-methanone
• Molecular Formula: C₁₃H₈F₂O
• Molecular Weight: 218.20
• CAS Registry Number: 345-92-6
• EC Number: 206-466-3
• SMILES: C1=CC(=CC=C1C(=O)C2=CC=C(C=C2)F)F

Properties

• Density: 1.2±0.1 g/cm³, Calc.^*
• Melting point: 102-105 °C (Expl.)
• Index of Refraction: 1.55, Calc.^*
• Boiling Point: 308.8±27.0 °C (760 mmHg), Calc.^*, 347.2-349.9 °C (Expl.)
• Flash Point: 118.4±17.9 °C, Calc.^*

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

Safety Data

• Hazard Symbols: GHS07;GHS09 Warning
• Risk Statements: H302-H315-H319-H335-H411
• Safety Statements: P261-P264-P270-P271-P273-P280-P301+P312-P302+P352-P304+P340-P305+P351+P338-P312-P330-P332+P313-P337+P313-P362-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315
Chronic hazardous to the aquatic environment	Aquatic Chronic	2	H411
Specific target organ toxicity - single exposure	STOT SE	3	H335
Eye irritation	Eye Irrit.	2	H319
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2A	H319

Discovery and Applications

4,4'-Difluorobenzophenone is an aromatic ketone compound with the molecular formula C13H8F2O. Structurally, it consists of a benzophenone core in which each of the para positions on the phenyl rings is substituted with a fluorine atom. This symmetrical substitution pattern contributes to the compound’s thermal and chemical stability. It is a white to off-white crystalline solid, typically synthesized through halogenation reactions involving benzophenone derivatives or through Friedel–Crafts acylation followed by fluorination.

The primary significance of 4,4'-difluorobenzophenone lies in its role as a monomer in the production of high-performance polymers, particularly poly(arylene ether ketones) (PAEKs) and poly(ether ketone ketone) (PEKK). The fluorine atoms in the para positions increase the reactivity of the aromatic rings toward nucleophilic aromatic substitution, making the compound highly suitable for the synthesis of these engineering thermoplastics. The resulting polymers exhibit excellent mechanical strength, chemical resistance, and high thermal stability, making them ideal for applications in aerospace, automotive, and electronic industries.

In polymer synthesis, 4,4'-difluorobenzophenone is typically reacted with bisphenols or other nucleophilic aromatic compounds under basic conditions to form ether linkages. The ketone group and the electron-withdrawing fluorine substituents together activate the aromatic ring toward substitution, allowing controlled chain growth and high molecular weight polymers.

Commercially, the compound has been integral in the development of polyetherketoneketone (PEKK) resins, which are used in applications requiring flame resistance, dimensional stability, and resistance to aggressive chemicals. Such materials are often processed into films, fibers, and structural components.

Additionally, 4,4'-difluorobenzophenone has been used in the production of copolymers to modify physical and processing properties of base resins. These materials find use in membranes, high-performance coatings, and components for demanding electrical and mechanical applications.

Its stability under thermal processing conditions, combined with its reactivity toward nucleophiles, makes 4,4'-difluorobenzophenone a foundational building block in modern polymer chemistry. It is also used as an intermediate in organic synthesis for compounds where controlled fluorination and rigidity are desired.

In summary, 4,4'-difluorobenzophenone is a well-characterized industrial chemical used primarily in the synthesis of high-performance polymers. Its utility is attributed to its fluorinated aromatic structure, which enables the formation of thermally and chemically resistant polymeric materials.

References

2024. Alkylation of azoles with alkenes catalyzed by the NiCl2Py2/IMes • HCl/ButONa system. Russian Chemical Bulletin, 73(9).
DOI: 10.1007/s11172-024-4380-x

2024. Nano-liquid Metal Manufacture. Handbook of Liquid Metals, 28.
DOI: 10.1007/978-981-97-1614-2_28

2023. Non-targeted metabolomics analysis of metabolite changes in two quinoa genotypes under drought stress. BMC Plant Biology, 23(10).
DOI: 10.1186/s12870-023-04467-6