Faculty of Science

Department of Chemistry

Hazards

Pyrophoric materials are those that ignite spontaneously in air below about 45 deg C. Consequently the main hazards arising from the use of such materials involve fire, either from direct contact with the pyrophoric material or as a result of secondary fires following ignition.

The most commonly used materials are alkyl lithiums, trialkylaluminium reagents and alkylboranes. t-BuLi is the most pyrophoric of the Li reagents but n-BuLi is also pyrophoric as a concentrated solution i.e.~ 10M.

These reagents are supplied in solution, in alkane, arene or ether solvents, the pyrophoric hazard increasing with concentration.

Risk

For an untrained person, the most probable source of injury is fire (likely) with injuries moderate to severe.

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Who is likely to be injured?

The most likely people to be injured are the users themselves but, if a secondary fire results, the damage may be widespread within a laboratory or beyond.

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Control Measures

Physical

  • Materials should be stored under a dry, inert atmosphere in "sure seal" containers or preferably in tubes sealed by Young's tap. Handling should be carried out in a fume hood over a spill tray.

Training

  • All users of pyrophoric materials must be trained by their Research Adviser/Supervisor or by a competent person nominated by their Research Adviser/Supervisor.

P.P.E.

  • Lab.coat, safety glasses and appropriate gloves should be worn.
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Operating Precautions

  • Pyrophoric material must not be used outside of normal working hours i.e. 8 a.m. to 6 p.m. Monday to Friday.
  • Transfer of pyrophoric may be carried out by syringe fitted with a lockable needle to prevent the needle from being dislodged accidentally. For the transfer of large amounts it is preferable to use a cannula pressurised by an inert gas. However, great care must be taken to avoid over-pressuring containers.
  • Dry sand should be kept at hand as a fire extinguishing medium. A small beaker of sand is useful to extinguish any fire that occurs at the syringe tip and to receive any last drops of reagent from the syringe.
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Remaining Risks

Even for experienced workers, pyrophoric materials present some risk of injury and should never be used by Undergraduates without the approval of their Supervisor i.e. use is rated Bu.

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Emergency Procedures

  • Fire:

    • In the event of material igniting, it should be extinguished with dry sand and left to evaporate/hydrolise. It is probable that the Emergency Alarms will be activated and the Building must be evacuated. Anyone causing such an alarm should inform PSSO IMMEDIATELY.
  • Skin Contact:

    • Wash the affected area thoroughly with water and seek First Aid.

Back to Completed Risk Assessment Forms

Adapted with permission from School of Chemistry, University of Bristol

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