Reaction Mechanism

AtoZ CHEMISTRY Reaction Mechanism

Reaction Mechanism (D) have low activation energy compare to that of 1. Introduction to Mechanism & Organic other steps Reaction Q 9. Which of the following is an example of Q 1. In the reaction substitution reaction? O OH −− CNCHBrCHCNBr+→+ + 33 CH333 – C – CH + H / CH OH CH3 – C – CH3

The nucleophile is (A) OCH3 – – (A) CN (B) CH3 (B) CHCHHBrCHCHBr=+→− – 2232 (C) Br (D) None of these O O Q 2. In the reaction (C) CH3 – C – Cl + CH3 OH CH33 – C – OCH + HCl HCCHHBrCHCHBr2232=+→− , (D) None of these the electrophile is Q 10. Which of the following reaction is an example of (A) HBr (B) Br– addition reaction ? (C) H+ (D) None of these O O CH – C – Cl + H+ /H O Q 3. Suggest a suitable mechanism for the reaction (A) 32CH3 – C – OH + HCl 2 Br 2 A 2+ B → C + D if Rate = K A B   H C = CH − CH + Br → CH − CH − CH Q 4. For the exothermic reaction happening in 3 steps 2 3 2 2 3 1. A → B fast (B) Br  2. BC+→ DE+ : slow (C) CHCHOHH322422−−+⎯⎯→= SOCHCH 3. AE2F+→ ; fast (D) None of these (A) write complete reaction Q 11. Which of the following reaction is an example of (B) Identify the Rds of the reaction elimination reaction? (C) Draw energy diagram for the reaction H + (A)CH33233 COOCHH+⎯⎯→+ OCH COOHCH OH (D) Identify the intermediate species formed (B)CH CHNaNHCH+⎯⎯→+ CC NaNH −+ Q 5. A and B can react at a certain temperature to give 3233 C, the rate controlled product. At a higher (C)  temperature they give D, the thermodynamic – CH3223323 CH CH CHClCHKOHCH+⎯⎯→= CH CHCHCH

controlled product. Draw the reaction diagram for ++KCl H2 O each cases. (D) None of these Q 6. Kinetically controlled products are formed with Q 12. Which of the following is an example of path having electrohilic addition reaction ? (A) Low Ea (B) high Ea (A) CH3333 COOCHNaOHCH+⎯⎯→+ COOHCH ONa (C) high +ve H (D) high −ve H + (B) CH COCl+ H O ⎯⎯→H CH COOH + HCl Q 7. Thermodynamically controlled products are 3 2 3  formed with (C) CH3232 CH=+⎯⎯→ CHBrClCH CHClCH Br ((A) Low Ea (B) high Ea (D) None of these (C) high +ve H (D) high −ve H Q 13. Which of the statement is wrong? Q 8. Rds of a reaction mechanism (A) A more stable product is formed at faster rate (A) is much slower compare to other steps (B) A less stable product is formed at slower rate (B) is slower compare to other steps (C) A more stable product is formed at slower (C) have high activation energy compare to that rate of other steps (D) All of these

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2. Substitution Reaction (D) Configuration is lost Q 1. SN1 mechanism involves Q 11. In SN1 reaction generally product is greater than (A) 1 step (B) 2 steps retention product Inversion. It occur when (C) 3 steps (D) None of these (A) Solvent is polar (B) Solvent is non – polar Q 2. SN1 mechanism for the hydrolysis of alkyl (C) Nucleophile is weaker halide involves formation of intermediate (D) Nucleophile is stronger (A) free radical (B) carbocation (C) carbanion (B) None of these Q 12. SNi Reaction Q 3. Which of the following path is not possible on (A) Form retention product SP3 carbon for nucleophilic substitution reaction? (B) a 2nd order reaction (A) First C-L bond is cleaved & then C-Nu bond (C) occur with R–OH with S o C l2 is formed (D) All of the above statements are correct (B) Both C-L bond cleavage & C-Nu bond Q 13. Which of the following reactions is an examples formation occur simultaneously of SN reaction (C) First C-Nu bond is formed & then C-L bond 2 is cleaved (A) CHCBrOHCHCOHBr−+→−+ −− ( 33)33( ) (D) All are possible (B) CHCHBrOHCHCHOHBr−+→−+ −− ( 33)22( ) Q 4. Transition state of SN2 reaction has −− (C) CHBrOHCHOHBr−+→−+ (A) sp2 carbon (B) sp3 carbon 33 23 (D) CH3222 CH OHH⎯⎯⎯⎯→= CCH (C) Both sp &sp characters (−HO2 ) (D) None of these Q 14. Which one of the following statements is wrong Q 5. SN Reaction leads to 1 about SN2 reaction? (A) Reteation of configuration (A) The rate of reaction is independent of the (B) Inversion of configuration concentration of nucleophile (C) Recemisation of configuration (B) Nucleophile attacks the carbon from the side (D) None of these opposite to where the leaving group is attached Q 7. SN2 Reaction is (C) Only in one step the bond formation and bond (A) Endothermic (B) Exothermic breaking takes place (C) Both endothermic & exothermic (D) Rate of reaction  [substrate][nucleophile] (D) Neither exothermic nor endothermic Q 15. Arrange the following in order of decreasing tendency towards SN reaction Q 8. SN1 Reaction is 2 (A) Stereospecific (B) Stereoselective CH3222 CH CH CH Cl, CH323 CH CHClCH , (C) Regiospecific (D) Regioselective (I) (II) Q 9. SN Reaction is CH CHCH Cl, CHCCl − 2 ( 32)2 ( 3)3 (A) Stereospecific (B) Stereoselective (III) (IV) (C) Regiospecific (D) Regioselective Q 16. The compound that does not undergo hydrolysis Q 10. SN Reaction on R-configured halide leads to 2 by SN1 mechanism is formation (A) H C= CHCH Cl (B) C H Cl (A) S-configured carbon 2265 (B) R-Configured carbon (C) C6 H 5 CH 2 Cl (D) C6 H 5 CH( C 6 H 5) Cl (C) May be S or R-configuration

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3. SN1, SN2 Reaction (i) C H C B r − (ii) C H C H B r ( 3 )3 ( 65)2 Q 1. Consider the following bromides (iii) CHCCHBr (iv) C H C H B r ( 653 )2 ( ) ( 3 )2 (A) i v i i i  i i i (B) i i i i i i i v (C) i i i i i i i v (D) i i i i i i i v  The correct order of SN1 Q 8. Consider the reactions, (i) CHCHCHBr−⎯⎯⎯⎯→ C25 H OH (A) I I I I I I (B) I I I I I I ( 32)2 (C) I I I I I I (D) I I I I I I CHCHCHOCHHBr−+ ( 3225)2 Q 2. The order of reactivities of the following alkyl − (ii) CHCHCHBr−⎯⎯⎯→ CH25 O halides for a SN2 reaction is ( 32)2 CHCHCHOCHBr−+− (A) RFRClRBrRI ( 3225)2 (B) RFRBrRClRI The mechanism of reactions (i) and (ii) are (C) RClRBrRFRI respectively

(D) RIRBrRClRF (A) SN1 and SN 2 (B) SN1 and SN1 Q 3. An SN reaction at an asymmetric carbon of a 2 (C) SN 2 and SN1 (D) SN 2 and SN 2 compound always gives Q 9. The hydrolysis of 2-bromo-3-methyl butane by (A) an enantiomer of the substrate SN1 mechanism gives mainly (B) a product with opposite optical rotation (A) 3-methyl-1-butanol (C) a mixture of diastereomers (B) 2-methyl-2-butanol (D) a single stereoisomer (C) 2,2-dimethyl-2-propanol Q 4. Which of the following undergoes nucleophilic (D) 2-methyl-1-butanol substitution exclusively by SN1 mechanism? Q 10. In a SN 2 substitution reaction of the type (A) Ethyl chloride (B) Isopropyl chloride −−DMF (C) Chlorobenzene (D) Benzyl chloride R− Br + Cl ⎯⎯⎯→ − R + Cl Br Which one of the following has the highest Q 5. CH BrNuCH+→+−− NuBr 33 relative rate? The decreasing order of the rate of the above (A) CH C− CH Br (B) CHCHBr ( 32)3 32 reaction with nucleophiles Nu− A to D is ( ) (C) CHCHCHBr (D) CHCHCHBr− 322 ( 32)2 −−−−− [ NuA= PhO( ) , B AcO( ) , C HO( ) , D CH( ) O 3 ] Q 11. Among the molecules (A) DCAB (B) DCBA ONCHBr22−− CHCHBr32−− I II (C) ABCD (D) BDCA   CH OCHBr−− Q 6. Which one is most reactive towards SN 32 1 III reaction? The order of SN2 reactivity is (A) C H CH C HBr 6565 ( ) (A) II III I (B) I III II

(B) C65365 H C( CHC)( HBr ) (C) I II III (D) III II I Q 12. The correct order of SN reactivity in the (C) C653 H CH( CHBr) 1 molecules (D) C6 H 5 CH 2 Br

Q 7. The SN1 reactivity of the following halides will be in the order

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CHCHCHBr22=−− , CH CH2 =− B r I II (A) 1 (B) 2 Br (C) Equal rate (D) Can’t predict Q 17. In general, Polar solvent favours (A) SN1 reaction (B) SN2 reaction II I , CH CH32−− B r IV (C) SNi reaction (D) Elimination reaction (A) I V I I I  I I I (B) I I V  I I I I I Q 18. The decreasing order of nucleophilicity among (C) I I V  I I I I I (D) I V I I I  I I I the nucleophiles is

Q 13. KI in acetone undergoes SN 2 reaction with each of P, Q, R, S. The rates of the reaction vary as

(A) I, II, III, IV (B) IV, III, II, I (A) PQRS   (B) SPRQ   (C) II, III, I, IV (D) III, II, I, IV

Q 14. The SN2 reactivity order for the following leaving group 4. SN1 vs SN2 Reaction & SNi Reaction −OTF(I) −I I( I ) Q 1. The correct SN1 Rate of the given compound is  –OH (III) 2 −ClIV( ) (A) IIIIIIIV (B) IIIIIIIV (C) IIIIVIII (D) IIIIIIVI (I) (II) Q 15. In the reaction CH 3 NaOH H Br (III) (IV) CH2 SH The product formed is (A) I II  III  IV (B) IV III  II  I CH3 CH3 H OH HO H (C) IV III  I  II (D) II I  III  IV

(A) CH2 SH (B) CH2 SH Q 2. SN1 Rate is maximum in

CH3 CH3 H SH HS H (A) (B) (C) CH2 OH (D) CH2 OH Q 16. Which reaction has faster speed

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Q 3. The given reaction intermediates are not observed in the given reaction is (C) (D) None of these

Q 7. The correct order of Nucleophilicity in polar protic solvent is

  C H C322 H C H –O C H322 C H C H – S (A) (B) I II

CH3 O

 O CH–3 C – C – O (C) (D)  CH3 CH CH32 C –O Q 4. The major product in the given reaction would be II I IV

(A) I I I I  I I  I V (B) I I I I I  I I V

Q 8. The correct order of SN2 rate of reaction is

Br Br (A) (B)

CH3 O (I) (II)

Br Br (C) (D) CH3 ON2 (III) (IV) Q 5. Correct order of SN1 Rate of given compound is (A) I II  III  IV (B) III I  II  IV

(A) IIIIIIIV (B) IIIIVIII Q 9. (C) IIIVIIII (D) IIIIVIII (Major product), P would be

Q 6. In which of the following case, SN1 rate is almost negligible (A) (B)

(A) (B) (C) (D)

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Q 10. Correct order of SN2 rate is Q 13. Major product (P), P would be

(A) (B)

(A) I I I I  I I  I V (B) I I I I I I  I V

Q 11. Products would not be

Q 14. P would be

(A) (B) (A) (B) (C) both A and B (D) None of these

major product (P), P would be

Q 12. Product (P), P would be (A) (B)

(A) (B) (C) (D)

Q 16. Kl in acetone, undergoes SN2 reaction with each of P,Q,R and S. The rates of the reaction vary as

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H Br Zn/ C = C HC CH K Br H 1

H H Zn/ C = C HC CH K (A) P Q R S (B) S P R  Q Br Br 2 (C) P R Q  S (D) R P S  Q  (A) KK12 (B) KK12= (C) KK12 (D) can’t predict

Zn Q 6. ⎯⎯→ Product (P), P would be

5. Elimination Reaction – E1 & E2 Reaction Q 1. In elimination reaction, if base is strong, if follows (A) (B) (A) E1 pathway (B) E2 pathway (C) EI C B pathway (D) E2C B pathway Q 2. E1 C B pathway is followed by a substrate (C) (D) None of these molecule is (A) Carbocation is stable Q 7. E1 − Elimination rate is maximum in (B) Carbocation is less stable (C) Carbanion is stable (D) Carbanion is less stable (A) CHCBr (B) ( 3 )3 Q 3. In elimination reaction of CHRCHCl22−−, Which of the following way(s) are possible ? (A) Both CH&CCl−− bonds are cleaved (C) (D) simultaneously (B) First C C− l bond is cleaved & there CH− bond is cleaved Q 8. E1 C B rate is maximum in (C) First CH− bond is Cleaved & there C C− l

bond is cleaved (A) Ph−−− CH22 CH F (D) All are possible

Q 4. Anti – elimination is preferred because (B) O N−−− CH22 CH F (A) Antiperiplanar transition state is eclipsed 2 form (B) Antiperiplanar transition state is staggered form (C) (C) Antiperiplanar transition state has double bond character (D) Antiperiplanar transition state has +M group (D) Q 5. In the reaction Q 9. Arrange the following in decreasing order of E2 reaction

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Q 13. Which of the following halides undergo E2 elimination ?

(A) XYZ (B) XZY (A) (B)

Q 10. ⎯⎯⎯⎯→Alc.KOH Major product (C) (D)

Q 14. Which of the following can give E1 cb reaction ?

(A) (B) (A) (B)

Q 12.

(A) (B)

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6. E1 Vs E2 Reaction, E1CB Reaction Q 5. Which of the following reactions will give least alkyl substituted alkene? alc. Q 1. ⎯⎯⎯→ P (major product), P KOH (A) would be

(B)

(A) (B) (C)

(D) (C) (D)

 Q 6. OH− ⎯ ⎯→ product Q 2. P (major), P would be (P), P would be (A) CHN ( 3)3 (B) CH33−=− CH CH CH (C) CHCHCHCH=−− (A) (B) 223 (D) A and C both Q 7. The Hoffmann’s product is not the major product in the given reaction is

Q 3. (B) How many structures for F are possible? (A) 2 (B) 5 (C) 6 (D) 3

Q 4. (C) (major product), P would be (A) CH C= C CH ( 33)22( ) (D)

(B) (C) (CHCCHCH32) −= (i)AgOH 3 Q 8. ⎯⎯⎯⎯⎯→ P (major), P (D) None of these (ii) would be

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Q 12. Major product

(A) (B)

Q 9.

(A) (B)

Q 13. Major Product

Q 11.

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F 7. Elimination vs Substitution Reaction + H C33 – N – C H Q 1. Match the following (A) (B) Ph Column I A. CH3-CHBr-CD3 on treatment with alc.  Cl KOH gives CH2=CH-CD3 as a major product S B. Ph-CHBr-CH3 reacts faster than CH3 (C) HC3 (D) Ph-CHBr-CD3 C. Ph-CH2-CH2Br on treatment with - Q 16. In the reaction C2H5OD/C2H5O gives Ph-CD=CH2 as the O major product D. PhCH CH Br and PhCD CH Br react with AlC. KOH 2 2 2 2 same rate . Br Column II CH3 Product formed is O P. El reaction O Q. E2 reaction R. ElcB reaction S. First order reaction [IIT JEE 2006]

(A) CH3 (B) CH3 O Q 2. Which of the following reactions have identical Rds ? (A) SN&SN12 (B) SN&E11 OH (C) SN&22 E (D) both B & C

(C) CH3 (D) None of these Q 3. Which of the following reaction are parallel Q 17. In the reaction reactions? Alc. KOH (A) SN&SN (B) SN&E 12 11 (A) (B) (C) SN&22 E (D) All of these Q 4. Which of the following favour elimination (C) (D) reaction? Q 18. In the reaction CH O 3

CH 3– C – Cl CH3 + t - BuO¯ K CH  (A) 3 Br Product is Cl O O CH3 – CH – CH 2 – CH 3 CH3 (B) CH3 (A) (B) (C) CH3222 – CH – CH – CH – Cl

O O CH32 – CH – CH – Cl

CH3 CH3 (D) CH3 (C) (D) Q 5. E2 reaction is favoured in 3 R-X because (A) Incipent double bond is more stable Rishi Sir [B.Tech. IIT Kanpur] www.atozchemistry.com 96 Be Topper with Topper in Chemistry in JEE Main & JEE-ADV Contact No. +91 9852476717

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(B) Incipent double bond has more B-H-atoms (A) ionic mechanism (B) radical mechanism (C) Activation energy of E2 pathway is less (C) substitution mechanism (D) All of these (D) rearrangement mechanism Q 6. Elimination reactions are Q 3. The addition of HBr to propylene takes place (A) Endothermic (B) Exothermic opposite to Markownikoff’s rule in presence of (C) both A & B (D) none of these (A) sunlight (B) hydrogen peroxide Q 7. Which of the following condition favour (C) platinum catalyst (D) none of these substitution reaction? Q 4. Anti-Markownikoff’s addition is not observed in (A) high temperature (B) low temperature (A) propene (B) 1-butene (C) high pressure (D) low pressure (C) 2-pentene (D) 2-butene Q 8. In case of which of the following base, Q 5. Which of the following orders is correct for the elimination reaction is favoured each of electrophile addition on these alkenes? (A) KOH (B) t B− uO K −+

N | (A) I I I I I I (B) I I I I I I N (C) (D) H (C) I I I I I I (D) I I I I I I Q 9. Carbocation intermediate is formed in Q 6. In which of the following molecules, addition of (A) E1 pathway (B) SN1 pathway H-Cl form major product according to anti – (C) both A & B (D) None of these markownikoff rule Q 10. In which of the following case, intermediate (A) CHCHCH32−= (B) CHOCHCH32−= resemble to product by larger extent (C) ONCHCH22−= (D) CHCH22= (A) SN (B) SN (C) E (D) E 1 2 1 2 Q 7. Electrophilic addition reaction on alkene is Q 11. Which of the following has least nucleophilic favoured by strength? (A) Electron donar group (A) CHNH32 (B) PhNH− 2 (B) Electron acceptor group (C) Electron rich group (C) CHNH (D) CHN ( 2) ( 3)3 (D) Electron deficient group Q 8. Nucleophilic addition reaction as hemolytic double bond is possible in (A) CH33 O−=− CH CH OCH (B) F−=− CH CH F (C) CH OCHCH−= 32 8. Electrophilic Addition Reaction (D) F−=− CH CH NO2 Q 1. The reaction between ethylene and bromine is an Q 9. The reaction order of following alkene towards example of addition of HCl is (A) electrophilic addition (B) electrophilic substitution O (C) nucleophilic addition O N (D) nucleophilic substitution I II III Q 2. In addition reactions of alkenes, the (A) I II III (B) III I II Markownikoff’s rule follow (C) III II I (D) II I III

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Q 10. The reactivity order of following alkene towards 9. Electrophilic Aromatic Substitution addition of HC l is Q 1. Electrophilic addition reaction on benzene ring CHCHCH32−= CHOCHCH32−= does not occur because I II (A) Cation formed is instable (B) Anion formed is unstable CH CH2 =− Cl III (C) Aromaticity is lost on addition reaction (A) I I I I I I (B) I I I I I I (D) Benzene has no character required to undergo (C) II I II (D) III I II addition Q 11. The reactivity order of following alkene towards Q 2. In the reaction additional HBr is + Br2 /Fe CHOCHCH32−= Cl−= CH CH2 Product, is I II Br Br F CH−= CH CH CH= Br 2 22 Br III IV (A) I I I I  I I  I V (B) I I I I  I I  I V (A) (B) Br (C) I I V  I I I I I (D) I I V  I I I I I Br Br – Br Q 12. The reactivity order of following alkene towards Br CH2 addition HBr is Br ONCHCH22−= FCHCH−=2 Br I II (C) Br (D) Br

ClCHCH−=2 CHCHCH32−= III IV Q 3. In electrophilic aromatic substitution, transition (A) IV III  II  I (B) IV II  III  I states form are + (C) I II  III  IV (D) None of these H H Q 13. The reactivity order of following alkenes towards , + E addition of HCl is E (A) + + H H CH23 = CH – CH , + E E I (B) + + II + H H

+ , E E ' (C) '+ + H NO OCH 2 3 + III IV E (A) IIIVIIII (B) IIIVIIII (D) (C) IVIIIIII (D) IVIIIIII Q 4. The electrophile formed in reagent 'Br2 + Fe' is (A) Br+ (B) Br− (C) Br2 (D) None of these Q 5. The electrophile formed in the reagent 'HNO34+ HSO ' is

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(C) Trimolecular reaction (A) SO3 (B) NO2 (D) None of these   Q 11. In electrophilic aromatic substitution sometimes (C) NO2 (D) HO2 isotopic effect is found because O (A) CH− bond is deaved in Rds ' ' Q 6. The electrophile formed in R – C – Cl + AlCl3 (B) C–H bond is not eleaved in Rds is (C) Rds is reversible  (D) Rds is irreversible  (A) R C−= O (B) Cl Q 12. Which one of the following is most reactive  towards electrophilic attack ? (C) R (D) CO= Q 7. The electrophile formed in the reagent 'H S2 2O 7 ' is   (A) (B) (A) HO2 (B) SO3 2− (C) SO3 (D) SO27 Q 8. The structure of Wheland intermediate obtained (C) (D) + Q 13. Identify the correct order of reactivity in after the attack of Br on anilinium ion is electrophilic substitution reactions of the + H Br + H following compounds NH3 NH3 + Br + (A) (B) H Br +

+ H NH NH3 + + 3 Br (A) 1 2  3  4 (B) 4 3  2  1 (C) (D) (C) 2134 (D) 2314 + Q 9. The electrophile, E attacks benzene ring to Q 14. Which of the following carbocations is most generate the intermediate − complex of the stable? following, which −complex is of lowest energy?

NO2

NO2 + (A) (B) + H (A) E (B) H E

NO2 H H + E + E (C) (D) (C) (D) + Q 15. Electrophile NO2 attacks on the following Q 10. Electrophilic substitution reaction on benzene is a (A) unimolecular reaction (B) bimolecular reaction

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OCH3 OCH3 Cl

NO + (A) NO2 (B) 2 In which cases will NO2 be at meta-position ? Cl OCH3 (A) II and IV (B) I, II and III (C) II and III (D) I only

electrophilic substitution is CHCl/AlCl33

NO2 Major product is

OCH3 (A) OCH3

NO2

NO2 (A) CH3 (B) CH3 (B) OCH3 OCH3 HC3 CH3

NH2 (D) + R – Cl/ AlCl 3

CH3 Major product, is NH NH 10. Examples of Electrophilic Aromatic 2 2 R substitution Q 1. In the reaction R OCH 3 (A) CH3 (B) CH3 R Cl2 /Fe Product, is NH2 (Major)

NO2

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CHO Br2 A) N + Cl/Fe2

COOH Major product, is C H O CHO + HO Cl B) OH Cl Cl CH2 -Cl (A) C O O H (B) COOH Br2 /Fe Cl C H O C)

D) D2SO4 (C) C O O H (D) C O Cl N D2O Q 5. Among the following pairs of compounds, which H O=S-CH of more reactive in electrophilic aromatic 3 Br.2 /Fe Substitution? E) O-CH 2CH3 CH2-O CH3 OH

A) Or AlCl3 CH NO -CH-CH 3 2 F) + CH3 2 B) CH3 NO2 NO 2 CH3 1.Mg G) 2.DCl C) Or Br N CH3CH3 CH3 H CH3O NO2 Cl D) Or Q 7. H CH3 N O Compound on hydrolysis in aqueous acetone will H CH3 CH3 give [ IIT JEE 2005]

E) Or CH3 CH3 CH3 NO2 CH3 (I) CH3O NO2

Or H OH CH3 F) N N CH CH3 CH3 H 3 (II) CH3O NO2

G) Or OH H CH3 N CH3CH3 CH3 Q 6. Write the major product (s) in each of the following reactions (III) CH3O NO2 H CH3 OH (A) Mixture of (i) & (ii) (B) Mixture of (i) & (iii) Rishi Sir [B.Tech. IIT Kanpur] www.atozchemistry.com 101 Be Topper with Topper in Chemistry in JEE Main & JEE-ADV Contact No. +91 9852476717

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Q 8. Which one is more reactive toward electrophilic Major product, is aromatic substitution reaction? CH3 NO2 CH3 NO2 I (A) (B)

CH3 II CH3

NO2 NO2 (A) I (B) II CH HC (C) I & II are equally reactive (D) None (C) 3 (D) 3 Q 9. In the reaction

CHCl/AlCl33

O Product (Major), is CH3 11. Addition Elimination Pathway Q 1. On Ph-Br, SN1 reaction is not possible because O CH3 O (A) (B)  CH3 (A) Ph is not stable (B) Attack of Nucleophile is not possible CH − (C) O CH3 (D) HC3 O 3 (C) Electronic repulsion between e pair of Q 10. In the reaction Nucleophile &  electro cloud of beuzene ring (D) It is possible + HNO / H SO 324 Q 2. On PhBr,− SN2 reaction is not possible N Major product, because is  NO2 (A) Ph is not stable (B) Attack of Nucleophile is not possible (C) Electronic repulsion between pair of N (A) N (B) NO2 Nucleophile & electro cloud of beuzene ring NO2 (D) It is possible  (C) N (D) Mixture of A & B Q 3. PhNCl2 + HO2 → PhOH follows Q 11. In the reaction (A) SN1 pathway (B) SN2 pathway (C) SNAr pathway (D) None of these + HNO3 /H 24 SO Q 4. In SNAr pathway, the intermediate formed is Major product, is E E + X + X (A) (B) E/n Nu (A) NO2 (B) O2N

NO2 + X – X NO2 (C) (D) (C) (D) Q 5. The reactivity order of Ph-X is in SNAr reaction Q 12. In the reaction (A) PhI PhBr  PhCl  PhF

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(B) PhFPhClPhBrPhI Q 10. In nucleophilic aromatic substitution, the least (C) PhClPhBrPhIPhF leaving group tendency is for (D) PhBrPhIPhClPhF (A) F− (B) Cl− (C) H− (D) OH− Q 6. The reactivity order of the compound in SNAr Q 11. The SNAr reaction involves reaction (A) wheeland in termediate F F F F (B) Areniom ion intermediate (C) Meisenheimer intermediate (D) Benzyne intermediate

NO2 Q 12. The major product of the following reaction is

NO2 OCH II III 3 [IIT JEE 2008] I IV Me Br - + (A) I I I I  I I  I V (B) I I I I  I I  I V F PhS Na Dimethylformamide (C) I I V  I I I I I (D) I I I V  I I I I Q 7. In the reaction F NO2 F NaOH Me SPh Me SPh F F (A) (B) NO2 Product (Major) is OH F NO2 NO2 F OH Me Br Me SPh SPh SPh (C) (D) (A) NO2 (B) NO2 NO NO OH OH 2 2 OH Q 13. The product in the reaction OH F Q + NO2 OH (C) (D) Cl Q 8. SNAr pathway is also called CH NO (A) Addition elimination pathway 2 product, is (B) Elimination addition pathway (C) Benzyne pathway (D) Nucleophilic substitution Cl O O Q 9. The oder of SNAr pathway among the given O HO molecules is f O

NO2 NO2 OCH3

F OCH3 (A) NO2 (B) NO2

I F F F II III IV (A) I II  III  IV (B) II I  IV  III (C) II III  I  IV (D) II III  IV  I

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(C) H HBAC H (D) HHHBCA NO Cl 2 O HA O HB (C) NO2 (D) None of these Q 4. In the ring, HC the relative acidic Q 14. In the reaction strength order is F (A) H H H (B) H H H Cl ABC ACB  + NaOH (C) H HCAB H (D) H HBAC H ON 2 Q 5. In the reaction CHO OCH Major product is 3 OH F NaNH NaNH 2 A 2 B Cl OH Br (Not stable)

OCH3 OCH3 OCH3 OCH3 ON2 ON2 (A) C H O (B) C H O , , NH NH OH (A) 2 (B) 2 OCH OCH3 OH 3

OCH OCH , ON2 3 3 NH (C) CHO (D) None of these 2 NH2 , (C) (D) Q 6. In the reaction

CH3 R-mg x

12. Benzyne Pathway NH4 Cl Q 1. Benzyne pathway is also called F (A) Addition elimination pathway product formed is (B) Elimination addition pathway CH3 (C) Nucleophilic aromatic substitution CH3 (D) Electrophilic aromatic sbust Q 2. In benzyne,  bond outside the ring is formed by (A) R (B) R (A) Pz - orbitals (B) Py − orbitals CH3 2 CH R R (C) Px − orbitals (D) SP − orbital 3 R OCH3 HA (C) (D) R Q 7. In the reaction HB NO2 Q 3. In the ring HC , Relative acidic strength KNH KNH order is 2 C 2 D (A) HHHABC (B) HHHCBA Cl Rishi Sir [B.Tech. IIT Kanpur] www.atozchemistry.com 104 Be Topper with Topper in Chemistry in JEE Main & JEE-ADV Contact No. +91 9852476717

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C & D are NO 2 NO2 NO2 NO2 NO 2

(A) NO2 (B) (A) CN1 (B) SN2

NO2 NO2 (C) Addition-elimination NO NO 2 2 (D) Elimination-addition Q 11. Which of the following molecules will form

NO2 (C) NO2 (D) NO2 Q 8. In the reaction CHO benzyne at same position as done by Cl Ph li OC H3 NHCl4 OC H Cl product, is 3 C H O Br CHO (A) (B) Br

OCH3 CHO (A) Ph (B) Ph CHO CHO Ph Ph (C) Cl (D) Cl Ph Q 12. Benzyne is stablised by (C) (D) Ph (A) electron donar group Q 9. Which of the following reaction leads to (B) electron acceptor group substitution at meta position? (C) Not stablised by any group

NO2 CHO (D) Not stable at all Q 13. Benzyne is (A) Aromatic (B) Non –aromatic (C) Anti-Aromatic (D) None of these

(A) Cl (B) Cl

Cl OCH3

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Answer Key (15). I > III > II > IV 1. Introduction to Mechanism & Organic (16). B Reaction (1). A (2). C 3. SN1, SN2 Reaction 22()ABCSlow+⎯⎯→ (1). B (2). D (3). D (3). (4). D (5). A (6). B CBDFast+⎯⎯→ () (7). D (8). D (9). B (4). (10). B (11). B (12). C (A) 22ACDF+⎯⎯→+ (13). B (14). B (15). C (B) 2nd Step (16). D (17). B (18). A

E 4. SN1 vs SN2 Reaction & SNi Reaction B D+E (1). C (2). B (3). D + D+2F (4). B (5). C (6). D (C) Reaction co-ordinate (7). D (8). B (9). C (D) B, E (10). A (11). B (12). B (5). Kinetically controlled product (13). A (14). C (15). D (16). B  E 5. Elimination Reaction – E1 & E2 Reaction (1). B (2). C (3). D C A+B (4). B (5). C (6). A (7). C (8). D (9). B R.C. (10). A (11). C (12). A Thermodynamically controlled Product (13). A, B (14). A, B (15). B, C, D

E 6. E1 Vs E2 Reaction, E1CB Reaction (1). A (2). B (3). D A+B D (4). B (5). C (6). D R.C. (7). D (8). B (9). A (10). C (11). A (12). D (6). A (13). C (14). A (15). D (7). D (8). A (9). C (16). A (17). B (18). C (10). B (11). C (12). C

(13). D 7. Elimination vs Substitution Reaction

(1). A – Q ; B – Q, P ; C – R ; D – P, S 2. Substitution Reaction (2). B (3). D (1). B (2). B (3). C (4). A (5). D (6). A (4). A (5). C (6). B (7). B (8). C (9). C (7). B (8). A (9). C (10). C (11). D (10). B, D (11). D (12). C

(13). A (14). C

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8. Electrophilic Addition Reaction (1). A (2). A (3). B (4). D (5). C (6). C (7). A (8). D (9). B (10). C (11). D (12). B (13). D

9. Electrophilic Aromatic Substitution (1). C (2). A (3). C (4). A (5). C (6). A (7). C (8). B (9). C (10). B (11). C (12). A (13). C (14). A (15). B (16). C

10. Examples of Electrophilic Aromatic substitution (1). B (2). A (3). B (4). B (5). SUBJ. (6). SUBJ. (7). A (8). B (9). A (10). C (11). C (12). B

11. Addition Elimination Pathway (1). A (2). C (3). A (4). D (5). B (6). A (7). B (8). A (9). B (10). C (11). C (12). A (13). C (14). A

12. Benzyne Pathway (1). B (2). D (3). C (4). B (5). B (6). B (7). B (8). A (9). C, D (10). D (11). B, C, D (12). A (13). D

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