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Organic Synthesis. How can we form this? Substitution? No; the pi bond will break before Br contributes to a substitution reaction We could use hydrogenation.

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Presentation on theme: "Organic Synthesis. How can we form this? Substitution? No; the pi bond will break before Br contributes to a substitution reaction We could use hydrogenation."— Presentation transcript:

1 Organic Synthesis

2 How can we form this? Substitution? No; the pi bond will break before Br contributes to a substitution reaction We could use hydrogenation of 1-bromo-1-butyne (provided only one of the pi bonds break) Performing an elimination on 1-bromo-2-butanol or 1-bromo-1-butanol would work best. CHCH 2 CH 2 CH 3 Br OH CHCHCH 2 CH 3 CH 2 CHCH 2 CH 3 CCCH 2 CH 3 CH 2 CHCH 2 CH 3 OH 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 1)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 2)Condensation is a reaction that involves the production of water. Examples: 1) elimination, 2) esterification, 3) condensation polymerization oxidation is not an example – the H 2 O comes from H 2 SO 4, not from an organic molecule

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

6 c) 2,2,3,3-tetrabromopentane can be formed via substitution using Br 2. It is more efficiently formed via the halogenation of 2-pentyne b) + H 2 Room temp. + Br 2 Room temp.

7 d) 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. + H 2 O catalyst heat e) Propanoic acid is best formed from the oxidation of propanal + K 2 Cr 2 O 7 + H 2 SO 4 + Cr 2 (SO 4 ) 3 + K 2 SO 4 + H 2 SO 4

8 f)Ethanol is most easily formed from the hydrolysis of ethene. g)Ethyl propanoate is an ester, formed via esterification (ethanol plus propanoic acid) acid catalyst + H 2 O + H+ heat + H 2 O

9 Formation of a polyamide

10 + H 2 O Formation of a polyamide

11 + H 2 O Formation of a polyamide

12 + H 2 O Formation of a polyamide

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

14 1) salicylic acid + methanol methyl salicylate + HOCH 3 + H 2 O H +, heat Esterification reactions Note that many of these names have been left as common names

15 2) salicylic acid + isoamyl alcohol isoamyl salicylate + + H 2 O H +, heat

16 3) acetic acid + isoamyl alcohol isoamyl acetate + H 2 O H +, heat +

17 4) propanoic acid + isobutyl alcohol isobutyl propionate + H 2 O H +, heat + For more lessons, visit


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