1. Hydrocarbons

3. Carbon: normally forms four covalent bonds and has no unshared pairs of electrons.
Hydrogen: forms one covalent bond and no unshared pairs of electrons.
Nitrogen: normally forms three covalent bonds and has one unshared pair of electrons.
Oxygen: normally forms two covalent bonds and has two unshared pairs of electrons.
Halogen: normally forms one covalent bond and has three unshared pairs of electrons. C H N . . . . .
O = . . . . . Cl . .

4. Hydrocarbons Large family of organic compounds
Composed of only carbon and hydrogen
Saturated hydrocarbons
Alkanes
Unsaturated hydrocarbons
Alkenes, Alkynes & Aromatics
C - C
C = C
C C

5. Alkanes

6. Expanded structural formula:
Methane
Tetrahedral
Expanded structural formula:
showing each bond line.
CH4
Molecular formula

7. Ethane
C2H6
Molecular formula
Expanded structural formula
CH3 – CH3
Condensed structural formula: with each carbon atom and
its attached hydrogen atoms.

8. Alkanes
CnH2n+2
n: number of carbon atoms

9. Naming of Alkanes
CnH2n+2
Prefix + ane

10. Line-angle Formula Propane CH3-CH2-CH3 Butane CH3-CH2-CH2-CH3 Pentane
CH3-CH2-CH2-CH2-CH3

11. Naming Substituents In the IUPAC system:
Removing a H from an alkane is called alkyl group.
-ane
Halogen atoms are named as halo.
-ine
-yl -O
-OH Hydroxyl
-NO2 Nitro

13. Give the name of: CH3 
CH3─CH─CH2─CH3
STEP Longest chain is butane.
STEP Number chain. CH3
CH3─CH─CH─CH3
STEP 3 Locate substituents and name.
2-Methylbutane

14. Give the name of: CH3 CH3
 
CH3─CH─CH─CH3
STEP Longest chain is butane.
STEP Number chain. CH3 CH3
 
STEP 3 Locate substituents and name.
2,3-dimethylbutane

15. Cl CH3
 
CH3─CH2─CH─CH─CH3
STEP Longest chain is pentane.
STEP Number chain from end nearest substituent.
Cl CH3
 
CH3─CH2─CH─CH─CH3
STEP 3 Locate substituents and name alphabetically.
3-chloro-2-methylpentane

16. CH CH3
| |
CH3─CH─CH2 ─CH─CH ,4-dimethylpentane
Cl CH3
CH3─CH2─CH─CH2─C─CH2─CH3 | Cl
3,5-dichloro-3-methylheptane

17. Br 
CH3─CH─CH2─CH2─Cl
STEP Longest chain has 4 carbon atoms.
C─C─C─C
STEP Number chain and add substituents.
C ─ C ─ C ─ C ─ Cl
STEP 3 Add hydrogen to complete 4 bonds to each C.
CH3─CH─CH2─CH2─Cl bromo-4-chlorobutane

18. Constitutional Isomers
Have the same molecular formula.
Have different atom arrangements (different structural formula).
CH3CH2CH2CH3
Butane
C4H10
CH3
2-Methylpropane
CH3CHCH3
C4H10

19. Cyclic Hydrocarbon - Cycloalkane
Cyclobutane = =
Cyclopentane =
Cyclohexane

20. Physical Properties of Alkanes
Nonpolar
Insoluble in water.
Lower density than water.
Low boiling and melting points.
Gases with 1-4 carbon atoms.
(methane, propane, butane)
Liquids with 5-17 carbon atoms.
(kerosene, diesel, and jet fuels)
Solids with 18 or more carbon atoms.
(wax, paraffin, Vaseline)

21. Boiling & melting points of Alkanes
Number of carbon atoms ↑
bp & mp ↑
Number of branches ↑
bp & mp ↓
CH3
CH3CH2CH2CH3
CH3CHCH3

22. Chemical reactions of Alkanes
Low reactivity
1- Combustion:
Alkanes react with oxygen.
CO2, H2O, and energy are produced.
Alkane + O CO2 + H2O + heat
CH4 + 2O2 CO2 + 2H2O + energy

23. Halogenation
Free Radical reaction
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Dr Seemal Jelani Chem-160

24. Chemical reactions of Alkanes
Low reactivity
2- Halogenation:
Alkanes react with Halogens.
CH4 + Cl2 CH3Cl + HCl
Chloromethane
Heat or light
Dichloromethane
CH3Cl+ Cl2 CH2Cl2 + HCl
Heat or light
CH2Cl2+ Cl2 CHCl3 + HCl
Trichloromethane
Heat or light
CHCl3+ Cl2 CCl4 + HCl
Tetrachloromethane
Heat or light

25. Product is hydrocarbon derivative
Reaction between a substance and a halogen in which one or more halogens atoms are incorporated into molecules of the substance
Product is hydrocarbon derivative
Halogenation is an example of Substitution reaction
It is a reaction in which part of a small reacting molecule replaces an atom or group of atoms on a hydrocarbons
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Dr Seemal Jelani Chem-160

26. General reaction heat or R-H + X2 R-X + H-X light R= Alkyl group
Halogenation means: X2 where X = F, Br, Cl, I
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Dr Seemal Jelani Chem-160

27. Radical Halogenation Terms
Mechanism
How the reaction occurs through multiple steps (most reactions actually occur in many steps)
Chain Reaction
Reactions that occur on their own after some initiating event
Free Radicals
Atoms that have one free electron—highly reactive
1/1/2019
Dr Seemal Jelani Chem-160

28. Radical Halogenation Terms
Initiation Step
Step where a bond is split by heat/light, producing free radicals
Propagation Step
Step where free radicals react with non-radicals, producing more free radicals and continuing the “chain reaction”
Termination Step
Step where free radicals react with each other, producing non-radicals and terminating the “chain reaction”
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Dr Seemal Jelani Chem-160

29. Initiation​ ​Reaction starts with one ​photon of light.​ Must be UV​
Wavelength less than ​400nm​
Energy less than 300kJ ​per mole​
Reaction proceeds to ​completion after this.
Reason is the chlorine ​molecule​
Light breaks the Cl-Cl ​bond​•​Homolytic fission​
​Each atom takes an ​electron
Forms radicals.
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Dr Seemal Jelani Chem-160

30. Initiation ​Homolytic fission forms radicals​
Radicals are very reactive atoms or groups.
Cl​2​ ​2Cl​.
Radicals react quickly with surrounding molecules.
1/1/2019
Dr Seemal Jelani Chem-160

31. Radical Halogenation of Alkanes
Reactions of Alkanes
Radical Halogenation of Alkanes
CH4 + Cl2  CH3Cl + HCl
Mechanism (chain reaction):
Step 1 Cl2 ⇌ Cl· + Cl ·
Step 2 Cl· + CH4  CH3· + HCl
Step 3 CH3· + Cl2  CH3Cl + Cl·
Step 4 Cl· + Cl·  Cl2
Type of Step h
Initiation
Propagation
Termination
(Free Radicals)
Overall reaction: CH4 + Cl2  CH3Cl + HCl
 chloromethane
Why not 1-chloromethane?
Halogenated product is a haloalkane
Naming: halogen atom is a substituent, replace –ine ending with –o
-F fluoro -Cl chloro -Br bromo -I iodo
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Dr Seemal Jelani Chem-160

32. CHLORINATION OF METHANE
Further
propagation If excess chlorine is present, further substitution takes place
The equations show the propagation steps for the formation of...
dichloromethane Cl• + CH3Cl ——> CH2Cl• HCl
Cl2 + CH2Cl• ——> CH2Cl Cl•
trichloromethane Cl• + CH2Cl2 ——> CHCl2• + HCl
Cl CHCl2• ——> CHCl Cl•
tetrachloromethane Cl• + CHCl3 ——> CCl3• + HCl
Cl CCl3• ——> CCl Cl•
Mixtures Because of the many possible reactions there will be a mixture of products.
Individual haloalkanes can be separated by fractional distillation.
1/1/2019
Dr Seemal Jelani Chem-160

33. CATALYTIC CRACKING Converts heavy fractions into higher value products
Involves the breaking of C-C bonds in alkanes
Converts heavy fractions into higher value products
THERMAL proceeds via a free radical mechanism
CATALYTIC proceeds via a carbocation (carbonium ion) mechanism
CATALYTIC
SLIGHT PRESSURE
HIGH TEMPERATURE °C
ZEOLITE CATALYST
CARBOCATION (IONIC) MECHANISM
HETEROLYTIC FISSION
PRODUCES BRANCHED AND CYCLIC ALKANES, AROMATIC HYDROCARBONS
USED FOR MOTOR FUELS
ZEOLITES are crystalline aluminosilicates; clay like substances
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Dr Seemal Jelani Chem-160

34. At each level a mixture of compounds in a similar boiling range is taken off
Rough fractions can then be distilled further to obtain narrower boiling ranges
Some fractions are more important - usually the lower boiling point ones, high boiling fractions may be broken down into useful lower boiling ones - CRACKING
1/1/2019
Dr Seemal Jelani Chem-160

35. Sources of Alkanes Natural gas 90 to 95 percent methane
5 to 10 percent ethane, and
a mixture of other low-boiling alkanes, chiefly propane, butane, and 2-methylpropane.
Petroleum
A thick liquid mixture of thousands of compounds, most of them hydrocarbons formed from the decomposition of marine plants and animals.

36. Alkenes and Alkynes

37. Alkenes and Alkynes Saturated compounds (alkanes):
Have the maximum number of hydrogen
atoms attached to each carbon atom.
Unsaturated compounds:
Have fewer hydrogen atoms attached to
the carbon chain than alkanes.
Containing double bond are alkenes.
CnH2n
Containing triple bonds are alkynes.
CnH2n-2

38. Naming Alkenes & Alkynes
Using the IUPAC alkane names:
Alkene names change the end to -ene.
Alkyne names change the end to -yne

39. Give the location
for double and
triple bond

40. Naming Alkenes & Alkynes
CH2= CH ─ CH2─ CH3 1-butene
CH3─ CH=CH─ CH3 2-butene
CH3 |
CH3─ CH=C─CH3 2-methyl-2-butene
CH3─ CC ─ CH3 2-butyne 1 2 3 4 1 2 3 4 4 3 2 1 1 2 3 4

41. Naming Alkenes & Alkynes
CH3─ CH2─ CC ─ CH pentyne
CH3
CH3─ CH2─ C=CH ─ CH methyl-2-pentene
CH2 – CH3
CH3─ CH2─ C=CH ─ CH ethyl-2-pentene 5 4 3 2 1 5 4 3 2 1 5 4 3 2 1

42. Chemical Properties of Alkenes
Addition Reactions
Combustion Reactions
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43. Chemical properties of Alkenes & Alkynes
More reactive than Alkanes
Addition of Hydrogen (Hydrogenation-Reduction)
Addition of Hydrogen Halides (Hydrohalogenation)
Addition of water (hydration)
Addition of Bromine & Chlorine (Halogenation)

44. Aromatic Hydrocarbons

45. Aromatic Compounds Aromatic compounds contain benzene. Benzene has:
6 C atoms and 6 H atoms.
Two possible ring structures.

46. Aromatic Compounds
Arene: A compound containing one or more benzene rings.
Aromatic compounds are named:
With benzene as the parent chain.
Name of substituent comes in front of the “benzene”.
methylbenzene chlorobenzene ethylbenzene Cl
CH2-CH3
CH3

47. Naming of Aromatic Compounds
Some substituted benzenes have common names.
CH3
Toluene

48. Naming of Aromatic Compounds
When two groups are attached to benzene, the ring is numbered to give
the lower numbers to the substituents.
Start numbering from special name (if we have).
If we do not have, number them to get the smallest set of numbers.
Name them by alphabetical order.
3-methyltoluene
Ortho
Meta
Para

49. Naming of Aromatic Compounds
If we have three or more substituents:
Start numbering from special name (if we have).
If we do not have, number them to get the smallest set of numbers.
Name them by alphabetical order.

50. Chemical properties of benzene
Resonance: stable
No addition reactions (almost unreactive)
Halogenation
Nitration
Sulfonation

51. Chemical properties of benzene
Halogenation
Nitration