nBu

nBu is a common shorthand in organic chemistry for the n‑butyl substituent, a straight‑chain alkyl group with four carbon atoms. When attached to a molecule, the group is bound through the terminal carbon, giving the fragment -CH2-CH2-CH2-CH3. The substituent’s formula is C4H9. As the linear butyl group, n‑butyl is the unbranched form of butyl isomers, with other isomers including sec‑butyl, isobutyl, and tert‑butyl.

In practice, the n‑butyl group is used to modify the properties of molecules, increasing hydrophobicity and altering steric and solubility characteristics. It appears in a wide range of organic compounds, including pharmaceuticals, polymers, and solvents, where it can influence lipophilicity and boiling points. In synthetic chemistry, the n‑butyl fragment can be introduced via alkylation or substitution reactions using n‑butyl reagents, such as n‑butyl halides, n‑butyl metal reagents, or related combinations. The shorthand nBu also appears in reagent names and in reaction schemes to indicate the presence of an n‑butyl moiety.

Safety and handling notes are common for compounds bearing n‑butyl groups when used as reagents. Reagents such as n‑butyllithium or n‑butyl Grignard reagents are highly reactive and moisture‑sensitive, typically stored and handled under inert atmosphere and strict anhydrous conditions. As with many alkyl reagents, they pose fire and chemical‑reactivity hazards and should be managed according to established laboratory safety protocols.