Chemical Identity and Structure

5-Chloro-2-methoxy-4-methylbenzenesulfonyl chloride (SKU: C187818) is an aromatically substituted sulfonyl chloride featuring three distinct substituents on the benzene ring: a chloro group at position 5, a methoxy group at position 2, and a methyl group at position 4, in addition to the sulfonyl chloride functionality. Its molecular formula is C8H8Cl2O3S. The combination of electron-donating (methoxy, methyl) and electron-withdrawing (chloro, sulfonyl chloride) substituents creates a uniquely balanced electronic environment on the ring, which can influence the reactivity and selectivity observed in downstream coupling reactions.

The sulfonyl chloride (–SO2Cl) group is the primary reactive site of this molecule. It is a potent electrophile susceptible to nucleophilic attack by amines, alcohols, and other heteroatom nucleophiles under mild conditions, making this compound a versatile intermediate in synthetic chemistry.

Synthetic Applications

The principal application of 5-Chloro-2-methoxy-4-methylbenzenesulfonyl chloride lies in its use as an electrophilic sulfonylating agent. Reaction with primary or secondary amines in the presence of a base (e.g., triethylamine or pyridine) affords the corresponding sulfonamides. Sulfonamides constitute an important pharmacophore in medicinal chemistry and are found in numerous bioactive molecules including antibacterials, diuretics, and enzyme inhibitors.

In addition to sulfonamide formation, this reagent can react with alcohols and phenols to generate sulfonate esters, and with thiols to yield sulfonothioates. The electron-withdrawing chloro substituent and the electron-donating methoxy and methyl groups modulate the electrophilicity of the sulfonyl chloride, potentially offering selectivity advantages compared to unsubstituted benzenesulfonyl chloride.

The aryl ring bearing multiple handles (the halogen at position 5 in particular) can also serve as a site for further functionalization via metal-catalyzed cross-coupling reactions such as Suzuki–Miyaura or Buchwald–Hartwig couplings, enabling the elaboration of complex, multi-functional structures from a single building block.

Handling, Safety, and Storage

As with all sulfonyl chlorides, 5-Chloro-2-methoxy-4-methylbenzenesulfonyl chloride is moisture-sensitive and hydrolyzes upon contact with water to release hydrochloric acid and the corresponding sulfonic acid. Researchers must handle this compound under anhydrous conditions, using dry solvents such as dichloromethane, tetrahydrofuran, or acetonitrile.

Standard laboratory safety precautions apply: use of appropriate personal protective equipment (PPE) including chemical-resistant gloves, laboratory coat, and eye protection is mandatory. Work should be performed in a well-ventilated fume hood. The compound should be stored in a tightly sealed container under cool, dry conditions and away from moisture and incompatible materials such as strong bases and reducing agents.

Disposal must comply with local regulations for halogenated organic waste. Consult the Safety Data Sheet (SDS) provided by Aladdin Scientific for comprehensive hazard information before use.

Purity, Specifications, and Quality

Aladdin Scientific supplies 5-Chloro-2-methoxy-4-methylbenzenesulfonyl chloride (SKU: C187818) as a research-grade reagent. Customers requiring specific purity data, analytical certificates (CoA), or technical specifications are encouraged to contact Aladdin Scientific directly or refer to the product page. Typical characterization of such sulfonyl chloride intermediates includes assessment by gas chromatography (GC) or high-performance liquid chromatography (HPLC) purity assays, along with nuclear magnetic resonance (NMR) spectral confirmation of structure.

For sensitive applications such as pharmaceutical lead optimization or precise stoichiometric reactions, verification of the lot-specific CoA is recommended prior to use to ensure the reagent meets the purity requirements of the intended application.