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Ch.9 - Alkynes
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Non è quello che usi tu?Cambia libro di testo
Capitolo 9, Problema 29d,e,f

Using hex-1-ene as your starting material, show how you would synthesize the following compounds. (Once you have shown how to synthesize a compound, you may use it as the starting material in any later parts of this problem.)
d. hex-2-yne
e. hexan-2-one
f. hexanal

Guida verificata passo dopo passo
1
Step 1: To synthesize hex-2-yne from hex-1-ene, first perform a halogenation reaction. React hex-1-ene with Br₂ in an inert solvent like CCl₄ to form 1,2-dibromohexane. This reaction adds bromine atoms across the double bond.
Step 2: Next, perform a double dehydrohalogenation reaction on 1,2-dibromohexane. Use a strong base like NaNH₂ in liquid ammonia to eliminate both bromine atoms and form hex-2-yne. This step involves two elimination reactions to create the triple bond.
Step 3: To synthesize hexan-2-one from hex-1-ene, first perform an oxymercuration-demercuration reaction. React hex-1-ene with Hg(OAc)₂ in water, followed by reduction with NaBH₄. This reaction adds a hydroxyl group to the more substituted carbon, forming hexan-2-ol.
Step 4: Oxidize hexan-2-ol to hexan-2-one using an oxidizing agent like PCC (Pyridinium chlorochromate) or Jones reagent (CrO₃ in H₂SO₄). This step converts the secondary alcohol into a ketone.
Step 5: To synthesize hexanal from hex-1-ene, perform a hydroboration-oxidation reaction. React hex-1-ene with BH₃·THF, followed by oxidation with H₂O₂ in a basic solution (NaOH). This reaction adds a hydroxyl group to the less substituted carbon, forming hexan-1-ol. Finally, oxidize hexan-1-ol to hexanal using PCC or another mild oxidizing agent.

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Alkene Reactions

Alkenes, such as hex-1-ene, are unsaturated hydrocarbons that can undergo various reactions, including electrophilic addition, oxidation, and polymerization. Understanding these reactions is crucial for synthesizing other compounds, as they allow for the transformation of alkenes into different functional groups, such as alkynes or carbonyls.
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Alkene Metathesis Concept 1

Synthesis of Alkynes

The synthesis of alkynes, like hex-2-yne, often involves the elimination of a leaving group from a dihaloalkane or the dehydrohalogenation of an alkene. This process is essential for creating triple bonds, which are characteristic of alkynes, and requires knowledge of reaction mechanisms and conditions to achieve the desired product.
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Alkyne Hydration

Carbonyl Chemistry

Carbonyl compounds, such as hexan-2-one and hexanal, are characterized by the presence of a carbonyl group (C=O). Their synthesis often involves reactions with alkenes or alkynes, such as hydroboration-oxidation or oxidation of alcohols, making it important to understand how to manipulate these functional groups to achieve the desired carbonyl compound.
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Carboxylic Acids Nomenclature