Bruice - Chimica Organica

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Chapter 12 423
Copyright © 2017 Pearson Education, Inc.
HCl Cl • +
propagation
CH3 CH3 + CH 3CH2
•
CH3 CH2Cl CH 3COCl
CH3
CH3
+ +
CH3CH2
•
CH3CO
CH3
CH3
•
This species enters the first propagation cycle.
termination
CH3CH 2CH2CH3 +
CH 3CH2
•
CH3CH2 Cl Cl • +
CH 3CH2
+
CH 3CO
CH3
CH3
• CH3CO
CH3
CH3
• CH3CO
CH 3
CH 3
OCCH3
CH 3
CH 3
+
CH 3CO
CH3
CH3
• Cl • CH 3COCl
CH 3
CH 3
CH 3CO
CH3
CH3
•
+
CH3 CH 2
•
CH 3COCH2CH3
CH3
CH3
Cl • Cl • Cl2
CH3 CH2
•
+
•
b. ∆ H° = bonds broken - bonds formed
Let x = the bond dissociation enthalpy of the O ¬ Cl bond.
-42 kcal >mol = 3101 kcal >mol + x kcal> mol4 - 3 85 kcal > mol + 105 kcal>mol4
- 143 kcal>mol = x kcal>mol - 190 kcal> mol
x = 47 kcal >mol
42. The reaction forms a product with two new asymmetric centers.
CH3CH2CH CCH2CH 3
CH3 CH 3
Br
Because the reaction involves both syn and anti addition, four stereoisomers are obtained.
CH2CH3
CH2CH3
CH 3
CH 3
H
Br
CH 2CH3
CH 2CH3
CH3
CH3
H
Br
CH2 CH3
CH2 CH3
H
CH3
CH3
Br
CH2CH 3
CH2CH 3
H
CH 3
CH3
Br