Chapter 24

The major organic compound formed by the reaction of \(1,1,1-\) trichloroethane with silver powder is: (a) Acetylene (b) Ethene (c) 2 - Butyne (d) 2 - Butene

The major product formed when \(1,1,1\)-trichloropropane is treated with aqueous potassium hydroxide, is: (a) propyne (b) 1-propanol (c) 2-propanol (d) propionic acid

The mechanism of \(\mathrm{S}_{\mathrm{N}} 1\) reaction is given as : \(\mathrm{R}-\mathrm{X} \longrightarrow \mathrm{R}^{\oplus} \mathrm{X}^{\ominus} \longrightarrow \mathrm{R}^{\oplus} \| \mathrm{X}^{\ominus} \stackrel{\mathrm{Y}}{\longrightarrow} \mathrm{R}-\mathrm{Y}+\mathrm{X}^{\Theta}\) lon pair \(\quad\) Solvent Separated ion pair A student writes general characteristics based on the given mechanism as : (1) The reaction is favoured by weak nucleophiles. (2) \(\mathrm{R}^{\oplus}\) would be easily formed if the substituents are bulky. (3) The reaction is accompanied by racemization. (4) The reaction is favoured by non-polar solvents. Which observations are correct? (a) (1) and (2) (b) (1) and (3) (c) (1), (2) and (3) (d) (2) and (4)

In a nucleophilic substitution reaction: $$ \mathrm{R}-\mathrm{Br}+\mathrm{Cl}^{-} \stackrel{\mathrm{DMF}}{\longrightarrow} \mathrm{R}-\mathrm{Cl}+\mathrm{Br}^{-} $$ which one of the following undergoes complete inversion of configuration? (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHC}_{6} \mathrm{H}_{5} \mathrm{Br}\) (b) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{Br}\) (c) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHCH}_{3} \mathrm{Br}\) (d) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CCH}_{3} \mathrm{C}_{6} \mathrm{H}_{5} \mathrm{Br}\)

Compound (A), \(\mathrm{C}_{8} \mathrm{H}_{9} \mathrm{Br}\), gives a yellow precipitate when warmed with alcoholic \(\mathrm{AgNO}_{3}\). Oxidation of (A) gives an acid (B), \(\mathrm{C}_{8} \mathrm{H}_{6} \mathrm{O}_{4}\). (B) easily forms anhydride on heating. Identify the compound (A).

The Wurtz-Fittig reaction involves condensation of : (a) two molecules of aryl halides (b) one molecule of each of aryl-halide and alkyl-halide. (c) one molecule of each of aryl-halide and phenol. (d) two molecules of aralkyl-halides.

The major product obtained from E2-elimination of 3 -bromo-2fluoropentane is :

Aryl fluoride may be prepared from arene diazonium chloride using : (a) \(\mathrm{HBF}_{4} / \Delta\) (b) \(\mathrm{HBF}_{4} / \mathrm{NaNO}_{2}, \mathrm{Cu}, \Delta\) (c) \(\mathrm{CuF} / \mathrm{HF}\) (d) \(\mathrm{Cu} / \mathrm{HF}\)

When phenyl magnesium bromide reacts with tert -butanol, the product would be (a) Benzene (b) Phenol (c) ter-butylbenzene (d) ter-butyl phenyl ether

Consider the following reactions: (1) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCH}(\mathrm{OH}) \mathrm{CH}_{3} \quad\) conc. \(\mathrm{H}_{2} \mathrm{SO}_{4}\) (2) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}(\mathrm{Br}) \mathrm{CH}_{3} \quad \stackrel{\text { alc. } \mathrm{KOH}}{\longrightarrow}\) (3) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCH}(\mathrm{Br}) \mathrm{CH}_{3} \quad \frac{\left(\mathrm{CH}_{3}\right)_{3} \mathrm{O}^{-\mathrm{K}} \mathrm{K}^{\oplus}}{\longrightarrow}\) (4) \(-\mathrm{CH}_{2}-\mathrm{CHO} \stackrel{\Delta}{\longrightarrow}\) Which of these reaction(s) will not produce Saytzeff product? (a) (1), (3) and (4) (b) (4) only (c) (3) only (d) (2) and (4)

\(\underset{\mathrm{H}_{3} \mathrm{C}}{\mathrm{OH}} \stackrel{\mathrm{CH}_{3}}{\stackrel{\mathrm{H}^{+}}{-\mathrm{H}_{2} \mathrm{O}}}[\mathrm{F}] \stackrel{\mathrm{Br}_{2}, \mathrm{CCl}_{4}}{\longrightarrow} \underbrace{\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{Br}_{2}}_{\begin{array}{l}5 \text { such products } \\ \text { are possible }\end{array}} .\) How many structures for \(\mathrm{F}\) are possible? (a) 2 (b) 5 (c) 6 (d) 3

The reaction of toluene with chlorine in presence of ferric chloride gives predominantly : (a) benzoyl chloride (b) \(m\)-chlorotoluene (c) benzyl chloride (d) \(o\) - and \(p\)-chlorotoluene

Chlorobenzene can be prepared by reacting aniline with : (a) hydrochloric acid (b) cuprous chloride (c) chlorine in presence of anhydrous aluminium chloride (d) nitrous acid followed by heating with cuprous chloride

Benzyl chloride \(\left(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{Cl}\right)\) can be prepared from toluene by chlorination with (a) \(\mathrm{SO}_{2} \mathrm{Cl}_{2}\) (b) \(\mathrm{SOCl}_{2}\) (c) \(\mathrm{Cl}_{2}\) (d) \(\mathrm{NaOCl}\)

The synthesis of alkyl fluorides is best accomplished by : (a) Finkelstein reaction (b) Swarts reaction (c) Free radical fluorination (d) Sandmeyer's reaction

Aryl halides are less reactive towards nucleophilic substitution reaction as compared to alkyl halides due to: (a) The formation of less stable carbonium ion (b) Resonance stabilization (c) Longer carbon-halogen bond (d) The inductive effect (e) \(s p^{2}\) hybridized carbon attached to the halogen.

In \(\mathrm{S}_{\mathrm{N}} 2\) reactions, the correct order of reactivity for the following compounds: \(\mathrm{CH}_{3} \mathrm{Cl}, \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl},\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCl}\) and \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}\) is: (a) \(\mathrm{CH}_{3} \mathrm{Cl}>\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCl}>\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}>\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}\) (b) \(\mathrm{CH}_{3} \mathrm{Cl}>\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}>\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCl}>\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}\) (c) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}>\mathrm{CH}_{3} \mathrm{Cl}>\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCl}>\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}\) (d) \(\left(\mathrm{CH}_{3}\right)_{2} \mathrm{CHCl}>\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{Cl}>\mathrm{CH}_{3} \mathrm{Cl}>\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CCl}\)

Given below are certain matching type questions, where two columns (each having 4 items) are given. Immediately after the columns the matching grid is given, where each item of Column I has to be matched with the items of Column II, by encircling the correct match(es). Note that an item of Column I can match with more than one item of Column II. All the items of Column II must be matched. Match the following : Column I (A) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CD}_{2} \mathrm{Br}\) on reaction with (B) \(\mathrm{PhCHBrCH}_{3}\) and \(\mathrm{PhCHBrCD}_{3}\), (C) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}\) on treatment with \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\)and \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{OD}\) gives \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CD}=\mathrm{CH}_{2}\) (D) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}\) reacts faster than \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CD}_{2} \mathrm{CH}_{2} \mathrm{Br}\) on reaction with \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-} \quad\) in ethanol Column II (p) E1 reaction \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{O}^{-}\)gives \(\mathrm{C}_{6} \mathrm{H}_{5}-\) \(\mathrm{CH}=\mathrm{CD}_{2}\) (q) E2 reaction both react with the same rate (r) E1cB reaction (s) First order reaction

For the compounds \(\mathrm{CH}_{3} \mathrm{Cl}, \mathrm{CH}_{3} \mathrm{Br}, \mathrm{CH}_{3} \mathrm{I}\) and \(\mathrm{CH}_{3} \mathrm{~F}\), the correct order of increasing C-halogen bond length is: (a) \(\mathrm{CH}_{3} \mathrm{~F}<\mathrm{CH}_{3} \mathrm{Cl}<\mathrm{CH}_{3} \mathrm{Br}<\mathrm{CH}_{3} \mathrm{I}\) (b) \(\mathrm{CH}_{3} \mathrm{~F}<\mathrm{CH}_{3} \mathrm{Br}<\mathrm{CH}_{3} \mathrm{Cl}<\mathrm{CH}_{3} \mathrm{I}\) (c) \(\mathrm{CH}_{3} \mathrm{~F}<\mathrm{CH}_{3} \mathrm{I}<\mathrm{CH}_{3} \mathrm{Br}<\mathrm{CH}_{3} \mathrm{Cl}\) (d) \(\mathrm{CH}_{3} \mathrm{Cl}<\mathrm{CH}_{3} \mathrm{Br}<\mathrm{CH}_{3} \mathrm{~F}<\mathrm{CH}_{3} \mathrm{I}\)

Read the following Statement-1 (Assertion) and Statement -2 (Reason) and answer as per the options given below: Statement-1 : Bromobenzene upon reaction with \(\mathrm{Br}_{2} / \mathrm{Fe}\) gives \(1,4-\) dibromobenzene as the major product. [2008S] Statement-2 : In bromobenzene, the inductive effect of the bromo group is more dominant than the mesomeric effect in directing the incoming electrophile. (a) Statement-1 is True, Statement-2 is True; Statement-2 is a correct explanation for Statement-1. (b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1 (c) Statement-1 is True, Statement- 2 is False (d) Statement-1 is False, Statement-2 is True

The order of reactivity of the given haloalkanes towards nucleophile is : (a) \(\mathrm{RI}>\mathrm{RBr}>\mathrm{KCl}\) (b) \(\mathrm{RCl}>\mathrm{RBr}>\mathrm{RI}\) (c) \(\mathrm{RBr}>\mathrm{RCl}>\mathrm{RI}\) (d) \(\mathrm{RBr}>\mathrm{RI}>\mathrm{RCl}\)

How will you prepare \(m\)-bromoiodobenzene from benzene (in not more than \(5-7\) steps)?

What would be the product formed when 1-bromo-3-chlorocyclobutane reacts with two equivalents of metallic sodium in ether?

Give reasons for the following : Aryl halides are less reactive than alkyl halides towards nucleophilic reagents

What happens when excess chlorine is passed through boiling toluene in the presence of sunlight?

A solution of \((+)-2\)-chloro-2-phenylethane in toluene racemises slowly in the presence of small amount of \(\mathrm{SbCl}_{5}\), due to the formation of (a) carbanion (b) carbene (c) free-radical (d) carbocation

\(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CMgCl}\) on reaction with \(\mathrm{D}_{2} \mathrm{O}\) produces : (a) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CD}\) (b) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{OD}\) (c) \(\left(\mathrm{CD}_{3}\right)_{3} \mathrm{CD}\) (d) \(\left(\mathrm{CD}_{3}\right)_{3} \mathrm{OD}\)

Isobutyl magnesium bromide with dry ether and ethyl alcohol gives:

The chief reaction product of reaction between \(n\)-butane and bromine at \(130^{\circ} \mathrm{C}\) is : (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{CH}_{2} \mathrm{Br}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CH}(\mathrm{Br}) \mathrm{CH}_{3}\) (c) \(\mathrm{CH}_{3}-\mathrm{CH}_{2} \mathrm{CH}(\mathrm{Br}) \mathrm{CH}_{2} \mathrm{Br}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{C}\left(\mathrm{Br}_{2}\right) \mathrm{CH}_{3}\)

1-Chlorobutane on reaction with alcoholic potash gives (a) 1-butene (b) 1 -butanol (c) 2-butene (d) 2-butanol

The number of structural and configurational isomers of a bromo compound, \(\mathrm{C}_{5} \mathrm{H}_{9} \mathrm{Br}\), formed by the addition of \(\mathrm{HBr}\) to 2 -pentyne respectively are (a) 1 and 2 (b) 2 and 4 (c) 4 and 2 (d) 2 and 1

n-Propyl bromide on treatment with ethanolic potassium hydroxide produces (a) Propane (b) Propene (c) Propyne (d) Propanol

The reaction conditions leading to the best yields of \(\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{Cl}\) are : (a) \(\mathrm{C}_{2} \mathrm{H}_{6}(\) excess \()+\mathrm{Cl}_{2} \stackrel{\text { uv light }}{\longrightarrow}\) (b) \(\mathrm{C}_{2} \mathrm{H}_{6}+\mathrm{Cl}_{2} \frac{\text { dark }}{\text { room temperature }}\) (c) \(\mathrm{C}_{2} \mathrm{H}_{6}+\mathrm{Cl}_{2}(\) excess \() \stackrel{\text { uv light }}{\longrightarrow}\) (d) \(\mathrm{C}_{2} \mathrm{H}_{6}+\mathrm{Cl}_{2} \stackrel{\text { uv light }}{\longrightarrow}\)

Among the following compounds, the most acidic is (a) \(p\)-nitrophenol (b) \(p\)-hydroxybenzoic acid (c) \(o\)-hydroxybenzoic acid (d) \(p\)-toluic acid

The number of stereoisomers obtained by bromination of trans-2butene is (a) 1 (b) 2 (c) 3 (d) 4

Which of the following compounds exhibits stereoisomerism? (a) 2-methylbutene-1 (b) 3-methylbutyne-1 (c) 3-methylbutanoic acid (d) 2-methylbutanoic acid

An \(\mathrm{S}_{\mathrm{N}} 2\) reaction at an asymmetric carbon of a compound always gives (a) an enantiomer of the substrate (b) a product with opposite optical rotation (c) a mixture of diastereomers (d) a single stereoisomer

The order of reactivity of the following alkyl halides for a \(\mathrm{S}_{\mathrm{N}} 2\) reaction is (a) \(\mathrm{RF}>\mathrm{RCl}>\mathrm{RBr}>\mathrm{RI}\) (b) \(\mathrm{RF}>\mathrm{RBr}>\mathrm{RCl}>\mathrm{RI}\) (c) \(\mathrm{RCl}>\mathrm{RBr}>\mathrm{RF}>\mathrm{RI}\) (d) \(\mathrm{RI}>\mathrm{RBr}>\mathrm{RCl}>\mathrm{RF}\)

Which of the following has the highest nucleophilicity? (a) \(\mathrm{F}^{-}\) (b) \(\mathrm{OH}^{-}\) (c) \(\mathrm{CH}_{3}^{-}\) (d) \(\mathrm{NH}_{2}^{-}\)

How many optically active stereoisomers are possible for butane-2, \(3-\) diol? (a) 1 (b) 2 (c) 3 (d) 4

The \(\mathrm{Cl}-\mathrm{C}-\mathrm{Cl}\) angle in \(1,1,2,2\)-tetrachloroethene and tetrachloromethane respectively will be about (a) \(120^{\circ}\) and \(109.5^{\circ}\) (b) \(90^{\circ}\) and \(109.5^{\circ}\) (c) \(109.5^{\circ}\) and \(90^{\circ}\) (d) \(109.5^{\circ}\) and \(120^{\circ}\)

The total number of alkenes possible by dehydrobromination of \(3-\) bromo-3-cyclopentylhexane using alcoholic \(\mathrm{KOH}\) is

Isomers which are ............... mirror images are known as ............... (superimposable, non-superimposable, enantiomers, diastereomers, epimers)

The compound prepared by the action of magnesium on dry ethyl bromide in ether is known as ............. reagent.

The halogen which is most reactive in the halogenation of alkanes under sunlight is ................... (chlorine, bromine, iodine)

An 'Assertion' and a 'Reason' are given below. Choose the correct answer from the following options : Assertion (A) : Vinyl halides do not undergo nucleophilic substitution easily. Reason (R) : Even though the intermediate carbocation is stabilized by loosely held p-electrons, the cleavage is difficult because of strong bonding. (a) Both (A) and (R) are wrong statements. (b) Both (A) and \((\mathrm{R})\) are correct statements and (R) is the correct explanation of (A). (c) Both (A) and \((\mathrm{R})\) are correct statements but \((\mathrm{R})\) is not the correct explanation of (A). (d) (A) is a correct statement but \((\mathrm{R})\) is a wrong statement.

Statement -1: Molecules that are not superimpossable on their mirror images are chiral. Statement -2: All chiral molecules have chiral centres. (a) If both Statement-1 and Statement-2 are correct, and Statement-2 is the correct explanation of the Statement-2. (b) If both Statement-1 and Statement-2 are correct, but Statement \(-2\) is not the correct explanation of the Statement-1. (c) If Statement-1 is correct but Statement-2 is incorrect. (d) If Statement-1 is incorrect but Statement-2 is correct.

Cyclobutyl bromide on treatment with magnesium in dry ether forms an organometallic (A). The organometallic reacts with ethanal to give an alcohol (B) after mild acidification. Prolonged treatment of alcohol (B) with an equivalent amount of HBr gives 1 -bromo-1methylcyclopentane (C). Write the structures of (A), (B) and explain how \((\mathrm{C})\) is obtained from (B).

An alkyl halide, \(X\), of formula \(\mathrm{C}_{6} \mathrm{H}_{13} \mathrm{Cl}\) on treatment with potassium tertiary butoxide gives two isomeric alkenes \(Y\) and \(Z\left(\mathrm{C}_{6} \mathrm{H}_{12}\right)\). Both alkenes on hydrogenation give2, 3-dimethylbutane. Predict the structures of \(X, Y\) and \(Z\)

Arrange the following in: Increasing reactivity in nucleophilic substitution reactions \(\mathrm{CH}_{3} \mathrm{~F}, \mathrm{CH}_{3} \mathrm{I}, \mathrm{CH}_{3} \mathrm{Br}, \mathrm{CH}_{3} \mathrm{Cl}\)