Chemistry · Aldehydes and Ketones
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Ketone reacts with Grignard reagent to form ______ in acidic media?
- A
Tertiary alcohol
- B
Isopropyl alcohol
- C
Primary alcohol
- D
Carboxylic acid
The correct answer is a tertiary alcohol. When a ketone, which has a carbonyl group (C=O) bonded to two carbon-containing groups, reacts with a Grignard reagent, the carbonyl carbon gets attacked. This nucleophilic addition forms an alkoxide intermediate. Upon protonation in acidic conditions, the alkoxide converts into an alcohol. As the carbonyl carbon is already attached to two other carbon groups, the alcohol formed is tertiary.
Isopropyl alcohol is incorrect as it forms from acetaldehyde, not a ketone. A primary alcohol is produced from formaldehyde, and a carboxylic acid forms from carbon dioxide with Grignard reagents, making these options irrelevant for this reaction.
When a ketone reacts with a Grignard reagent (RMgX) in acidic media, the Grignard reagent adds to the carbonyl carbon, forming an alkoxide intermediate. Upon protonation, this intermediate forms a tertiary alcohol. This is because the ketone's carbonyl carbon is bonded to two other carbon groups, making the resulting alcohol tertiary.
Isopropyl alcohol is a secondary alcohol that forms from the reaction of acetaldehyde with a Grignard reagent, not a ketone. Hence, this option is incorrect for the reaction involving a ketone.
A primary alcohol results from the reaction of formaldehyde with a Grignard reagent. Since a ketone is involved in the given reaction, this option is incorrect.
Carboxylic acids are formed when carbon dioxide reacts with a Grignard reagent. This reaction does not involve ketones, so this option is incorrect.
Tagged under Chemistry · Aldehydes and Ketones · 2015