Carbon dioxide reacts with organolithiums and Grignard reagents to give carboxylate salts. Protonating the salt with acid gives a carboxylic acid with one more carbon atom than the starting organometallic. The reaction is usually done by adding solid CO₂ to a solution of the organolithium in THF or ether, but it can also be done using a stream of dry CO₂ gas.

The example belows shows the three stages of the reaction: (1) forming the organometallic, (2) reaction with the electrophile (CO₂), and (3) the acidic work-up or quench, which protonates the product and destroys any unreacted organometallic. The three stages of the reaction have to be monitored carefully to make sure that each is finished before the next is begun. In particular it is absolutely essential that there is no water present during either of the first two stages—water must be added only at the end of the reaction, after the organo metallic has all been consumed by reaction with the electrophile. You may occasionally see schemes written out without the quenching step included, but it is nonetheless always needed.

carboxylic acids from organometallics

This next example shows that even very hindered chlorides can be used successfully. The significance of this will be clearer when you reach Chapter 15.

مواضيع ذات صلة

The product of nucleophilic addition to a carbonyl group is not always a stable compound

Oxidation of alcohols

?Secondary and tertiary alcohols: which organometallic, which aldehyde, which ketone

Making primary alcohols from organometallics and formaldehyde

Using organometallics to make organic molecules

Halogen–metal exchange

Making organometallics by deprotonating alkynes

Organometallics as bases

How to make organolithium reagents

Making organometallics, How to make Grignard reagents

Organometallic compounds contain a carbon–metal bond

Lewis acids and bases