BUTYLLITHIUMS

Butyllithiums (and related alkyl lithium reagents)
n-butyllithium: CAS 109-72-8
s-butyllithium (1-methylpropyllithium): CAS 598-30-1
t-butyllithium (1,1-dimethylethyllithium) : CAS 594-19-4

C₄H₉Li

Usually supplied and handled as solutions in ether or hydrocarbon solvents

Odor of the solvent

There is little toxicity data available for the butyllithiums; for data on ether and hydrocarbon solvents, see the appropriate LCSSs.

Highly reactive; violent reactions may occur on exposure to water, CO₂ and other materials; may ignite spontaneously on exposure to air; highly corrosive to the skin and eyes.

Solutions of the butyllithiums are corrosive to the skin, eyes, and mucous membranes. Reaction with water generates highly corrosive lithium alkoxides and lithium hydroxide.

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 should be conducted in a fume hood under an inert gas such as nitrogen or argon. Safety glasses, impermeable gloves, and a fire-retardant laboratory coat are required.

In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 min (lifting upper and lower lids occasionally) and obtain medical attention. If butyllithium solution is ingested, obtain medical attention immediately. If large amounts of butyllithium solution are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, remove all ignition sources, and allow the butyllithium to react with atmospheric moisture. Carefully treat the residue with water, soak up with a spill pillow or absorbent material, place in an appropriate container, and dispose of properly. Respiratory protection may be necessary in the event of a large spill or release in a confined area.

Excess butyllithium solution can be destroyed by dilution with hydrocarbon solvent to a concentration of approximately 5 wt %, followed by gradual addition to water with vigorous stirring under an inert atmosphere. Alternatively, the butyllithium solution can be slowly poured (transfer by cannula for s- or t-butyllithium) into a plastic tub or other container of powdered dry ice.

The residues from the above procedures and excess butyllithium should be placed in an appropriate container, clearly labeled, and handled according to your institution's waste disposal guidelines.

The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994. This summary is intended for use by trained laboratory personnel in conjunction with the NRC report Prudent Practices in the Laboratory: Handling and Disposal of Chemicals. This LCSS presents a concise summary of safety information that should be adequate for most laboratory uses of the title substance, but in some cases it may be advisable to consult more comprehensive references. This information should not be used as a guide to the nonlaboratory use of this chemical.

Copyright 1995 National Academy of Sciences. All rights reserved.