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How do aldehydes react with Grignard reagents to form alcohols?
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aldehyde
Alcohols may be oxidized to give aldehydes, ketones, and carboxylic acids. The oxidation of organic compounds generally increases the number of bonds from carbon to oxygen, and it may decrease the number of bonds to hydrogen.
Grignard reagents (RMgX) are powerful nucleophiles that react with the carbonyl group of aldehydes to form alcohols through a two-step process.123
- Nucleophilic Addition: The Grignard reagent acts as a carbon nucleophile, attacking the electrophilic carbon atom of the aldehyde's carbonyl group. This addition produces a magnesium alkoxide intermediate (ROMgX).143
- Hydrolysis: The intermediate is subsequently treated with aqueous acid (hydrolysis), which converts the magnesium alkoxide into the final alcohol product.13
The type of alcohol produced depends on the specific aldehyde used:
* Formaldehyde: Reaction with a Grignard reagent yields a primary alcohol with one additional carbon atom.513
* Other Aldehydes: Reaction with any aldehyde other than formaldehyde yields a secondary alcohol.513
These reactions are fundamental in organic chemistry for assembling complex carbon skeletons.3