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प्रश्न
Write the mechanism of acid-catalysed dehydration of ethanol to yield ethene.
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उत्तर
In the presence of conc. acids such as H3PO4 and H2SO4 alcohols undergo dehydration to yield alkenes.
\[\ce{\underset{Ethanol}{H3C - CH2 - OH} ->[conc{.} H+/Delta] \underset{Ethene}{CH2 = CH2} + H2O}\]
The mechanism for this reaction is:
Protonation of ethanol (Step 1):
Formation of carbocation (Step 2):
Formation of ethene and regeneration of proton (Step 3):
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संबंधित प्रश्न
Write the final product(s) in each of the following reactions:
Write the mechanism of the following reaction :
Show how will you synthesize pentan-1-ol using a suitable alkyl halide.
Name the reagent used in the following reaction:
Oxidation of a primary alcohol to aldehyde.
When 3-methylbutan-2-ol is treated with HBr, the following reaction takes place:
\[\begin{array}{cc}
\phantom{...................................}\ce{Br}\\
\phantom{..................................}|\\
\ce{CH3 - CH - CH - CH3 ->[HBr] CH3 - C - CH2 - CH3}\\
|\phantom{.........}|\phantom{...................................}|\phantom{...........}\\
\ce{CH3}\phantom{...}\ce{OH}\phantom{...............................}\ce{CH3}\phantom{.......}\\
\end{array}\]
Give a mechanism for this reaction.
(Hint: The secondary carbocation formed in step II rearranges to a more
stable tertiary carbocation by a hydride ion shift from 3rd carbon atom.)
Dehydration of 2-butanol yields:
Lucas test is done to differentiate between ____________.
Which one of the following on oxidation gives a ketone?
Identify the secondary alcohols from the following set:
- \[\ce{CH3CH2CH(OH)CH3}\]
- \[\ce{(C2H5)3COH}\]
Ethers can be prepared by Williamson synthesis in which an alkyl halide is reacted with sodium alkoxide. Di-tert-butyl ether can’t be prepared by this method. Explain.
Assertion: Bond angle in ethers is slightly less than the tetrahedral angle.
Reason: There is a repulsion between the two bulky (–R) groups.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid dehydration of ethanol to yield ethene.
Write the mechanism of acid-catalysed dehydration of ethanol to yield ethene.
Write the mechanism of acid-catalysed dehydration of ethanol to yield ethene
