Advices For Studying Organic Chemistry

i) Structures in which opposite charges are separated have greater energy than

those that have no charge separation.

CH 2 CH Cl

−

H 2 CCHCl

(^1314)

13.6 ALKADIENES AND POLYUNSATURATED HYDROCARBONS

1. Alkadiene and alkatriene ⇒ diene and triene;
   alkadiyne and alkenyne ⇒ diyne and enyne.

CH^2 CCH^2

123

CH^2 CH CH CH^2

1234

HC C CH^2 CH CH^2

5 4 3 2 1

1,2-Propadiene (allene) 1,3-Butadiene 1-Penten-4-yne

CC

CH

H H

H 3 C 5

4 3

(^2) CH^1
(^2)
CC
CC
H
H CH 3
H 3 C
H
H
1
(^532)
(^64)
CC
CC
H
CH 3
H
H
H
H 3 C
1
3 2
5 4
6
(3Z)-1,3-Pentadiene (2E,4E)-2,4-Hexadiene (2Z,4E)-2,4-Hexadiene
(cis-1,3-pentadiene) (trans,trans-2,4-hexadiene) ( cis,trans-2,4-hexadiene)
CC
CC
CC
H 3 C
H
H
H
H
H
H
CH 3
1
2 3
5
67
8
4
1
2
4
5
6
3
6
1
4
5
2
3
(2E,4E,6E)-2,4,6-Octatriene 1,3-Cyclohexadiene 1,4-Cyclohexadiene
(trans,trans,trans-2,4,6-octatriene)

2. The multiple bonds of polyunsaturated compounds are classified as being
   cumulated, conjugated, or isolated.

1. The double bonds of allene are said to be cumulated because one carbon (the
   central carbon) participates in two double bonds.
   i) Hydrocarbons whose molecules have cumulated double bonds are called
   cumulenes.