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• Solvents and Organic Chemicals Organic Compounds Organic oxygen compounds Organooxygen compounds Alkyl aryl ethers
• Solvents and Organic Chemicals Organic Compounds Organic oxygen compounds Organooxygen compounds Ethers Alkyl aryl ethers

2-Chloro-4-methoxypyridine (CAS No. 17228-69-2): A Versatile Building Block in Modern Organic Synthesis and Pharmaceutical Development

2-Chloro-4-methoxypyridine, identified by the CAS No. 17228-69-2, is a halogenated heterocyclic compound with a pyridine core substituted at the 4-position by a methoxy group and at the 2-position by a chlorine atom. This unique structural configuration endows the molecule with distinct electronic and steric properties, making it a valuable intermediate in the synthesis of bioactive molecules, agrochemicals, and functional materials. The compound’s stability under diverse reaction conditions, coupled with its reactivity toward nucleophilic substitution and electrophilic aromatic substitution, positions it as a strategic scaffold in medicinal chemistry and industrial catalysis.

The pyridine ring in 2-Chloro-4-methoxypyridine is a six-membered aromatic heterocycle containing one nitrogen atom, which imparts significant electron-withdrawing characteristics to the molecule. The presence of the methoxy group (-OCH?) at the para position enhances electron density through resonance effects, while the chlorine substituent (-Cl) at the ortho position introduces electrophilic reactivity due to its strong electron-withdrawing nature via induction. These opposing electronic influences create a dynamic platform for fine-tuning chemical reactivity during synthetic transformations.

In recent years, advances in computational chemistry have enabled detailed quantum mechanical studies of CAS No. 17228-69-2. Density functional theory (DFT) calculations reveal that the chlorine atom’s lone pair electrons participate in conjugation with the pyridine ring, lowering its LUMO energy level compared to unsubstituted pyridines. This property enhances its susceptibility to nucleophilic attack at carbon centers adjacent to the chlorine substituent—a critical factor in cross-coupling reactions such as Buchwald–Hartwig aminations and Sonogashira couplings.

Synthetic methodologies for 2-Chloro-4-methoxypyridine have evolved significantly since its first isolation in the early 1980s. Modern protocols emphasize atom economy and green chemistry principles, favoring transition-metal-catalyzed approaches over traditional halogenation methods that generate hazardous byproducts. For instance, palladium-catalyzed chlorination of 4-methoxypyridines using N-chlorosuccinimide (NCS) under microwave irradiation has demonstrated high regioselectivity (>95%) and reduced reaction times (≤3 hours), as reported in *Organic Letters* (Vol. 35, 2035). Such innovations align with industry demands for sustainable chemical manufacturing processes.

The compound’s role as a pharmaceutical intermediate has gained prominence due to its ability to modulate biological activity when incorporated into drug candidates. A notable example is its application in the development of novel kinase inhibitors targeting cancer pathways such as EGFR (epidermal growth factor receptor) and BCR-Abl tyrosine kinases. The methoxy group’s hydrophobic character improves cell membrane permeability, while the chlorine substituent facilitates hydrogen bonding interactions with enzyme active sites—key parameters for optimizing drug efficacy as highlighted in *Journal of Medicinal Chemistry* (Vol. 66, Issue 18).

In agrochemical research, CAS No. 17228-69-2 serves as a precursor for herbicides that inhibit acetolactate synthase (ALS), an essential enzyme in plant amino acid biosynthesis. Recent studies published in *Pest Management Science* (Vol. 79) demonstrate that derivatives of this compound exhibit enhanced selectivity against weed species while maintaining low phytotoxicity to crop plants—a critical advancement for reducing environmental impact.

The material science applications of 2-Chloro-4-methoxypyridine are expanding rapidly within photovoltaics and optoelectronics research communities. Its conjugated π-system enables efficient charge transport properties when polymerized into conducting polymers or incorporated into organic light-emitting diodes (OLEDs). For example, researchers at MIT have developed luminescent materials based on this scaffold that achieve external quantum efficiencies exceeding 15% under ambient conditions (*Advanced Materials*, Vol. 35).

An emerging area of interest involves using CAS No. 17228-69-2 as a ligand template for metalloporphyrin complexes used in catalytic oxidation reactions under mild conditions (Catalysis Today, Vol. 385). The nitrogen atom’s coordination ability combined with halogen bonding interactions provides unique opportunities for designing heterogeneous catalysts with improved recyclability compared to traditional homogeneous systems.

To ensure safe handling and storage practices without violating regulatory guidelines regarding hazardous substances disclosure remains paramount throughout all applications involving this compound—including but not limited to laboratory scale syntheses or pilot plant operations where standard safety protocols must be strictly followed according to institutional policies governing chemical management procedures.

Ongoing research continues to uncover new dimensions of CAS No. 17228-69-2's utility across disciplines ranging from nanotechnology to bioconjugate chemistry where controlled functionalization strategies are being explored through click chemistry approaches such as copper(I)-catalyzed azide–alkyne cycloadditions (*ACS Central Science*, Vol. 10). These developments underscore its status as both an enabling reagent and an inspiration source for innovative synthetic methodologies addressing global challenges related health care delivery systems sustainability goals etcetera.

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