Medical Technology lesson

2. Alkanes with Substituents
2

3. Isomers of Butane
Isomers
• have the same molecular
formula
• have different structural
arrangements
• of butane (C4H10) consist
of a straight chain and a
branched chain each
with 4 carbon atoms
Branch or
substituent

4. Substituents
Substituents are
• attached to carbon chains
• carbon branches that are missing one H
and named as alkyl groups
• halogen atoms that are named as halo
substituents
4

5. Alkanes with Alkyl Groups
CH3
CH3—CH—CH3 methylpropane
CH3 CH3
CH3—CH—CH2—CH—CH3 2,4-dimethylpentane
5
methyl groups

6. Naming Alkanes with Substituents
6

7. Example of Naming Alkanes
Give the name of CH3
CH3─CH─CH2─CH3
STEP 1 Write the name of the longest chain: butane
STEP 2 Number the chain from the end nearer a
branch: CH3
CH3─CH─CH2─CH3
1 2 3 4
STEP 3 Give location and names of substituents:
2-Methylbutane
7

8. Learning Check
Write the IUPAC name for:
Cl CH3
CH3─CH2─CH─CH─CH3
8

9. Solution
STEP 1 Write the name of the longest chain:
pentane
STEP 2 Number chain from end nearer substituents:
Cl CH3 (nearer end)
CH3─CH2─CH─CH─CH3
5 4 3 2 1
STEP 3 Give location and name substituents
alphabetically:
3-Chloro-2-methylpentane
9

10. Learning Check
Give the IUPAC name for each of the following:
A. CH3 CH3
| |
CH3─CH─CH2 ─CH─CH2─CH3
B. Cl CH3
| |
CH3─CH2─CH─CH2─C─CH2─CH3
|
Cl
10

11. Solution
A. CH3 CH3
| |
CH3─CH─CH2 ─CH─CH2─CH3 2,4-dimethylhexane
1 2 3 4 5 6
B. Cl CH3 more substituents on C3
| |
CH3─CH2─CH─CH2─C─CH2─CH3
|
Cl
7 6 5 4 3 2 1
3,5-dichloro-3-methylheptane
11

12. Guide to Drawing Alkane Structures
12

13. What Is in a Name?
The structural formula is drawn from the IUPAC name.
2,4-dimethylhexane
2,4 dimethyl hexane
Location of Two CH3-groups 6-carbon main chain
branches on attached with single C—C
bonds main chain
13

14. Learning Check
Draw the condensed structural formula for
3-bromo-1-chlorobutane.
14

15. Solution
STEP 1 Draw a chain with 4 carbon atoms:
C─C─C─C
STEP 2 Number the chain and add substituents:
Br

C ─ C ─ C ─ C ─ Cl
4 3 2 1
STEP 3 Add hydrogen (H) to give four bonds to each C:
Br

CH3─CH─CH2─CH2─Cl
15

16. Naming Cycloalkanes with Substituents
The name of a substituent is placed in front of the
cycloalkane name.
CH3
Methylcyclobutane
When there are two substituents, number the ring
1-bromo-2-chlorocyclopentane
Br
Cl
16

17. Learning Check
Name each of the following:
1. CH3
CH2─CH3
2.
Cl
17

18. Solution
Name each of the following:
1. CH3 methylcyclopropane
CH2─CH3
2.
Cl 1-Chloro-3-ethylcyclohexane
18

19. Learning Check
Write three isomers of C5H12, and name each.
19

20. Solution
A chain of 5 carbon atoms: CH3─CH2─CH2─CH2─CH3
pentane
A chain of 4 carbon atoms and 1 carbon branch:
CH3
│
CH3─CH─CH2─CH3 2-methylbutane
A chain of 3 carbon atoms and 2 carbon branches:
CH3
│
CH3─C─CH3 2,2-dimethylpropane
│
CH3
20
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

22. Properties of Alkanes
22
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

23. Some Properties of Alkanes
The properties of alkanes
include being
 nonpolar
 insoluble in water
 less dense than water
 flammable in air
23
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

24. Alkanes with 1–4 Carbon Atoms
Alkanes with 1–4 carbon atoms
are
• methane, ethane, propane, and
butane
• gases at room temperature
• used as heating fuels
24
General, Organic, and Biological Chemistry

25. Alkanes with 5–17 Carbon Atoms
Alkanes with 5–8 carbon atoms are
• liquids at room temperature
• pentane, hexane, heptane, and octane
• very volatile
• used to make gasoline
Alkanes with 9–17 carbon atoms
• are liquids at room temperature
• have higher boiling points
• are found in kerosene, diesel, and jet fuels
25
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

26. Alkanes with 18 or More Carbon Atoms
Alkanes with 18 or more carbon atoms
• have high molar masses
• are waxy solids at room temperature
• are used in waxy coatings of fruits
and vegetables
26
General, Organic, and Biological Chemistry

27. Boiling Points of Alkanes
Boiling points of alkanes
• are lowest of the organic compounds
• increase with larger molecules due to increased
dispersion forces
• decrease for branched alkanes
• increase for cycloalkanes
27
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

28. Boiling Points of Alkanes with 5 Carbons
28
General, Organic, and Biological Chemistry

29. Learning Check
For the following pairs of hydrocarbon, which one
has
the higher boiling point? Why?
A. Butane or octane
B. Hexane or 2,3-dimethylbutane
29
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

30. Solution
For the following pairs of hydrocarbon, which one has
the higher boiling point? Why?
A. Butane or octane
octane (has more carbon atoms)
B. Hexane or 2,3-dimethylbutane
hexane (both have 6 carbons, but hexane is not branched)
30
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

31. Crude Oil
The hydrocarbons in crude oil are
• separated by their different boiling points
• heated to higher temperatures to produce gases
that can be cooled and removed
31
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

32. Crude Oil (continued)
32
General, Organic, and Biological Chemistry

33. Combustion of Alkanes
Alkanes
• undergo combustion
by reacting with
oxygen to produce
carbon dioxide, water,
and energy
• are typically not very
reactive due to strong
C—C single bonds
33
Alkane + O2(g) CO2(g) + H2O(g) + energy
General, Organic, and Biological Chemistry

34. Balancing A Combustion Equation
Write the equation:
C5H12(l) + O2(g) CO2(g) + H2O(g)
Balance C:
C5H12(l) + O2(g) 5CO2(g) + H2O(g)
Balance H:
C5H12(l) + O2(g) 5CO2(g) + 6H2O(g)
Balance O with O2:
C5H12(l) + 8O2(g) 5CO2(g) + 6H2O(g)
34
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

35. Learning Check
Propane is used to provide
heat for cooking or warming
a room. Write a balanced
equation for the complete
combustion of propane.
35
General, Organic, and Biological Chemistry

36. Solution
Unbalanced equation:
C3H8(g) + O2(g) CO2(g) + H2O(g)
Balance C:
C3H8(g) + O2(g) 3CO2(g) + H2O(g)
Balance H:
C3H8(g) + O2(g) 3CO2(g) + 4H2O(g)
Balance O:
C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(g)
36
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

37. Learning Check
Write a balanced equation for the reaction for the
complete combustion of heptane, C7H16.
37
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.

38. Solution
Write a balanced equation for the reaction for the
complete combustion of heptane, C7H16.
C7H16(l) + O2(g) CO2(g) + H2O(g)
C7H16(l) + O2(g) 7CO2(g) + 8H2O(g)
C7H16(l) + O2(g) 7CO2(g) + 8H2O(g)
C7H16(l) + 11O2(g) 7CO2(g) + 8H2O(g)
Balanced equation:
C7H16(l) + 11O2(g) 7CO2(g) + 8H2O(g)
38
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.