MIND MAP AND MECHANISM SK025

MIND MAP ALKANE

Equation combustion of Methane, CH4: Equation combustion of Propane, CH3CH2CH3:

Excess oxygen CH4 + 2O2 CO2 + 2H2O Excess oxygen CH3CH2CH3 + 5O2 3CO2 + 4H2O

Limited/ Very limited oxygen CH4 + 3/2 O2 CO + 2H2O Limited/ Very limited oxygen CH3 CH2CH3 + 7/2 O2 3CO + 4H2O
CH4 + O2 C + 2H2O CH3 CH2CH3 + 2O2 3C + 4H2O

CH4 + Br2 UV CH3Br + HBr CH3CH2CH3 + Br2 UV CH3CH(Br)CH3 + Br
CH2Cl2 CH2Cl2

Bromine test: Br2/ CH2Cl2 (UV) Bromine test: Br2/ CH2Cl2 (UV)
The reddish brown colour of bromine is decolourised The reddish brown colour of bromine is decolourised

Chain Initiation Step Chain Initiation Step

Br Br uv 2 Br Br Br uv 2 Br

Chain Propagation step CH3 + HBr Chain Propagation step CH3CHCH3 + HBr
Br
H H
CH3CHCH3 + Br
CH3 + Br CH3CHCH3+ Br
Br2
Br Br + CH3 CH3Br + Br Br Br + CH3CHCH3
Br2
Chain termination step Chain termination step

Br + Br Br + Br

CH3 + CH3 CH3CH3 CH3CHCH3 + CH3CHCH3 CH3CHCH3
CH3CHCH3
CH3 + + Br CH3Br CH3CHCH3 + Br
Prepared by: NFAG Br
CH3CHCH3

ANSWER SCHEME ALKENE

Markovnikov’s rule: Saytzeff rule:
In the addition of HX to unsymmetrically alkene, the H atom In an elimination, alkene with greater no alkyl group
added to the carbon double bond having greater no of H. at C=C is the most stable and as major product.

*Mechanism OH H OH H Br
CH3CH2CCH3 CH3CHCCH3 CH3CHCCH3
Hydration
CH3 CH3 CH3

*Mechanism Br H2O/ H+ *Mechanism Dehydration KOH Dehydrohalogenation
CH3CH2CCH3 Conc H2SO4 EtOH Br
Hydrohalogenation
CH3 HBr H Br2 , CH2Cl2 CH3CH CCH3
Hydrohalogenation Br2 , H2O
(Anti Markovnikov’s) Br HBr CH3C=CCH3 Br CH3
CH3CHCHCH3 H2O2 CH3
H2 OH
CH3 Pt CH3CH CCH3

Hydrogenation H Br CH3
CH3CH2CCH3
i. O3 ii. Zn, H 2O KMnO4/OH- cold, diluted
CH3

Ozonolysis H KMnO4 , H+ OH Bromine test: Br2/ CH2Cl2 (UV/ dark place)
CH3C=O CH3CH CCH3 Bromine aqueous/water
+ O=CCH3 + MnO 2
CH3 OH CH3 The reddish brown colour of bromine is
decolourised
OH Baeyer’s test: Diluted KMnO4 , -OH/ cold
CH3C=O + O=CCH3
CH3 The purple colour of KMnO4 is decolourised
and brown precipitate formed

Oxidation

Prepared by: NFAG

ALKENE

DEHYDRATION HYDRATION

OH conc H2SO4 H3C CH CH CH3
CH3CH2CHCH3
major product HH H2O, H + OH
STEP 1 H3C C C H CH3CHCH3
+

CH3CH2CH=CH2

major product

H +H3C CH2 CH CH3 STEP 1 HH H H slow H3C H H
+ O+ C+ CH
H3C CH2 CH +CH3 H2O H3C CC H+ H H
OH OH
+
H
OH

H 2O carbocation
H
STEP 2

H H HH
OH
H3C CH2 CH CH3 + +CH3 H2O + H H3C C C H

+ H3C CH2 C C C H+

OH H3C H + H

O

STEP 2 H H
H

STEP 3

H HH H HH

+H fast H3C C CH
H3C CH CH CH3 H3C C CH
+ +CH3 OH
H3C CH OH + OH H
H C major product H
O

H
H

H

H fast H3C CH2 CH CH2

+H3C CH2 C+ CH2 OH minor product

H

Prepared by: NFAG

ALKENE

HYDROHALOGENATION HYDROHALOGENATION

H H Br Br H H
H3C C CH
+CH3CH=CH2 HBr H +CH3CCH=CH2 HBr H3C C CC H
Br
CH3 CH3 H H

STEP 1 STEP 1

H H H H HH
C C C+ HH
slow
H3C H + H Br H3C +C H slow H3C CH + H

H H Br CC
H3C CH CC H

CH3 H

20 carbocation CH3

2O carbocation

H HH rearrangement C+ HH
H3C C (1,2 - hydride shift) CC H
+
H H3C
CC

CH3 H CH3 H H

2O carbocation 3O carbocation

STEP 2 STEP 2

H H H H HH Br H H
C+ fast H3C C C C H
H3C +C H Br- fast H3C C + +C C H Br-
Br CH3 H H
C H H3C C
haloalkanes
H H CH3 H H 2 - bromo - 2 - methylbutane

haloalkanes

Prepared by: NFAG

BENZENE

Br

*Mechanism

Halogenation

*Mechanism

Friedel Crafts alkylation Br2 FeBr3

COOH CH3 conc. HNO3 , NO2
conc. H2SO4
KMnO4 , H+ CH3Cl
heat FeCl3 50-55 oC

Cl2 uv CH3COCl AlCl3 Nitration
CH2Cl COCH3
*Mechanism

Friedel Crafts acylation

*Mechanism

Prepared by: NFAG

BENZENE

NITRATION HALOGENATION

conc. HNO3 , NO2 Br2 , FeBr3 Br
conc. H2SO4 + H2O + HBr

50-55ºC

STEP 1 .. H .. STEP 1

.. . . + O : + + O:
N O.. ..:- + HSO4-
HO3SO.. H + H .O. N O.. ..:- H .O.

.. .. .. B....r+......-FeBr3 Br+ + FeBr4-
:O : :B..r B..r: + FeBr3 :B..r

H2O + N +
:O:

STEP 2 STEP 2

NO2+ Slow NO2 NO2 + NO2 Br+ Slow Br Br + Br
HH H H
H H
+
+ ++

STEP 3 NO2 + STEP 3 Br
+ FeBr3 + HBr
NO2+ Slow H NO2 + NO2 + Br
H H H FeBr4 -
+

Prepared by: NFAG

BENZENE

FRIEDEL-CRAFTS ALKYLATION FRIEDEL-CRAFTS ACYLATION

CH3CH2Cl , AlCl3 CH2CH3 O O
+ HCl CH3CCl , AlCl3 CCH3

+ HCl

STEP 1 STEP 1

H H C....l+......-AlCl3 H
CH3C
CH3C .. CH3C + + AlCl4- O .. O O
H C..l: + AlCl3 H C..l: + AlCl3 CH3C C....l+.....-.AlCl3 CH3C + + AlCl4-

H CH3C

STEP 2 CH2CH3 CH2CH3 + CH2CH3 STEP 2 O O O
H H CCH3 + CCH3
+CH2CH3 Slow H O CCH3 H
+CCH3 Slow H H
++
+
+

STEP 3 STEP 3

+ CH2CH3 CH2CH3 O O
H AlCl4- + AlCl3 + HCl CCH3
+ CCH3
H AlCl4- + AlCl3 + HCl

Prepared by: NFAG

ALCOHOL

(Dehydration of alcohol) CH3CH=CHCH3 CH2=CHCH2CH3 (Hydration of alkene)
Saytzeff rule: Conc H2SO4 H2O/ H+ Markovnikov’s rule:
In an elimination, alkene with In the addition of HX to
greater no alkyl group at C=C unsymmetrically alkene, the
is the most stable and as hydrogen atom added to the
major product. carbon double bond having
greater no of hydrogen.
O-Na+
CH3CHCH2CH3 Na
OH
Metal reaction
CH3CHCH2CH3 I2 / NaOH O
O Na+O-CHCH2CH3 + CHI3
OCCH3 O
CH3CHCH2CH3 CH3C-OH H+ Iodoform test: I2/ NaOH
To detect methyl carbinol
Esterification KMnO4 / H+ + Conc HCl / ZnCl 2 Yellow precipitate formed

O Cl
CH3CCH2CH3 CH3CHCH2CH3

Oxidation: KMnO4 @ K2Cr2O7 @ Na2Cr2O7 , H+ / ∆ Lucas Test: Conc HCl/ ZnCl2

10 alcohol: Carboxylic acid 10 alcohol: No cloudiness formed within 10 minutes
20 alcohol: Ketone 2o alcohol: Cloudiness formed within 5-10 minutes
30 alcohol: No reaction 3o alcohol: Cloudiness solution immediately formed

Prepared by: NFAG

CARBONYL

OH KMnO4 / H+ + O
CH3CH CH3COH

H

PCC CH2Cl2

OH H2O/ H+ O I2 / NaOH
CH3CH
CH3CH NaCN/ H3O+ O
OH Na+ O- CH + CHI 3
OH
CH3CH [Ag(NH3)2]+ / -OH Iodoform test: I2/ NaOH
To detect methyl carbonyl
CN Yellow precipitate formed

O
CH3CO- + Ag

Tollen’s test: [Ag(NH3)2]+ / -OH
To differentiate aldehyde from ketone

Silver mirror formed

Prepared by: NFAG