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

What happens when chlorobenzene is subjected to hydrolysis? - Chemistry

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प्रश्न

What happens when chlorobenzene is subjected to hydrolysis?

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लघु उत्तर
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उत्तर

Chlorobenzene does not undergo hydrolysis under normal conditions. However, it undergoes hydrolysis when heated in an aqueous sodium hydroxide solution at a temperature of 623 K and a pressure of 300 atm to form phenol.

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पाठ 6: Haloalkanes and Haloarenes - Exercises [पृष्ठ १९१]

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एनसीईआरटी Chemistry Part 1 and 2 [English] Class 12
पाठ 6 Haloalkanes and Haloarenes
Exercises | Q 6.22 (iii) | पृष्ठ १९१

संबंधित प्रश्‍न

Write the structure of an isomer of compound C4H9Br which is most reactive towards SN1 reaction


Write the structures of A, B and C in the following:


Write the isomers of the compound having the formula C4H9Br.


Write the structure of the major organic product in the following reaction:

\[\ce{CH3CH2Br + KCN ->[aq.ethanol]}\]


Out of C6H5CH2Cl and C6H5CHClC6H5, which is more easily hydrolysed by aqueous KOH.


C–Cl bond length in chlorobenzene is shorter than C–Cl bond length in CH3–Cl.


In the reaction, \[\ce{R - X + NaOR' -> ROR’ + X}\] ( – ve ion). The main product formed is:


Which of the following is a primary halide?


Which of the following is a chiral compound?


The increasing order of reactivity towards SN1 mechanism is:

(I) \[\begin{array}{cc}
\ce{CH3-CH-CH2-CH3}\\
|\phantom{........}\\
\ce{CH3}\phantom{.....}
\end{array}\]

(II) CH3CH2CH2Cl

(III) P–CH3O–C6H4–CH2Cl


Complete the following analogy:

Same molecular formula but different structures: A : : Non superimposable mirror images: B


Which reagent will you use for the following reaction?

\[\ce{CH3CH2CH2CH3 -> CH3CH2CH2CH2Cl + CH3CH2CHClCH3}\]


Ethylene chloride and ethylidene chloride are isomers. Identify the correct statements.

(i) Both the compounds form same product on treatment with alcoholic KOH.

(ii) Both the compounds form same product on treatment with aq.NaOH.

(iii) Both the compounds form same product on reduction.

(iv) Both the compounds are optically active.


How do polar solvents help in the first step in SN1 mechanism?


Which of the following is the definition of chirality?


Which one is the correct order of nucleophilic strength (pKa) of following nucleophiles?


Among the following compounds I - IV, which one forms a yellow precipitate on reacting sequentially with (i) NaOH (ii) dil. HNO3 (iii) AgNO3?

I II III IV

Convert bromoethane to propanamine.


The following questions are case-based questions. Read the passage carefully and answer the questions that follow:

Nucleophilic Substitution:
Nucleophilic substitution reaction of haloalkane can be conducted according to both SN1 and SN2 mechanisms. SN1 is a two-step reaction, while SN2 is a single-step reaction. For any haloalkane, which mechanism is followed depends on factors such as the structure of haloalkane, properties of leaving group, nucleophilic reagent and solvent.

Influences of solvent polarity:
In SN1 reaction, the polarity of the system increases from the reactant to the transition state, because a polar solvent has a greater effect on the transition state than the reactant, thereby reducing activation energy and accelerating the reaction. In SN2 reaction, the polarity of the system generally does not change from the reactant to the transition state, and only charge dispersion occurs. At this time, the polar solvent has a great stabilizing effect on Nu than the transition state, thereby increasing activation energy and slow down the reaction rate. For example, the decomposition rate (SN1) of tertiary chlorobutane at 25°C in water (dielectric constant 79) is 300000 times faster than in ethanol (dielectric constant 24).

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


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