Haloalkanes are organic compounds containing
A –OH group
B –COOH group
C halogen atom bonded to sp³ carbon
D halogen atom bonded to sp² carbon
Haloalkanes (alkyl halides) have halogen attached to saturated carbon.
Haloarenes differ from haloalkanes because in haloarenes the halogen is attached to
A sp³ carbon
B sp² carbon of aromatic ring
C carbonyl carbon
D alkene carbon
In haloarenes, halogen is bonded directly to benzene ring carbon.
Which of the following is a haloalkane
A chlorobenzene
B benzyl chloride
C bromobenzene
D iodobenzene
Halogen is attached to sp³ carbon in benzyl chloride.
Order of reactivity of alkyl halides towards SN1 reaction is
A 1° > 2° > 3°
B 2° > 1° > 3°
C 3° > 2° > 1°
D all equal
SN1 proceeds via carbocation; stability governs rate.
SN1 reaction proceeds through formation of
A carbanion
B free radical
C carbocation
D bromonium ion
Rate-determining step is carbocation formation.
SN1 reaction is
A bimolecular
B unimolecular
C concerted
D radical
Rate depends only on substrate concentration.
SN2 reaction is
A two-step
B unimolecular
C concerted bimolecular
D free radical
Bond breaking and making occur simultaneously.
Rate of SN2 reaction depends on
A substrate only
B nucleophile only
C solvent only
D both substrate and nucleophile
SN2 is bimolecular.
Order of reactivity in SN2 reaction is
A 3° > 2° > 1°
B 2° > 3° > 1°
C 1° > 2° > 3°
D all equal
Steric hindrance slows SN2.
SN2 reaction leads to
A retention of configuration
B racemisation
C inversion of configuration
D rearrangement
Known as Walden inversion.
SN1 reaction often results in
A inversion only
B retention only
C racemisation
D no stereochemical change
Planar carbocation allows attack from both sides.
Rearrangement is possible in
A SN2
B SN1
C both SN1 and SN2
D neither
Carbocation intermediate can rearrange.
Which solvent favours SN1 reaction
A non-polar
B polar protic
C polar aprotic
D ether
Stabilises carbocation and leaving group.
Which solvent favours SN2 reaction
A polar protic
B acidic
C polar aprotic
D aqueous
Enhances nucleophilicity.
Which is the best leaving group
A F⁻
B Cl⁻
C Br⁻
D I⁻
Larger ions stabilise negative charge better.
Which nucleophile is strongest in polar aprotic solvent
A F⁻
B Cl⁻
C Br⁻
D I⁻
Smaller ion is less solvated and more reactive.
Reaction of alkyl halide with aqueous KOH gives
A alkene
B ether
C alcohol
D aldehyde
OH⁻ substitutes halogen.
Reaction of alkyl halide with alcoholic KOH gives
A alcohol
B alkene
C ether
D aldehyde
Elimination (E2) is favoured.
Which reaction competes with SN1
A SN2
B E1
C E2
D addition
Both proceed via carbocation.
Which reaction competes with SN2
A E2
B E1
C SN1
D rearrangement
Strong base promotes elimination.
Haloarenes are less reactive towards SN reactions due to
A steric hindrance
B resonance stabilisation of C–X bond
C inductive effect
D polarity
Partial double bond character reduces cleavage.
SN1 reaction does not occur in haloarenes because
A carbocation is unstable
B halogen is bulky
C solvent effect
D weak nucleophile
Phenyl carbocation is highly unstable.
Which haloarene undergoes nucleophilic substitution easily
A chlorobenzene
B bromobenzene
C nitrochlorobenzene
D fluorobenzene
–NO₂ group stabilises Meisenheimer complex.
Nucleophilic aromatic substitution occurs via
A SN1
B SN2
C benzyne or addition–elimination
D free radical
Special mechanisms operate in haloarenes.
Electron-withdrawing group facilitates nucleophilic substitution by
A destabilising intermediate
B increasing carbocation stability
C stabilising negative charge in intermediate
D increasing steric hindrance
Meisenheimer complex is stabilised.
Order of reactivity of halides towards SN reactions is
A R–F > R–Cl > R–Br > R–I
B R–I > R–Br > R–Cl > R–F
C R–Cl > R–Br > R–I > R–F
D R–Br > R–Cl > R–I > R–F
C–I bond is weakest.
Which reaction converts alkyl halide to nitrile
A reaction with KOH
B reaction with KCN
C reaction with NH₃
D reaction with AgNO₃
CN⁻ acts as nucleophile.
Reaction with AgCN gives mainly
A alkyl cyanide
B isocyanide
C alcohol
D amine
AgCN is covalent; N attacks.
Which reagent converts alkyl halide to amine
A KOH
B NaCN
C NH₃
D AgNO₃
Ammonolysis gives amines.
Reaction of haloalkane with Na in dry ether is
A Sandmeyer reaction
B Wurtz reaction
C Finkelstein reaction
D Swarts reaction
Coupling of alkyl halides.
Finkelstein reaction converts
A R–Cl to R–Br
B R–Br to R–I
C R–I to R–Cl
D alcohol to halide
NaI in acetone is used.
Swarts reaction prepares
A alkyl iodides
B alkyl bromides
C alkyl fluorides
D alcohols
Uses metal fluorides.
Haloalkanes show which type of bond cleavage
A heterolytic only
B homolytic only
C both homolytic and heterolytic
D no cleavage
Depends on reaction conditions.
Which alkyl halide undergoes SN1 fastest
A methyl chloride
B ethyl chloride
C isopropyl chloride
D tert-butyl chloride
Forms most stable carbocation.
Which alkyl halide undergoes SN2 fastest
A tert-butyl chloride
B isopropyl chloride
C ethyl chloride
D methyl chloride
Least steric hindrance.
Polar protic solvents slow SN2 because they
A destabilise nucleophile
B stabilise nucleophile
C destabilise substrate
D increase steric hindrance
Solvation reduces nucleophilicity.
Which reaction gives inversion of configuration
A SN1
B SN2
C E1
D E2
Backside attack causes inversion.
Racemisation occurs due to
A free radical intermediate
B planar carbocation
C carbanion formation
D benzyne intermediate
Allows attack from both sides.
Which reaction does not involve carbocation
A SN1
B E1
C SN2
D rearrangement
SN2 is concerted.
Which halide is least reactive in SN reactions
A R–I
B R–Br
C R–Cl
D R–F
Strong C–F bond.
Which factor does NOT affect SN1 reaction
A substrate structure
B solvent
C nucleophile strength
D carbocation stability
Rate depends only on substrate.
Which factor does NOT affect SN2 reaction
A nucleophile
B substrate
C solvent
D carbocation stability
No carbocation involved.
Allylic halides undergo SN1 rapidly due to
A inductive effect
B resonance stabilised carbocation
C steric effect
D hyperconjugation only
Allyl carbocation is stabilised.
Benzylic halides show high reactivity because
A C–X bond is weak
B benzylic carbocation is resonance stabilised
C steric hindrance is high
D halogen is bulky
Resonance enhances stability.
Which halide reacts fastest with aqueous AgNO₃
A methyl chloride
B ethyl chloride
C isopropyl chloride
D tert-butyl chloride
SN1 occurs rapidly.
Reaction with moist Ag₂O gives
A ether
B alcohol
C alkene
D aldehyde
OH⁻ substitutes halide.
Which compound will NOT undergo Wurtz reaction
A CH₃Cl
B C₂H₅Br
C C₆H₅Cl
D C₃H₇Cl
Haloarenes do not undergo Wurtz reaction.
Which reaction forms ether from alkyl halide
A Wurtz
B Williamson synthesis
C Finkelstein
D Swarts
Alkoxide reacts with alkyl halide.
Which alkyl halide favours elimination most
A methyl
B primary
C secondary
D tertiary
Steric hindrance favours elimination.
Correct statement is
A SN2 occurs via carbocation
B SN1 shows inversion only
C Haloarenes are more reactive than haloalkanes
D SN2 is favoured by strong nucleophile and less steric hindrance
Key condition for SN2 mechanism.