1. Organic Synthesis

2. How can we form this? C H Br Substitution?2 3 Br
Substitution?
No; the pi bond will break before Br contributes to a substitution reaction C H 2 3 C H 2 3 Br
We could use hydrogenation of 1-bromo-1-butyne (provided only one of the pi bonds break) C H 2 3 Br O
Performing an elimination on 1-bromo-2-butanol or 1-bromo-1-butanol would work best. C H 2 3 Br O
Best choice: only one product possible.

3. How do we choose between reactions?
Notice that their may be more than one way to form a particular compound
The handout is an oversimplification …
There are thousands of reaction mechanisms, many of which are very specific
Considerations when choosing include …
Yield (how much product forms)
Potential for multiple products
Ease of separating contaminating structures
Type of isomer desired
Economics: e.g. cost of starting materials

4. Answers: 1, 2
An addition reaction involves breaking a double bond and adding two parts of a molecule across the bond
Examples: 1) halogenation, 2) hydrogenation, 3) hydrolysis, 4) addition polymerization
The ‘opposite’ of breaking the bond is forming a double bond - i.e. elimination
Condensation is a reaction that involves the production of water.
Examples: 1) elimination, 2) esterification, 3) condensation polymerization
oxidation is not an example – the H2O comes from H2SO4, not from an organic molecule

5. Answers: 3
a) 1,2-dichlorocyclopentane is best formed via halogenation of cyclopentene. Substitution using Cl2 would work, but would not be efficient because many other products would form (e.g. 1,2,4-trichlorocyclopentane, etc.)
+ Cl2
Room temp. Cl
The only way to prepare octane from 4-octyne is via hydrogenation of both pi bonds.
(see top of next page for diagram)

6. + H2
Room temp.
2,2,3,3-tetrabromopentane can be formed via substitution using Br2. It is more efficiently formed via the halogenation of 2-pentyne
+ Br2
Room temp.

7. Propanoic acid is best formed from the oxidation of propanal
1-butene can be formed from the elimination reaction involving 1-butanol. Using 2-butanol could result in either 1-butene or 2-butene and therefore is a less desirable choice.
+ H2O
catalyst
heat
Propanoic acid is best formed from the oxidation of propanal
+ K2Cr2O7
+ H2SO4
+ Cr2(SO4)3
+ K2SO4

8. Ethanol is most easily formed from the hydrolysis of ethene.
acid
catalyst
+ H2O
Ethyl propanoate is an ester, formed via esterification (ethanol plus propanoic acid) + H+
heat
+ H2O

9. Formation of a polyamide

10. Formation of a polyamide
+ H2O

11. Formation of a polyamide
+ H2O
+ H2O

12. Formation of a polyamide
+ H2O
+ H2O
+ H2O

13. Formation of a polyamide
A polyamide “backbone” forms with R groups coming off. This protein is built with amino acids.

14. Esterification reactions
1) salicylic acid + methanol  methyl salicylate
H+, heat
+ H2O
+ HOCH3
Note that many of these names have been left as common names

15. 2) salicylic acid + isoamyl alcohol
 isoamyl salicylate +
H+, heat
+ H2O

16. 3) acetic acid + isoamyl alcohol
 isoamyl acetate +
H+, heat
+ H2O

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4) propanoic acid + isobutyl alcohol
 isobutyl propionate +
H+, heat
+ H2O
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