One of the most useful chemical properties of n-BuLi is its ability to deprotonate a wide range of weak Brønsted acids. t-Butyllithium and s-butyllithium are more basic. n-BuLi can deprotonate (that is, metalate) many types of C−H bonds, especially where the conjugate base is  stabilized by electron delocalization or one or more heteroatoms (non-carbon atoms). Examples include acetylenes (H−CC−R), methyl sulfides (H−CHSR), thioacetals (H−CH(SR), e.g. dithiane), methylphosphines  (H−CHPR), furans, thiophenes and ferrocene (Fe(H−CH)(CH)). In addition to these, it will also deprotonate all more acidic compounds such as alcohols, amines, enolizable carbonyl compounds, and any overtly acidic compounds, to produce alkoxides, amides, enolates and other salts of lithium, respectively. The stability and volatility of the butane resulting from such deprotonation reactions is convenient, but can also be a problem for large-scale reactions because of the volume of a flammable gas produced.
: LiCH + RH →  CH + RLi
The kinetic basicity of n-BuLi is affected by the solvent or cosolvent. Ligands that complex Li such as tetrahydrofuran (THF), tetramethylethylenediamine (TMEDA), hexamethylphosphoramide (HMPA), and 1,4-diazabicyclo[2.2.2]octane (DABCO) further polarize the Li−C bond and accelerate the metalation. Such additives can also aid in the isolation of the lithiated product, a famous example of which is dilithioferrocene.
:Fe(CH) + 2 LiCH + 2 TMEDA → 2 CH + Fe(CHLi)(TMEDA)
Schlossers base is a superbase produced by treating butyllithium with potassium t-butoxide. It is kinetically more reactive than butyllithium and is often used to accomplish difficult metalations. While some n-butylpotassium is present and is a stronger base than n-BuLi, the reactivity of the mixture is not exactly the same as isolated n'-butylpotassium.
An example of the use of n-butyllithium as a base is the addition of an amine to methyl carbonate to form a methyl carbamate, where n-butyllithium serves to deprotonate the amine:
: n-BuLi + RNH + (MeO)CO → RNCOMe + LiOMe + BuH