1) Conjugation affords trans-1,3-pentadiene an extra stability of 15 kJ mol–1 ⇒
conjugated dienes are more stable than isolated dienes.
- What is the source of the extra stability associated with conjugated dienes?.
- In part from the stronger central bond that they contain (sp^2 - sp^2 C–C bond).
- In part from the additional delocalization of the π electrons that occurs in
conjugated dienes.
13.9 ULTRAVIOLET-VISIBLE SPECTROSCOPY
13.9A UV-VIS SPECTROPHOTOMERS
13.9B ABSORPTION MAXIMA FOR NONCONJUGATED
AND CONJUGATED DIENES
13.9C ANALYTICAL USES OF UV-VIS SPECTROSCOPY
13.10 ELECTROPHILIC ATTACK ON CONJUGATED DIENES:
1,4-ADDITION
- 1,3-butadiene reacts with one molar equivalent of HCl to produce two products:
3-chloro-1-butene and 1-chloro-2-butene.
CH 2 CH CH CH 2 25 HCloC CH 3 CH CH CH 2 +
Cl
CH 3 CH CH CH 2
Cl
1,3-Butadiene 3-Chloro-1-butene 1-Chloro-2-butene
1) 1,2-Addition:
