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कर्नाटक बोर्ड पी.यू.सी.पीयूसी विज्ञान 2nd PUC Class 12

In Kolbe’s reaction, instead of phenol, phenoxide ion is treated with carbon dioxide. Why?

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प्रश्न

In Kolbe’s reaction, instead of phenol, phenoxide ion is treated with carbon dioxide. Why?

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उत्तर

Phenoxide ion is more reactive than phenol towards electrophilic substitution. The negative charge on oxygen is transferred to benzene through resonance. This helps in the attachment of CO2 which is a weak electrophile to the benzene ring finally giving salicylic acid.

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पाठ 11: Alcohols, Phenols and Ethers - Multiple Choice Questions (Type - I) [पृष्ठ १६०]

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एनसीईआरटी एक्झांप्लर Chemistry Exemplar [English] Class 12
पाठ 11 Alcohols, Phenols and Ethers
Multiple Choice Questions (Type - I) | Q 48 | पृष्ठ १६०

संबंधित प्रश्‍न

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 carboxylic acid.


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.)


Lucas reagent is ____________.


The compound which reacts fastest with Lucas reagent at room temperature is:


Which of the following are used to convert RCHO into RCH2OH?

(i) H2/Pd

(ii) LiAlH4

(iii) NaBH4

(iv) Reaction with RMgX followed by hydrolysis


Which of the following is not true in case of reaction with heated copper at 300°C?


During dehydration of alcohols to alkenes by heating with cone. H2SO4 the initial step is ____________.


Identify the secondary alcohols from the following set:

  1. \[\ce{CH3CH2CH(OH)CH3}\]
  2. \[\ce{(C2H5)3COH}\]



The process of converting alkyl halides into alcohols involves ______.


Suggest a reagent for the following conversion.


Explain why is OH group in phenols more strongly held as compared to OH group in alcohols.


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-catalysed 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


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