Working Safely with Organolithium Compounds - PowerPoint Presentation

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Working Safely with Organolithium Compounds

I-Ting HoSessler Group Safety TalkFebruary 19 , 2013

References :

http

://

www.yale.edu/ehs/onlinetraining/OrganoLithium/OrganoLithium.htm

How to use

a syringe

http://chem.chem.rochester.edu/~

nvd/howtosyringe.html

Safe handling of organolithium compounds in the

laboratory

http

://

www.sciencedirect.com/science/article/pii/S1074909802002952

A

Fatal Accident in a Laboratory of UCLA

Sheharbano

(Sheri)

Sangji

,

died

from burns sustained in a chemical fire in UCLA's Molecular Sciences Building on Dec. 29, 2008. She was working with

t

-butyl lithium

, a highly flammable compound that spontaneously burns upon exposure to air.

The plunger

on the syringe she was using became dislodged

,

and the compound ignited and

burned

her clothing

.

The lack

of a lab coat

was the single most significant factor in the severity of the burns that led to

Sangji's

death

.

Hazards

Organolithium compounds are:

Corrosive

Flammable

Pyrophoric –

capable of spontaneously igniting when exposed to air, oxygen or moisture

For the same concentration, the

pyrophoricity

increased in the order:

n

-

butyllithium

<

s

-

butyllithium

<

t

-

butyllithium

Typically purchased diluted in a flammable solvent (such as Hexane) which increased the flammability hazard.

Before conducting any work with an organolithium compounds, appropriate planning should be conducted to

minimize hazards to personnel.

Storage, Transport and Disposal

Reagent bottles are stored in refrigerators prior to use and between uses.You must date the container when it is first opened.Use up the contents of the reagent bottle quickly but it should not be kept for more than one month after being opened.Transport the reagent bottle in a secondary container when taking it to another lab or through public spaces.Disposal: diluted to less than 5 wt.% with an inert solvent, such as heptane. The solution should be added slowly to well-stirred solution 2 M of 2-propanol in heptane under an external cooling bath.

Facility and PPE Requirements

FacilityWork with organolithium compounds must take place in a fume hood ideally fitted with a horizontal sash.You must know where the location of the closest emergency shower and eyewash and how to activate them.A class B dry chemical fire extinguisher must be immediately available.Personal Protective Equipment (PPE)A regular lab coat, nitrile gloves and safety glasses may be worn when setting up your apparatus.You must wear flame resistant clothing and additional eye and face protection when handling the organolithium compound.

The reagent Bottle of Organolithium compound

The organolithium within the reagent bottle is blanketed with nitrogen and separated from the atmosphere with a Teflon seal.

To access the organolithium compound, the seal must be punctured with a needle or cannula.

The Teflon seal is self-sealing when the needle is removed as long as it is not too big and the seal has not been punctured too many times.

If the Teflon seal fails, moisture and atmospheric gases will enter the reagent bottle and a fire could result.

Syringe Transfers

Syringe transfers should only be used when transferring

small amount (less than 50 mL)

The transfer of larger volumes is most easily accomplished with

cannula

The syringe selected must be capable of containing twice the volume you wish to transfer

The needle must be able to screw onto and lock on the syringe

The needle should be approximately 16 gauge and at least 8-12 inches long

Place an extra needle and syringe in the hood before you get started in case you have a problem with the first

(1) Place in a metal bowl and clamped well

(2) Purged with an inert gas

(The needle does not place at the center of seal, slightly off-center)

(3) Proper needle selected and locked into syringe. (Inserting the needle into a rubber stopper

to test

for leak

)

(4) After being purged, the syringe insert into the seal opposite to the N2 line

(5) Pull

the liquid into the syringe, taking slightly MORE than you need for your experiment. Flip the syringe needle-up, so that air/inert gas bubbles rise to the top. Use the plunger to remove the air/gas, and adjust the amount of liquid in the syringe to the exact amount you need.

(6) Now

that you know exactly how much liquid is in the syringe, tip the needle up again and draw a small layer of gas (air or argon) into the syringe.

This keeps you from spilling and if necessary, protects the liquid from exposure to air during transfer

.

The needle was carefully insert into the destination

septum. Keeping the air layer between the syringe and needle (you need a long needle for this), and then flip the syringe over. Holding the plunger down, inject the air/nitrogen cushion in your reaction first, then continue to inject your liquid into the flask (dropwise if needed). After complete addition, pull back the plunger and draw some nitrogen into the syringe (keeping the syringe tip pointing up at all times).Immediately flush the syringe and needle with Hexane to remove residual organolithium. The flushing solvent is added into propanol which activated the residual organolithium.