Free NEET Chemistry multiple-choice questions on Haloalkanes: SN1 vs SN2. Attempt each question and reveal the answer with a full explanation.
Which of the following compounds will undergo S N 1 reaction most readily? (CH 3) 3C-Br (CH 3) 2CH-Br (CH 3)CH 2-Br (CH 3)Br The bond dissociation energy of C-X bond in alkyl halides follows the order: CH 3F > CH 3Cl > CH 3Br > CH 3I CH 3I > CH 3Br > CH 3Cl > CH 3F CH 3Cl > CH 3F > CH 3Br > CH 3I CH 3F > CH 3Br > CH 3Cl > CH 3I Which of the following compounds will react with AgNO 3 to give a white precipitate of AgCl most rapidly? (C 6 H 5 ) 3 CCl C 6 H 5 Cl CH 2 =CHCl CH 3 Cl The reaction of an alkyl halide with sodium metal in dry ether to form a hydrocarbon is called Wurtz reaction. If a mixture of CH 3 I and C 2 H 5 I is used, how many different alkanes are formed? 3 1 2 4 Which of the following alkyl halides cannot be used to prepare a Grignard reagent? BrCH 2 CH 2 OH CH 3 CH 2 Br C 6 H 5 Br CH 2 =CHBr The heating of an alkyl halide with dry silver oxide ( Ag 2 O ) yields: Ether Alcohol Alkene Ester The reaction of CH 3 CH 2 CH 2 Cl with AlCl 3 (anhydrous) results in the formation of which major carbocation? Isopropyl carbocation n-Propyl carbocation Ethyl carbocation Methyl carbocation What is the major product formed when 1-chlorobutane is treated with sodium ethoxide in ethanol? Butyl ethyl ether 1-Butene 2-Butene Butanol Which among the following has the highest value of dipole moment? CH 2 Cl 2 CHCl 3 CCl 4 CH 3 Cl The correct order of boiling points for the following compounds is: CH 3 CH 2 CH 2 CH 2 Br > (CH 3 ) 2 CHCH 2 Br > (CH 3 ) 3 CBr (CH 3 ) 3 CBr > (CH 3 ) 2 CHCH 2 Br > CH 3 CH 2 CH 2 CH 2 Br (CH 3 ) 2 CHCH 2 Br > CH 3 CH 2 CH 2 CH 2 Br > (CH 3 ) 3 CBr (CH 3 ) 3 CBr > CH 3 CH 2 CH 2 CH 2 Br > (CH 3 ) 2 CHCH 2 Br What is the major product of the following reaction? CH 3 -CH=CH 2 + Cl 2 (at 500 C) CH 2 Cl-CH=CH 2 CH 3 -CHCl-CH 2 Cl CH 3 -CCl=CH 2 CH 3 -CH=CHCl The reaction of an alcohol with thionyl chloride ( SOCl 2 ) in the presence of pyridine follows which mechanism? S N 2 with inversion of configuration S N i with retention of configuration S N 1 with racemization Electrophilic substitution In S N 2 reactions, the 'Walden Inversion' refers to: Change in the spatial arrangement of groups around the chiral center Formation of a racemic mixture Rearrangement of the carbocation Conversion of cis to trans isomer Which of the following solvent systems would favor the S N 2 reaction between CH 3Br and OH - the most? Dimethyl sulfoxide (DMSO) Water Ethanol 50 % Ethanol - 50 % Water Which of the following compounds will have the highest melting point? p-Dichlorobenzene o-Dichlorobenzene m-Dichlorobenzene Chlorobenzene Which statement is true regarding the reactivity of Vinyl chloride ( CH 2=CHCl ) towards nucleophilic substitution? It is less reactive than ethyl chloride It is more reactive than ethyl chloride It is equally reactive as ethyl chloride It reacts via S N 1 very easily The reaction of an alkyl halide with Na/Pb alloy yields: Tetraethyl lead Diethyl lead Ethyl lead chloride Sodium ethoxide Identify the product C in the sequence: CH 3CH 2CH 2Br alc. KOH A HBr B aq. KOH C . 2-propanol 1-propanol Propene Propanal Hydrolysis of a gem-dihalide like CH 3CHCl 2 with aqueous KOH yields: Acetaldehyde Ethylene glycol Ethyl alcohol Acetic acid The correct order of density among the following is: CH 2I 2 > CH 2Br 2 > CH 2Cl 2 > C 2H 5Cl C 2H 5Cl > CH 2Cl 2 > CH 2Br 2 > CH 2I 2 CH 2Cl 2 > CH 2Br 2 > CH 2I 2 > C 2H 5Cl CH 2I 2 > C 2H 5Cl > CH 2Br 2 > CH 2Cl 2 Which of the following will undergo dehydrohalogenation most rapidly when treated with alcoholic KOH ? 2-Iodopentane 2-Chloropentane 2-Bromopentane 2-Fluoropentane Which of the following molecules has a zero dipole moment? trans-1,2-dichloroethene cis-1,2-dichloroethene Vinyl chloride Methylene chloride Which of the following halides will give the most stable carbocation upon ionization? (C 6H 5) 3CCl (C 6H 5) 2CHCl C 6H 5CH 2Cl (CH 3) 3CCl Treatment of CS 2 with Cl 2 in the presence of AlCl 3 gives: CCl 4 CHCl 3 CH 2Cl 2 CH 3Cl What happens when 2-bromobutane is treated with Na in dry ether? 3,4-dimethylhexane is formed n-octane is formed Butane is formed 2-butene is formed Which of the following metal fluorides is NOT typically used in the Swarts reaction? CaF 2 AgF Hg 2F 2 SbF 3 The reaction of an alkyl halide with potassium nitrite ( KNO 2 ) yields mainly: Alkyl nitrite ( R-ONO ) Nitroalkane ( R-NO 2 ) Alkyl amine Alcohol Hydrolysis of 2,2-dichloropropane with aqueous KOH yields: Acetone Propanal Propane-2,2-diol Isopropyl alcohol The correct order of boiling points for isomeric butyl chlorides is: n-butyl chloride > isobutyl chloride > sec-butyl chloride > tert-butyl chloride tert-butyl chloride > sec-butyl chloride > isobutyl chloride > n-butyl chloride n-butyl chloride > sec-butyl chloride > isobutyl chloride > tert-butyl chloride isobutyl chloride > n-butyl chloride > sec-butyl chloride > tert-butyl chloride Which of the following statements explains why p -dichlorobenzene has a higher melting point than its ortho and meta isomers? It has a more symmetrical structure that fits better into the crystal lattice It has a higher dipole moment It is more soluble in organic solvents It has stronger C-Cl bonds Which of the following is the most suitable solvent to increase the rate of an S N 2 reaction? N,N-Dimethylformamide (DMF) Water Ethanol Acetic acid In the presence of UV light, toluene reacts with Cl 2 at its boiling point to form benzyl chloride. Further chlorination yields: Benzotrichloride o -chlorotoluene p -chlorotoluene 2,4-dichlorotoluene The reaction of an alkyl halide with LiAlH 4 typically produces: Alkane Alcohol Alkene Alkyne Chlorine is more electronegative than Iodine, yet the rate of S N 2 reaction is faster for alkyl iodides than alkyl chlorides because: I - is a better leaving group than Cl - I - is a weaker nucleophile C-I bond is stronger than C-Cl bond Iodine has a smaller atomic size Synthesis of alkyl fluorides is best accomplished by: Swarts reaction Free radical fluorination Sandmeyer's reaction Finkelstein reaction Which of the following is used to prepare vinyl chloride from acetylene? HCl in the presence of HgCl 2 Cl 2 in the presence of FeCl 3 HCl in the presence of CuCl Cl 2 in water How many chiral centers are present in the molecule 2,3-dichlorobutane? 2 1 0 3 The major product formed when 1-bromo-1-methylcyclohexane is treated with a bulky base like potassium tert-butoxide is: Methylenecyclohexane 1-methylcyclohexene 1-methylcyclohexanol Cyclohexane In an S N 2 reaction, which of the following solvents will provide the highest rate of reaction for the displacement of Br - from CH 3 Br by OH - ? DMSO H 2 O CH 3 OH CH 3 CH 2 OH Identify the organic product of the reaction: CH 3 CH 2 Cl → (Li, –78 ℃ , dry ether ) . Ethyl lithium Ethane Butane Ethyl magnesium chloride The reaction of CH 3 CH 2 CH 2 Br with Mg in dry ether followed by treatment with D 2 O yields: CH 3 CH 2 CH 2 D CH 3 CH 2 CH 3 CH 3 CH(D)CH 3 CH 3 CH 2 CH 2 OD Which among the following is the correct order of bond dissociation enthalpy for methyl halides? CH 3 -F > CH 3 -Cl > CH 3 -Br > CH 3 -I CH 3 -I > CH 3 -Br > CH 3 -Cl > CH 3 -F CH 3 -Cl > CH 3 -F > CH 3 -Br > CH 3 -I CH 3 -F > CH 3 -I > CH 3 -Br > CH 3 -Cl What is the product B in the following sequence? Ethyne → (HCl, 1 eq ) → A → (HCl, 1 eq ) → B 1,1-dichloroethane 1,2-dichloroethane Vinyl chloride Ethylidene chloride The transition state of an S N 2 reaction involves a carbon atom that is: sp 2 hybridized sp 3 hybridized sp hybridized Unhybridized In the presence of light, CH 4 reacts with Cl 2 to give CH 3 Cl, CH 2 Cl 2 , CHCl 3 and CCl 4 . The best way to obtain CH 3 Cl as the major product is to use: Excess of CH 4 Excess of Cl 2 Equal amounts of CH 4 and Cl 2 High temperature and catalyst Among the following, which one is a vicinal dihalide? 1,2-Dichloroethane Ethylidene chloride Methylene chloride 1,1-Dichloroethane Which of the following has the highest dipole moment among the isomers of dichlorobenzene? o-dichlorobenzene m-dichlorobenzene p-dichlorobenzene All have the same Reaction of CH 3 I with Na in dry ether yields Ethane. If the reaction is carried out in the presence of CH 3 CH 2 I , the product(s) formed is/are: Ethane, Propane, and Butane Only Propane Ethane and Butane Only Butane Which of the following methods for preparing alkyl chlorides is considered superior due to the formation of gaseous side products that escape the reaction mixture? Reaction of alcohols with thionyl chloride ( SOCl 2 ) Reaction of alcohols with PCl 3 Reaction of alcohols with PCl 5 Reaction of alcohols with HCl/ZnCl 2 Identify the correct order of nucleophilicity in a polar aprotic solvent like DMSO . F - > Cl - > Br - > I - I - > Br - > Cl - > F - Cl - > F - > Br - > I - I - > Cl - > Br - > F - The dehalogenation of a vicinal dihalide like 1,2-dibromoethane to form an alkene is best achieved using: Zinc dust and ethanol Alcoholic KOH Aqueous NaOH Sodium in dry ether What is the product formed when n -butyl bromide is treated with Li metal in dry ether? n -butyl lithium n -octane But-1-ene Butane The reaction of an alkyl halide with sodium acetylide ( HC CNa ) leads to the formation of: Higher alkynes Alkenes Alkanes Alcohols Which of the following will have the highest rate of S N 1 solvolysis in aqueous acetone? 3-Chloro-3-methylpentane 2-Chloro-2-methylbutane 2-Chlorobutane 1-Chlorobutane Which of the following compounds will produce a racemic mixture of alcohols when hydrolyzed with aqueous KOH ? 2-Bromobutane 1-Bromobutane 2-Bromo-2-methylpropane Bromobenzene Which property of p -dichlorobenzene makes it more suitable for use as a moth repellent compared to its isomers? High volatility and symmetrical structure High solubility in water Lower melting point Reaction with oxygen In the presence of AlCl 3 , benzene reacts with CH 3Cl to produce toluene. This reaction is an example of: Electrophilic substitution Nucleophilic substitution Free radical substitution Electrophilic addition What is the effect of increasing the polarity of the solvent on the rate of an S N 1 reaction? It increases the rate by stabilizing the transition state and intermediate ions It decreases the rate by solvating the nucleophile It has no effect on the rate It changes the mechanism to S N 2 When 2-bromopropane is treated with alcoholic KOH , the major product is propene. What is the mechanism of this reaction? E2 E1 S N 1 S N 2 The ease of hydrolysis of the following halides follows the order: (I) CH 3 CH 2 Cl , (II) CH 2 =CHCl , (III) C 6 H 5 Cl . I > II > III III > II > I I > III > II II > I > III In the reaction: R-X + NaOR' R-O-R' + NaX , which type of alkyl halide R-X gives the best yield of ether? Primary alkyl halide Secondary alkyl halide Tertiary alkyl halide Aryl halide The dipole moment of CH 2 Cl 2 is non-zero because: The C-Cl and C-H bond dipoles do not cancel each other out The molecule is linear The C-Cl bond is non-polar The molecule has a center of symmetry What is the product B in the sequence: CH 3 I KCN A LiAlH 4 B ? CH 3 CH 2 NH 2 CH 3 NH 2 CH 3 CH 3 CH 3 CONH 2 Among the following alkyl halides, which one has the lowest rate of S N 2 reaction due to maximum steric hindrance at the -carbon? (CH 3 ) 3 CCH 2 Cl (CH 3 ) 2 CHCH 2 Cl CH 3 CH 2 CH 2 CH 2 Cl CH 3 CH(CH 3 )CH 2 CH 2 Cl The reaction of an alkyl halide with AgNO 2 primarily produces a nitroalkane ( R-NO 2 ), whereas with KNO 2 it yields an alkyl nitrite ( R-O-N=O ). This is because: AgNO 2 is covalent, so the nitrogen lone pair attacks the carbon. KNO 2 is covalent, so the oxygen attacks the carbon. AgNO 2 is ionic, and the oxygen is the more electronegative center. The Ag-O bond is stronger than the K-O bond. In the chlorination of propene at 773 K , the major product is CH 2 =CH-CH 2 Cl . This reaction proceeds via which mechanism? Free radical substitution Electrophilic addition Nucleophilic substitution Free radical addition Which of the following compounds will react with terminal alkynes (like propyne) in the presence of a base to form a higher alkyne? CH 3 Br CH 2 =CHCl C 6 H 5 Cl (CH 3 ) 3 CCl What is the product of the reaction of 1-bromopropane with Na in dry ether? n-Hexane n-Propane Propene Cyclopropane The major product of the reaction between n -propyl bromide and potassium cyanide in aqueous ethanol is n -propyl cyanide. If silver cyanide is used instead, the major product is n -propyl isocyanide. This happens because: CN - is an ambident nucleophile. KCN is covalent while AgCN is ionic. AgCN is a better reducing agent. Propyl group prefers nitrogen over carbon. In the transition state of an S N 2 reaction, the central carbon atom is bonded to five groups. What is the approximate hybridization and geometry of this carbon? sp 2 , Trigonal bipyramidal sp 3 , Pentagonal dsp 2 , Square planar sp 3 d , Octahedral Which of the following compounds has the highest dipole moment? CH 3 Cl CH 3 F CH 3 Br CH 3 I Which of the following is an example of an S N 1 reaction with rearrangement? Hydrolysis of 2-bromo-3-methylbutane Hydrolysis of 2-bromobutane Reaction of methyl chloride with KOH Reaction of ethyl bromide with aq. NaOH The reaction of toluene with Cl 2 in the presence of FeCl 3 yields o - and p -chlorotoluene, but in the presence of light and heat it yields benzyl chloride. This is because: Light facilitates free radical substitution on the side chain. Light acts as a Lewis acid catalyst. FeCl 3 stabilizes the benzyl radical. The side chain is more deactivated than the ring. The E2 elimination reaction of 2-bromobutane with ethoxide ion follows which stereochemical requirement? Anti-periplanar geometry Syn-periplanar geometry Staggered conformation only Planar transition state with no specific orientation Which of the following orders is correct for the density of the given haloalkanes? CH 3 I > CH 3 Br > CH 3 Cl > H 2 O CH 3 Cl > CH 3 Br > CH 3 I > H 2 O H 2 O > CH 3 I > CH 3 Br > CH 3 Cl CH 3 Br > CH 3 I > CH 3 Cl > H 2 O Which of the following alkyl halides is expected to be the most reactive towards an S N 1 reaction in a polar protic solvent? (C 6 H 5 ) 3 C-Cl (C 6 H 5 ) 2 CH-Cl C 6 H 5 CH 2 -Cl C 6 H 5 Cl In the S N 2 reaction of CH 3 I with OH - , if the concentration of OH - is doubled and the concentration of CH 3 I is halved, the rate of the reaction will: Remain the same Double Halve Increase by four times The major product of the treatment of 'Westron' ( CHCl 2 CHCl 2 ) with alcoholic KOH is 'Westrosol'. What is the IUPAC name of 'Westrosol'? Trichloroethene 1,1,2,2-tetrachloroethene 1,1-dichloroethene 1,2-dichloroethene What is the correct order of C-X bond length in the following methyl halides? CH 3I > CH 3Br > CH 3Cl > CH 3F CH 3F > CH 3Cl > CH 3Br > CH 3I CH 3Cl > CH 3F > CH 3Br > CH 3I CH 3I > CH 3Cl > CH 3Br > CH 3F Which of the following compounds will not undergo S N 2 reaction even with a strong nucleophile due to excessive steric hindrance at the -carbon? Neopentyl bromide n -Propyl bromide Isobutyl bromide Isopropyl bromide What is the product of the reaction between 1-bromobutane and Mg in dry ether, followed by reaction with CH 3 OH ? n -Butane 1-Butanol Methyl n -butyl ether Pentane The reaction of an alkyl halide with AgCN produces an isocyanide. This is because: The bond between Ag-C is predominantly covalent. The bond between Ag-C is predominantly ionic. The cyanide ion is a monodentate nucleophile. Silver is a highly reactive metal. Which of the following haloalkanes would react most rapidly with AgNO 3 to produce a precipitate? Allyl bromide Vinyl bromide Bromobenzene Ethyl bromide The rate of S N 1 reaction is fastest in which of the following solvents? H 2 O CH 3 OH CH 3 CH 2 OH Acetone The treatment of ethyl bromide with excess ammonia under pressure yields: Ethylamine Diethylamine Triethylamine Tetraethylammonium bromide Which of the following is the correct decreasing order of nucleophilicity in a polar protic solvent like water? I - > Br - > Cl - > F - F - > Cl - > Br - > I - Cl - > Br - > I - > F - I - > Cl - > Br - > F - What happens when 2-bromopentane is treated with sodium ethoxide in ethanol? Pent-2-ene is the major product. Pent-1-ene is the major product. 2-ethoxypentane is the only product. Pent-2-yne is formed. Which of the following compounds will undergo racemisation when solution of KOH hydrolyses? (i) and (ii) (ii) and (iv) (iii) and (iv) (i) and (iv) For the following reactions :- Which of the following statements is correct ? (a) and (b) are elimination reaction and (c) is addition reaction (a) is elimination, (b) is substitution and (c) is addition reaction (a) is elimination, (b) and (c) are substitution reactions (a) is substitution, (b) and (c) are addition reaction Which of the following statements is FALSE regarding the S N 2 reaction? The rate of reaction depends only on the concentration of the alkyl halide. The reaction proceeds through a single-step transition state. The reaction is accompanied by complete inversion of configuration. The order of reactivity for alkyl halides is Methyl > Primary > Secondary > Tertiary. Elimination reaction of 2-Bromo-pentane to form pent-2-ene is (a) -Elimination reaction (b) Follows Zaitsev rule (c) Dehydrohalogenation reaction (d) Dehydration reaction (a), (c), (d) (b), (c), (d) (a), (b), (d) (a), (b), (c) Identify the final product [D] obtained in the following sequence of reactions. C 4 H 10 HC C - Na + The compound that will undergo S N1 reaction with the fastest rate is Major products A and B formed in the following reaction sequence, are The following two reactions give the same foul smelling product Z. X and Z, respectively, are : X = AgCN; Z = C2H5CN X = AgCN; Z = C2H5NC X = KCN; Z = C2H5CN X = KCN; Z = C2H5NC An organic compound A on reaction with Na in ether gives a hydrocarbon which on monochlorination gives only one chloro derivative. A is: t -butyl chloride s -butyl chloride n -butyl chloride Isobutyl chloride The reaction of ethyl bromide with AgNO 2 produces: Nitroethane Ethyl nitrite Ethane Nitrobenzene Among the following, the one which has the highest dipole moment is: CH 2Cl 2 CH 3Cl CHCl 3 CCl 4 The reaction of an alcohol with thionyl chloride ( SOCl 2 ) in the absence of pyridine proceeds via which mechanism to give an alkyl chloride with retention of configuration? S N i S N 1 S N 2 S N Ar The reaction of vinyl chloride with HCl gives: 1,1-Dichloroethane 1,2-Dichloroethane Chloroethane No reaction In the replacement of -OH from an alcohol by -Cl using PCl 5 , the other products are: POCl 3 and HCl PCl 3 and HCl POCl 3 and H 2 H 3PO 3 and HCl Identify 'Z' in the following sequence: C 2H 5I alc. KOH X Br 2 Y KCN Z Succinic nitrile Butanenitrile Propionitrile Malonic nitrile The dipole moment of CH 3Cl is greater than that of CH 3F because: The C-Cl bond length is significantly larger than the C-F bond length Fluorine is more electronegative than chlorine Chlorine has more electrons than fluorine The C-F bond is more polar than the C-Cl bond The major product formed when 2-bromo-3-methylbutane is treated with potassium tert-butoxide ( t-BuOK ) is: 3-methyl-1-butene 2-methyl-2-butene 2-methyl-1-butene 2-ethoxy-3-methylbutane The reaction of 1,1,1-trichloroethane with aqueous KOH yields: Acetic acid Acetaldehyde Ethyl alcohol Chloroform The reaction of vinyl chloride with HI gives: 1-chloro-1-iodoethane 1-chloro-2-iodoethane 1,2-dichloroethane Vinyl iodide The reaction of 2-bromo-3,3-dimethylbutane with ethanol at high temperature leads to which major product via a carbocation rearrangement? 2-ethoxy-2,3-dimethylbutane 2-ethoxy-3,3-dimethylbutane 3-ethoxy-2,2-dimethylbutane 1-ethoxy-3,3-dimethylbutane For the S N 1 reaction of (R)-2 -bromooctane with KOH in an aqueous ethanol solvent, the product obtained is: Nearly racemic 2-octanol with slight inversion Pure (S) -2-octanol Pure (R) -2-octanol Nearly pure (R) -2-octanol with slight retention Which of the following is the most reactive towards nucleophilic substitution ( S N 2 )? CH 3 OCH 2 Cl CH 3 CH 2 Cl (CH 3 ) 2 CHCl CH 3 Cl Which of the following alkyl halides is practically inert to both S N 1 and S N 2 mechanisms due to structural constraints? 1-bromobicyclo[2.2.1]heptane 1-bromopentane 2-bromopentane Allyl bromide What is the major product formed when 1-bromo-2,2-dimethylpropane reacts with ethanol under S N 1 conditions? 2-ethoxy-2-methylbutane 1-ethoxy-2,2-dimethylpropane 2-ethoxy-3-methylbutane 2,2-dimethyl-1-butanol Which of the following has the highest boiling point? CH 3 CH 2 CH 2 CH 2 I CH 3 CH 2 CH 2 CH 2 Cl CH 3 CH 2 CH 2 CH 2 Br CH 3 CH 2 CH 2 CH 2 F The reaction of CH 3CH 2Cl with AgCN produces X as the major product. The functional group in X is: Isocyanide Cyanide Amine Nitrite In the presence of peroxide, addition of HCl to propene gives: 2-chloropropane 1-chloropropane 1,2-dichloropropane Propyl alcohol During the S N 2 reaction of a methyl halide, the carbon atom in the transition state is in which hybridization state? sp 2 sp 3 sp sp 3d What is the major product when neopentyl bromide is heated with ethanol via the S N 1 mechanism? 2-ethoxy-2-methylbutane 1-ethoxy-2,2-dimethylpropane 2-ethoxy-3-methylbutane 2-methyl-2-butene What is the major product obtained when ethyl bromide reacts with silver thiocyanate ( AgSCN )? Ethyl isothiocyanate ( C 2H 5NCS ) Ethyl thiocyanate ( C 2H 5SCN ) Ethyl sulfide Ethyl mercaptan Which of the following alkyl halides will undergo S N 2 reaction most slowly due to steric hindrance (beta-branching)? 1-Bromo-2,2-dimethylpropane 1-Bromobutane 1-Bromo-2-methylpropane 1-Bromo-3-methylbutane Which of the following is produced when 2-methylbutane undergoes monochlorination in the presence of sunlight? A mixture of four structural isomers Only one structural isomer A mixture of two structural isomers A mixture of three structural isomers Which of the following alkyl halides is essentially inert to both S N 1 and S N 2 mechanisms due to the high strain associated with forming a planar carbocation or undergoing backside attack? 1-bromobicyclo[2.2.1]heptane 1-bromopentane 2-bromopropane Benzyl bromide In the S N 2 reaction of (S)-2 -iodobutane with sodium cyanide in DMSO , the product formed is: (R)-2 -methylbutanenitrile (S)-2 -methylbutanenitrile Racemic 2-methylbutanenitrile (R)-2 -iodobutane The reaction of an alkyl halide with sodium in liquid ammonia is primarily used for: Reduction to alkanes Synthesis of higher alkanes Elimination to alkenes Formation of alkynes The major product formed by the reaction of 1-chloro-2,2-dimethylpropane with C 2 H 5 ONa/C 2 H 5 OH is: 2-ethoxy-2-methylbutane 1-ethoxy-2,2-dimethylpropane 2-methyl-2-butene No reaction Which among the following is the best leaving group? I - Br - Cl - F - In the S N 2 reaction of I - with CH 3 Cl , the transition state possesses which of the following characteristics? Carbon is sp 2 hybridized with a p-orbital overlapping with both nucleophile and leaving group Carbon is sp 3 hybridized and maintains tetrahedral geometry Carbon is sp 2 hybridized with no p-orbital involvement Carbon forms a stable carbocation intermediate The reaction of 1 -chloropropane with Cl 2 in the presence of UV light produces how many isomeric dichloropropanes? 4 3 2 5 Which of the following alkyl halides is most likely to undergo rearrangement during an S N 1 reaction? 2-Chloro-3-methylbutane 2-Chloropentane 1-Chloropropane 3-Chloro-3-methylpentane In S N 1 reactions, the formation of a racemic mixture is often accompanied by 'partial inversion'. This phenomenon occurs because: The leaving group hinders the attack of the nucleophile from the front side. The carbocation is not perfectly planar. The solvent molecules stabilize only the inverted transition state. The reaction follows a mixed S N 1/S N 2 pathway. Which of the following alkyl halides will be most reactive towards S N 1 solvolysis in aqueous ethanol? C 6 H 5 CH(Cl)CH 3 C 6 H 5 CH 2 Cl CH 2 =CHCH 2 Cl CH 3 CH 2 CH 2 Cl Identify the major product formed when 1-bromo-2,2-dimethylpropane is reacted with ethanol at high temperature. 2-ethoxy-2-methylbutane 1-ethoxy-2,2-dimethylpropane 2-ethoxy-3-methylbutane 2,2-dimethyl-1-pentene Which of the following statements is correct regarding the stereochemistry of the E2 elimination reaction of alkyl halides? It requires an anti-periplanar geometry of the H and X atoms. It requires a syn-periplanar geometry of the H and X atoms. It proceeds with complete racemization of the -carbon. It proceeds via a planar carbocation intermediate. The compound (S) -2-chlorobutane reacts with KCN in DMSO to give a product that is: Optically active (R) -2-cyanobutane Optically active (S) -2-cyanobutane A racemic mixture of 2-cyanobutane Optically inactive 2-cyanobutane If the rate of S N 1 reaction of an alkyl halide in 50% aqueous ethanol is R , then increasing the water content to 80% will: Increase the rate Decrease the rate Not change the rate Stop the reaction The process of splitting a racemic mixture into its pure enantiomers is known as: Resolution Racemization Inversion Retention What is the correct order of the rate of S N 2 reaction for the following alkyl halides: (I) CH 3 Cl , (II) CH 3 CH 2 Cl , (III) (CH 3 ) 2 CHCl , (IV) (CH 3 ) 3 CCl ? I > II > III > IV IV > III > II > I I > III > II > IV III > II > I > IV What is the expected order of reactivity for E2 elimination for the following halides? R-I > R-Br > R-Cl > R-F R-F > R-Cl > R-Br > R-I R-Cl > R-Br > R-I > R-F R-Br > R-I > R-Cl > R-F The reaction C 2 H 5 Br + KSH C 2 H 5 SH + KBr is an example of: Nucleophilic substitution Electrophilic substitution Nucleophilic addition Free radical substitution Which of the following leads to the formation of a 'Vinylic halide'? Addition of HCl to acetylene Reaction of ethanol with PCl 5 Chlorination of methane Reaction of propene with Cl 2 at 500 C Treatment of 2-chlorobutane with NaI in acetone results in the formation of 2-iodobutane. This reaction is an example of: Finkelstein reaction Swarts reaction Wurtz reaction Etard reaction The solubility of haloalkanes in water is very low because: They cannot form hydrogen bonds with water molecules. They are non-polar compounds. The C-X bond is too strong to be broken by water. Water molecules are too small to solvate the halides. Arrange the following compounds in increasing order of their boiling points: (I) CH 3CH 2CH 2CH 2Br , (II) (CH 3) 2CHCH 2Br , (III) (CH 3) 3CBr . III < II < I I < II < III II < I < III III < I < II The C-X bond energy follows the order: C-F > C-Cl > C-Br > C-I C-I > C-Br > C-Cl > C-F C-Cl > C-F > C-Br > C-I C-F > C-Br > C-Cl > C-I The reaction of CH 3CH 2CH 2Br with NaI in dry acetone is known as: Finkelstein reaction Swarts reaction Wurtz reaction Sandmeyer reaction Which of the following is most reactive towards S N 2 reaction? CH 3Cl CH 3CH 2Cl (CH 3) 2CHCl (CH 3) 3CCl The reaction R-Br + Mg dry ether R-Mg-Br requires anhydrous conditions because Grignard reagents react with water to form: Alkanes Alcohols Ketones Acids What is the role of anhydrous AlCl 3 in the Friedel-Crafts alkylation of benzene? To produce an electrophile To produce a nucleophile To absorb water To act as a solvent Which of the following is the correct order of decreasing S N 2 reactivity? R-I > R-Br > R-Cl > R-F R-F > R-Cl > R-Br > R-I R-Cl > R-Br > R-I > R-F R-Br > R-I > R-Cl > R-F Reaction of CH 3Br with Na in dry ether gives ethane. This is an example of: Wurtz reaction Fitting reaction Wurtz-Fittig reaction Frankland reaction The boiling point of ethyl chloride ( 12 C ) is much lower than that of ethyl alcohol ( 78 C ) because: Ethyl alcohol molecules form intermolecular hydrogen bonds Ethyl chloride is more volatile Ethyl alcohol has a higher molecular weight Ethyl chloride is non-polar The reaction of n -propyl bromide with KCN in aqueous ethanol gives n -propyl cyanide as the major product. The nucleophile in this reaction is: CN - K + OH - CH 3CH 2O - The best method for the preparation of alkyl chlorides from alcohols is the reaction of alcohol with: Thionyl chloride in the presence of pyridine PCl 3 PCl 5 Dry HCl in the presence of anhydrous ZnCl 2 The boiling points of alkyl halides follow the order: RI > RBr > RCl > RF RF > RCl > RBr > RI RCl > RBr > RF > RI RBr > RI > RCl > RF The reaction of chlorine with excess methane in the presence of diffused sunlight gives mainly: CH 3 Cl CH 2 Cl 2 CHCl 3 CCl 4 Which alcohol will show turbidity immediately upon treatment with Lucas reagent at room temperature? 2-methylpropan-2-ol Butan-1-ol Butan-2-ol Ethanol The reaction R-X + 2Na → R-R + 2NaX is most efficient when R is: Primary alkyl group Tertiary alkyl group Aryl group Vinyl group The IUPAC name of the compound (CH 3) 2CH-CH 2-CH 2-Br is: 1-Bromo-3-methylbutane 4-Bromo-2-methylbutane 2-Methyl-4-bromobutane Isobutyl bromide The conversion of an alkyl halide into an ether by reacting with sodium alkoxide is known as: Williamson Synthesis Fittig Reaction Wurtz Reaction Kolbe's Synthesis Which reagent is most suitable for the 'Allylic Bromination' of propene to produce 3-bromopropene? N -Bromosuccinimide (NBS) / hv Br 2 in CCl 4 / Dark HBr / Peroxide PBr 3 Finkelstein reaction is used to prepare: Alkyl iodides Alkyl fluorides Alkyl chlorides Alkyl bromides The dehydrohalogenation of 2-bromo-2-methylbutane using sodium ethoxide in ethanol yields predominantly 2-methyl-2-butene. This follows: Saytzeff's rule Hofmann's rule Markovnikov's rule Anti-Markovnikov's rule The Beilstein test is used for the qualitative detection of which elements in an organic compound? Halogens Nitrogen Sulphur Oxygen Which of the following haloalkanes has the highest density? CH 3 I CH 3 Br CH 3 Cl CH 3 F Which of the following compounds will not show optical activity? 2-chlorobutane 2-bromopentane 1-chloro-2-methylbutane 1-chlorobutane Reaction of 1,2-dibromoethane with zinc dust in ethanol yields: Ethene Ethane Ethyl bromide Ethyne Which of the following is used as the 'Halogen Carrier' in the chlorination of benzene to stabilize the electrophile? FeCl 3 AlCl 3 (hydrated) H 2 SO 4 NaOH Identify the 'ambident' nucleophile among the following options: NO 2 - OH - NH 3 Cl - In the Sandmeyer reaction, the catalyst used for the conversion of benzene diazonium chloride to chlorobenzene is: Cu 2 Cl 2 /HCl Cu/HCl FeCl 3 AlCl 3 Identify the reagent 'X' in the conversion: CH 3 CH 2 OH + X CH 3 CH 2 Cl + H 3 PO 3 . PCl 3 PCl 5 SOCl 2 HCl/ZnCl 2 The boiling point of alkyl halides increases with the increase in the size of the halogen atom. This is primarily due to: Increase in van der Waals forces Increase in dipole-dipole interactions Decrease in molecular mass Increase in hydrogen bonding Which of the following is the chemical formula for 'Ethylidene chloride'? CH 3 CHCl 2 ClCH 2 CH 2 Cl CH 3 CH 2 Cl Cl 2 CHCHCl 2 Which of the following represents the correct order of bond dissociation enthalpy for the carbon-halogen bond in methyl halides? CH 3 -F > CH 3 -Cl > CH 3 -Br > CH 3 -I CH 3 -I > CH 3 -Br > CH 3 -Cl > CH 3 -F CH 3 -Cl > CH 3 -F > CH 3 -Br > CH 3 -I CH 3 -F > CH 3 -Br > CH 3 -Cl > CH 3 -I The Finkelstein reaction ( R-X + NaI R-I + NaX ) is usually carried out in dry acetone. The role of acetone is to: Precipitate NaCl or NaBr to shift the equilibrium forward. Act as a catalyst for the S N 1 mechanism. Solvate the Na + ions more effectively than water. Increase the boiling point of the reaction mixture. In S N 2 reactions, the correct order of reactivity for the following halides is: CH 3F < CH 3Cl < CH 3Br < CH 3I CH 3I < CH 3Br < CH 3Cl < CH 3F CH 3Cl < CH 3F < CH 3Br < CH 3I CH 3I < CH 3Cl < CH 3Br < CH 3F Which of the following properties of dichloromethane ( CH 2 Cl 2 ) makes it a common choice as a solvent for paint stripping? High volatility and ability to dissolve organic coatings. Highly non-flammable and low toxicity. High boiling point and strong ionic character. Ability to form hydrogen bonds with the surface. The reaction C 2 H 5 Cl + KCN C 2 H 5 CN + KCl is carried out in aqueous ethanol. What is the role of ethanol? To act as a co-solvent to dissolve both the alkyl halide and the salt. To act as a catalyst. To prevent the hydrolysis of the cyanide. To increase the nucleophilicity of CN - . When ethyl alcohol is treated with PCl 3 , the products formed are ethyl chloride and: H 3 PO 3 POCl 3 and HCl H 3 PO 4 P 2 O 5 The reaction C 2 H 5 Br + CH 3 COOAg A + AgBr . The organic product A is: Ethyl acetate Methyl propionate Diethyl ether Ethyl methyl ketone In the nomenclature of 2-bromo-3-methylbutane, the carbon atoms are numbered such that: The carbon with bromine gets the lower number. The carbon with the methyl group gets the lower number. Alphabetical order determines the lowest number (Bromo over Methyl). The chain is numbered from the end nearest to any substituent. The reaction of n -butyl bromide with sodium iodide in dry acetone to form n -butyl iodide is an example of which mechanism? S N 2 S N 1 E2 E1 Which of the following undergoes nucleophilic substitution exclusively by S N1 mechanism : Ethyl chloride Isopropyl chloride Benzyl chloride Chlorobenzene For (i) I - , (ii) Cl - , (iii) Br - , the increasing order of nucleophilicity would be Cl - < Br - < I - I - < Cl - < Br - Br - < Cl - < I - I - < Br - < Cl - Which of the following reactions is an example of nucleophilic substitution reaction ? RX + Mg RMgX RX + KOH ROH + KX 2RX + 2Na R – R + 2NaX RX + H 2 RH + HX Which of the following will react faster through S N 1 mechanism ? CH3CH2Cl H2C=CH-CH2Cl CH2=CHCl The major product formed in dehydrohalogenation reaction of 2-Bromo pentane is Pent-2-ene. This product formation is based on? Hund's Rule Hofmann Rule Huckel's Rule Saytzeff's Rule The given compound is an example of . Benzylic halide Aryl halide Allylic halide Vinylic halide Which of the following molecules has a chiral center? 2-Bromobutane 1-Bromobutane 2-Bromopropane 2-Bromo-2-methylpropane The products A and B obtained in the following reactions, respectively, are 3ROH + PCl3 -> 3RCl + A ROH + PCl5 -> RCl + HCl + B POCl3 and H3PO3 POCl3 and H3PO4 H3PO4 and POCl3 H3PO3 and POCl3 Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : CH3CH2CH2CH2I undergoes S N2 reaction faster than CH3CH2CH2CH2Cl , Reason (R) : Iodine is a better leaving group because of its large size. In the light of the above statements, choose the correct answer from the options given below: A is false but R is true Both A and R are true and R is the correct explanation of A Both A and R are true but R is not the correct explanation of A A is true but R is false The correct order of increasing reactivity of C-X bond towards nucleophile in the following compounds is: (I) CH 3CH 2X , (II) (CH 3) 2CHX , (III) CH 2=CH-CH 2X , (IV) C 6H 5CH 2X II < I < III < IV I < II < III < IV IV < III < II < I III < II < I < IV The reaction of C 6H 5CH 2Br with aqueous NaOH follows: S N 1 mechanism S N 2 mechanism Any of the above two depending upon the temperature of reaction Saytzeff rule The reaction of CH 3Br with KCN gives A , while with AgCN it gives B . A and B are: A = CH 3CN, B = CH 3NC A = CH 3NC, B = CH 3CN A = CH 3CN, B = CH 3CN A = CH 3NC, B = CH 3NC When CH 3CH 2CHCl 2 is treated with NaNH 2 , the product formed is: CH 3-C CH CH 3-CH=CH 2 CH 3-CH 2-CH(NH 2) 2 CH 3-CH 2-CH 2NH 2 The reaction of toluene with Cl 2 in the presence of FeCl 3 gives predominantly: o- and p-chlorotoluene m-chlorotoluene Benzyl chloride Benzoyl chloride The major product formed when 2-bromopentane is heated with alcoholic KOH is: Pent-2-ene Pent-1-ene Pent-2-yne 2-ethoxypentane Which of the following molecules is chiral? 2-chlorobutane 1-chlorobutane 2-chloropropane Chlorocyclohexane S N 1 reaction of an optically active alkyl halide leads to: Racemization Retention of configuration Inversion of configuration Formation of a meso compound The catalyst used in the preparation of an alkyl chloride by the action of HCl on an alcohol is: Anhydrous ZnCl 2 Anhydrous AlCl 3 FeCl 3 CuCl Which of the following is a gem-dihalide? Ethylidene chloride Ethylene dichloride Propylene dichloride 1,3-dichloropropane Which of the following alkyl halides is most reactive towards S N 1 reaction due to the stability of the intermediate carbocation? (C 6H 5) 3C-Cl (C 6H 5) 2CH-Cl C 6H 5CH 2-Cl CH 3CH 2-Cl When 2-bromo-2-methylpropane is treated with CH 3ONa in CH 3OH , the major product is: 2-Methylpropene 2-Methoxy-2-methylpropane t-Butyl alcohol Isobutane The reaction of alkyl halide with 'moist' Ag 2O produces: Alcohols Ethers Alkenes Aldehydes In the reaction CH 3CH 2Br + KCN A H 3O + B , compound B is: Propanoic acid Ethanoic acid Propanamide Ethylamine Which of the following species is the most powerful nucleophile in a polar protic solvent like water? I - Br - Cl - F - Which statement regarding the S N 1 mechanism is incorrect? The rate depends on the concentration of the nucleophile. It is a two-step process. The first step is the slowest and rate-determining step. A planar carbocation intermediate is formed. The major product of the reaction between CH 3CH 2CH(Cl)CH 3 and alcoholic KOH is: But-2-ene But-1-ene Butan-2-ol Butane Which of the following can be used as a solvent for Grignard reagents? Diethyl ether Ethanol Water Acetic acid Which of the following has the highest dipole moment? CH 2Cl 2 CHCl 3 CCl 4 CH 3Cl What is the major product of the reaction between propene and HBr in the presence of peroxide? 1-bromopropane 2-bromopropane 1,2-dibromopropane Propyl alcohol Which of the following statements about S N 2 mechanism is true? The reaction proceeds with the formation of a pentacoordinate transition state. The reaction is favored by polar protic solvents. Tertiary alkyl halides react faster than primary ones. The rate is independent of the nucleophile concentration. Which of the following alkyl halides will react fastest with NaI in acetone? CH 3CH 2Cl CH 3CH 2Br (CH 3) 2CHCl (CH 3) 3CCl The reaction of CH 3MgBr with ethyl alcohol ( C 2H 5OH ) yields: Methane Ethane Propane Ethyl methyl ether Which of the following compounds will give a racemic mixture on nucleophilic substitution with OH - via S N 1 mechanism? 2-bromobutane 1-bromobutane 2-bromo-2-methylpropane 1-bromo-2-methylpropane Which of the following solvents is most suitable for an S N 1 reaction? Water Benzene Ether Hexane Which of the following will have the highest melting point? p-dichlorobenzene o-dichlorobenzene m-dichlorobenzene Chlorobenzene In the presence of light, toluene reacts with Cl 2 to give benzyl chloride. This reaction follows which mechanism? Free radical substitution Electrophilic substitution Nucleophilic substitution Elimination Allyl chloride is more reactive than n-propyl chloride towards S N 1 because: The allyl carbocation is resonance stabilized The allyl carbocation is more substituted Chlorine in allyl chloride is more electronegative The C-Cl bond in allyl chloride is weaker In the reaction of chlorobenzene with Mg in dry ether, which solvent can replace ether to effectively stabilize the Grignard reagent formed? Tetrahydrofuran (THF) Benzene n-Hexane Chloroform The major product of the reaction between n -propyl bromide and alcoholic KOH is propene. If we use sodium tert-butoxide instead of KOH , what is the primary effect on the reaction? Increased rate of elimination due to increased base bulkiness Increased rate of substitution ( S N 2 ) No change in the product or rate Formation of an ether as the major product