Chemical Identity and Key Properties

5-Chloro-4-iodo-2-(trifluoromethyl)pyridine (Aladdin SKU C195183) is an electron-deficient, polyhalogenated pyridine derivative. The trifluoromethyl (CF₃) group at the 2-position exerts a strong inductive and resonance electron-withdrawing effect, reducing electron density across the ring. This activation is particularly pronounced at the 4-position, where the C–I bond resides.

The molecule contains two distinct halogen handles: a carbon–iodine bond at C4 and a carbon–chlorine bond at C5. Because C–I bonds are inherently weaker and more reactive toward oxidative addition than C–Cl bonds, these two sites display orthogonal reactivity under appropriate catalytic conditions. This orthogonality is the primary synthetic value of this compound.

Note: Verify the exact molecular weight, CAS number and purity specification from the product Certificate of Analysis (CoA) supplied with each lot.

Recommended Handling and Storage Protocol

Personal Protection: Handle in a well-ventilated fume hood. Wear appropriate personal protective equipment including chemically resistant gloves, safety goggles and a lab coat. The compound contains iodine and a fluorinated moiety; consult the Safety Data Sheet (SDS) before use.

Storage Conditions: Store the reagent in a tightly sealed container under an inert atmosphere (nitrogen or argon) in a cool, dry location away from direct light and moisture. Avoid contact with strong bases, strong oxidisers and moisture, all of which may degrade the compound or release hazardous by-products.

Stability: As with most polyhaloaromatics bearing iodo substituents, prolonged exposure to air, light or elevated temperatures may lead to gradual decomposition. Always inspect the material visually and by TLC or NMR before use in critical synthetic steps. If discolouration or decomposition is suspected, request a fresh CoA or replace the lot.

Waste Disposal: Dispose of all waste in accordance with local institutional and governmental regulations for halogenated organic compounds.

Synthetic Applications and Reaction Guidelines

Selective C–I Functionalization (Step 1): The C4–I bond undergoes facile palladium-catalysed cross-coupling reactions under mild conditions. Standard protocols including Suzuki–Miyaura (arylboronic acids), Sonogashira (terminal alkynes), Negishi (organozinc), and Stille (organostannane) couplings are well-suited for the iodo position. Typical conditions employ Pd(PPh₃)₄ or Pd(dppf)Cl₂ as the catalyst, with an appropriate base (e.g., K₂CO₃, Et₃N) and solvent system (DMF, THF, dioxane, or aqueous mixtures) at temperatures ranging from room temperature to 80 °C.

Selective C–Cl Functionalization (Step 2): After exhaustion of the iodo position, the remaining C5–Cl bond can be engaged using more active Pd catalysts or elevated temperatures. Buchwald–Hartwig amination, Miyaura borylation, or nucleophilic aromatic substitution (SNAr) leveraging the strongly electron-withdrawing CF₃ and ring nitrogen are viable approaches. SNAr is particularly facilitated by the electron-poor character of the ring.

Sequential Diversification: The combination of orthogonal halogen reactivity and the ring-activating CF₃ group makes this compound an ideal scaffold for library synthesis, enabling introduction of two independent substituents in a defined sequence.

Reaction Monitoring: Monitor reactions by TLC (UV-active compound) or HPLC. Confirm product identity and purity by ¹H NMR, ¹⁹F NMR and LCMS.

Quality, Purity and Ordering Information

Specification: Aladdin Scientific supplies 5-Chloro-4-iodo-2-(trifluoromethyl)pyridine under SKU C195183. Purity grades and available pack sizes should be confirmed on the current product page or by contacting our technical sales team, as specifications may be updated between catalogue editions.

Certificate of Analysis: A lot-specific CoA is available upon request or via the Aladdin website. The CoA typically includes purity (GC or HPLC), melting point, NMR confirmation and appearance. Review the CoA before use in GMP-adjacent or publication-critical experiments.

Ordering: Place orders via the Aladdin Scientific website or through your local distributor. For bulk quantities, custom packaging or volume pricing, contact our procurement team directly. Reward points and promotional pricing may apply; see the current promotions page for details.

Troubleshooting Common Issues

Low Coupling Yield at C4–I: Check catalyst loading, base and solvent compatibility. Ensure the reaction is performed under inert atmosphere to prevent catalyst poisoning. Degassing solvents thoroughly before use is recommended. Consider switching to a more active Pd source such as Pd₂(dba)₃ with an appropriate phosphine ligand if standard conditions underperform.

Undesired Protodeiodination: This side reaction can occur under basic aqueous conditions at elevated temperature. Use milder bases (e.g., Cs₂CO₃) or switch to anhydrous conditions where possible.

Both Halogens Reacted Simultaneously: If sequential selectivity is lost, reduce catalyst loading, lower reaction temperature and use a less reactive Pd catalyst for the first step to preserve the C–Cl bond for subsequent functionalization.

Compound Decomposition: If the starting material appears discoloured or gives anomalous NMR spectra, replace the lot and verify storage conditions. Contact Aladdin Scientific customer service for return and replacement procedures.