Notes on the use of tertiary-butyllithium and other highly pyrophoric liquids

Please remember to do a risk assessment!

Tert-butyllithium is usually supplied as a solution dissolved in flammable solvents.

It is extremely pyrophoric and must be used with all due care and attention.

Users must wear the usual personal protective clothing:

  • Laboratory glasses
  • Laboratory coat (preferably 100% cotton – this will be stocked in stores soon)
  • Shoes that completely cover the feet

Additional considerations:

  • Clothing under lab coat should cover most of the body and should not be made of purely synthetic cloth
  • If gloves are worn they should be flame-resistant. Wearing of thin synthetic gloves is NOT recommended.

All work must be conducted in a fume-hood with the sash pulled down as far as possible.

Out-of-hours or lone working is forbidden when handling or quenching tert-butyllithium or other highly pyrophoric materials (reactions can run un-attended PROVIDED THEY ARE AT STEADY STATE and this has been addressed in the risk assessment).

Any vessel containing tert-butyllithium must be clearly labelled as such including hazards labelling.

If you are uncomfortable with, or unfamiliar with, techniques to handle air-sensitive compounds then you must ask your supervisor to arrange for additional training.

Solutions of tert-butyllithium are supplied in Sure/Seal bottles. Please check the condition of the seal before use.

The major techniques for transferring solution are listed below. Full details of these techniques can be found in the Aldrich technical bulletin AL-134.

Use of needles and syringes

  • This is only recommended for the transfer of small amounts of a pyrophoric solution (< 50 mL)
  • Glass syringe bodies and three-part polypropylene syringes with a rubber seal should NOT be used as the plunger may stick
  • Recommended syringes are the two-part polypropylene type. These are stores items 17194L - 2mL; 17195L - 5mL; 17196L - 10mL;17197L - 20mL
  • Needles, syringes and receiving flasks must be flushed with N2 or Ar prior to their use with tert-butyllithium
  • Remember the Sure/Seal bottle must be slightly pressurised with N2 or Ar before you attempt to draw out any solution from it.
  • Do not force the syringe plunger when drawing liquid.
  • Small amounts of excess solution in the needle/syringe can be safely quenched by pumping into a large container of vermiculite or laboratory-grade sand. Needles and syringes should be rinsed into vermiculite/sand with a mixture of 80:20 toluene:iso-propylalcohol.

Use of double needles/cannulas

  • Can be used for any volume and should be used for larger volumes
  • Needles and receiving flasks must be flushed with N2/Ar prior to their use with tert-butyllithium
  • Transferring solutions using double needles uses N2/Ar pressure to push the solution from one vessel to another. Double-check that you have connected the gas inlet the right way around (it goes into the flask that already contains the solution for transfer)
  • Use a gentle stream of gas
  • Receiving flasks must also be connected to a bubbler so that they are not over-pressured
  • Transferring solutions to a graduated flask/measuring cylinder fitted with a septum-sealed T-tap or to a pipettefitted with a Young’s tap makes measuring out specific volumes easier.

Quenching tert-butyllithium and treatment of empty bottles

This should only be done forsmallresidual quantities, large quantities of unwanted solution should be disposed of as special chemical waste

Using a needle and syringe to transfer reagent:

  • Add in small quantities to significant excess of 80:20 toluene:iso-propylalcohol mixture under a N2 atmosphere
  • Flask must also be connected to a bubbler so that it is not over-pressured
  • Progressive additions of ethanol, methanol, and then water should be made to the mixture – this should not be rushed and several hours should be left between additions of each more protic solvent.
  • The empty Sure/Seal bottle should be treated by trickling 80:20 toluene:iso-propylalcohol mixture into it under a N2 atmosphere with connection to a bubbler to prevent over-pressurisation. As before, slow progressive additions of ethanol, methanol, and then water should be made.
  • If the waste mixture is un-reactive to water it can be disposed of as organic solvent waste