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Organic Synthesis.

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Presentation on theme: "Organic Synthesis."— Presentation transcript:

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

17 For more lessons, visit
4) propanoic acid + isobutyl alcohol  isobutyl propionate + H+, heat + H2O For more lessons, visit

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