1. Introduction to Hydrocarbons
Unit 2
Introduction to Hydrocarbons

2. Differences between organic and inorganic compounds:
1. Organic compounds are mostly covalent molecules where most inorganics are ionic 2. Most organics don’t dissolve in water and most inorganics do 3. Organic compounds decompose on heating easier than inorganics 4. Organic reactions are much slower (min, hours, days) than inorganic reactions (seconds)

3. Fun Facts (Don’t have to Copy)
More than 18 Million organic compounds [with 10,000 new ones discovered each year]
1.7 Million inorganic compounds so about 85% of compounds are organic

4. 2 Reasons for the abundance of organic compounds:
Carbon atoms bond to each other to form long chains(up to 200 carbons)
Catenation – the ability of an element to bond to itself
The same number of carbon atoms can rearrange to form different structures (isomers)
Isomer – compounds with the same molecular formula but different structures

5. Isomer Example
C5H12
C C
-C-C-C-C-C- -C-C-C-C C-C-C- C

6. How Carbon Bonds
C ground state is 2s22p2 but bonds as *2s12p3 giving 4 sp3 hybrid orbitals
Hybrid orbitals – orbitals of equal energy formed by mixing orbitals of different energies
Hybridization – the mixing of orbitals of different energies to give orbitals of equal energy 

7. Carbon’s 4 covalent bonds form a tetrahedron (109.5° bond angle)
How Carbon Bonds
Carbon’s 4 covalent bonds form a tetrahedron (109.5° bond angle)

8. Hydrocarbons – compounds containing only hydrogen and carbon
Alkanes – hydrocarbons that have all C-C single bonds

9. Naming Name Structural Formula Condensed Formula Molecular Formula -C-
# of C
Name
Structural Formula
Condensed Formula
Molecular Formula 1
Methane
-C-
CH4 2
Ethane
-C-C-
CH3CH3
C2H6 3
Propane
-C-C-C-
CH3CH2 CH3
C3H8 4
Butane
-C-C-C-C-
CH3(CH2)2 CH3
C4H10 5
Pentane
-C-C-C-C-C-
CH3(CH2)3 CH3
C5H12 6
Hexane
-C-C-C-C-C-C-
CH3(CH2)4 CH3
C6H14 7
Heptane
-C-C-C-C-C-C-C-
CH3(CH2)5 CH3
C7H16 8
Octane
-C-C-C-C-C-C-C-C-
CH3(CH2)6 CH3
C8H18 9
Nonane
-C-C-C-C-C-C-C-C-C-
CH3(CH2)7 CH3
C9H20 10
Decane
-C-C-C-C-C-C-C-C-C-C-
CH3(CH2)8 CH3
C10H22

10. Naming *Know roots and endings*  Each step, you add a CH2 group
 Homologous Series – a series of compounds where each member differs from the next by a constant unit (CH2)
Members are called homologous
Since alkanes are homologous – we can write a General Formula = CnH2n+2

11. Naming
Alkanes are Saturated Hydrocarbons – hydrocarbons where each C has 4 single covalent bonds (no more atoms can be added)

12. Alkenes
Alkenes – hydrocarbons with one C=C double bond – sp2 hybridization on the 2 C atoms in the double bond.
Ethene C=C CH2CH2 C2H4
Propene C=C-C CH2CHCH3 C3H6
Butene C=C-C-C CH2CHCH2CH3 C4H8
Octene C=C-C-C-C-C-C-C- CH2CH(CH2)5CH3 C8H16

13. Ways to Show Organics Space Filling Model Skeletal Form
Ball and Stick Form
Ways to Show Organics
Structural Formula
Line Bond Form
Space Filling Model
Skeletal Form

14. Alkenes Also a homologous series General Formula CnH2n
Unsaturated hydrocarbons – have C-C multiple bonds which can be broken to add more atoms to the molecule
H H H H
Ex: C=C H2  H-C -C-H
H H H H

15. Alkynes
Alkynes – hydrocarbons containing a C = C triple bond – sp hybtidization
Ethyne -C=C- CHCH C2H2
(acetylene)
Propyne -C=C-C- CHCCH3 C3H4
Butyne -C=C-C-C- CHCCH2CH3 C4H6
Heptyne -C=C-C-C-C-C-C- CHC(CH2)4CH3 C7H12
General Formula = CnH2n-2

16. Alkadienes General Formula = CnH2n-2
Alkadienes – hydrocarbons containing two C=C double bonds
Butadiene -C=C-C=C- CH2(CH)2CH2 C4H6
Pentadiene -C=C-C=C-C- CH2(CH)3CH3 C5H8
Heptadiene -C=C-C=C-C-C-C- CH2(CH)3(CH2)2CH C7H12
General Formula = CnH2n-2

17. Alkadienes 3 placements for the two double bonds
Conjugated double bonds (most common) – two double bonds separated by one singe bond
Isolated double bonds – two double bonds separated by more than one single bond
Allenes – hydrocarbons that have two consecutive double bonds

18. The first 4 Series of hydrocarbons are Aliphatic Hydrocarbons
Aliphatic hydrocarbons – hydrocarbon where carbon atoms bond together in open chains

19. Arenes
Aromatic Hydrocarbons – hydrocarbons containing rings of 6 carbon atoms joined by alternating single and double bonds
Simplest aromatic hydrocarbon = benzene

20. Arenes All bonds are actually identical (C-C and C=C “mixed”)
Can also be shown as

21. Arenes
We use
The e-‘s are actually shared by all 6 carbons and move freely around the ring (delocalized)
This makes benzene behave like saturated hydrocarbons

22. Resonance
Compounds like these are resonance hybrids (compounds that can be represented by more than one Lewis structure)
General Formula = CnH1/2n+3

23. Resonance examples

24. IUPAC Naming Rules Name the longest chain (the parent chain) first.
Label the chain to give the lowest numbers to groups or bonds. Priority  C=C then C=C You give the number for the carbon where the multiple bond begins. (Separate numbers and words with a hyphen, and numbers and numbers with a comma).
C-C-C-C=C-C 2 –hexene
C-C-C=C-C-C-C 3 – heptyne

25. IUPAC Naming Rules
3. Give the numbers for any attached groups for the carbons they are attached to, a number for each attached group. Use the number with the groups name. [in front of “main” chain]
If more than one of any group = di-, tri-, tetra-, penta-, hexa-, etc.
Group Names:
F = fluoro I = iodo
Cl = chloro OH = hydroxo
Br = bromo NO2 = nitro

26. IUPAC Naming Rules
c. If there is more than one group attached, the names are listed in alphabetical order (ignore prefixes) in front of the “main” chain
d. If the numbers for the side groups are the same from either side of the chain, # from the side that gives the lowest # to the first group in the alpha order.

27. Hydrocarbons (straight chains)
Summary
Hydrocarbons (straight chains)
Locate and name attached groups
Locate multiple bonds (priority for numbering)
Name base/parent chain

28. IUPAC Naming Rules 4. Branched chains
Longest continuous chain containing any multiple bonds (if present)
# to give multiple bonds lowest numbers (priority)
Name side groups (alphabetical order)

29. IUPAC Naming Rules 5. Benzene Use the lowest set of #’s possible
1-chloro-3,5 - dimethylbezene
5. Benzene
Number starting with a C bonded to an attached group and then continue around the ring
Use the lowest set of #’s possible

30. IUPAC Naming Rules
1,3 – dibromo – 2 – fluorobenzene

31. IUPAC Naming Rules Ortho = 1, 2 bonding position
c. If there are just two of the same group attached, we can use the following terms to simplify the bonding positions
Ortho = 1, 2 bonding position
Meta = 1, 3 bonding position
Para = 1, 4 bonding position

32. O,M, P

33. Isomer Practice
Isomers – compounds having the same molecular formula but having different structures
Example: C5H11Cl
Draw all isomers by moving Cl (we are only going to use straight chains for C’s)

34. Isomer Practice Cl
C – C – C – C – C
C –C – C – C – C

35. Isomer Practice
C4H8Cl2

36. Try C4H8ClI, C4H7I3, C5H10FBr, and C4H7F2Br
Isomer Practice
Try C4H8ClI, C4H7I3, C5H10FBr, and C4H7F2Br