1. CHAPTER 17
Organic Chemistry
17.1 Hydrocarbon Molecules

2. Carbon can form covalent bonds with itself and create networks
No other element has this ability

3. Carbon
Diamond
Each carbon atom can make four single bonds and form a tetrahedral structure
Tetrahedral structure
Diamond has a tetrahedral lattice, and it is the hardest substance known to date

4. Carbon
Tetrahedral structure
Carbon has 4 valence electrons but can bond to fewer than 4 atoms and form double and triple bonds

5. Hydrocarbons The simplest organic compounds are called hydrocarbons
hydrogen
carbon
In an unsaturated hydrocarbon, the double or triple bond can be broken and carbon can bond to one more atom.

6. Alkanes
Saturated hydrocarbons (all single bonds) are called alkanes
Formula for butane:
Butane C H ? ?

7. Alkanes
Saturated hydrocarbons (all single bonds) are called alkanes
Formula for butane:
Butane C H 4 10

8. Alkanes
Saturated hydrocarbons (all single bonds) are called alkanes
Formula for butane:
Butane C H 4 10
Formula for alkanes: C H n ?

9. Alkanes
Saturated hydrocarbons (all single bonds) are called alkanes
Formula for butane:
Butane C H 4 10
Formula for alkanes: C H n
(2n+2)

10. Alkanes
Saturated hydrocarbons (all single bonds) are called alkanes
Formula for butane: C H 4 10
Formula for alkanes: C H n
(2n+2)

11. Alkanes
Saturated hydrocarbons (all single bonds) are called alkanes

12. Alkanes Saturated hydrocarbons (all single bonds) are called alkanes
Butane
When you observe the structure of butane, you see that a “straight” chain is really not straight nor linear

13. Naming alkanes To name alkanes: Count the number of carbons
Find the corresponding Greek root
Add “-ane” to indicate it is an alkane

14. Naming alkanes
Organic chemists call this n-pentane, where n indicates the longest straight chain
Longest chain

15. Naming alkanes To name branched alkanes:
1) Find the parent compound (the longest continuous chain) and add “-ane” to the Greek root

16. Naming alkanes To name branched alkanes: heptane
1) Find the parent compound (the longest continuous chain) and add “-ane” to the Greek root
heptane

17. Naming alkanes To name branched alkanes: heptane ethyl
Find the branch(es) not included and add “-yl” to the Greek root
heptane
ethyl

18. Naming alkanes To name branched alkanes: heptane ethyl
3) Find the position at which the branch(es) is (are) located on the parent compound
Start counting from the shortest end of the parent compound
(here, it is position “4” from both ends)
heptane
ethyl

19. Naming alkanes 4-ethyl-heptane heptane ethyl
This branched alkane is called:
4-ethyl-heptane
heptane
ethyl

20. Naming alkanes Here, R = CH2CH3 heptane ethyl
The branching group is called the R group
Here, R = CH2CH3
heptane
ethyl

21. n-butane (C5H12) and isobutane (C5H12) are structural isomers
structural isomer: molecule with the same number and type of atoms as another molecule but has a different bonding pattern.

22. Naming alkanes same molecule isobutane 2-methyl-propane
methyl group at position “2”
same molecule
isobutane
2-methyl-propane
methyl group at the second-to-last position
4 carbons in total

23. Structural isomers
Draw and name the structural isomers of pentane (C5H12).

24. Structural isomers
Draw and name the structural isomers of pentane (C5H12).
Make a chain of 5 carbons and add hydrogens.
n-pentane

25. Structural isomers
Draw and name the structural isomers of pentane (C5H12).
Remove a carbon and form a branch in one position.
2-methyl-butane
n-pentane

26. Structural isomers
Draw and name the structural isomers of pentane (C5H12).
We can remove 2 carbons and form 2 branches in one position.
isopentane
n-pentane

27. (2,2,4-trimethyl-pentane)
Petroleum chemistry
octane
isooctane
(2,2,4-trimethyl-pentane)
Refinement of petroleum generates branched hydrocarbons such as isooctane.
Isooctane is better for the car engine because it burns more slowly and more completely than octane.

28. (2,2,4-trimethyl-pentane)
Petroleum chemistry
octane
isooctane
(2,2,4-trimethyl-pentane)
87% isooctane, 13% octane
Isooctane is a branched hydrocarbon and has a high octane rating.

29. (2,2,4-trimethyl-pentane)
Petroleum chemistry
octane
isooctane
(2,2,4-trimethyl-pentane)
High-performance cars require high-octane fuel
Isooctane is a branched hydrocarbon and has a high octane rating.

30. Types of intermolecular attractions Intermolecular attractions
From Chapter 8.3
strong
London dispersion
Dipole-dipole
Hydrogen bonding
Types of intermolecular attractions
Between
polar molecules
nonpolar molecules
Intermolecular attractions
weak
Intermolecular attractions are also called van der Waals attractions

31. Types of intermolecular attractions Intermolecular attractions
From Chapter 8.3
strong
London dispersion
Dipole-dipole
Hydrogen bonding
Types of intermolecular attractions
Between
polar molecules
nonpolar molecules
Intermolecular attractions
weak
Hydrocarbons
Intermolecular attractions are also called van der Waals attractions

32. Properties of hydrocarbons
Between
nonpolar molecules
With weak intermolecular attraction forces, small hydrocarbons are gases at room temperature.
London dispersion

33. Properties of hydrocarbons
As hydrocarbon chains become longer, attraction forces become stronger. Longer hydrocarbons are liquids at room temperature.

34. n Unsaturated hydrocarbons Polyethylene
Ethene or ethylene is a gas at room temperature.
It can be used to create the polymer polyethylene in plastics

35. Unsaturated hydrocarbons
Ethyne or acetylene is a hydrocarbon that contains a triple bond.
There is more energy in a triple bond than in a double or single bond.
Acetylene torches reach temperatures up to 3,300oC (6,000oF)
Acetylene torch

36. Naming unsaturated hydrocarbons
To name unsaturated hydrocarbons:
Count the number of carbons
Find the corresponding Greek root
Add “-ene” to indicate a double bond Add “-yne” to indicate a triple bond

37. Naming unsaturated hydrocarbons
To name unsaturated hydrocarbons:
Count the number of carbons
Find the corresponding Greek root
Add “-ene” to indicate a double bond Add “-yne” to indicate a triple bond

38. Isomers Structural isomers Same formula Different bonding order
n-pentane
C5H12
2-methyl-butane
C5H12
Isopentane
C5H12

39. Isomers Structural isomers Same formula
Different bonding order
Stereoisomers Same bonding order
Different spatial arrangement

40. Isomers Structural isomers Same formula
Different bonding order
Stereoisomers Same bonding order
Different spatial arrangement
Geometric isomers
Butene
cis configuration
(R groups on same side of the C=C bond)
double bond

41. Isomers Structural isomers Same formula
Different bonding order
Stereoisomers Same bonding order
Different spatial arrangement
Geometric isomers
trans configuration
(R groups opposite sides of the C=C bond)
Butene
cis

42. Isomers Structural isomers Same formula
Different bonding order
Stereoisomers Same bonding order
Different spatial arrangement
Geometric isomers
Optical isomers
The central carbon is attached to four different groups.
Optical isomers are two different molecules!

43. Aromatic hydrocarbons
Cinnamon, cloves, wintergreen and vanilla beans have pleasant, distinctive smells
What else do they have in common?

44. Aromatic hydrocarbons contain one or more benzene rings
What else do they have in common?
Benzene ring
Aromatic hydrocarbons contain one or more benzene rings

45. Aromatic hydrocarbons
Resonance structures of benzene
Electrons are always moving, so the single and double bonds on the benzene ring are never fixed.
To show that electrons are “delocalized” and equally shared, a circle is used instead.

46. Naming of hydrocarbons
Alkanes Greek root + “-ane”
Alkenes Greek root + “-ene”
Alkynes Greek root + “-yne”
R groups Greek root + “-yl”
Saturated hydrocarbons
Unsaturated hydrocarbons
Hydrocarbon constituents
Naming of hydrocarbons
Parent compound

47. Structural isomers Same formula
Different bonding order
Stereoisomers Same bonding order
Different spatial arrangement
Geometric isomers
Optical isomers
cis
trans