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 reaction mechanism Lewis base  electrons nucleophile
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 H3C C C H – Cl H H – Cl H + Cl- .. H – O – H ..+ -
H – Cl
H – O – H H .. + +
Cl- ..
H – O – H ..
H3O+ = H+

9. Addition of HX step 1 2o carbocation 1o carbocation C H H3C + H-Cl

10. 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

11. Addition of HX
step 2
major product
minor product

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