The risk of fire or explosion on exposure of butyllithium solutions to the atmosphere depends on the identity of the organolithium compound, the nature of the solvent, the concentration of the solution, and the humidity. t-Butyllithium solutions are the most pyrophoric and may ignite spontaneously on exposure to air. Dilute solutions (1.6 M, 15% or less) of n-butyllithium in hydrocarbon solvents, although highly flammable, have a low degree of pyrophoricity and do not spontaneously ignite. Under normal laboratory conditions (25 °C, relative humidity of 70% or less), solutions of -20% concentration will usually not ignite spontaneously on exposure to air. More concentrated solutions of n-butyllithium (50 to 80%) are most dangerous and will immediately ignite on exposure to air. Contact with water or moist materials can lead to fires and explosions, and the butyllithiums also react violently with oxygen.

The butyllithiums are extremely reactive organometallic compounds. Violent explosions occur on contact with water with ignition of the solvent and of the butane produced. t-Butyllithium will ignite spontaneously in air. The butyllithiums ignite on contact with water, carbon dioxide, and halogenated hydrocarbons. The butyllithiums are incompatible with acids, halogenated hydrocarbons, alcohols, and many other classes of organic compounds.

Butyllithium solutions should be handled in the laboratory using the "basic prudent practices" described in Chapter 5.C, supplemented by the additional precautions for work with flammable (Chapter 5.F) and reactive (Chapter 5.G) substances. In particular, butyllithium should be stored and handled in areas free of ignition sources, and containers of butyllithium should be stored under an inert atmosphere. Work with butyllithium