Reactions

There are many organometallic reactions and these are just a few of the key basic ones.

Reactions As Bases

Organometallics act as very good bases which means they react extremely exothermally with water to produce alkanes as any normal acid/ base would proceed. This means they need to be kept free of moisture including that in the air and so are handled in inert atmospheres such as nitrogen or argon. Organolithiums are very reactive and so are usually used at -78oC in a ether solvent.

Organometallic reagents, particularly organolithiums and organomagnesiums are very good nucleophiles. This is because the metals are electropositive and therefore the carbon-metal bond is highly polarized towards the carbon atom. They can therefore perform one of the most important reactions in organic chemistry and that is to make a new carbon-carbon bond. This is a very important reaction as it allows chemists to manipulate compounds and is therefore important in pharmaceuticals as the main way of creating a new carbon- carbon bond.

The way in which this new bond is formed is shown below:-

new bond formation

The organometallic reagent is added to a THF solvent and it attacks the carbonyl group of another compound as a nucleophile to produce an alcohol. This reaction does however need to be done in a certain way. The organometallic needs to be added first, this can then be added to the aldehyde or ketone, the addition is carried out and then the water can be added. It is important water is added last or else or else the organometallic will become protonated because they are strong bases to give an alkane and thus the reaction would not work.

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Author: Gillian Cooper (document modification date: 22nd May 2003)

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