1. Ch 11. Unsaturated Hydrocarbons- Alkenes and Alkynes
Hydrocarbons with double, triple bonds

2. Alkanes vs. Alkenes, Alkynes
Alkanes: have max # of Hydrogens –saturated with H
Alkenes/Alkynes: double/triple bonds between C leading to less Hydrogens-unsaturated with H

3. Alkene Naming Same prefixes as alkanes, followed by -ene
ethene, propene, butene…..
Simplest Ethene C2H4

4. Alkyne Naming
Same prefixes followed by –yne: ethyne, propyne, butyne….
Simplest ethyne, C2H2

5. Location of double/triple bonds
Number carbons so that double/triple bonds receive lowest possible location number!
Do not number if there is only one, possible location (small alkynes)
Beats side chain locations

6. Name
2-Pentene

7. Multiple double/triple bonds
List location followed by alkane prefix followed by -diene, triene

8. Name
1,2-pentadiene

9. Name

10. Branched unsaturated HC
Parentchain needs to contain double/triple bond!!!
Naming:
1. Double bond location needs to have lowest C-number, beats lowest location for side chains
2. List all side chains alpha, then list all double bond locations followed by –diene, triene….

11. Draw in condensed 2-bromo-3-chloro-1-pentene
3,4- dimethyl-4,5,6-octatriene
1,3,5-heptatriyne

12. Cis/trans configuration
Alkene Isomers
Cis/trans configuration

13. Two Types of Double bonds
Trans: carbons before and after the double bonds are on opposite (trans) sides Cis: carbons before and after the double bond are on the same (cis) side

14. Bowtie Structural Drawings for Alkenes
Cis-2- butene Trans-2-butene
C1 double bond never has cis/trans!!!
Name cis/trans if your structural drawing shows it: Kekule and Bowtie only
Cis/trans before location number
Triple bonds are flat and never have cis/trans

15. Drawing Double Bonds in Kekule
Draw as double line
But all molecules, always, start on an upward swing, regardless of double bond location
Trans does not disrupt zig-zag!

16. Drawing Bowtie Improved condensed drawing
Double bonds are always horizontal
Draw double bonds first
Example: 2-pentene in cis an trans

17. Drawing Triple bonds in Kekule
Draw as triple line
All molecules start on an upward swing!!!
Single bonds before and after triple bond need to have the same angling as the triple bond

18. Cis and trans in one molecule
List cis before trans!
draw in Kekule and Bowtie:
Cis-2-trans-4-hexadiene

19. Practice –Draw in Kekule
1-Butene
Cis-2-Butene
Trans-2-butene
1- Butyne
2-Butyne

20. Blend of condensed/Kekule

22. Cyclical Alkenes

23. Cyclical Alkenes
Benzene, famous molecule for process chemistry, has it’s own name!
Has alternating single/double bonds
What’s the IUPAC name?

24. Aromatic
Many molecules in Nature contain Benzene rings: Aromatic Hydrocarbons
Cinnamon

25. Benzene as a side chain
Called Phenyl

26. 4-phenyl-1-hexene

27. Benzene as a parent

28. MP/BP trends Generally
cis-double bonds lower the MP/BP: disruption of zig/zag
There is little difference in MP/BP between single bonds or trans-double bds
Triple bonds straighten molecule and raise the boiling beyond single bonds