Q.4.
Question
Question: Acid-catalyzed dehydration of β-hydroxy carbonyl compounds occurs by the mechanism discussed in Section 9.8. With this in mind, draw a stepwise mechanism for the following reaction.
Step-by-Step Solution
Verified Answer
Answer
1Step 1: Dehydration reaction
The reverse of the dehydration reaction is hydration reaction. Hydration means addition of water, whereas dehydration means removal of water.
Alkene is formed in dehydration of alcohol, while alcohol is formed in hydration of alkene.
2Step 2: Mechanism of the reaction
In the first step of the reaction, oxygen of hydroxyl group abstracts a proton from acid following removing of water to form carbocation.
In the next step, the hydrogen sulfate ion abstracts the alpha hydrogen and results in the formation of (E)-but-2-enal.
The mechanism is shown below:
Mechanism of the reaction
Other exercises in this chapter
Q.2.
Question: Which carbonyl compounds do not undergo an aldol reaction when treated with OH- in H2O ?
View solution Q.3.
Question: What unsaturated carbonyl compound is formed by dehydration of each β-hydroxy carbonyl compound?
View solution Q.5.
Question: What aldehyde or ketone is needed to prepare each compound by an aldol reaction?
View solution Q.6.
Question: 2-Pentylcinnamaldehyde, commonly called flosal, is a perfume ingredient with a jasmine-like odor. Flosal is an α,β -unsaturated aldehyd
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