GameChanger Academy
Tutors
Courses
CEE
About
Physical chemistry
1. The solid state
2. Language of Chemistry
3. Gaseous and Liquid states
4. Stoichiometry
5. Solutions
6. Structure of Atom
7. Chemical equilibrium
8. Nuclear chemistry (Radioactivity)
9. Ionic equilibrium
10. Chemical Bonding
11. Chemical kinetics
12. Concepts of Acids, Bases and Salts
13. Surface catalysis and Colloids
14. Redox reactions
15. Chemical energetics
16. Volumetric analysis
17. Electrochemistry
18
Inorganic chemistry
18. Introduction
19. Periodic table
20. Hydrogen and its compounds
21. General aspects of Metallergy
22. Alkali metals
23. Alkaline metals
24. Boron family
25. Carbon family
26. Nitrogen family
27. Oxygen family
28. Fluorine family
29. Inert gases
30. Transition metals
31. Coordination compounds
32. Analytical chemistry
33
Organic chemistry
33. Purification and analysis of organic compounds
34. Nomenclature of Organic compounds
35. Reaction Mechanisms
36. Hydrocarbons
37. Haloalkanes (Alkyl halides)
38. Alcohol, Phenol and Ether
39. Aldehyde and Ketones
40. Carboxylic acids
41. Compounds conatining Nitrogen
42. Polymers
43. Chemistry in daily life
44
Organic chemistry
37. Haloalkanes (Alkyl halides)
Edit
ALIPHATIC HALOALKANE
▢
General Methods of Preparation of Alkyl Halide:
❖
From Alkane:
◉
Direct Halogenation:
◈
Reaction:
\[R−H + X₂ \xrightarrow{\text{hν or 250–400°C}} R−X + H−X [X = Cl, Br, I]\]
◈
Mechanism:
Free radical substitution
◈
Products:
Mixture of mono- and poly-halogen derivatives
◈
Example:
CH₄ + Cl₂ →(hν or 250–400°C) CH₃Cl + CH₂Cl₂ + CHCl₃ + CCl₄ + HCl
◈
Notes:
Not used in lab due to difficulty in separation
Commercially important method (from petroleum & natural gas)
Excess alkane favors monosubstituted product
◈
Example_2:
CH₃−CH₃ + Cl₂ →(hν or 250–400°C) CH₃−CH₂−Cl (Ethyl chloride, Major) + HCl
◉
Reactivity Order:
◈
Alkane:
Tertiary > Secondary > Primary
◈
Halogen:
F₂ > Cl₂ > Br₂ > I₂
◉
Fluorination:
◈
Notes:
Highly reactive, ruptures C−C bonds in higher alkanes
Alkyl fluorides generally prepared by halide exchange
◈
Swart's Reaction:
■
Equation:
R−Cl + AgF/Hg₂F₂/AsF₃/SbF₃ → R−F
■
Example:
CH₃CH₂Cl + AgF → CH₃CH₂F + AgCl
◉
Chlorination_vs_Bromination:
Chlorination = fast, Bromination = slow
◉
Iodination:
◈
Direct:
Not possible (reversible & endothermic)
◈
Modified:
■
Oxidizing agents:
Conc. HNO₃
HIO₃
■
Reaction:
R−H + I₂ ⇋(heat) R−I + HI; 5HI + HIO₃ → 3I₂ + 3H₂O
■
Note:
Methane does not undergo iodination
◉
Finkelstein Reaction:
◈
Equation:
R−Cl + NaI →(acetone, Δ) R−I + NaCl
R−Br + NaI →(acetone, Δ) R−I + NaBr
◈
Note:
Only iodoalkanes obtained (displacement of Cl and Br)
❖
From Alkenes:
◉
Addition of Halogen Acids:
◈
Reactions:
CH₂=CH₂ + HI → CH₃−CH₂−I (Iodoethane)
CH₂=CH₂ + HBr → CH₃−CH₂−Br (Bromoethane)
CH₂=CH₂ + HCl → CH₃−CH₂−Cl (Chloroethane)
CH₂=CH₂ + HF → CH₃−CH₂−F (Fluoroethane)
◈
Reactivity Order:
HI > HBr > HCl > HF
◉
Markownikoff_vs_AntiMarkownikoff:
◈
Markownikoff:
■
Condition:
All halogen acids except HBr (in absence of peroxide)
■
Rule:
Negative part adds to C with more H
■
Example:
CH₃−CH=CH₂ + HBr → (2-Bromopropane)
◈
Anti-Markownikoff (Kharasch effect):
■
Condition:
HBr in presence of peroxide (C₆H₅OO)₂
■
Rule:
Negative part adds to C with fewer H
■
Example:
CH₃−CH=CH₂ + HBr → (1-Bromopropane)
◈
Mechanism:
■
Markownikoff:
●
Type:
Electrophilic addition
●
Intermediate:
Carbocation
●
Rearrangement:
Possible (1,2-hydride or alkyl shift)
■
Anti-Markownikoff:
●
Type:
Free radical addition
●
Intermediate:
Free radical
●
Rearrangement:
Not observed
❖
From Alcohols:
◉
General Reaction:
R−OH + H−X → R−X + H₂O (SN reaction)
◉
Halogen Acids:
◈
Groove/Lucas Process:
■
Reaction:
R−OH + conc. HCl(g) →(anh. ZnCl₂) R−Cl + H₂O
■
Notes:
Conc. HCl + anhy. ZnCl₂ = Lucas reagent
ZnCl₂ helps cleavage of C−O bond
Reactivity of alcohols: Tertiary > Secondary > Primary
1° follows SN2, 2° & 3° follow SN1 (via carbocation)
■
Halogen Acid Reactivity:
HI > HBr > HCl
◉
Phosphorus Halides:
◈
Equations:
3R−OH →(PCl₃) 3R−Cl + H₃PO₃
R−OH →(PCl₅, Δ) R−Cl + POCl₃ + HCl
R−OH →(P + I₂) R−I + H₃PO₃
R−OH →(P + Br₂) R−Br + H₃PO₃
◈
Notes:
PBr₃ and PI₃ are prepared in situ using red P + Br₂/I₂
Good yield for 1° haloalkanes, poor for 2° and 3° (due to dehydration to alkenes)
◉
Thionyl Chloride (Darzen’s Method):
◈
Reaction:
R−OH + SOCl₂ →(Pyridine, reflux) R−Cl + SO₂↑ + HCl↑
◈
Notes:
Best method for chloroalkanes (by-products gaseous → pure product)
Not used for bromides/iodides (SOBr₂ unstable, SOI₂ does not exist)
❖
From Ethers:
◉
Reaction:
R−O−R′ + 2HX →(Δ) R−X + R′−X + H₂O
◉
Example:
C₂H₅−O−CH₃ + 2HCl → C₂H₅Cl + CH₃Cl + H₂O
❖
Borodine–Hunsdiecker Reaction:
◉
Reaction:
(CH₃COOAg) + Br₂ →(CCl₄) CH₃Br + CO₂ + AgBr
◉
Mechanism:
Free radical
◉
Yield Order:
Primary > Secondary > Tertiary
◉
Uses:
Reduces chain length (descent of series)
Only bromides obtained in good yield
Chlorides in low yield, iodides not obtained
◉
Special Case:
◈
Birnbaum–Simonini Reaction:
■
Equation:
2RCOOAg + I₂ → RCOO−R + CO₂ + 2AgI
■
Example:
2CH₃COOAg + I₂ → CH₃COOCH₃ (Methyl ethanoate) + CO₂ + 2AgI
1.
When chloroform is boiled with aqueous KOH followed by acidification it gives [IOM 2008]
[
2008
]
Methoxy methane
Methanol
Methanoic acid
Ethanal
(
c
)
2.
An alkyl halide can be converted into alcohol by [IOM 2008, IOM 2004]
[
2008,
2004
]
Addition
Elimination
Substitution
Dehydrogenation
(
c
)
3.
Chlorine reacts with Benzaldehyde to give [IOM 2063]
[
2063
]
Benzal chloride
Benzoyl chloride
Chlorobenzene
Benzyl chloride
(
a
)
4.
Tear gas is [IOM 2005]
[
2005
]
Chloretone
Ethyl carbonate
Chloropicrin
Methylene chloride
(
c
)
5.
Chloral is [MOE 2064]
[
2064
]
Cl₃CH
CCl₃COCH₃
Cl₃CCHO
Cl₃CCOOH
(
c
)
6.
The reaction between benzene diazonium chloride and CuCl₂/HCl is [Bangladesh Embassy, BPKIHS]
Gattermann reaction
Sandmeyer reaction
Both (a) and (b)
Acylation reaction
(
c
)
7.
The reaction between aniline and chloroform in presence of NaOH is called [Bangladesh Embassy]
Cannizzaro reaction
Hofmann reaction
Riemer-Tiemann reaction
Carbylamine reaction
(
d
)
8.
The purpose of using anhydrous AlCl₃ as a catalyst in Friedel-Crafts reaction is to [MOE 2053]
[
2053
]
Initiate the reaction
Increase the activation energy
Provide necessary electrophile
Provide the necessary nucleophile
(
c
)
9.
A sample of chloroform is tested by which of the following before being used as anaesthetic? [IOM 2053, 2054]
[
2053,
2054
]
AgNO₃ solution
Fehling's solution
Ammoniacal cuprous chloride
AgNO₃ + KOH
(
d
)
10.
Anaesthetic chloroform is always stored in yellow bottles filled up to stopper because [Indian Embassy]
It is explosive in air and direct sunlight
It produces carbon tetrachloride in air and sunlight
It produces phosgene in air and sunlight
It produces ethyl alcohol in air and sunlight
(
c
)
11.
The compound which gives negative iodoform test is [BPKIHS]
CH₃CHO
CH₃CH₂OH
C₆H₅COCH₃
C₆H₅CH₂CH₂OH
(
d
)
12.
Chloroform is used for the test of ... amines [IOM 2004]
[
2004
]
Primary
Secondary
Tertiary
All
(
a
)
13.
Chloretone is obtained by chemical reaction of [MOE]
Chlorine and acetone
Chlorine and ethanol
Chloroform and conc. nitric acid
Chloroform and acetone
(
a
)
14.
Chloroform reacts with nitric acid to form an insecticide called chloropicrin. Its formula is [MOE 2051]
[
2051
]
CCl₂NO₂
CHCl₃NO₂
CCl₃NO₂
CCl₃CHNO
(
c
)
15.
Dehydro-halogenation of alkyl halide gives [MOE 2049]
[
2049
]
Alkane
Alkene
Alkyne
Ether
(
b
)
16.
The reaction C₆H₅NH₂ + CHCl₃ + KOH →(Alcoholic) C₆H₅NC + KCl is called [MOE, IOM 2051]
[
2051
]
Sandmeyer reaction
Carbylamine reaction
Coupling reaction
Wurtz reaction
(
b
)
17.
The reaction of benzene with haloalkane in presence of anhydrous AlCl₃ is [IOM 2054]
[
2054
]
Friedel-Crafts reaction
Wurtz's reaction
Frankland reaction
Riemer-Tiemann's reaction
(
a
)
18.
Which of the following compound is used in tear gas? [IOM 2051]
[
2051
]
Benzyl chloride
Chloroform
Benzoyl chloride
Chlorobenzene
(
a
)
ADDITIONAL QUESTIONS
1.
Among the following compounds, the one with the highest percentage of chlorine is
Chloral
Pyrene
PVC
Gammexene
(
a
)
2.
The order of reactivity of alkyl halides towards an SN2 reaction is
RI > RBr > RCl > RF
RF > RBr > RI > RCl
RF > RCl > RBr > RI
RI > RCl > RBr > RF
(
a
)
3.
Which of the following possesses highest melting point?
Chlorobenzene
o-Dichlorobenzene
m-Dichlorobenzene
p-Dichlorobenzene
(
b
)
4.
Which of the following will have the maximum dipole moment?
CH3F
CH3Cl
CH3Br
CH3I
(
a
)
5.
The order of reactivities of methyl halides in the formation of Grignard reagent is
CH3Br > CH3Cl > CH3I
CH3Br > CH3I > CH3Cl
CH3I > CH3Br > CH3Cl
CH3Cl > CH3Br > CH3I
(
c
)
6.
1-Chlorobutane when treated with alcoholic potash gives
1-Butene
1-Butanol
2-Butene
2-Butanol
(
a
)
7.
C2H5Cl + KCN → X → hydrolysis → Y. Compounds X and Y are
C2H6 and C2H5CN
C2H5CN and C2H6
C2H5CN and C2H5CH2NH2
C2H5CN and C2H5COOH
(
c
)
8.
Most reactive halide towards SN1 reaction is
n-Butyl chloride
sec-Butyl chloride
tert-Butyl chloride
Allyl chloride
(
c
)
9.
Which of the following alkyl halides is used as a methylating agent?
C2H5Cl
C2H5Br
C2H5I
CH3I
(
d
)
10.
The reactivity order of halides for dehydrohalogenation is
R-F > R-Cl > R-Br > R-I
R-I > R-Br > R-Cl > R-F
R-I > R-Cl > R-Br > R-F
R-F > R-I > R-Br > R-Cl
(
b
)
11.
The order of reactivity of alkyl halides towards elimination reaction is
3° > 2° > 1°
2° > 1° > 3°
3° > 1° > 2°
1° > 2° > 3°
(
a
)
12.
Which is not an organometallic compound?
C2H5MgI
C2H5ONa
(C2H5)3Al
TEL
(
b
)
13.
Formaldehyde gives an addition product with methyl magnesium iodide which on aqueous hydrolysis gives
Isopropyl alcohol
Ethyl alcohol
Methyl alcohol
Propyl alcohol
(
c
)
14.
CO2 on reaction with ethyl magnesium bromide gives
Ethane
Propanoic acid
Acetic acid
None of these
(
b
)
15.
Chlorobenzene is prepared commercially by
Dow's process
Deacon's process
Raschig's process
Etard's process
(
a
)
16.
The reaction of C6H5N2+Cl- with CuCl gives
C6H5Cl
C6H6
C6H5-C6H5
C6H4Cl2
(
a
)
17.
Chlorobenzene on heating with aqueous NH3 under pressure in the presence of cuprous chloride gives
Benzamide
Aniline
Nitrobenzene
Chloroaminobenzene
(
b
)
18.
The industrial preparation of chloroform employs acetone and
Sodium chloride
Chlorine gas
Calcium hypochlorite
Phosgene
(
c
)
19.
CHCl3 on oxidation by air in presence of light gives
Phosgene
Formic acid
Chloropicrin
CCl4
(
a
)
20.
AgNO3 does not give precipitate with chloroform because
CHCl3 is insoluble in water
CHCl3 does not ionize in water
CHCl3 is an organic compound
AgNO3 is insoluble in CHCl3
(
b
)
21.
When ethylamine is heated with chloroform and alcoholic KOH, a compound with offensive smell is obtained. This compound is
A secondary amine
An isocyanide
A cyanide
An acid
(
b
)
22.
C2H5NC is known as
Ethyl isocyanide
Ethyl carbylamine
Both
None of these
(
c
)
23.
Chloroform on warming with Ag powder gives
C6H6
C2H4
C2H2
None of these
(
d
)
24.
When chloroform is treated with concentrated HNO3 it gives
CHCl2NO2
CCl3NO2
CHCl2HNO3
None of these
(
b
)
25.
Chloropicrin is
C2H5C(NO)2SH
CCl3CHO
CCl3NO2
CCI3NO2
(
c
)
26.
Chloropicrin is used as
Anaesthetic
Insecticide
Hypnotic
All of these
(
b
)
27.
The final product formed by the hydrolysis of chloroform by aqueous KOH is
HCOOH
HCOOK
CH3OH
None of these
(
b
)
28.
When chloroform reacts with acetone the product is
Ethylidene chloride
Mesitylene
Chloretone
Chloral
(
d
)
29.
The following reaction is known as: Phenol → CHCl/NaOH → Salicylaldehyde
Gattermann aldehyde synthesis
Dull'reaction
Perkin reaction
Reimer-Tiemann reaction
(
d
)
30.
Which of the following is an anaesthetic?
C2H4
CHCl3
CH3Cl
C2H5OH
(
b
)
31.
Which of the following is known as freon?
CCl2F2
CHCl3
CH2F2
CF4
(
a
)
32.
Which of the following is mainly responsible for depletion of ozone layer?
Methane
Carbon dioxide
Water
Chlorofluorocarbons
(
d
)
33.
Which of the following compounds is used as a refrigerant?
Acetone
CCl4
CF4
CCl2F2
(
d
)
34.
Ethyl alcohol gives ethyl chloride with the help of
SOCl2
NaCl
Cl2
KCl
(
a
)
35.
Carbon tetrachloride reacts with C6H5OH and NaOH to form
Salicylic acid
Salicylaldehyde
Both
None of these
(
b
)
36.
What happens when CCl4 is treated with AgNO3?
NO2 will be evolved
A white ppt. of AgCl will be formed
CCl4 will dissolve in AgNO3
Nothing will happen
(
d
)
37.
Which of the following compounds is used as fire extinguisher?
C2H5OC2H5
CH2Cl2
CHCl3
CCl4
(
d
)
38.
CCl4 is used as fire extinguisher because
It has high melting point
Of its covalent bond
Of its low boiling point
It gives incombustible vapour
(
d
)
39.
The pesticide DDT slowly changes to
CCl3-CHO and chlorobenzene
p,p'-dichlorodiphenylethene
p,p'-dichlorodiphenyldichloroethane
p,p'-dichlorodiphenyldichloroethene
(
b
)
40.
In which of the following p-electrons halogen are not involved in delocalisation?
Chlorobenzene
Bromobenzene
Alkyl chloride
Vinyl chloride
(
c
)
41.
Aryl halides are less reactive toward nucleophilic substitution reaction as compared to alkyl halides due to
The formation of less stable carbonium ion
Resonance stabilisation
Longer carbon-halogen bond
Inductive effect
(
b
)
42.
The formula for freon-12 is
CCIF3
CH2Cl2
CCl2F2
CH2F2
(
c
)
43.
Which of the following gives Iodoform test upon reaction with I2 and NaOH?
PhCHOHCH3
CH3CH2CHOHCH2CH3
C6H5CH2CH2OH
(CH3)2CHCH2OH
(
a
)
44.
Which is liquid at room temperature?
CH3F
CH3Cl
CH3Br
CH3I
(
b
)
45.
When an alkyl halide is heated with dry Ag2O, it produces
Ester
Ether
Ketone
Alcohol
(
b
)
46.
Allyl chloride on dehydrochlorination gives
Propadiene
Propylene
Acetone
Propyne
(
a
)
47.
An organic compound which produces a bluish green coloured flame on heating in presence of copper is
Chlorobenzene
Benzaldehyde
Aniline
Benzoic acid
(
a
)
48.
Ethylene oxide when treated with Grignard reagent yields
Tertiary alcohol
Cyclopropyl alcohol
Primary alcohol
Secondary alcohol
(
c
)
49.
The compound added to prevent chloroform from forming phosgene gas is
CH3COOH
CH3OH
CH3COCH3
C2H5OH
(
c
)
50.
Acetone is mixed with bleaching powder to give
Acetaldehyde
Chloroform
Ethanol
Phosgene
(
b
)
51.
Which of the following gives trichloromethane on distilling with bleaching powder?
Methanal
Phenol
Ethanol
Methanol
(
a
)
52.
Which reagent can convert butan-2-one to propanoic acid?
Tollen's reagent
Fehling solution
NaOH/I2/H+
NaOH/NaI/H+
(
c
)
53.
Which of the following is formed when the product of oxidation of chloroform is treated with ethyl alcohol?
Ethyl chloride
Diethyl carbonate
Chloral hydrate
Chloral
(
b
)
54.
Teflon polymer is formed by polymerisation of
CI2C=CH2
F2C=CF2
CH2=CHCN
CH2CHCl
(
b
)
55.
Which of the following is the most reactive in Grignard reagent formation?
n-butyl iodide
Isobutyl iodide
Sec-butyl iodide
Cannot be said
(
a
)
56.
SN1 reaction of alkyl halides leads to
Retention of configuration
Racemisation
Inversion of configuration
None
(
b
)
57.
A sample of chloroform being used as anesthetic is tested with
Fehling solution
Ammonical Cu2Cl2
AgNO3 solution
AgNO3 solution after boiling with alc. KOH
(
d
)
58.
At higher temperature iodoform reaction is given by
CH3COOCH3
CH3COOC2H5
C6H5COOCH3
CH3COOC6H5
(
b
)
59.
C-CI bond is difficult to cleave in CH2=CH-Cl due to
Resonance
Electromeric effect
Inductive effect
Hyperconjugation
(
a
)
60.
CCl4 is used in fire extinguishers under the name of
Pyrene
Phosgene
Phosphine
None
(
d
)
61.
SN2 mechanism proceeds through the formation of
Carbonium ion
Transition state
Free radical
Carbanion
(
b
)
62.
Both methane and ethane can be prepared in single step by the use of
C2H4
CH3OH
CH3Br
CH3CHO
(
c
)
63.
How many monochlorobutanes will be possible on chlorination of n-butane?
1
2
3
5
(
c
)
64.
Isopropyl chloride undergoes hydrolysis by
SN1 mechanism
SN2 mechanism
SN1 and SN2 mechanisms
Neither SN1 nor SN2 mechanism
(
a
)
65.
SN1 reaction of alkyl halides causes racemization because of
Inversion of configuration
Retention of configuration
Conversion of configuration
Both inversion and retention
(
d
)
66.
Vinyl chloride undergoes
Only addition reactions
Only elimination reactions
Both addition and elimination
None
(
c
)
67.
Tertiary alkyl halides are practically inert to substitution by SN2 mechanism because of
Insolubility
Instability
Inductive effect
Steric hindrance
(
d
)
68.
Which of the following undergoes nucleophilic substitution exclusively by SN1 mechanism?
Benzyl chloride
Ethyl chloride
Chlorobenzene
Isopropyl chloride
(
a
)
69.
Isoamyl halide is
1-halide
2-halide
3-halide
None
(
a
)
70.
Which of the following reacts fastest with Lucas reagent?
Carbinol
Methyl carbinol
Dimethyl carbinol
Trimethyl carbinol
(
d
)
71.
Which of the following is most reactive for halogenation?
n-butane
Isobutane
Neopentane
Cannot be said
(
a
)
72.
Which of the following reacts fastest in SN2?
n-butyl iodide
Isobutyl iodide
Sec-butyl iodide
Tertiary butyl iodide
(
a
)
