Organic Compounds Containing Halogens — JEE Main PYQs

Correct statements regarding alkyl halides (R$-$X) among the following are :

A. Alcohol being less polar solvent as compared to water, alcoholic KOH favours elimination reaction with R$-$X.

B. Order of reactivity towards $\mathrm{S_N1}$ mechanism is $\mathrm{C_6H_5{-}CH_2{-}Cl > C_6H_5{-}CHCl{-}C_6H_5}$.

C. Non substituted aryl halides exhibit properties similar to alkyl halides.

D. Vinyl chloride is an example of haloalkene and allyl chloride is an example of haloalkyne.

E. R$-$Cl can be prepared by reacting R$-$OH with $\mathrm{SOCl_2}$ but Ar$-$Cl cannot be prepared by reacting Ar$-$OH with $\mathrm{SOCl_2}$.

Choose the correct answer from the options given below :

Match the LIST-I with LIST-II

List-I (Name of reaction)	List-II (Reagent or catalyst used)
A. Finkelstein reaction	I. $\mathrm{SbF_3}$
B. Swarts reaction	II. Na, dry ether
C. Sandmeyer's reaction	III. $\mathrm{NaI}$
D. Fittig reaction	IV. $\mathrm{Cu_2Cl_2}$

Choose the correct answer from the options given below:

Benzyl isocyanide can be obtained from

A. [Figure: benzyl bromide] $\mathrm{C_6H_5CH_2Br \xrightarrow{AgCN}}$ B. [Figure: benzylamine] $\mathrm{C_6H_5CH_2NH_2 \xrightarrow[\text{Aq NaOH}]{CHCl_3}}$ C. [Figure: bromobenzene] $\mathrm{C_6H_5Br \xrightarrow{AgCN}}$ D. [Figure: aniline] $\mathrm{C_6H_5NH_2 \xrightarrow[\text{Aq NaOH}]{CHCl_3}}$ E. [Figure: (2-bromoethyl)benzene] $\mathrm{C_6H_5CH_2CH_2Br \xrightarrow{KCN}}$

Choose the correct answer from the options given below:

RMgI when treated with ice cold water liberated a gas which occupied $1.4\ \mathrm{dm^3/g}$ at STP. The gas produced is further reacted with iodine in presence of $\mathrm{HIO_3}$ to give compound (X). Compound (X) in presence of Na and dry ether produced compound (Y). Molar mass of compound (Y) is ________ $\mathrm{g\ mol^{-1}}$. (Nearest integer)

Given below are two statements:

Statement I: 3-phenylpropene reacts with HBr and gives secondary alkyl bromide having a chiral carbon atom as the major product.

Statement II: Aryl chlorides and aryl cyanides can be prepared by Sandmeyer reaction as well as Gattermann reaction.

In the light of the above statements, choose the correct answer from the options given below

An optically active alkyl bromide $\mathrm{C_4H_9Br}$, reacts with ethanolic KOH to form major compound [A] which reacts with bromine to give compound [B]. Compound [B] reacts with ethanolic KOH and sodamide to give compound [C]. One molecule of water adds to compound [C] on warming with mercuric sulphate and dilute sulphuric acid at 333 K to form compound [D]. The functional group in compound D will be confirmed by :

n-Butane on monochlorination under photochemical condition gives an optically active compound "P". "P" on further chlorination gives dichloro compounds.

The number of dichloro compounds obtained (ignore stereoisomers) is :

Given below are two statements :

Statement I : Due to increase in van der Waals forces, the order of boiling points is $\mathrm{CH_3CH_2CH_2I > CH_3CH_2I > CH_3I}$.

Statement II : As para-dichlorobenzene is more symmetric, its melting point is higher than ortho-dichlorobenzene, however its boiling point is lower than ortho-dichlorobenzene. [Figure: benzene ring structures of 1,4-dichlorobenzene and 1,2-dichlorobenzene]

In the light of the above statements, choose the correct answer from the options given below :

An optically active alkyl halide $\mathrm{C_4H_9Br}$ [A] reacts with hot KOH dissolved in ethanol and forms alkene [B] as major product which reacts with bromine to give dibromide [C]. The compound [C] is converted into a gas [D] upon reacting with alcoholic $\mathrm{NaNH_2}$. During hydration 18 gram of water is added to 1 mole of gas [D] on warming with mercuric sulphate and dilute acid at 333 K to form compound [E]. The IUPAC name of compound [E] is :

Match List - I with List - II.

List - I (Reaction)

(A) $\mathrm{2\,C_6H_5X + 2Na \xrightarrow{\text{Dry Ether}} C_6H_5{-}C_6H_5 + 2NaX}$ [Figure: two halobenzene molecules coupling to biphenyl]

(B) $\mathrm{ArN_2^{+}X^{-} \xrightarrow[\text{HCl}]{\text{Cu}} ArCl + N_2\uparrow + CuX}$

(C) $\mathrm{C_2H_5Br + NaI \xrightarrow{\text{Dry Acetone}} C_2H_5I + NaBr}$

(D) \mathrm{CH_3C(OH)(CH_3)CH_3 \xrightarrow[\text{ZnCl_2}]{\text{HCl}} CH_3C(Cl)(CH_3)CH_3}

List - II (Name of reaction)

(I) Lucas reaction

(II) Finkelstein reaction

(III) Fittig reaction

(IV) Gatterman reaction

Choose the correct answer from the options given below :

$\mathrm{2\text{-}Bromopentane \xrightarrow{\text{alcoholic KOH}} P\ (\text{Major Product}) \xrightarrow{Br_2} Q}$

[Figure: skeletal structure of 2-bromopentane with Br on carbon 2]

Consider the above sequence of reactions. 151 g of 2-bromopentane is made to react. Yield of major product P is 80% whereas Q is 100%.

Mass of product Q obtained is __________ g.

(Given molar mass in $\mathrm{g\ mol^{-1}}$ H : 1, C : 12, O : 16, Br : 80)

Given below are two statements :

Statement (I) : Alcohols are formed when alkyl chlorides are treated with aqueous potassium hydroxide by elimination reaction.

Statement (II) : In alcoholic potassium hydroxide, alkyl chlorides form alkenes by abstracting the hydrogen from the $\beta$-carbon.

In the light of the above statements, choose the most appropriate answer from the options given below :

Which of the following is the correct IUPAC name of given organic compound (X)?

[Figure: alkene with $\mathrm{H_3C}$ and H on one doubly-bonded carbon, and $\mathrm{CH_3}$ and $\mathrm{CH_2Br}$ on the other; i.e. $\mathrm{CH_3CH{=}C(CH_3)CH_2Br}$, labelled (X)]

Given below are two statements :

Statement (I) : (Z)-1,2-dichloroethene ($cis$ $\mathrm{CHCl=CHCl}$) is more polar than (Z)-1,2-dibromoethene ($cis$ $\mathrm{CHBr=CHBr}$).

Statement (II) : Boiling point of (E)-1,2-dibromoethene ($trans$ $\mathrm{CHBr=CHBr}$) is lower than (Z)-1,2-dibromoethene ($cis$ $\mathrm{CHBr=CHBr}$) but it is more polar than (Z)-1,2-dibromoethene ($cis$ $\mathrm{CHBr=CHBr}$).

In the light of the above statements, choose the most appropriate answer from the options given below :

[Figure: Statement I compares cis-CHCl=CHCl with cis-CHBr=CHBr; Statement II compares trans-CHBr=CHBr with cis-CHBr=CHBr]

Match List - I with List - II.

List - I (Conversion)	List - II (Reagents, Conditions used)
(A) Chlorobenzene $\rightarrow$ phenol	(I) Warm, $\mathrm{H_2O}$
(B) 4-chloronitrobenzene $\rightarrow$ 4-nitrophenol	(II) (a) NaOH, 368K; (b) $\mathrm{H_3O^+}$
(C) 1-chloro-2,4-dinitrobenzene $\rightarrow$ 2,4-dinitrophenol	(III) (a) NaOH, 443K; (b) $\mathrm{H_3O^+}$
(D) 2-chloro-1,3,5-trinitrobenzene (picryl chloride) $\rightarrow$ 2,4,6-trinitrophenol (picric acid)	(IV) (a) NaOH, 623K, 300 atm; (b) $\mathrm{H_3O^+}$

Choose the correct answer from the options given below :

[Figure: structures showing aryl chloride to phenol conversions in List-I]

Choose the correct set of reagents for the following conversion.

Ethyl benzene $\longrightarrow$ [Figure: benzene ring with a $\mathrm{CH{=}CH_2}$ group and a Br at the para position (4-bromostyrene)]

Given below are two statements :

Statement I : $\mathrm{CH_3-O-CH_2-Cl}$ will undergo $S_N1$ reaction though it is a primary halide.

Statement II : $\mathrm{(CH_3)_3C-CH_2-Cl}$ will not undergo $S_N2$ reaction very easily though it is a primary halide.

In the light of the above statements, choose the most appropriate answer from the options given below :

$\mathrm{RBr} \xrightarrow{\text{(i) Mg, dry ether ; (ii) } \mathrm{H_2O}}$ 2-Methylbutane

[Figure: skeletal structure of 2-methylbutane drawn as the product]

The maximum number of RBr producing 2-methylbutane by above sequence of reactions is __________. (Consider the structural isomers only)

On chlorination under photochemical conditions, propane molecule gives two dichloro products "x" and "y". Among "x" and "y", "x" is an optically active molecule. How many trichloro products (consider structural isomers only) will be obtained from "x" when it is treated with chlorine again under photochemical conditions?

Match the LIST-I with LIST-II

	LIST-I (Name reaction)		LIST-II (Product obtainable)
A.	Swarts reaction	I.	Ethyl benzene
B.	Sandmeyer's reaction	II.	Ethyl iodide
C.	Wurtz Fittig reaction	III.	Cyanobenzene
D.	Finkelstein reaction	IV.	Ethyl fluoride

Choose the correct answer from the options given below:

The ascending order of relative rate of solvolysis of following compounds is :

[Figure: four bromo compounds]

• (A) 1-bromo-3,3,5,5-tetramethylcyclohexane (tertiary bromide on a gem-dimethyl-substituted cyclohexane ring)
• (B) 1-bromo-1,2,3,4-tetrahydronaphthalene (benzylic secondary bromide, with a methyl at the 4-position)
• (C) bromodiphenylmethane, $\mathrm{(C_6H_5)_2CHBr}$ (dibenzylic secondary bromide)
• (D) 3-bromo-2-methylpentane (a secondary alkyl bromide)

Given below are two statements:

Statement I: The conversion proceeds well in the less polar medium. $$\mathrm{CH_3-CH_2-CH_2-CH_2-Cl \xrightarrow{HO^-} CH_3-CH_2-CH_2-CH_2-OH + Cl^{(-)}}$$

Statement II: The conversion proceeds well in the more polar medium. $$\mathrm{CH_3-CH_2-CH_2-CH_2-Cl \xrightarrow{R_3N:} CH_3-CH_2-CH_2-CH_2-\overset{(+)}{N}R_3\ Cl^{(-)}}$$

In the light of the above statements, choose the correct answer from the options given below:

The structure of the major product formed in the following reaction is :

[Figure: 1-(chloromethyl)-3-bromo-5-iodobenzene (a benzene ring bearing $\mathrm{-CH_2Cl}$, and at the two meta positions an $\mathrm{I}$ and a $\mathrm{Br}$)] $\xrightarrow{\text{AgCN}}$ major product

Given below are two statements:

Statement I: [Structure: $\mathrm{Et_2N{-}CH_2CH_2{-}Cl}$] will undergo alkaline hydrolysis at a faster rate than [Structure: $\mathrm{Et_2CH{-}CH_2CH_2{-}Cl}$]

Statement II: In [Structure: $\mathrm{Et_2N{-}CH_2CH_2{-}Cl}$] , intramolecular substitution takes place first by involving lone pair of electrons on nitrogen.

In the light of the above statements, choose the most appropriate answer from the options given below

The products A and B in the following reactions, respectively are

$$\mathrm{A} \xleftarrow{\mathrm{Ag{-}NO_2}} \mathrm{CH_3{-}CH_2{-}CH_2{-}Br} \xrightarrow{\mathrm{AgCN}} \mathrm{B}$$

The major product of the following reaction is :

[Figure: a dibromide bearing a phenyl group — 4-phenyl chain with two bromine atoms on adjacent-region carbons — treated with excess KOH/EtOH, $\Delta$ (double dehydrohalogenation)]

[Figure: compound (A) is 1-bromo-4-(2-bromoethyl)benzene — a benzene ring with Br at the para position and a $\mathrm{-CH_2CH_2Br}$ side chain]

$$\mathrm{(A) \xrightarrow{NaOH_{(alc)}} \ (B) \ \xrightarrow[Ether]{HBr} \ (C)}$$

Identify (B) and (C) and how are (A) and (C) related ?

Identify the correct set of reagents or reaction conditions 'X' and 'Y' in the following set of transformation.

$$\mathrm{CH_3-CH_2-CH_2-Br \xrightarrow{'X'} Product \xrightarrow{'Y'} \underset{\underset{\mathrm{Br}}{|}}{CH_3-CH}-CH_3}$$

Find out the major product formed from the following reaction. [Me : $-\mathrm{CH_3}$]

[Figure: 3,5-dibromocyclopent-1-ene $\xrightarrow{\mathrm{Me_2NH\ (2\ equiv)}}$ ?]

[Figure: 2-bromo-3-methyl-1-phenylbutane, $\mathrm{C_6H_5CH_2\text{-}CH(Br)\text{-}CH(CH_3)_2}$ $\xrightarrow[\Delta]{\mathrm{KOH(alc)}}$ major product "P"]

Product P is

The number of halobenzenes from the following that can be prepared by Sandmeyer's reaction is ________.

[Figure: five monosubstituted benzenes — I : $\mathrm{C_6H_5F}$, II : $\mathrm{C_6H_5Cl}$, III : $\mathrm{C_6H_5Br}$, IV : $\mathrm{C_6H_5I}$, V : $\mathrm{C_6H_5At}$]

Which one of the following reactions is NOT possible ?

Identify the major product in the following reaction.

[Figure: 1-bromo-1-methylcyclopentane $\xrightarrow[\mathrm{C_2H_5OH}]{\bar{\mathrm{O}}\mathrm{H}}$ Major Product]

Match List I with List II

LIST I (Compound)	LIST II (Uses)
A. Iodoform	I. Fire extinguisher
B. Carbon tetrachloride	II. Insecticide
C. CFC	III. Antiseptic
D. DDT	IV. Refrigerants

Choose the correct answer from the options given below:

[Figure: cyclohexane ring attached to $\mathrm{CH(Cl)CH_2CH_3}$, i.e. (1-chloropropyl)cyclohexane] $+ \mathrm{NaOH} \xrightarrow{\mathrm{H_2O}}$ Major Product "A"

Consider the above chemical reaction. Product "A" is :

Which among the following compounds will undergo fastest $\mathrm{S_N2}$ reaction.

Given below are two statements :

Statement (I) : $\mathrm{S_N2}$ reactions are 'stereospecific', indicating that they result in the formation of only one stereo-isomer as the product.

Statement (II) : $\mathrm{S_N1}$ reactions generally result in formation of product as racemic mixtures.

In the light of the above statements, choose the correct answer from the options given below :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : $\mathrm{S_N2}$ reaction of $\mathrm{C_6H_5CH_2Br}$ occurs more readily than the $\mathrm{S_N2}$ reaction of $\mathrm{CH_3CH_2Br}$. Reason (R) : The partially bonded unhybridized p-orbital that develops in the trigonal bipyramidal transition state is stabilized by conjugation with the phenyl ring. In the light of the above statements, choose the most appropriate answer from the options given below :

In the following sequence of reaction, the major products B and C respectively are :

[Figure: 1-bromo-3-chlorocyclobutane (Cl and Br on opposite corners of a cyclobutane ring) $\xrightarrow{\mathrm{Na/Et_2O}}$ A ; A $\xrightarrow[\mathrm{(ii)\ D_2O}]{\mathrm{(i)\ Mg/Et_2O}}$ B ; A $\xrightarrow{\mathrm{CoF_2}}$ C]

[Figure: $\mathrm{C_6H_5-CH(CH_3)-CH(Br)(OCH_3)}$ (benzylic carbon bears $\mathrm{CH_3}$; adjacent carbon bears Br and $\mathrm{OCH_3}$)] $\xrightarrow[\Delta]{\mathrm{KCN\ (alc)}}$ Major Product 'P'

In the above reaction product 'P' is

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : Haloalkanes react with KCN to form alkyl cyanides as a main product while with AgCN form isocyanide as the main product.

Reason (R) : KCN and AgCN both are highly ionic compounds.

In the light of the above statements, choose the most appropriate answer from the options given below :

Identify A and B in the following sequence of reaction

$$\mathrm{C_6H_5CH_3} \xrightarrow{\mathrm{Cl_2}/h\nu} \mathrm{A} \xrightarrow[\text{373 K}]{\mathrm{H_2O}} \mathrm{B}$$

[Figure: toluene (benzene ring with CH$_3$) treated with Cl$_2$/h$\nu$ to give A, then H$_2$O at 373 K to give B]

Match List - I with List - II.

List - I (Compound)	List - II (Use)
(A) Carbon tetrachloride	(I) Paint remover
(B) Methylene chloride	(II) Refrigerators and air conditioners
(C) DDT	(III) Fire extinguisher
(D) Freons	(IV) Non Biodegradable insecticide

Choose the correct answer from the options given below :

$\mathrm{C_2H_5Br \xrightarrow{\text{alc. KOH}} A \xrightarrow[CCl_4]{Br_2} B \xrightarrow[\text{Excess}]{KCN} C \xrightarrow[\text{Excess}]{H_3O^+} D}$

Acid D formed in above reaction is :

The correct statement regarding nucleophilic substitution reaction in a chiral alkyl halide is :

Given below are two statements : one is labelled as Assertion A and the other is labelled as Reason R :

Assertion A : Aryl halides cannot be prepared by replacement of hydroxyl group of phenol by halogen atom.

Reason R : Phenols react with halogen acids violently.

In the light of the above statements, choose the most appropriate from the options given below :

Example of vinylic halide is :

Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).

Assertion (A) : $\mathrm{CH_2{=}CH{-}CH_2{-}Cl}$ is an example of allyl halide.

Reason (R) : Allyl halides are the compounds in which the halogen atom is attached to sp$^2$ hybridised carbon atom.

In the light of the above statements, choose the most appropriate answer from the options given below :

Given below are two statements:

Statement - I: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not have bulky substituents will follow $\mathrm{S_N^2}$ mechanism.

Statement - II: A secondary alkyl halide when treated with a large excess of ethanol follows $\mathrm{S_N^1}$ mechanism.

In the light of the above statements, choose the most appropriate from the options given below:

$$\text{2-chlorobutane} + \mathrm{Cl_2} \rightarrow \mathrm{C_4H_8Cl_2}\ \text{(isomers)}$$

Total number of optically active isomers shown by $\mathrm{C_4H_8Cl_2}$, obtained in the above reaction is ________.

The product (C) in the below mentioned reaction is :

$$\mathrm{CH_3-CH_2-CH_2-Br \xrightarrow[\Delta]{KOH_{(alc)}} A \xrightarrow{HBr} B \xrightarrow[KOH_{(aq)}]{\Delta} C}$$

$\mathrm{CH_3CH_2Br + NaOH}$ gives Product A with $\mathrm{C_2H_5OH}$ and Product B with $\mathrm{H_2O}$.

[Figure: branched reaction scheme — CH3CH2Br + NaOH with C2H5OH giving Product A, and with H2O giving Product B]

The total number of hydrogen atoms in product A and product B is ________.

Identify structure of 2,3–dibromo–1–phenylpentane.

Identify A and B in the following reaction sequence.

$$\text{Bromobenzene} \xrightarrow{\text{Conc } \mathrm{HNO_3}} \mathrm{A} \xrightarrow[\text{(ii) } \mathrm{HCl}]{\text{(i) } \mathrm{NaOH}} \mathrm{B}$$

[Figure: reaction scheme starting from bromobenzene]

Number of isomeric products formed by monochlorination of 2-methylbutane in presence of sunlight is ________.