4kloorofenyyli

4kloorofenyyli, commonly known as 4-chlorophenyl or para-chlorophenyl, denotes the aryl substituent derived from chlorobenzene where a chlorine atom occupies the para position relative to the point of attachment to the rest of the molecule. It is a widely used building block in organic synthesis and appears as a substituent in many pharmaceutical, agrochemical, and dye compounds.

The 4-chlorophenyl group has the molecular formula C6H4Cl and a molecular weight of about 112.56 g/mol. The chlorine atom exerts an electron-withdrawing inductive effect and the ring is generally deactivated toward further electrophilic substitution, though the halogen also directs new substitutions to the ortho and para positions. The group increases hydrophobicity and can influence the metabolic and pharmacokinetic properties of compounds containing it.

In practice, 4-chlorophenyl functionality is introduced by chlorination or by attaching a para-chloro substituent to a phenyl precursor during synthesis. It is readily available as a reagent or as part of larger building blocks and is commonly used in cross-coupling reactions, such as Suzuki-Miyaura and related palladium-catalyzed processes, where the aryl chloride bond serves as a handle for forming new carbon–carbon bonds.

Applications of 4-chlorophenyl-containing compounds span pharmaceuticals, agrochemicals, dyes, and polymers. The para-chloro substituent helps tailor electronic, steric, and lipophilic properties, enabling optimization of activity, selectivity, and stability in various products. See also chlorobenzene, aryl chlorides, and para-substituted aromatic compounds.