Advertisements
Advertisements
प्रश्न
Explain why Lewis acid is not required in bromination of phenol?
Advertisements
उत्तर
Usual halogenation is carried out in the presence of Lewis acid, \[\ce{FeBr3}\] which polarises the halogen molecule. In case of phenol, the polarisation of bromine occurs even in the absence of Lewis acid. This is because of highly activating effect of –OH group on the benzene ring. The reaction follows:
Note: In aqueous solution, phenol ionizes to give phenoxide ion. Due to the presence of the negative charge, the oxygen atom of the phenoxide ion donates electrons to the benzene ring to a large extent. As a result, the ring gets highly activated leading to the formation of trisubstituted product. On the other hand, in the non-polar solvents, the ionization of phenol does not occurs to a large extent. As a result, the -OH group donates electrons to the benzene ring only to a small extent. Consequently, the ring is activated slightly and, therefore, only monosubstitution occurs.
APPEARS IN
संबंधित प्रश्न
Name the following compound according to the IUPAC system.
\[\begin{array}{cc}
\ce{CH3 - C = C - CH2OH}\\
|\phantom{......}|\phantom{.....}\\
\ce{CH3}\phantom{.}\ce{Br}\phantom{....}\\
\end{array}\]
Write the IUPAC name of the following compound:
\[\begin{array}{cc}
\ce{CH3 - CH - CH - CH3}\\
|\phantom{.........}|\phantom{...}\\
\ce{OH}\phantom{....}\ce{OH}\\
\end{array}\]
Write the IUPAC name of the following compound:
\[\begin{array}{cc}
\ce{CH3 - O - CH2 - CH - CH3}\\
\phantom{................}|\\
\phantom{....................}\ce{CH3}
\end{array}\]
3-Methylbutane-2-ol on heating with HI gives ______
How is phenol converted into the following?
benzoquinone
How is phenol converted into the following?
picric acid
Write the IUPAC name of the following compound:
Resorcinol on distillation with zinc dust gives _________.
The compound HOCH2 – CH2OH is __________.
Cresol has ____________.
HBr reacts fastest with ____________.
The major product formed by the reaction:
\[\begin{array}{cc}
\ce{CH3CH-CH2Br ->[CH3O^-][CH3OH] is}\\
|\phantom{................}\\
\ce{CH3}\phantom{.............}
\end{array}\]
The product of acid catalysed hydration of 2-phenylpropene is:
IUPAC name of the compound \[\begin{array}{cc}
\ce{CH3 - CH - OCH3}\\
\phantom{}|\phantom{....}\\
\phantom{}\ce{CH3}\phantom{..}
\end{array}\] is ______.
Explain why p-nitrophenol is more acidic than phenol.
Assertion: Addition reaction of water to but-1-ene in acidic medium yields butan-1-ol.
Reason: Addition of water in acidic medium proceeds through the formation of primary carbocation.
Draw structure of the following compound.
Prop-2-en-1-ol
Write the IUPAC name of the following compound:
\[\begin{array}{cc}
\phantom{..............}\ce{CH3}\\
\phantom{............}|\\
\ce{CH3 - CH - CH - C - CH3}\\
|\phantom{.....}|\phantom{......}|\\
\phantom{...}\ce{CH3}\phantom{.}\ce{OH}\phantom{...}\ce{CH3}
\end{array}\]
