1. Organic Reactions:

2. C11-5-22 REACTIONS AND POLYMERS
OUTCOME QUESTION(S):
C REACTIONS AND POLYMERS
Outline the transformation of alkanes to alkenes, to alkynes and vice versa.
Include: dehydrogenation / hydrogenation
Outline the creation of other functional groups through chemical reactions.
Include: hydration / dehydration, addition reactions
Describe the process of polymerization and identify important natural and synthetic polymers.
Vocabulary & Concepts
monomer

4. Thermal cracking:
Process of using heat to break long chain-alkanes found in petroleum into shorter alkanes/alkenes.
alkane
Writing something over the reaction arrow indicates that it is required for the reaction to proceed.
CH3CH3
heat ()
CH3CH2CH2CH2CH3 +
long alkane
CH2=CHCH3
alkene
Remember petroleum is a mix of many short and long chain organic molecules

5. C C C C Addition Reactions
Addition of a functional group at the site of a multiple bond.
Reverse reactions are called Elimination Reactions
Diverse and useful reactions ? ?
C C H
addition
C C
+ ? H H
elimination H H
alkene
?-alkane
Multiple bonds welcome addition…we will cover a few important additions

6. Partial hydrogenation creates trans double bonds – bad fats
Hydrogenation (addition reaction)
Creates alkanes from reactive alkenes/alkynes by adding hydrogen.
Common in food industry to solidify vegetable oils
Labelled as “partially hydrogenated "or “hydrogenated” H H
C C H
C C
+ H2
Ni,  H H H H
alkene
alkane
Partial hydrogenation creates trans double bonds – bad fats

7. Needs a platinum catalyst and/or heat
Dehydrogenation (elimination reaction)
Converts relatively useless alkanes into reactive alkenes/alkynes by removing hydrogen.
Alkenes are a precursor to creating other compounds
Usually requires high heat (endothermic) or a catalyst H H H H
Hydrogen is diatomic…
Needs a platinum catalyst and/or heat
C C
C C H H H
Pt, 
+ H2 H H
alkane
alkene
C C
C C H H H
+ H2
alkyne H H H H
alkene

8. C C C C Hydration (addition reaction)
Creates alcohols from reactive alkenes/alkynes by adding water.
Reversible elimination reaction – Dehydration reaction
Hydrate – to add water HO H
C C H
C C
+ H2O
acid H H
dehydration reaction H H
alkene
alcohol

9. H2C CH2 H2C CH2 H2C CH2 H2C CH2 Halogenation (addition reaction)
Creates alkyl halides from reactive alkenes/alkynes by adding halogens.
Elimination reaction – Dehalogenation reaction H Cl
H2C CH2
H2C CH2
+ HCl
alkene
dehalogenation reaction
alkyl halide
Fluorine reacts violently with organic molecules, iodine reacts the weakest (F>Cl>Br>I) Cl Cl
H2C CH2
H2C CH2
+ Cl2
alkene
dehalogenation reaction
alkyl dihalide

10. This is reversible too…
Substitution Reactions
Replacement of one functional group in a compound by another.
Products can be predicted from the reactivity of the reactants
Substitution reactions are versatile and fundamental to creating the variety of compounds in organic chemistry
C C H Cl
C C H
Cl-
base
+ OH- OH
alkyl halide
alcohol +
This is reversible too…

11. C C C C Halogenation (substitution reaction)
Creates alkyl halides from a substitution reaction with the a hydrogen of the alkane.
C C H H
C C H H hv
+ Cl2 Cl Cl
alkane
alkyl halide +
Substitutions are common for benzene – switching with a hydrogen on the ring

12. “poly” – many “mer” – part
Polymers are very large molecules made of many smaller repeating units.
Each individual part is called a monomer.
“poly” – many “mer” – part
monomer
polymer

13. Examples: Polypropylene, Teflon, Polyvinyl chloride (PVC)
Polymerization is a type of Addition Reaction:
Chain Polymerization (addition):
Only 1 type of monomer added together to form a long chain polymer.
Monomer is usually an alkene
Occurs quickly by addition to the end of the growing chain
Usually requires an initiator to kick start the reaction
Remember what we know of the reactivity of double bonds…
Examples: Polypropylene, Teflon, Polyvinyl chloride (PVC)

14. ~ ~ C C C C C C C C Polyethylene H H H H ethene
The beginning and ends of the chain will be “capped” with another compound
Polyethylene

15. Examples: Polycarbonate, Polyester, Polyurethane
Step Polymerization (condensation):
Reactions with two or more different monomers alternatingly linked A-B-A-B…
Occurs slowly by multiple smaller chains that eventually link A B
Examples: Polycarbonate, Polyester, Polyurethane

16. Nylon A B B A

17. More Examples of Synthetic Polymers

18. C11-5-22 REACTIONS AND POLYMERS
CAN YOU / HAVE YOU?
C REACTIONS AND POLYMERS
Outline the transformation of alkanes to alkenes, to alkynes and vice versa.
Include: dehydrogenation / hydrogenation
Outline the creation of other functional groups through chemical reactions.
Include: hydration / dehydration, addition reactions
Describe the process of polymerization and identify important natural and synthetic polymers.
Vocabulary & Concepts
monomer