Skip to main content
Ch.9 - Alkynes
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoWade 9th EditionCh.9 - AlkynesProblema 21c
Capitolo 9, Problema 21c

For each compound, give the product(s) expected from (1) HgSO4/H2SO4 - catalyzed hydration and (2) hydroboration–oxidation.
c. hex-3-yne

Guida verificata passo dopo passo
1
Step 1: Analyze the structure of hex-3-yne. It is a six-carbon alkyne with a triple bond located between carbons 3 and 4. This is a symmetrical internal alkyne.
Step 2: For HgSO4/H2SO4-catalyzed hydration, the reaction follows Markovnikov's rule. The triple bond undergoes hydration to form an enol intermediate, which tautomerizes to a ketone. The ketone will form at the more substituted carbon of the triple bond.
Step 3: For hydroboration-oxidation, the reaction follows anti-Markovnikov's rule. The triple bond undergoes hydroboration with a bulky borane reagent, followed by oxidation with H2O2/NaOH. This results in the formation of an enol intermediate, which tautomerizes to an aldehyde. The aldehyde will form at the less substituted carbon of the triple bond.
Step 4: Write the expected products for each reaction. For HgSO4/H2SO4-catalyzed hydration, the product will be a ketone. For hydroboration-oxidation, the product will be an aldehyde.
Step 5: Ensure the stereochemistry and regiochemistry of the products are consistent with the reaction mechanisms. Verify that the ketone and aldehyde products are correctly positioned based on Markovnikov and anti-Markovnikov rules.

Risposta video verificata per un problema simile:

Questa soluzione video è stata consigliata dai nostri tutor come utile per risolvere questo problema.
Durata del video:
11m

Concetti chiave

Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.

Alkyne Hydration

Alkyne hydration involves the addition of water across the triple bond of an alkyne, typically catalyzed by acids like HgSO4 and H2SO4. This reaction leads to the formation of a carbonyl compound, such as a ketone, through a Markovnikov addition mechanism, where the more substituted carbon atom receives the hydroxyl group.
Video consigliato:
09:11
Alkyne Hydration

Hydroboration-Oxidation

Hydroboration-oxidation is a two-step reaction that converts alkynes into alcohols. In the first step, borane (BH3) adds to the alkyne in a syn addition, resulting in a trialkylborane intermediate. The second step involves oxidation with hydrogen peroxide and sodium hydroxide, yielding an alcohol with anti-Markovnikov orientation, where the hydroxyl group attaches to the less substituted carbon.
Video consigliato:
06:38
General properties of hydroboration-oxidation.

Markovnikov's Rule

Markovnikov's Rule states that in the addition of HX to an alkene or alkyne, the hydrogen atom will attach to the carbon with the greater number of hydrogen atoms already attached. This principle helps predict the outcome of hydration reactions, guiding the formation of more stable carbocation intermediates and influencing the final product distribution in reactions involving unsaturated hydrocarbons.
Video consigliato:
03:54
The 18 and 16 Electron Rule
Pratica correlata
Domanda del libro di testo

The hydroboration–oxidation of internal alkynes produces ketones.

b. When hydroboration–oxidation is applied to pent-2-yne, two products are obtained. Show why a mixture of products should be expected with any unsymmetrical ­internal alkyne.

1961
views
Domanda del libro di testo

Predict the product(s) you would expect from treatment of each compound with (1) dilute, neutral KMnO4 and (2) warm basic KMnO4, then dilute acid.

(a) hex-1-yne

563
views
Domanda del libro di testo

For each compound, give the product(s) expected from (1) HgSO4/H2SO4 - catalyzed hydration and (2) hydroboration–oxidation.

d. cyclodecyne

1424
views
Domanda del libro di testo

Disiamylborane adds only once to alkynes by virtue of its two bulky secondary isoamyl groups. Disiamylborane is prepared by the reaction of BH3·THF with an alkene.

a. Draw the structural formulas of the reagents and the products in the preparation of disiamylborane.

b. Explain why the reaction in part (a) goes only as far as the dialkylborane. Why is Sia3B not formed?

1163
views
Domanda del libro di testo

For each compound, give the product(s) expected from (1) HgSO4/H2SO4 - catalyzed hydration and (2) hydroboration–oxidation.

b. hex-2-yne

1837
views
Domanda del libro di testo

For each compound, give the product(s) expected from (1) HgSO4/H2SO4 - catalyzed hydration and (2) hydroboration–oxidation.

a. hex-1-yne

1281
views