Chemical Identity and Physical Properties

3-Chloro-2-fluoro-5-(trifluoromethyl)pyridine (CAS 89402-29-9, Aladdin SKU C124354) is a polyfluorinated pyridine derivative with the molecular formula C₆H₂ClF₄N and a molecular weight of 215.53 g/mol. The compound bears three distinct halogen or fluorine-containing substituents on the pyridine ring: a chloro group at position 3, a fluoro group at position 2, and a trifluoromethyl (–CF₃) group at position 5.

The cumulative electron-withdrawing effect of the ring nitrogen, the C-2 fluorine, the C-3 chlorine, and the C-5 trifluoromethyl group renders the aromatic system strongly electron-deficient. This electronic depletion significantly lowers the LUMO energy of the ring, facilitating nucleophilic aromatic substitution (SNAr) reactions, particularly at the C-2 position where fluorine acts as the preferred leaving group due to its ability to stabilize the Meisenheimer complex.

The compound is typically handled as a colorless to pale yellow liquid at room temperature. It is miscible with common organic solvents such as dichloromethane, tetrahydrofuran, dimethylformamide, and acetonitrile, but it is not miscible with water. Researchers should verify specific physical constants (boiling point, density, refractive index) against the current Certificate of Analysis supplied with each lot.

Synthetic Applications and Reactivity

The primary synthetic utility of 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine lies in its role as a versatile electrophilic building block for constructing fluorinated heterocyclic frameworks relevant to crop-protection chemistry and medicinal chemistry.

Nucleophilic Aromatic Substitution (SNAr): The C-2 fluorine is highly activated toward displacement by oxygen, nitrogen, sulfur, and carbon nucleophiles under mild to moderate conditions. This selectivity allows chemists to introduce diverse heteroatom-containing substituents at C-2 while retaining the C-3 chlorine for subsequent cross-coupling steps, enabling sequential functionalization strategies.

Transition-Metal-Catalyzed Cross-Coupling: The C-3 chlorine is amenable to palladium- or nickel-catalyzed cross-coupling reactions (e.g., Suzuki–Miyaura, Negishi, Buchwald–Hartwig amination) after the C-2 fluorine has been elaborated via SNAr. The orthogonal reactivity of C–F (SNAr) versus C–Cl (cross-coupling) provides a powerful two-step diversification handle.

Agrochemical and Pharmaceutical Intermediates: Trifluoromethylpyridine-containing motifs are prevalent in commercial herbicides, fungicides, and insecticides, as well as in CNS-active and anti-infective drug candidates, owing to the metabolic stability, lipophilicity modulation, and enhanced membrane permeability conferred by fluorine substituents.

Handling, Safety, and Storage Guidelines

Personal Protective Equipment (PPE): Handle 3-chloro-2-fluoro-5-(trifluoromethyl)pyridine in a well-ventilated fume hood. Wear chemical-splash goggles, a lab coat, and solvent-resistant gloves (e.g., nitrile or neoprene). Avoid inhalation of vapors; the compound may cause irritation to the respiratory tract, eyes, and skin upon exposure.

Storage: Store in a tightly sealed container away from moisture, heat sources, and strong bases or nucleophiles that could react with the activated C–F bond. A cool, dry location (typically 2–8 °C or as specified on the product label) under an inert atmosphere (nitrogen or argon) is recommended to maintain stability and prevent hydrolysis or decomposition over extended storage periods. Always confirm storage conditions with the current product specification sheet.

Waste Disposal: Dispose of waste material in accordance with local, regional, and national regulations governing halogenated organic solvents and reagents. Do not pour down the drain. Use appropriate labeled waste containers and consult your institution's Environmental Health and Safety (EHS) office.

Emergency Measures: In case of skin or eye contact, flush immediately with copious amounts of water for at least 15 minutes and seek medical attention. Refer to the Safety Data Sheet (SDS) supplied with the product for full hazard classification, first-aid measures, and regulatory information.

Quality, Purity, and Procurement Considerations

Purity Requirements: For most synthetic applications, a purity of ≥97% (GC) is sufficient. However, for sensitive catalytic reactions or when the compound is used as a reference standard in analytical methods, higher purity grades may be required. Researchers should confirm the purity specification stated on the Certificate of Analysis (CoA) provided with each batch.

Analytical Characterization: Identity and purity are typically confirmed by a combination of GC or HPLC purity assay, ¹H and ¹⁹F NMR spectroscopy, and mass spectrometry. The ¹⁹F NMR spectrum is particularly diagnostic: the CF₃ group and the ring fluorine at C-2 resonate at characteristically distinct chemical shifts, enabling unambiguous assignment.

Ordering from Aladdin Scientific: 3-Chloro-2-fluoro-5-(trifluoromethyl)pyridine is available from Aladdin Scientific under SKU C124354. Bulk quantities for scale-up or custom purities may be available upon request. Contact Aladdin customer service for lead times, volume pricing, and availability. Ensure that the product SDS and CoA are downloaded and reviewed prior to use.