n-Butyllithium (NBL) is a very strong base, exceedingly useful in organic synthesis styrene butadiene rubber (SBR). NBL has found particular utility in deprotonation and metal-halogen exchange reactions. NBL is also a very effective initiator of anionic polymerization of styrene and conjugated dienes. The synthesis of solution SBR and of styrenic thermoplastic elastomers (TPEs), in particular, is facilitated by NBL. References: The Chemistry of Organolithium Compounds, ed. Zvi Rappoport and Ilan Marek, Wiley, 2004, West Sussex, England.