What is ketal group?
In organic chemistry, a ketal is a functional group derived from a ketone by replacement of the carbonyl (C=O) group by two alkoxy groups. Therefore, a ketal can also be defined as “an acetal derived from a ketone.”
How are acetals used as protecting groups?
Acetals are used as protecting groups for carbonyl groups in organic synthesis because they are stable with respect to hydrolysis by bases and with respect to many oxidizing and reducing agents.
Why are ketals good protecting groups?
It turns out that different varieties of ethers are great protecting groups because they’re unreactive towards strong bases and nucleophiles. Specifically in the case of ketones and aldehydes, a functional group called an acetal (sometimes called “ketal”) is great for the job.
Do acetals protect aldehydes?
Acetals are commonly used to protect the carbonyl groups of aldehydes and ketones from basic, nucleophilic reagents. Once the protection is no longer needed, the acetal protect- ing group is easily removed, and the carbonyl group re-exposed, by treatment with dilute aqueous acid.
Why are aldehyde and ketone carbonyl groups protected?
Because of this versatile reactivity, synthetic sequences involving polyfunctional molecules frequently require that aldehyde and/or ketone carbonyl groups be protected in order to stop undesirable side reactions. The protecting group is then removed at a later stage in the synthesis.
How are acetals used to protect a ketone?
To protect a ketone using a straight chain alcohol, like methanol, you react two molecules of alcohol and a ketone and produce one molecule of water and an acetal. To protect a ketone using a diol, you react one molecule of diol and a ketone and produce one molecule of water and an acetal.
Can a methanol acetal protect a carbonyl group?
In terms of protecting on a test or homework assignment, it doesn’t matter, because an acetal from methanol will protect a carbonyl just like an acetal from 1,2-ethandiol would. Comment on Jeffrey Cragin’s post “Not necessarily, any alco…”
How are aldehydes and ketones used in organic synthesis?
Aldehydes and ketones are extremely versatile compounds for organic synthesis, acting either as electrophiles ( i.e. nucleophilic addition) or as nucleophiles ( i.e. enol/enolate reactions).