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प्रश्न
Out of C6H5CH2Cl and C6H5CHClC6H5, which is more easily hydrolysed by aqueous KOH.
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उत्तर
C6H5CHClC6H5 is hydrolysed faster.
- The hydrolysis of an alkyl halide is a nucleophilic substitution reaction. For aryl halides, this occurs through the SN1 method, resulting in a carbocation.
- C6H5CH2Cl or benzyl chloride gives
a carbocation, while C6H5CHClC6H5 generates 
. - Out of I and II, carbocation II is more stable. Two attached phenyl rings on the carbon carry the positive charge.
- This leads to increased delocalisation of the positive charge and greater carbocation stability. This leads to faster formation of (II) and easier hydrolysis of the resulting halide than benzyl chloride.
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संबंधित प्रश्न
Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction
Which compound in the following pair will react faster in SN2 reaction with OH−?
CH3Br or CH3I
How will you bring about the following conversion?
Toluene to benzyl alcohol
Write the structure of the major organic product in the following reaction:
\[\ce{CH3CH2CH2OH + SOCl2 ->}\]
Given reasons: SN1 reactions are accompanied by racemization in optically active alkyl halides.
Arrange the following organic compounds in descending order of their reactivity towards SN1 reaction.
C6H5CH2Br, C6H5CH(C6H5)Br, C6H5CH(CH3)Br, C6H5C(CH3)(C6H5)Br
Which of the following is an example of SN2 reaction?
Halogenation of alkanes is ____________.
In the SN1 reaction, racemization takes place. It is due to:
Isopropyl chloride undergoes hydrolysis by:
Which of the following is the correct order of decreasing SN2 reactivity?
Which of the following is an optically active compound?
Which of the following compound will undergo racemisation when reacts with aq. KOH?
(i)
(ii)
CH3CH2CH2Cl
(iii)
\[\begin{array}{cc}
\ce{CH3}\phantom{..}\\
|\phantom{....}\\
\ce{CH3-CH-CH2Cl}
\end{array}\]
(iv)
\[\begin{array}{cc}
\phantom{..}\ce{H}\\
\phantom{..}|\\
\ce{CH3-C-Cl}\\
\phantom{..}|\\
\phantom{.....}\ce{C2H5}
\end{array}\]
Aryl halides are extremely less reactive towards nucleophilic substitution. Predict and explain the order of reactivity of the following compounds towards nucleophilic substitution:
| (I) |  |
| (II) |  |
| (III) |  |
The number of chiral carbons present in the molecule given below is ______.
The following questions are case-based questions. Read the passage carefully and answer the questions that follow:
|
Nucleophilic Substitution: Influences of solvent polarity: The reaction rate (SN2) of 2-bromopropane and NaOH in ethanol containing 40% water is twice slower than in absolute ethanol. Hence the level of solvent polarity has an influence on both SN1 and SN2 reactions but with different results. Generally speaking, a weak polar solvent is favourable for SN2 reaction, while a strong polar solvent is favourable for SN1. Generally speaking, the substitution reaction of tertiary haloalkane is based on SN1 mechanism in solvents with a strong polarity (for example ethanol containing water). |
Answer the following questions:
(a) Why racemisation occurs in SN1? (1)
(b) Why is ethanol less polar than water? (1)
(c) Which one of, the following in each pair is more reactive towards SN2 reaction? (2)
(i) CH3 – CH2 – I or CH3CH2 – Cl
(ii)
OR
(c) Arrange the following in the increasing order of their reactivity towards SN1 reactions: (2)
(i) 2-Bromo-2-methylbutane, 1-Bromo-pentane, 2-Bromo-pentane
(ii) 1-Bromo-3-methylbutane, 2-Bromo-2-methylbutane, 2-Bromo-3- methylbutane
Discuss SN2 mechanism of methyl bromide using aqueous KOH.
Which of the following reactions is an example of nucleophilic substitution reaction?
Assertion (A): 
undergoes SN2 reactions faster than 
.
Reason (R): Iodine is a better leaving group because of its large size.
In the light of the above statements, choose the correct answer from the options given below:
