ORGANIC COMPOUNDS

1. Presented by
K.BINDU MEENAKSHI
REGD NO:11AB1R0028
Under the Guidance of
MR.A.VISWANATH M.Pharm
Associate Professor
Department Of Organic Chemistry
VIGNAN PHARMACY COLLEGE
(Approved by AICTE, PCI & affiliated to JNTU-K)
VADLAMUDI, GUNTUR DISTRICT – ANDHRA PRADESH, INDIA
PIN NO: 522213
PREPARATION OF
ALKANES,ALKENES,ALKYNES

2. CONTENTS:
INTODUCTION
NOMENCLATURE
METHOD OF PREPARATION
PHYSICAL PROPERTIES
CHEMICAL PROPERTIES

3. STRUCTURE OF ALKANES:
Alkanes contains only a single bond.
•General formula for alkanes is CnH2n+2.

4. All the carbon atoms are sp3 hybridized.
C-C Bond length is 1.54A˚(or)0.154nm and the C-H Bond
length is 1.10A˚(or)0.110nm.
The bond angle is109.28˚.
Sp3-Sp3
SP3-S
SP3-S
σ
σ
σ
1.10A˚
1.54A
˚
109.28˚

5. NOMENCLATURE OF ALKANES:
Suffix:-ane

6. CH3 CH CH3
CH3
METHYLPROPANE
CH3 CH CH2
CH3
CH3
CH2
2-METHYLPENTANE
CH3 CH CH2
CH3
CH3
CH3
2,2-DIMETHYLBUTANE
1 2 3 4 5
1 2 3 4

7. METHODS OF PREPARATIONS OF
ALKANES:
HYDROGENATION OF ALKENES OR ALKYNES:
a) R-CH=CH2 + H2
Ni
∆
R-CH2-CH3
ALKENE ALKANE
CH2=CH2 + H2 CH3-CH3
ETHYLENE ∆ ETHANE
Ni
b) R-C=CH + 2H2 R-CH2-CH3
Ni
∆
ALKYNE ALKANE
CH=CH + 2H2 CH3-CH3
Ni
∆
ACETYLENE ETHANE
−
−

8. REDUCTION OF ALKYL HALIDE:
Alkyl halides undergoes reduction with nascent hydrogen to form
alkanes.
R-X + 2[H] R-H + HX
ALKYLHALIDE ALKANE
CH3CH2-Br + 2[H] CH3-CH3 + HBr
ETHYL BROMIDE ETHANE
DECARBOXYLATION OF CARBOXYLIC ACID:
When the sodium salts of carboxylic acid is heated strongly with
soda lime(NaOH +CaO) , carbonate and an alkane is formed.
R-COONa + NaOH RH + NaCO3
∆
CH3-COONa + NaOH CH4 + Na2CO3
SODIUM ACETATE ∆ METHANE
ALKANE

9. HYDROLYSIS OF GRIGNARD REAGENT:
Alkyl halide on treatment with magnesium in anhydrous ether
gives Grignard reagent.
RX + Mg RMgX
ALKYL MAGNESIUM HALIDE
CH3CH2Br + Mg CH3CH2MgBr
ETHYLBROMIDE ETHYL MAGNESIUM BROMIDE
This reagent on treatment with water gives alkanes.
RMgX + HOH RH +MgX(OH)
ALKANE
CH3MgI + HOH CH4 + MgI(OH)
METHYL MAGNESIUM IODIDE METHANE
ETHER
ETHER

10. WURTZ SYNTHESIS:
Higher alkanes are produced by heating an alkyl halide with
sodium metal in dry ether solution.
CH3-Br + 2Na + Br-CH3 CH3-CH3 + 2NaBr
METHYL BROMIDE ETHANE
The reaction between 2 different alkyl halides and sodium gives a
alkane.
CH3CH2-Cl + 2Na + Cl-CH3 CH3CH2-CH3 + 2NaCl
ETHYL CHLORIDE METHYL CHLORIDE PROPANE
LIMITATIONS:
Separation of compounds is difficult due to little difference in the
boiling point.
R-X + 2Na + X-R R-R + 2NaX
ETHER
ETHER
SYMETRICAL ALKANE
ETHER

11. COREY HOUSE ALKANE SYNTHESIS:
Developed by E.J.Corey and Herbert House in 1960s.
Lithium dialkyl copper and an alkyl halide on reaction gives
alkanes.
R2-CuLi + R′X R-R′ + RCu + LiX
LITHIUM ALKYL ALKANE
DIALKYL HALIDE
COPPER
Synthesis of propane from ethyl bromide
CH3CH2BR CH2CH2Li (CH3CH2)2 CuLi
CH3Br
CH3CH2CH3
PROPANE
LITHIUM DIETHYL COPPER
ETHYL LITHIUM
BROMO ETHANE
Li CuI

12. KOLBE’S SYNTHESIS:
When a concentrated solution of sodium salt of a carboxylic
acid is electrolyzed, an alkane is formed.
2RCOO Na + 2H
⁻ ⁺ 2O R-R +2CO2 +2NaOH +H2
2CH3COO¯Na⁺+ 2H2O CH3-CH3+2CO2+2NaOH+H2
SODIUM CARBOXYLATE AT ANODE AT CATHODE
SODIUM ACETATE
AT ANODE
AT CATHODE
ETHANE

13. Soluble in non-polar solvents .
Insoluble in polar solvents like water.
Densities of alkanes are around 0.7g/ml ,
which is less than water . Hence insoluble in water.
Both the boiling and melting point of alkanes
increases with increase in molecular weight.
PHYSICIAL PROPERTIES OF ALKANES:

14. gases
liquids
solids

15. IR Spectrum :
The IR spectra of alkanes show absorption corresponding to the C-H
stretching frequencies at 2850-3000cm¯1.

16. CHEMICAL PROPERTIES OF ALKANES:
Halogenation:
Alkanes react with chlorine in the presence of UV light or diffused
sunlight or at a temperature of 300-400˚c yielding a mixture of
product. This reaction is not stopped at this stage.
CH4 + Cl2 CH3Cl + HCl
METHANE METHYL CHLORIDE
This reaction is not stopped at this stage.
CH3Cl + Cl2 CH2Cl + HCl
METHYLENE CHLORIDE
hυ
∆

17. CH2Cl + Cl2 CHCl3 + HCl
CHLOROFORM
CH3Cl + Cl2 CCl4 + HCl
CARBON TETRACHLORIDE
MECHANISM:
1)Chain initiation step:
Cl : Cl Cl + Cl
∙ ∙
2)Chain propagation step:
Cl · + H  CH3 H  Cl + · CH3
H3C · + Cl : Cl H3C :Cl + Cl
METHANE
METHYL CHLORIDE
METHYL RADICAL
a)
b)
hυ
∆

18. Both a and b steps are repeated .Thus chain reaction is
propagated.
3)Chain termination reaction:
Cl • + • Cl Cl-Cl
CH3 • + • Cl CH3-Cl
CH3 • + • CH3 CH3-CH3

19. REACTION WITH SULFURYLCHLORIDE:
Alkanes react with sulfurylchloride in presence of benzoyl peroxide at
60-80˚c to form alkyl halide.
BENZOYL
PEROXIDE
SOCl2
PEROXIDE
2,3-DIMETHYL BUTANE
1-CHLORO-2,3-DI
METYL BUTANE
2-CHLORO-2,3-DI
METYL BUTANE
+ CH3 C C CH3
CH3 CH3
Cl
H
C C CH3
CH3 CH3
CH3
CH3 C C CH2Cl
CH3
CH3
H
H
CH3
CH3─
R-H + Cl-S-Cl R-Cl + SO2 +HCl
O
O

20. NITRATION:
Nitration of ethane with HNO3 at 400 to 500 c and under high
̊
pressure gives a mixture of nitro methane and nitro ethane.
CH3-CH3 +HO-NO2 CH3-CH2-NO2 +CH3-NO2 +H2O
ETHANE NITROETHANE NITROMETHANE
MECHANISM:
Chain initiation step:
˙ ETHANE ETHYL FREE RADICAL
CH3CH2:H CH3CH2˙ + H˙
400-500 ˚C
CH3 : CH3 2CH3
METHYL FREE RADICAL
ETHANE

21. Chain propagation step:
CH3CH2• + HO:NO2
CH3CH2
-
NO2 +HO•
CH3CH2  H + HO• CH3CH2• + H2O
Chain termination step:
CH3˙ +CH3 CH
̇ 3:CH3
ETHANE
CH3CH3 + CH
̇ 3CH3 CH
̇ 3CH2:CH2CH3
BUTANE
NITROETHANE HYDROXYL
RADICAL
ETHYL FREE RADICAL
ETHANE
ETHYL RADICAL

22. SULFONATION:
This involves the substitution of hydrogen atom of alkane with –
SO3H group .
R-H + HO-SO3H R-SO3H + H2O
ALKANE FUMING ALKANE SULFONIC
ACID
R=C6H15 or Larger alkyl group
Lower alkanes like methane and ethane do not give this reaction.
∆

23. COMBUSTION(OXIDATION):
General equation of the combustion of hydrocarbon is
CxHy +(x+y/4)O2 xCO2 + y/2 H2O
CH4 + 2O2 CO2 + 2H2O
The heat of combustion of 2 isomers , pentane and
2-methylbutane are 845.2kcal/mol and 843.5kcal/mol.
The mass balance equation for the combustion of these 2 isomers
are the same.
C5H12 (g) + 8O2(g) 5CO2(g) + 6H2O + Heat

24. ISOMERIZATION:
Normal alkanes are converted to their branched chain isomers in
the presence of aluminum chloride and HCl at 25 c.
̊
CH3-CH2-CH2-CH3
n-BUTANE
ISOBUTANE
(2-METHYL PROPANE)
AROMATIZATION:
n-Hexane is passed over Cr2O3 supported over alumina at 600 c ,
̊
benzene is produced.
CH3CH2CH2CH2CH2CH3 +4H2
n-HEXANE BENZENE
CH3-CH-CH3
CH3
AlCl3
O
Cr2O2-Al2O3
HCl

25. PYROLYSIS(CRACKING):
Ethane when heated to 500 c in the absence of air , gives a
̊
mixture of methane , ethylene and hydrogen.
CH3CH3 CH2=CH2 + CH4 +H2
ETHANE ETHYLENE METHANE
MECHANISM:
Chain initiation step:
H3C:CH3 2H3C•
Chain propagation step:
∆
ETHANE METHANE ETHYL RADICAL
H3C· + HCH2CH3 CH4 + ·CH2CH3
METHYL FREE RADICAL
ETHANE
METHYL
RADICAL

26. b)
c)
Step (b) and (c) are repeated over and over again.
Chain termination step:
CH3CH2 ∙ + ∙ H CH3CH3
ETHYL RADICAL ETHANE
H2C CH2 +H·
H2C CH3
·
·
H
·
H · + H : CH2CH3
H-H + ·CH2CH3
ETHYLENE
ETHYL RADICAL
ETHANE
ETHYL RADICAL

27. CYCLOALKANES:
Cycloalkanes or cycloparaffins are saturated hydrocarbon in which
the carbon atom are joined by single covalent bond to form a ring.
General formula – CnH2n.
First member of the series is cyclopropane , C3H6.
=
CYCLOBUTANE CYCLOPENTANE CYCLOHEXANE

28. ALKENES:
Alkenes are the hydrocarbons with Double bond.
General formula is CnH2n.
Commonly known as Olefins.
First member of alkenes is Ethylene.
Bond angle is 120˚.
C-C Bond length is 1.34A˚.
C-H Bond length is 1.09A˚.

29. Longest chain containing double bond is taken as parent chain.
Numbering is done so that the double bond has lowest possible
number.
When 2 or more double bonds are present the ending name is
replaced with –adiene or –atriene.
NOMENCLATURE:
Suffix: -ylene.
CH2= CH CH
─ 2 CH
─ 3
1-butene
3-ethyl-2-pentene
l
CH2 – CH3
CH3 CH
─ 2 C=CH CH
─ ─ 3
5 4 3 2 1
1 2 3 4

30. METHOD OF PREPARATION OF ALKENES:
BY DEHYDRATION OF ALCOHOL:
When alcohol is heated in the presence of sulfuric acid, a molecule
of water is eliminated and alkene is formed.
R CH CH2
O OH
R CH CH2 +H2O
H2SO4
∆ ALKENE
CH CH2
O OH
CH CH2 +H2O
CH3 CH3
H2SO4
170˚C
1-PROPANOL
PROPENE

31. With unsymmetrical 2˚ and 3˚ alcohol elimination can proceed in 2
ways and a mixture of alkenes is formed.
This is in accordance with SATYZEFF RULE.
CH CH
OH
CH3 CH3
H
CH3 CH CH CH3
H2SO4
∆
2-BUTANOL
2-BUTENE(80%)
H2SO4
∆
CH2 CH
OH
CH3 CH2 CH3 CH2 CH CH2
H

32. BY DEHYDROHALOGENATION OF ALKYL
HALIDE:
When an alkyl halide is heated with an alcoholic solution of
sodium or potassium hydroxide , a molecule of hydrogen halide is
eliminated and an alkene is formed.
CH CH2 + KOH
H X
CH CH2 + KX + H2O
R
R
ALCOHOL
∆
ALKYL HALIDE
ALKENE
H3C CH CH2 + KOH
H Br
CH2 + KBr + H2O
CH3 CH
ALCOHOL
∆
PROPENE
1-BROMOPROPANE

33. BY DEHALOGENATION OF VICINAL
DIHALIDE:
Alkenes are formed when vic-dihalide are heated with zinc dust
in ethyl alcohol.
R CH3 CH2 + Zn
Br Br
R CH CH2 + ZnBr2
VIC-DIHALIDE
ALCOHOL
∆
ALKENE
H3C CH CH2 + Zn
Br Br
CH3 CH2 + ZnBr2
CH3
ALCOHOL
∆
1,2-DIBROMOPROPANE
PROPENE

34. BY CONTROLLED HYDRGENATION OF
ALKYNES:
Alkynes react with lindlar’s catalyst to give alkenes.
ALKYNE
R C C H + H2 R CH CH2
ALKENE
Pd-CaCO3
QUINOLINE
CH3 C C H+H2 CH3 CH CH2
Pd-CaCO3
QUINOLINE
PROPYNE PROPENE

35. BY CRACKING OF ALKANES:
Alkanes when heated at 500-800˚c in the absence of air decompose
to yield lower molecular weight alkenes,alkanes,hydrogen.
CH3-CH3 CH2=CH2 + CH4 + H2
ETHANE ETHYLENE
CH3-CH2-CH3 CH3-CH=CH2 + CH2=CH2
PROPANE PROPENE ETHYLENE
+ CH4+ H2

36. PHYSICAL PROPERTIES:
 All are colorless and odorless except ethene.
Insoluble in water and quiet soluble in non polar solvents.
Less dense than water.
Boiling point increases with carbon number.
Melting point , boiling point, specific
gravity rises with increase of molecular
weight in homologous series.
IR Spectra of alkenes show C-H
stretching absorption at 3000-3100cm¯ .
1

37. CHEMICAL PROPERTIES:
Alkenes are more reactive than alkanes because of π electrons of
the double bond.
ADDITION OF HYDROGEN HALIDES:
Alkenes react with hydrogen halide to form alkyl halide.
CH3-CH=CH-CH3 + HBr CH3-CH2-CH-CH3
2-BUTENE 2-BROMOBUTANE
MARKOVNIKOV RULE:
This rule on the basis of mechanism of HX addition.
Br
|
Br
|
CH3-CH=CH2 + HBr CH3-CH-CH3
PROPENE 2-BROMOPROPENE

38. MECHANISM:
STEP 1:
STEP 2:
CH3 CH CH2 +H Br
CH3 CH2 CH2 + Br
CH3 CH3 CH3 + Br
PROPENE
1˚CARBOCATION
2˚CARBOCATION
CH3 CH CH3 + Br CH3 CH CH3
Br
2˚CARBOCATION 2-BROMOPROPENE

39. MECHANISM OF ADDITION OF HYDROGEN
HALIDE:
STEP 1:
STEP 2:
CH3 C C CH3 + H
H H
CH3 C C CH3 + Br
H H
H
Br
2-BUTENE CARBOCATION
CH3 C C CH3 + Br
H H
H
CH3 C C CH3
H H
H Br
NUCLEOPHILE
2-BROMOBUTANE

40. ADDITION OF HYPOHALOUS ACID:
Alkenes react with hypohalous acid to give halohydrins.
ADDITION OF HYDROGEN:
Alkenes add hydrogen under pressure and in the presence of Ni , Pt
or Pd catalyzed to produce saturated hydrocarbons.
CH2 = CH2 + H2 CH3 – CH3
ETHYLENE ETHANE
CH2 CH2 + HO Cl CH2 CH2
OH Cl
ETHYLENE ETHYLENE CHLOROHYDRIN
Ni
∆

41. ADDITION OF WATER:
Alkenes react with water in the presence of a strong acidic catalyst
to form alcohol.
CH3-CH=CH2 + H2O CH3-CH-CH3
MECHANISM:
STEP 1:
STEP 2:
OH
l
PROPENE 2-PROPANOL
CH3 CH CH2 + H+
CH3 CH CH3
CH3 CH CH3 + H2O CH3 CH CH3
O H
H
PROPENE 2˚CARBOCATION
PROTONATED ALCOHOL
H⁺

42. ADDITION OF H2SO4:
Alkene react with H2SO4 yields an alkyl hydrogen sulfate.
MECHANISM:
STEP 1:
CH3-CH=CH2 + H CH
⁺ 3- CH-CH
⁺ 3
CH3-CH=CH2 + H-OSO3H CH3-CH-CH3
OSO3H
l
PROPENE 1-METHYL ETHYL
HYDROGEN SULFATE
STEP 2:
PROPENE 2˚CARBOCATION
CH3- CH-CH
⁺ 3 + ¯OSO3H CH3-CH-CH3
l
OSO3H
1-METHYL ETHYL HYDROGEN SULFATEA

43. OXIDATION WITH COLD KMnO4 SOLUTION:
Alkenes react with cold dil.KMnO4 solution to form glycols.
CATALYTIC OXIDATION:
Alkenes react with O2 in the presence of silver catalyst at 250-400˚c
to form epoxides.
CH2=CH2 CH2-CH2
OH
l
OH
l
KMnO4
H2O
ETHYLENE
ETHYLENE OXIDE
CH2 CH2 + O2 H2C CH2
O
ETHYLENE
ETHYLENE GLYCOL

44. ADDITION OF HALOGEN:
Alkenes react rapidly with halogens in carbon tetrachloride solvent to
form dihalide.
MECHANISM:
STEP 1:
STEP 2:
CCl4
C C
H
H3C H
H
+ Br2 H C C H
H
H Br
Br
C C
H
H3C H
H
+ Br Br C C
H Br H
H
CH3
+ Br
C C
H Br H
H
CH3
Br
CH3 C C H
Br
H
Br
H
PROPENE 1,2-DIBROMOPROPENE
1,2-DIBROMOPROPENE
PROPENE
BROMONIUM ION

45. OXYMERCURATION-DEMERCURATION OF
ALKENES:
Mercuric acetate and water add to alkenes in a reaction called
oxymercuration.
The product of oxymercuration is reduced with sodium borohydride
in a subsequent reaction called demercuration.
CH3 CH CH2 CH3 CH CH2
HgO
OH
C
O
CH3
Hg(O C
O
CH3)2
H2O
CH3 CH CH2
HgO
OH
C
O
CH3
CH3 CH CH3
OH
NaBH4
PROPENE
2-PROPANOL

46. MECHANISM:
STEP 1:
R CH CH2 R CH CH2
Hg
OAc
R CH C H
H
HgOAc
O
H H
R C C H
OH H
HgOAc
H
Hg OAc
OAc
H2O
OAc
R C C H
OH H
HgOAc
H
R CH CH2
OH H
STEP 2:
ALKENE
MERCURIC
ACETATE
MERCURINIUM ION
ORGANOMERCURY
COMPOUND
ALOCHOL
NaBH4
C
O
CH3
Ac=

47. HEAT OF HYDROGENATION:
It is the energy difference between the starting alkene and the
product alkane.
COMUSTION:
Alkenes when burnt in air , oxidizes to CO2 and water.
CH2=CH2 + 3O2 2CO2 + 2H2O + HEAT
ETHYLENE

48. OXIDATION WITH HOT KMnO4 SOLUTION:
On treatment with hot KMnO4 alkenes split double bond to form
ketones and acid.
CH3-CH=CH2 CH3-C-OH +CO2 + H2O
POLYMERISATION:
simple alkenes polymerize to form long chain addition polymer.
nCH2=CH2 CH2-CH2
O
ll
[O]
HOT KMnO4
ACETIC ACID
PROPYLENE
POLYMERISATION
ETHYLENE
POLYETHYLENE

49. ALKYNES:
 Alkynes are unsaturated hydrocarbons containing triple bond.
 General formula is CnH2n-2.
 First member of the series is Acetylene.
 H-C-C Bond angle is 180˚.
 C-H Bond length is 1.09A˚.
 C-C Bond length is 1.20A˚. sp-sp
s-sp
s-sp

50. NOMENCLTURE:
common names: “ alkyl acetylene .”
Suffix : -yne
Long continuous chain with triple bond –parent chain.
Position of triple bond is indicated by prefixing the no. of carbon
preceding it to the name of alkyne.
CH3CH2CCH HCCCHCH2CH3
1-butyne 3-methyl-1-pentyne
ethyl acetylene sec-butyl acetylene
CH3
|
1
2
3
4 1 2 3 4 5

51. METHOD OF PREPARATION OF ALKYNES:
DEHYDROHALOGENATION OF VICINAL
DIHALIDES:
Alkynes are obtained by treating vicinal dihalides with alcoholic
KOH followed by sodium amide(NaNH2).
H C C H H C C H
H Br
Br H
H Br
H C C H
KOH
ALCOHOL
NaNH2
1,2-DIBROMO ETHANE
VINYL BROMIDE ACETYLENE

52. DEHALOGENATION OF TETREHALIDE:
When 1,1,2,2-tetrahalide are heated with zinc dust in alcohol ,
alkynes are formed.
REACTION OF CALCIUM CARBIDE WITH H2O:
Calcium carbide react with water to yield acetylene.
R C C R + 2Zn R C C R + 2ZnX2
X X
X X
TETRAHALIDE
ALKYNE
ALCOHOL
∆
CaC2 + H2O H C C H + Ca(OH)2
CALCIUM CARBIDE ACETYLENE

53. REACTION OF SODIUM ACETYLIDE WITH 1˚
ALKYL HALIDE:
Sodium acetylide react with primary alkyl halide to form alkynes.
H C C:Na+CH3CH2Br H C C CH2CH3 +NaBr
SODIUM ACETYLIDE ETHYL
BROMIDE
1-BUTYNE

54. PHYSICAL PROPERTIES OF AKLYNES:
Colorless and odorless except acetylene.
Slightly soluble in water.
Readily soluble in organic solvents.
Boiling , melting point and specific gravities show regular
increase with increase in mol. Wt.
IR Spectra of alkynes show C-H stretching absorptions at
~3300cm¯.
1

55. CHEMICAL PROPERTIES:
Alkynes give same type of addition reactions as alkenes.
ADDITION OF HYDROGEN:
In presence of Ni,Pt or Pd, alkynes with hydrogen gives alkenes
and alkanes.
R C CH + H2 R CH CH2 R CH2 CH3
ALKYNE ALKENE ALKANE
PROPYNE PROPENE
PROPANE
Ni
Ni
H2
Ni
H2
Ni
C CH+ H2 CH3
CH3 CH CH2 CH3 CH2 CH3

56. METAL-AMMONIA REDUCTION TO TRANS
ALKENES:
Sodium metal in liquid ammonia reduces alkynes with
antistereochemistry into trans alkenes.
MECHANISM:
STEP 1:
CH3 C C CH3 C C
CH3
H
H
CH3
2-BUTYNE
TRANS-2-BUTENE
CH3 C C CH3 + •Na C CH + Na+
CH3
H3C
RADICAL ANION
2-BUTYNE
Na
Liq NH3

57. STEP 2:
STEP 3:
STEP 4:
C C + H
CH3
H3C
NH2 C C
CH3
H3C H
+ NaNH2
C C
CH3
H3C H
+ H NH2 C C
CH3
H3C H
+ NaNH2
H
C C
CH3
H3C H
+ •Na C C
CH3
H3C H
+ Na+
TRANS-2- BUTENE

58. ADDITION OF HALOGEN:
Halogen added to alkyne to form a dihalide and then tetra halide.
R C CH +X2 R C CH
X X
R C C H
X X
X X
C CH+Br2
CH3 CH3 CBr CHBr CH3 CBr2 CHBr2
PROPYNE 1,2-DIBROMOPROPENE
1,1,2,2-TETRABROMO PROPANE

59. ADDITION OF HALOGEN ACIDS :
Two molecules of acid when added to symmetrical alkynes gives
the following products.
MECHANISM:
STEP 1:
H C C H + HBr H C C H
H Br
H C C H
H
H X
Br
ACETYLENE 1-BROMOMETHANE
1,1-DIBROMOMETHANE
H3C C C H + H+ CH3 C CH2
+
PROPYNE CARBOCATION

60. STEP 2:
STEP 3:
STEP 4:
CH3 C CH2 + :Br-
+
CH3 C CH2
Br
2-BROMO PROPENE
CH3 C CH2 + H+
Br
CH3
C CH3
Br
+
2-BROMO PROPENE
CH3
C CH3 + :Br-
Br
+
CH3
C CH3
Br
Br
2,2-DIBROMOPROPANE
CARBOCATION

61. ADDITION OF HYPOHALOUS ACID:
Addition of 2 molecules of hypohalous acid to alkynes gives
dihaloketone.
ADDITION OF HYDROGEN CYANIDE:
Alkynes react with HCN in the presence of Ba(CN)2 catalyst gives
vinyl cyanide.
CH3 C CH + 2HO Br CH3
C CHBr2
OH
OH
CH3 C CHBr2
o
PROPYNE 1,1-DIBROMO ACETONE
-H2O
H C C H + HCN CH2 CH CN
ACETYLENE
Ba(CN)2
PRESSURE VINYL CYANIDE

62. OXIDATION WITH KMnO4:
Oxidation of alkynes with alkaline KMnO4 forms carboxylic acid
and CO2.
POLYMERIZATION:
Alkynes when passed through a red hot tube gives aromatic
hydrocarbons.
CH3 COOH + CO2
CH3 C C H + 4
PROPYNE ACETIC ACID
C
CH3
CH
HC
C C
CH3
CH3 CH
C
HC CH
C C
C
CH3
CH3
CH3
HOT TUBE
400˚C
1,3,5-TRIMETHYL BENZENE
PROPYNE

63. OZONOLYSIS:
Alkynes react with ozone to give ozonide gives following product.
ALKYNE
R C C R + O3 R C C
O
O O
R
R C C R + H2O
R C OH + R C OH
O O
O O
OZONIDE
DIKETONE
CARBOXYLIC ACIDS
H2O

64. MERCURIC ION-CATALYSED HYDRATION:
Alkynes undergo acid-catalyzed addition of water , in the
presence of mercuric ion as a catalyst.
MECHANISM:
STEP 1:
CH3 C C H + H2O CH3 C CH2
OH
CH3 C CH3
O
PROPYNE
H2SO4
HgSO4
ENOL
ACETONE
H⁺
CH3 C C CH3 C C
H H
Hg2+
: Hg2+
A BRIDGED MERCURIUM
ION INTERMEDIATE

65. STEP 2:
STEP 3:
CH3 C C H
Hg2+
O
H H
C C
H
Hg+
H3C
+O
H H
O
H
H
C C
H
Hg+
H3C
+O
H H
+ C C
H
Hg+
H3C
O
H
+ H3O+
ORGANOMERCURY

66. STEP 4:
STEP 5:
STEP 6:
C C
H3C
HO
Hg+
H
CH3 C CH2 Hg+
o
H O H + CH3
H
C CH2 Hg+
O
+
CH3 C CH2 Hg+ + H2O
O
H +
CH3 C CH2 Hg+
O
H +
Hg2+ + CH3 C CH2
O
H
CH3 C CH3
O
ENOL FORM
KETO FORM
ENOL FORM KETO FORM
OXONIUM ION

67. CONCLUSION:
Alkane , Alkenes , alkynes are the basic fundamental structure in
organic chemistry.
Almost all the compounds contains single or double or triple bonds
in their structure.
Alkanes and Alkenes are used as fuel and in production of
polymers.
Alkynes are pharmaceutically used in the preparation of
contraceptives.

68. REFERENCES:
Arun Bahl,B.S Bahl , Advanced Organic Chemistry ,
Pg No:184-240,262-356.
Morrison and Boyd , Organic Chemistry ,
6th
edition , Pg No:112-158,309-327.
Bruice , Organic Chemistry, 3rd
edition,
Pg No:111-171,240-398,461-476.

69.  Vogel's, Practical Organic Chemistry, 5th
edition,
Pg No:470-517.
Lloyd N . Ferguson , Textbook of Organic
Chemistry,2nd
edition , Pg No. 59-138 .
Raj . K . Bansal , Textbook of Organic
Chemistry , 5th
edition , Pg No. 168-269.

70. ACKNOWLEDGEMENT
I would like to thank my guide MR.A.VISWANATH sir
for his constant support and guidance.
I also thank our principal Dr . P.SRINIVAS BABU sir and
SEMINAR COMMITTE for giving me this opportunity.