Name: China Supplier Top Quality 5-Chloro-2-fluoro-4-iodopyridine CAS 659731-48-3 with good service
Brand: Wuhan Fortuna Chemical Co., Ltd.

5-Chloro-2-fluoro-4-iodopyridine is a synthetic organic compound belonging to the class of halogen-substituted pyridine derivatives. Here's a detailed breakdown of its chemical identity:

Core Structure: Pyridine

A 6-membered heterocyclic aromatic ring.
Contains one nitrogen atom (N).
The carbon atoms in the ring are numbered according to IUPAC rules. The nitrogen is position 1. Adjacent carbons are 2 and 6 (equivalent), followed by 3 and 5 (equivalent), and the carbon opposite nitrogen is position 4.
Substituents (Halogens):

Chloro (Cl): Attached to the carbon at position 5.
Fluoro (F): Attached to the carbon at position 2.
Iodo (I): Attached to the carbon at position 4.
Chemical Formula: C₅H₂ClFIN

Represents the elemental composition: 5 Carbon (C), 2 Hydrogen (H), 1 Chlorine (Cl), 1 Fluorine (F), 1 Iodine (I), 1 Nitrogen (N).
Molecular Weight: 285.43 g/mol

Calculated as: (5×12.01) + (2×1.008) + 35.45 + 19.00 + 126.90 + 14.01 = 285.43 g/mol.
CAS Registry Number: 1020719-94-8

A unique numerical identifier assigned to this specific chemical by the Chemical Abstracts Service (CAS).
Key Structural Features:

Iodine (Position 4): Most reactive in Pd-catalyzed cross-coupling.
Fluorine (Position 2): Highly reactive in nucleophilic aromatic substitution (SNAr).
Chlorine (Position 5): Least reactive of the three, requires harsher conditions for substitution or coupling.
Multiple Halogens: Possesses three different halogens (F, Cl, I) at specific positions (2, 5, 4).
Position 2 & 4: Positions adjacent (ortho) or opposite (para) to the ring nitrogen are inherently more electron-deficient and thus more reactive towards nucleophilic aromatic substitution (SNAr). The 2-fluoro group is particularly activated for SNAr due to the ortho-nitrogen.
Position 4 (Iodo): The iodine atom is an excellent leaving group for transition metal-catalyzed cross-coupling reactions (e.g., Suzuki, Stille, Negishi).
Position 5 (Chloro): While less reactive than iodine in cross-coupling, the chlorine can participate under appropriate conditions (e.g., Buchwald-Hartwig amination with strong ligands/high temperatures) or serve as a site for further functionalization after the more reactive sites are modified.
Reactivity Hierarchy: The halogens exhibit different reactivities allowing for selective sequential functionalization:
Synonyms (Common Names/Labels):
5-Chloro-2-fluoro-4-iodopyridine (Systematic name, most common)
4-Iodo-5-chloro-2-fluoropyridine
2-Fluoro-5-chloro-4-iodopyridine
Pyridine, 5-chloro-2-fluoro-4-iodo- (CAS format)
Often abbreviated in chemical vendor catalogs simply by its substitution pattern (e.g., "2F,5Cl,4I-Pyridine").
In Summary:
5-Chloro-2-fluoro-4-iodopyridine is a multifunctional heterocyclic building block characterized by a pyridine ring substituted with three distinct halogens (F, Cl, I) at positions 2, 5, and 4. Its chemical identity is defined by its molecular formula (C₅H₂ClFIN), molecular weight (285.43 g/mol), CAS number (1020719-94-8), and its specific substitution pattern which dictates its unique reactivity profile, making it a valuable intermediate in synthetic organic chemistry, particularly medicinal chemistry.