1. Alkenes
CnH2n
sp2 hybridized carbons s p p
sp2 H H C C H H

2. Alkenes no rotation at C=C geometric isomers cis- trans- Cl Cl Cl H H

3. Nomenclature 1. Longest chain with C=C is parent.
2. C numbered from end nearest to C=C.
3. Designate cis- or trans- if necessary.
4. Name substituents.
5. Replace ane with ene ending.
6. If more than one C=C, give smallest
numbers and call diene or triene.

4. Nomenclature octene trans- 2- cis- 2- octene trans- 5-methyl-1 2 4 6 8
octene 3 5 7
trans- 2-
cis- 2-
octene
trans-
5-methyl-
3-propyl-
1,3-
hex ene
adi 3 5 1
3-propyl 2 4 6
5-methyl

5. Alkene - reactions  electrons Lewis Base Lewis Base e- pair donor
nucleophile
Lewis Acid
e- pair acceptor
electrophile

6. Addition Reactions Hrxn = bonds broken - bonds formed Hrxn =+
Hrxn =
bonds broken -
bonds formed
Hrxn =
(-bond + -bond) -
(2 -bonds)
< 0
exothermic

7. Addition of HX C C H3C H Cl C C H3C H H+ + Cl- C C H3C H Cl
reaction mechanism
Lewis base
 electrons
nucleophile
Lewis acid H+
electrophile

8. Addition of HX step 1 C H H3C H+ + Cl- H+ formal charge = group #
- ½ shared e-
- lone pair e- 2o
carbocation 1o
carbocation

9. Addition of HX 2o carbocation 1o carbocation Stability of carbocations
most stable intermediate
Stability of carbocations
3o >
2o > 1o
carbocations are e- deficient
electrophiles
react with
nucleophile
Lewis acids
Lewis base

10. Addition of HX
step 2
major product
minor product

11. Markovnikov’s Rule C with the most H gets the H major product
minor product
2-chloropropane
1-chloropropane
C with the most H gets the H

12. Addition of water, H - OH + H2O major product 2-methyl-2-butene
minor product

13. Mechanism of hydration
step 1 H+
+ H2O
catalyst
nuclophile
 e-
electrophile
add H+ H+

14. Mechanism of hydration
step 2 .. + H O
electrophile
nucleophile
step 3
oxonium ion
+ H+
alcohol

15. Addition of Br2 .. .. bromination Br Br Br-Br Br step 1 Br+ Br :
step 1 Br .. + +
bromonium ion - - .. Br

16. Addition of Br2 .. “anti” addition stereospecific trans isomer - Br:
step 2
“anti” addition
stereospecific
trans isomer

17. Addition of H2 hydrogenation C H H-H alkenes  alkanes+
alkenes  alkanes
heterogeneous catalyst Pt Cl
“syn” addition Cl
cis isomer
H H -
stereospecific

18. . . . . . Polymerization monomer polymer small molecule
large molecule built of
monomers
catalyst .
CH2=CH2 .
CH2 CH2 .
CH2 CH2 .
CH2 CH2 .
polyethylene
ethylene H H
–(CH2 – CH – CH2 – CH)– n
C6H5 C
H5C6 H
styrene
polystyrene