2nitrofenyl

2-nitrofenyl, or 2-nitrophenyl, denotes the phenyl ring of a molecule in which a nitro group (−NO2) is attached at the ortho (position 2) relative to the point of attachment to the rest of the compound. In systematic terms it is the ortho-nitrophenyl substituent and is common as a building block in organic synthesis. The name is often shortened to “o-nitrophenyl” in many contexts.

Structure and properties: The nitro group is a strong electron-withdrawing and polar substituent. An o-nitrophenyl group reduces the electron density of the ring, decreasing reactivity toward electrophilic substitution. The presence of the nitro group influences both reactivity and physical properties, such as polarity and, in some cases, color. The term refers to a substituent pattern rather than a specific compound, so exact physical properties vary with the rest of the molecule.

Synthesis and transformations: 2-nitrophenyl motifs are encountered as intermediates or building blocks in organic synthesis. They can be introduced by regioselective nitration of appropriately substituted arenes or by transformations that place a nitro group at the ortho position relative to a leaving group or directing group. The nitro group is commonly targeted for reduction to yield 2-aminophenyl derivatives, which are valuable intermediates in dyes, pharmaceuticals, and heterocyclic chemistry. Other reactions include further functionalization of the ring or cross-coupling using nitro as a leaving or activating group.

Applications and related compounds: The o-nitrophenyl moiety appears in pharmaceuticals, dyes, and agrochemicals as part of more complex structures. Related substituents include the 4-nitro (para) and 3-nitro (meta) phenyl groups, as well as 2-nitroaniline and 2-nitrophenol, which illustrate common transformations of the nitrophenyl scaffold.

Safety: Nitroaromatic compounds can be toxic and potentially hazardous. Proper handling, storage, and disposal are important in all practical contexts.