10.32 What happens when (i) N-butyl chloride is treated with alcoholic KOH (ii) Bromobenzene is treated with Mg in the presence of dry ether (iii) Chlorobenzene is subjected to hydrolysis (iv) Ethyl chloride is treated with aqueous KOH (v) Methyl bromide is treated with sodium in the presence of dry ether (vi) Methyl chloride is treated with KCN?

This is a classic question from the chapter Haloalkanes and Haloarenes. Let us solve each one as follows:

(1) When n - butyl chloride is treated with alcoholic KOH, the formation of but - l - ene takes place. This reaction is a dehydrohalogenation reaction.

$C{H}_3-C{H}_2-C{H}_2-C{H}_2-\mathrm{Cl}\underset{\text{KOH (alc), Δ}}{\overset{\text{Dehydrohalogenation}}{\to }}C{H}_3-C{H}_2-CH=C{H}_2+\mathrm{KCl}+H_{2}O$

When N-butyl chloride or 1-chlorobutane is treated with alcoholic potassium hydroxide (KOH), elimination reaction takes place. This leads to alkene formation. 1-butene is the major product here. 

(ii) When Bromobenzene is treated with Mg in the presence of dry ether, it undergoes a reaction to produce phenylmagnesium bromide which is the Grignard reagent. This reagent is very re

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This is a classic question from the chapter Haloalkanes and Haloarenes. Let us solve each one as follows:

(1) When n - butyl chloride is treated with alcoholic KOH, the formation of but - l - ene takes place. This reaction is a dehydrohalogenation reaction.

$C{H}_3-C{H}_2-C{H}_2-C{H}_2-\mathrm{Cl}\underset{\text{KOH (alc), Δ}}{\overset{\text{Dehydrohalogenation}}{\to }}C{H}_3-C{H}_2-CH=C{H}_2+\mathrm{KCl}+H_{2}O$

When N-butyl chloride or 1-chlorobutane is treated with alcoholic potassium hydroxide (KOH), elimination reaction takes place. This leads to alkene formation. 1-butene is the major product here. 

(ii) When Bromobenzene is treated with Mg in the presence of dry ether, it undergoes a reaction to produce phenylmagnesium bromide which is the Grignard reagent. This reagent is very reactive organomagnesium compound. Ether solvent is important since it produces a complex with Grignard reagent.

(iii) Chlorobenzene is aryl halide does not easily react with dilute adequate bases or water. However, under extreme conditions like high temperature and pressure and in the presence of strong base/acid catalyst, chlorobenzene undergoes hydrolyosis to form phenol.

The Haloalkenes and Haloarenes NCERT excercise covers many different types of reaction based questions which have been even asked in competitive exams like JEE Main entrance exam.

 

(iv) When Ethyl Chloride or Chloroethane is treated with the aqueous KOH, a nucleophilic substitution reaction (mostly $S_{N}2$ ) take place. This leads to the formation of ethanol.

 

$C{H}_{3}C{H}_2\mathrm{Cl}+KOH\text{\hspace{0.17em}(aq)}\to C{H}_{3}C{H}_{2}OH+K\mathrm{Cl}$

(v) When Methyl bromide is treated with sodium in the presence of dry ether, it undergoes Wurtz coupling reaction. Due to this reaction, carbon-carbon bond is formed which leads to the production of ethane. Here, sodium metal and dry ether are the solvents.

$\underset{\text{Methyl bromide}}{2C{H}_3-\mathrm{Br}}+2\mathrm{Na}\stackrel{\text{Dry ether (Wurtz reaction)}}{\to }\underset{\text{Ethane}}{C{H}_3-C{H}_3}+2\mathrm{Na}\mathrm{Br}$

 

(vi) When Methyl chloride is treated with KCN, a nucleophilic substitution reaction takes places. Cyanide ion attack carbon atom which is bonded to chlorine in methyl chloride. This results in methyl cyanide.

 

$C{H}_3\mathrm{Cl}+KCN\to C{H}_{3}CN+K\mathrm{Cl}$

 

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<p>This is a classic question from the chapter Haloalkanes and Haloarenes. Let us solve each one as follows:</p><p>(1) <strong>When n - butyl chloride is treated with alcoholic KOH,</strong> the formation of but - l - ene takes place. This reaction is a dehydrohalogenation reaction.</p><p><span class="mathml" contenteditable="false"> <math > &lt;!-- Reactant: CH3–CH2–CH2–CH2–Cl --&gt; <mrow> <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub><mo>−</mo> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub><mo>−</mo> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub><mo>−</mo> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub><mo>−</mo> <mi>Cl</mi> </mrow> <mspace width="0.8em"></mspace> &lt;!-- Arrow with condition (top) and process name (bottom) --&gt; <munderover> <mo>→</mo> <mtext>KOH (alc), Δ</mtext> &lt;!-- Δ --&gt; <mtext>Dehydrohalogenation</mtext> </munderover> <mspace width="0.8em"></mspace> &lt;!-- Products: CH3–CH2–CH=CH2 + KCl + H2O --&gt; <mrow> <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub><mo>−</mo> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub><mo>−</mo> <mi>C</mi><mi>H</mi><mo>=</mo> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub> <mo>+</mo> <mi>KCl</mi> <mo>+</mo> <msub><mi>H</mi><mn>2</mn></msub><mi>O</mi> </mrow> </math> </span></p><p>When N-butyl chloride or 1-chlorobutane is treated with alcoholic potassium hydroxide (KOH), elimination reaction takes place. This leads to alkene formation. 1-butene is the major product here.&nbsp;</p><p>(ii)<strong> When Bromobenzene is treated with Mg in the presence of dry ether, </strong>it undergoes a reaction to produce phenylmagnesium bromide which is the Grignard reagent. This reagent is very reactive organomagnesium compound. Ether solvent is important since it produces a complex with Grignard reagent.</p><div class="photo-widget-full"><div class="figure"><picture><source srcset="" media="(max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/1753259780phplBIC0U.jpeg" alt="bromobenzene reaction" width="227" height="128" loading="lazy"></picture></div></div><p>(iii) Chlorobenzene is aryl halide does not easily react with dilute adequate bases or water. However, <strong>under extreme conditions like high temperature and pressure and in the presence of strong base/acid catalyst,</strong> chlorobenzene undergoes hydrolyosis to form phenol.</p><div class="photo-widget-full"><div class="figure"><picture><source srcset="" media="(max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/1753260737phpU5aB2S.jpeg" alt="chlorobenzene" width="239" height="134" loading="lazy"></picture></div><div class="figure">The &lt;a href="https://www.shiksha.com/preparation/chemistry-ncert-solutions-class-12th-haloalkanes-and-haloarenes-4511-ns" target="_blank" rel="noopener"&gt;<em><strong>Haloalkenes and Haloarenes NCERT excercise</strong></em>&lt;/a&gt; covers many different types of reaction based questions which have been even asked in competitive exams like &lt;a href="https://www.shiksha.com/engineering/jee-main-exam" target="_blank" rel="noopener"&gt;<em><strong>JEE Main entrance exam</strong></em>&lt;/a&gt;.</div><div class="figure">&nbsp;</div><div class="figure">(iv) When Ethyl Chloride or Chloroethane is treated with the aqueous KOH, <strong>a nucleophilic substitution reaction</strong> (mostly <span class="mathml" contenteditable="false"> <math > <msub> <mi>S</mi> <mi>N</mi> </msub> <mn>2</mn> </math> </span>) take place. This<strong> leads to the formation of ethanol.</strong></div><div class="figure">&nbsp;</div><div class="figure"><span class="mathml" contenteditable="false"> <math > <mrow> &lt;!-- CH3CH2Cl --&gt; <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub><mi>Cl</mi> <mo>+</mo> &lt;!-- KOH (aq) --&gt; <mi>K</mi><mi>O</mi><mi>H</mi> <mtext> (aq)</mtext> <mo>→</mo> &lt;!-- CH3CH2OH --&gt; <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub> <mi>C</mi><msub><mi>H</mi><mn>2</mn></msub><mi>O</mi><mi>H</mi> <mo>+</mo> &lt;!-- KCl --&gt; <mi>K</mi><mi>Cl</mi> </mrow> </math> </span></div></div><p><picture><source srcset="https://images.shiksha.com/mediadata/images/articles/1690445802phpEIuJf9_480x360.jpeg" media=" (max-width: 500px)"></picture></p><div><div><picture><source srcset="https://images.shiksha.com/mediadata/images/articles/1690445802phpEIuJf9_480x360.jpeg" media=" (max-width: 500px)"></picture></div><div>(v) When Methyl bromide is treated with sodium in the presence of dry ether, <strong>it undergoes Wurtz coupling reaction</strong>. Due to this reaction, carbon-carbon bond is formed which leads to the <strong>production of ethane.</strong> Here, sodium metal and dry ether are the solvents.</div><div><span class="mathml" contenteditable="false"> <math > <mrow> &lt;!-- 2CH3–Br (Methyl bromide) --&gt; <munder> <mrow> <mn>2</mn> <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub> <mo>−</mo><mi>Br</mi> </mrow> <mtext>Methyl bromide</mtext> </munder> <mo>+</mo> &lt;!-- 2Na --&gt; <mn>2</mn><mi>Na</mi> &lt;!-- Arrow with condition above --&gt; <mover> <mo>→</mo> <mtext>Dry ether (Wurtz reaction)</mtext> </mover> &lt;!-- CH3–CH3 (Ethane) --&gt; <munder> <mrow> <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub> <mo>−</mo> <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub> </mrow> <mtext>Ethane</mtext> </munder> <mo>+</mo> &lt;!-- 2NaBr --&gt; <mn>2</mn><mi>Na</mi><mi>Br</mi> </mrow> </math> </span></div><div>&nbsp;</div><div>(vi) When Methyl chloride is treated with KCN, a nucleophilic substitution reaction takes places. Cyanide ion attack carbon atom which is bonded to chlorine in methyl chloride. <strong>This results in methyl cyanide.</strong></div><div>&nbsp;</div><div><span class="mathml" contenteditable="false"> <math > <mrow> &lt;!-- CH3Cl --&gt; <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub><mi>Cl</mi> <mo>+</mo> &lt;!-- KCN --&gt; <mi>K</mi><mi>C</mi><mi>N</mi> <mo>→</mo> &lt;!-- CH3CN --&gt; <mi>C</mi><msub><mi>H</mi><mn>3</mn></msub><mi>C</mi><mi>N</mi> <mo>+</mo> &lt;!-- KCl --&gt; <mi>K</mi><mi>Cl</mi> </mrow> </math> </span></div></div><div><div>&nbsp;</div></div>

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