CLASS 12ᵗʰ -

CBSE -
2023

Haloalkanes &
Halo are nes
HANDWRITTEN NOTES

with **¥¥#
Panchal Sir
By Bharat

ʰ• *&•⇐É÷¥s¥¥É¥
⇐:•¥A÷•¥gBÉEG¥ÉAB÷&G¥É PBhharaattpaannehha.at $ #

GBAGBO Bharat Panchal -

Chemistry Guruji 2.0

 Haloalkanes and Haloarenes
INTRODUCTION : -

me derivatives of aliphatic
halogen
and aromatic hydrocarbons are called alkyl
halide Chalo alkahest and aryl halide ( Halo . aren.es )

Halo alkanes contain halogen atom attached to

the Sps hybridised c- atom
of an alkyl grouts :

whereas Haloarenes
contain halogen atom attached to spa hybridised
c- atom of an
aryl grouts .

CLASSIFICATION OF HALO ALKANES & HALO ARENE

( *) On the basis of no .
(A) On the basis of
hybridisation state
of halogen atoms
.

µ
it 4115 ✗
&
-

'

( Mono halo alkanes ) R _

-
✗

it ( 1° Primary )
44 ✗ H -
-

( Dimaio alkanes)
,R
'

( Ha -

✗
"

"it
R C- ✗ C2 : secondary)
41 ✗
-
-

halo alkanes,
CH -
✗
te
'

EH, ✗ ↑
Fenian
-

f- ✗ (
"
R -

✗
cmonohaloarenes )
,
-

R
'"
Haloalkane)

( Dihaloarenes )
✗ = f, U, Br I ,

( Trihaloarenes )
✗
 ALLYLIC HALIDES : -

the halogen is bonded to an

Sps c- atom next to the c=c .

§i- Allylic
e-
9 .
R -
CH - CH -
CH -
✗
,

Allylic # carbon .

carbon

BENZYLIC HALIDE : -

the halogen atom is bonded

to ]
c- atom to
sing
an sp next an aromatic

g ith ✗
-

e.
-

¥1
PROPAGYL HALIDE ! -

the halogen atom is bonded to

]
an sp c- atom next to a CEC bond
, .

e.g R -
CE C -
CH
,
-
✗

Vinyltlaide :
Aryltlalidei .

halogen atom is bonded is

the the halogen atom
to an spa c- atom bonded to sb'
✗ ✗
e. c- atom of an
G R CH -

,
__ en -
✗ ,
I
ring
'
aromatic .

NOMENCLATURE OF HALO ALKANES

common Name IUPAC Name

•
CH -4
, Methyl chloride chloro methane

• CH, CH CH Br n -
Propyl Bromide Bromo propane
, ,

U isobath chloride 1- chloro

cYµjCH
• CH
]
-
- -

2- methyl
,
propane
CH
] 1- chloro -2,2

&µ,- neobentyl chloride

•
CH CH -6
]
-

,
-
dimethyl
propane
-
.
a) When both halogen atoms b) when two halogen
are attached to the same atoms are present
c- atom , these are called at adjacent c-

gem - di halides then they are

also called albylidene called vicinal
dihalide .

di halide
called alkylene
CHILL
✗ also
*(✗ e.g CH -

] dihalide
✗ ✗
etheelidene
gem dihalide
-4¢ CHA CHA
-
-

dichloride -

'
ce Le
ethylene dichloride
NOMENCLATURE OF HALOARENES
a

! * ce il
"
a tu
chlorobenzene 1,2 -
Pichon benzene
1,3 -

Rich / on 14 Pichon
-

co Pichon
-
benzene benzene
benzene ) ( M Pichon
-

( b- Dickon
benzene ) benzene)
6 ortho
ortho -
a

melee 5¥ 's meta stingy

O Mgb
para ,
 Nature of C- ✗ Bond
the c- ✗ bond is covalent
but the
electronegativity of halogen atom
is more than C, due to which C- ✗ bond is bolar

& &E✗s polar Bond

-

-
-

✗ → -

•
Molecular structure of ctfu
the c- ✗ bond is formed

Sps hybrid orbital

by the
overlaying of of
c- atom and b- orbital of U - atom

C
METHODS OF PREPARATION b. orbital

OF HALO ALKANES : -
000
②
.

①
1. from Alcohol

a) By the action of halogen acid

R -
OH + HX → R -

✗ +
H2O
1° & 2° alcohols form chloro alkanes when
,
hydrochloric acid
gas is passed
through
alcohol in the presence of anhydrous 2nd
,

This is known as
"
Groove 's
poocessu
?⃝
 2h42 help in the cleavage of C- 0 bond .

→ 3. alcohols are very reactive , they react with

HU at
conc .

room tenets . without 2h42

CH OH + HU K CH]
CHA U -1110
CHA
-
-
•
- -

]
2h6

die ? OH
,
"

die ?u
"
CH + Ha ah ctg Hao
-

}
-
+

2h42
ftlz PM]
CH -
C OH + tell ¥ CH
G U -1110
-

} - -

* Mb ]
↳ .

Cpg
Note 2° & I
'
bromides and iodides can not

be prepared from the respective alcohols

because 2° & so alcohols on
heating with cone .

and
Has 04 Undergo dehydration form alkene

is least reactive
fluoro alkane is
→ Hf .
So not
formed .

of reactivity of alcohol → 3723in 1°

Order
Reactivity of halogens → HI > Hbo > tell
•

By the action of Phosphorous Halides :

R OH -
+ PUS → R U -
+ Polls + HU

R -
OH + Pll] → R U -
+ Hypo]
Note PBB & PI are not stable , so they
}
are prepared on the site of reaction CSITU )

By the action of thionyl Chloride

R OH-
+ SOU
,
É R I -
+ SO ↑ + HUT
,
Ka This method is preferred than other method
because both the side products C SO, & Hell
are
gaseous and can easily escape .

# from Hydrocarbons
a) From Alkanes
ce , & Bo reacts with alkanes in
,

the light to form halo alkanes

presence of Uv

free radical
"

This reaction is
"
substitution reaction

ex . CH] CH CH]
, g CH, CH
, CHAU + CH ] CHCH ]
he
145%1 ( 55 %)
Note -7 Thereactivity of different type of
hydrogen in halo compound are
{ Benzylic allylic > Alkyl > Vinyl aoyig
=
-
_

→
Allylic and benzylic halides can be easily
prepared
CH CH + Cl, A- CH CH -
CHAU + HU
Ctf
-
=
=
•

, ,

FH] "

€4 + U
,
→
+ HU

→ Both are highly reactive and this can be explained

in terms of stabilisation by resonance
CH ÉH
,
EH -

CH =
Ctf
,
 ÷ .
¥]
From Alkenes

> c=cf + tex →

-
i - i -

' '
n ✗
•
It is possible in symmetrical alkenes C- CH -
-
CH -7

Markovnikov 's Rule : -

In unsymmetrical alkenes ,
the - ve
part of addendum goes to that
the
carbon
having lower no of Hydrogen .

otcet Negative )
(H CHIH THX → CH] -
' _
'%
did
-

lower , ,

Edd* Hydrogen
ANTI MARKONIKOV 'S RULE
- : -

↳ Applicable to te Br
☒ -
É
-
o -
o 'É.☐
↳ takes place Ñn the presence of organic peroxide
In unsymmetrical alkenes ,
the negative part of
the additive goes to that carbon having
higher no -

of hydrogen
+ HB.ir#desCHz-CH
CH
CHI CH
-

(
Hz
,
- ,
, '
Br
Anti Markovnikov 's Rule is also known as

peroxide effect or Kharasch effect .

Test Negative )
EI Higher
Edd# Hydrogen .
 Addition of Halogen : when Brz & U
,
is added to
alkenes the addition occur at the double bond

forming vicinal di halide Bo

Po
> c=cf + Br, > d- cc
c vicinal di halides )

N0Ñee% This test is used to check unsaturation

because reddish brown colour of Bra
disappeared when reacts with alkene

By Halogen Exchange : -

Acetone NAX
R ✗
-

+ NAI > R I + a,Br)

(✗
-

=
Heat
Finkelstein Reaction

•
Fluoro alkanes are difficult to poebare directly
these chloride
are prepared by treating alkyl
and bromide with
inorganic fluoride such as
and this reaction is
( Hgs Fa g Agf Cofz
, , Sbfz )
termed as Swarts reaction

CH ] -
Br +
Agf → CH
]
-
f + Ag Br
•
From Silver salt of Acids : -

CH, COO Ag + By # CHzBr -110, ICH

}
, COOAG -11-2
+ A9Br
CH, COOCH, -119+2 Aest

Boro dine
"

Hllnsdiecker "
Birnbaum Simonin
Reaction "

Reaction
"
 Methods of Preparation of Haloarenes
•

.
Electrophilic substitution of Arches or
Direct Halogenation of aromatic
ring :

↑
+ ✗
Halogen carrier
a " + HX (✗ = Cl, Br )
310 -320k

{ Here Halogen carrier → red ] / re Br ] IAIU }

LEWIS ACID }
Mechanism: -

sHb-1_ Generation of electrophile

-1
U + fell ] → fell i + Cl
,

skkʰ_ formation of carbocation intermediate

¥Fie+→i¥+i÷↑ É¥
Slept loss of brown from the intermediate
6

+ Fedie →
1T¥ + tell + feel
]

If excess of Halogen is used ,

the second
halogen attached to ortho & bara position

' +
9ex.is#Eii- ¥%
Note The reaction with fluorine is violent
→
or

vigorous and can not be controlled

→
The reaction with Ign is not possible because
when product is formed ,
HI reduce to back

+ Ia É + HI

→
So the reaction is carried out in the presence
of oxidising agent CHIO ] , Hgo ) to oxidise HI .

r Side Chain Halogenation :

f Hall
É+u .
3%4 ☒ + HU
"
☆ in
"
is
"
"
If U excess than all H are replaced by U
,

when the side chain is larger than a methyl

group , halogenation occur at c- atom next to
benzene ring .

¥k
CH
%
-

CHIH] - ]

-1cg
To From Diazonium Salt :
◦
Diazotization Reaction
NANO + HU → Nall + HOMO
,
NIU
-

Nᵗʰ + Homo + tell °

-

+11,0
☒
Sand Meyer Reaction
✗ cx=4Br )
É
'
^5
-
"
-

+ Na
→ Gaiter Mann Reaction

ÉI ¥ + %

+ KI ← É☒ + ix. + KU

roo Balz Schliemann Reaction

-

[ ☒ Nini]
^5'4- HBF I +
BIG
-

,
,

→ from Silver salt of Aromatic Acid :

00^-8 + Bra c÷ - +
coat Ag Br

Note Haloarenes can't be prepared from phenol because

it is difficult to replace -
OH group This . is
due to resonance in phenol .

Physical Properties of Halo alkanes : -

→ In general halo alkanes are colourless 1 when bare)

sweet
smelling liquids .

→ They are
slightly soluble in water because of
low tendency to form Hydrogen Bond .

→
Density :
fall < Bo LI
more no .

of H -
atom ,
less is density
e-
G CH, Uz { CHU ]
→
Boilingpoint-B.pt ✗ Moi Mass .

B- Pt ✗ 1-
Branching
# Physical Properties of Haloarenes :

1. These are generally colourless liquid or crystalline

solid .

2. The aryl halides are heavy than water .

insoluble in water but soluble in organic solvents .

3. The m.pt & b.pt of aryl halides are nearly

the same of alkyl halide containing the same
no .

of carbon atoms .

B. Pt → ortho > Para > meta

M.pt → Para > ortho > meta

Chemical Properties Of Halo alkanes

*) Nucleophilic substitution Reaction : -

¥-1T
°
Ni Ie
-

Nu ✗
→ c- ✗
-

+
→ + -

Reactivity order : - R I > R Br > R U > R F

- - -
-

Types Uni molecular Nucleophilic sub Rxn )

SN (
' .

{
SN ' ( Bimolecular Nucleophilic Sub .
Ran )

SNL R ✗ + NUO → R NY- +✗

_

X]
Rate ✗ TR
-

Mechanism fH ]
CH}

É [⊕ + ✗
°

Steb -1 Ctf f ×
-
-

/ -
CH
Formation of C+ CHS Ctf ]

CH,

%!
3 ,
step -2 + Ny◦t C- Nu

!
"
Attack Of Nucleophile CH CH CH
, , CH
}
 ra Retention as well as inversion of configuration
takes place

CHIC (CHIH
'
order of SN reaction -
✗ > -
✗ > ( Hjctf X -

> CH, ✗-

Allylic and
benzylic halides show
higher reactivity
towards the SN reaction
'
.

The carbocation thus formed get stabilised

through resonance .

SNL ( Bimolecular Nucleophilic Substitution Rxnl

°
R ✗
-
+ Nuo → R Nu-
+ ✗

Rate ✗ ER X ] [ Nuo]
-

Mechanism
H H
th , H
,
•
no a → no . . . .
c.E.cl → no - C + 6-0
'
'
n h n

Order of SNZ reaction ÷ CHSX > 1° > 273°

roo inversion of configuration takes place

A beam of ordinary light consist of electsomag .

when
metic waves
vibrating in all planes
-

pass through Nicol prism ,

vibrates in one blane
called PPL ( Plane polarised light)
Dextrorotation -
which rotate PPL towards
right
Levu -
Rotatory - which rotate PPL towards left .

>
I
dextro
rotatory

BHF
_gIbk ally
inactive

i. I
laevo
Rae¥ Mt_¥ rotatory
equi molar mixture
of d and l , so that met rotation of
ppl is zero .

i.

÷
Nucleophilic Substitution Reaction

substitution by Amino Group :

NH, R AH, + HX
R X -
+ → -

when halo alkanes in excess amount then

is
R)
all three of NH] is replaced by group (
R X-
+ NH] → BN + HX
( excess )
reaction
"
"

Holtman Ammo no lysis

R ✗ + KNO A-
•
R O N -0 + KX
-
- -
-

,
A-
R -
✗ + Agnos R -
N
f+Ag✗ ,

-
•
Substitution by -
OH
group . .

R ✗ ^-
-
+ KOH : R OH
-
+ KX or
or Agx
Agon
•
Substitution by alkoxy group
Na⊕_ OR Max
A '

R ✗
-
+ > R O R
-
-
+

This reaction is known as Williamson synthesis

•
Substitution by cyano Group coni.HU
"
TONY

,
R ✗ + KCN
-
→ R CN -

+ KX
pil.HU or NaOH
CH, COOH
4145 I
-
+ KCN → qq.cn,
MEY CH CH
, Nha
M
,
LiAttlee ,

Mendius Reaction : The formation of 1° amines by reduction

with nascent
hydrogen obtained by
the action of sodium on alcohol .

Substitution by isocyanide group :

R ✗ -
+
Agent → R NC +
-

Agx
activate N & K activate c- group
Note Ag
-

group

• Substitution by azide group :

R X + Nan,
- → R N,- + Wax

◦ Substitution by carboxyl group :

R
'
- di 0 Ag
- + x R - KER '
-
É - OR + Agx
 Elimination Reaction (
Dehydrogenation )
•

when a halo alkane with B H atom- is

healed
with ale . KOH there is an elimination of H atom -

from p -
C and a halogen from ✗ -
C
,
result an
alkene is formed
H

? I 1

-1×0
top
¥
B
-

→ -
C. = c- + BH
1
I

( here B- base ✗
leaving group]
-

If there is a
possibility of formation of more than one
alkene due to
availability of more than one § H usually -

alkene is formed bro duct

one as
major .

→ (
Hs Ctf CH CH CH ( 81%1
- - -
-

]
_

CH } Ctf Ctf gu Ctg

-
-
- - -

( 19%7
Ctf Ctf Ctb
- -
-

CH -
-
CH
→ }
" "
•
Acc . to
saytzeffis Rule the alkene with greater no of alkyl
,
-

group is preferred [ Rac CR, > Rac CHR > BECH, > RCH :(Ha ]
= =

Note → A primary alkyl halide prefer a SNL he action .

→ A Sec . halide prefer SNL & SN

'
depending
upon the
strength of
°
base / Nu and a tert .
halide
prefer SN '

Reactivity 37271° > CH, ✗ Cas carbocation

-

→ Alcoholic KOH causes elimination ,

while aqueous
leads to substitution
solution of base
Aa Reaction with active metals -

-
A Reaction with magnesium
# ( U Bo I]
R ✗
R ✗ +
Mg Mg
→
- - -

✗ , ,

ether
Grignard Reagent
→ These grignard reagents are very reactive
compounds .

They react with any source of Proton

to form hydrocarbons So it is very necessary
.

avoid traces of moisture from grignard

to
reagent -

R Mgx
Hg÷◦µ.,→
+ R H +
mg
-
-

a
carbon
* Reaction with Nac work Rxnl

r-i.i.IIn.iq?-iI.i-rDM-r-R+2Nax
ether to brebare used
alkanes
Symmetrical
.

* Reaction with 2h ( Frankland Reaction )

2 GHS -

Br + 22h → GHS -
Zn -

↳ Hs + 2h BK
diethyl zinc ( Frankland
Reagent I
→ Reduction Reaction :

R X
-
+ 2M ) → R - H + HX

↳ Hs Ut 2Gt ) → GHG 1- HU

Clan following reagents are used too reduction

2h / HU NA / ↳ Hs OH liA1H4 ,
Red P / HI
, ,
 Reaction
Rearrangement
→

CHactb.UA#sCHy-c&-CHzcHs-&?cHiAf-YcHs-&H?cHz-CHz
CH ]

'

CH,
he
# Chemical Properties of Haloarenes :

Haloarenes
are less reactive than Halo alkanes due to

1. Resonance Effect →
pelocalisation of H e -0
⑦
iii. ⑦
it : :

RJ
Jo
2. Difference in hybridisation of C- ✗ Bond

spa R -
cµ¥ˢb3
more s -
character more
electronegative so ,

hold e◦ pair more tightly so less reactive

,

3. Polarity of C- ✗ Bond
In c- ✗ bond of aryl halide
polarity is less ,
so reactivity is less

tea Nucleophilic Substitution Reaction

Do%Pr
•

once

°
"

+ Noon
÷÷ ¥÷:
↳ Effect of substituent in Haloarenes on Reactivity :

→ The presence of co
withdrawing groups such as -
NO
,,
-
CN , -
COOH de . at ortho and para position to the

halogen atom
greatly activates the halogen towards
Nucleophilic substitution
↑
.

e.g is NaOH 623k 1-

% " Pheno
iildil.HU 300am

¥1
OH

1¥
it 15% NaOH 443k ,

>
I iildil.HU '

Nk
"
% in
ftp.NAOH 368k ^"
NO
,
it ,
+ A-
÷ iildil.HU ¥
NO OH
N°2
--
,
NO No,
9*7^192
¥
"
323k ¥
NO
,
Nda

NOTE → Nitro
group C- NO, ) meta to the chlorine has
no effect on
reactivity .

Explanation : -
NO
,
at para positions .

É% [É¥
• On
U OH
OH cl OH U

¥ slowness
#
Yo ☒
]
Mo
"

-0-4*-0 GT
" -
-

- - o
o
In case
of ortho and Para structures , one of
the
resonating structures bears a negative charge
atom
on the c-
bearing the -
NO, grouts .

These stabilized by the NO,

Carbo anions are -

group
well
as as it eo of benzene ring .

However in structure
case of m -

,
none
of
the
resonating SH .
bear the -
ve charge on carbon atom .

bearing the -
NO, group .

: The - NO grouts does not stabilise

,
the Carbo anion and thus has no effect towards Reactivity .

9 Out of chlorobenzene and cyclo hexyl chloride , which

one is more reactive towards nucleophilic
substitution reaction and why ?
At cyclo chloride is more reactive towards
hexyl
'

nucleophilic substitution reaction because c- 4

bond
strength is less in cyclo hexyl chloride than
chlorobenzene .

atom is bonded
to
In cyclo hexyl chloride ,
I -

Sps hybrid c- atom while in chlorobenzene

U is bonded to stir hybrid c- atom
A bond in
chlorobenzene and
c-
less
is more
reactive towards nucleophilic Suh
strong .

9 Identify the chiral molecule in the following pairs .

~ and a
~
ce

AE
is chiral molecule as it contains
asymmetric
an c- atom which
U
is denoted by *
.
 4,011 pH
=
÷
fast
stop
¥
"

④N N°2
"
is
E-A NO
,
at ortho position :

É¥::÷1i¥¥ Step
¥
:-p
ÉÉ¥% * ÷: ↳I

[ ñ
.
≤

6-• NO at meta
,
position

¥E: ¥¥÷¥i¥o
"
%

ii. [ ⑦
to
"
o

111

EH
fast N°2
Sth
Cea substitution of Amino Grout :

il NHL

2 + INH, + Ago 4751<-2

book .
¥1 +
cuff -1110
Aniline
Cea substitution by cyano Group
for in
+ CUCN É ☒ + Cee
Br
475k
Cyano benzene
f0Nᵗk nitrile
or Benzo
pm
.¥É
alk His Benzamidec
.

Partial
Hydrolysis )
¥9
"
>
Benzoic
( complete
Alan acid

benzene
liAIHcey.CH NH , ,
hydrolysis )
Na / ↳ Hs OH
BenlglaminecReduction )
-

Cea Reaction with Metal : -

mgbr Grignard
1¥ -1mg IE ( phenyl
Reagent
magnesium
bromide )
↳ Reaction with sodium
,

Wurtz -

tiltigrxu filtig Reaction

☒U + 2Nd -1 U -

Ctb -4+2 Na + UKI

¥g 7-1-41 ¥er☒-47
Cea Reaction with Copper Ullmann Reaction

☒ -
I -124 + I -4¥ 4-7-17 + beats
Cea Reduction

¥4 + an + the

Benzene

Qa Electrophilic Substitution Reaction

Note d) Haloarenes undergo electrophilic substitution

reaction slowly as compared to benzene
ii ] is Otho and
( Halogen group Dara directing
Halogenation :

E) +4 ¥j +
% + the

te Cmajoo ) (Minor )
Nitration :

¥4 + H Nosecone , ¥ÉiN " -1

T¥ +110
(minor ] Into ,C major )
sulpho nation :

É + Hasoy
→^-
%%H+É%gµ -1110

Frieda Craft Alkylation :

" +416
I
AIU
}
%ᵗʰ +
¥% ,
+ the

Frieda craft Acylation :

" "" I -144
↳ _
+
+ CHIOU AIU,
{ OCH ]
Poly halogen Derivatives
→ Chloroform C Trichloromethane ,
CHU} )
< the -1342 ÉÉ CHU} -1344
Controlled
oxidation
→ Iodoform ( tri iodoform CHI] ]
,

NaOH CHI ↓ -13 Nat + CH, COO Na

Ctf coats +
31-2-14 →
]
+3110
Bae Carbon Tetrachloride [ Cela ]

is CH, +44 , sunlight Cap -14 HCl

>

%) CHU} -142 c.CH -12 HU

Cela b a colourless ,
non -
inflammable poisonous liquid
, ,

soluble in alcohol and ether .

☆ Uses
as solvent for oils , fats resins
•
a
,
in dry extinguisher
cleaning
•
◦
as fire

Dichlorodiphenyltrichloroethane )
'
DDT ( b b -

a- n
-8-4
"
g- if
? ,
-

te a-☒ he
ce
-

-
%& -
bis 6- chloro
chloral
Chlorobenzene phenyl )
1,1 I -

Kichwa ethane
,