3-Chloro-2-fluorobenzoic acid
[CAS# 161957-55-7]

Identification

• Classification: Organic raw materials >> Organic fluorine compound >> Fluorobenzoic acid series
• Name: 3-Chloro-2-fluorobenzoic acid
• Molecular Formula: C₇H₄ClFO₂
• Molecular Weight: 174.56
• CAS Registry Number: 161957-55-7
• EC Number: 630-303-9
• SMILES: C1=CC(=C(C(=C1)Cl)F)C(=O)O

Properties

• Density: 1.5±0.1 g/cm³, Calc.^*
• Melting point: 177-180 °C (Expl.)
• Index of Refraction: 1.558, Calc.^*
• Boiling Point: 278.9±20.0 °C (760 mmHg), Calc.^*
• Flash Point: 122.5±21.8 °C, Calc.^*

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

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H302-H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P270-P271-P280-P301+P317-P302+P352-P304+P340-P305+P351+P338-P319-P321-P330-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

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

Discovery and Applications

3-Chloro-2-fluorobenzoic acid is a halogenated aromatic acid that contains two halogen substituents—chlorine and fluorine—on the benzene ring. The chlorine atom is located at position 3 and the fluorine atom at position 2. These halogen substituents significantly impact the chemical reactivity and physical properties of the compound. As a benzoic acid derivative, 3-chloro-2-fluorobenzoic acid is an important intermediate in organic synthesis, with various applications in pharmaceuticals, agrochemicals, and material science.

The discovery of 3-chloro-2-fluorobenzoic acid can be traced to the ongoing development of halogenated aromatic acids for use in synthetic chemistry. The introduction of halogens onto the benzene ring often enhances the molecule's electrophilicity and solubility, providing advantageous reactivity in a wide range of chemical reactions. The fluorine and chlorine atoms on this compound also provide unique steric and electronic effects, which can influence the molecule’s behavior in different chemical environments. This makes 3-chloro-2-fluorobenzoic acid a valuable building block for more complex compounds with varied applications.

One of the primary applications of 3-chloro-2-fluorobenzoic acid is in the synthesis of pharmaceutical compounds. The presence of halogen atoms can help modulate the biological activity of drug candidates, improving their potency, selectivity, and pharmacokinetic properties. For example, halogenated aromatic acids are often incorporated into molecules designed to interact with enzymes or receptors in the body. In some cases, the introduction of chlorine and fluorine atoms can enhance metabolic stability, reducing the rate at which a compound is broken down in the body, which is crucial for prolonging its therapeutic effects. Additionally, the introduction of halogens can influence the lipophilicity of a compound, making it more likely to penetrate cell membranes and reach its target site.

In the field of agrochemicals, 3-chloro-2-fluorobenzoic acid can also be used as an intermediate in the production of herbicides, fungicides, and insecticides. The chlorofluoro substitution pattern enhances the compound’s ability to interact with biological systems, making it an ideal candidate for the development of effective plant protection products. Halogenation can increase the selectivity and toxicity of these chemicals toward specific pests or plants, while reducing their environmental impact.

Another important application of 3-chloro-2-fluorobenzoic acid is in material science. The compound can be used to modify the properties of organic semiconductors and light-emitting materials. The presence of the chlorine and fluorine atoms can influence the electronic structure of the aromatic ring, which is essential for fine-tuning the conductivity and light-emitting properties of organic materials used in electronic devices. By incorporating such compounds into organic light-emitting diodes (OLEDs) or organic photovoltaics (OPVs), researchers can improve the efficiency and stability of these devices.

In summary, 3-chloro-2-fluorobenzoic acid is a versatile compound with a broad range of applications in the pharmaceutical, agrochemical, and material science industries. Its halogenated structure enhances its reactivity and solubility, making it an important intermediate for the synthesis of bioactive molecules, plant protection chemicals, and functional materials. The unique properties imparted by the chlorine and fluorine substituents continue to drive research into its potential uses in various fields.

References

2016. Synthesis, characterization and pharmacological evaluation of some new 1,3,4-oxadiazole derivatives bearing 3-chloro-2-fluoro phenyl moiety. Research on Chemical Intermediates, 42(12), 8285-8300.
DOI: 10.1007/s11164-016-2561-4

2013. Photoassisted defluorination of fluorinated substrates and pharmaceuticals by a wide bandgap metal oxide in aqueous media. Photochemical & Photobiological Sciences, 12(5), 884-889.
DOI: 10.1039/c2pp25358e

U.S. Environmental Protection Agency. TSCA Chemical Substance Inventory. https://www.epa.gov/tsca-inventory.