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Ch.9 - Alkynes
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh.9 - AlkynesProblem 30g
Chapter 9, Problem 30g

Using cyclooctyne 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.)
(g) cyclooctane-1,2-dione

Verified step by step guidance
1
Step 1: Begin with cyclooctyne as the starting material. Cyclooctyne is an alkyne with a strained eight-membered ring. The first step involves performing an oxidative cleavage of the triple bond to generate two carbonyl groups. Use a strong oxidizing agent such as potassium permanganate (KMnO₄) or ozone (O₃) followed by reductive workup (e.g., Zn/H₂O). This will yield cyclooctane-1,2-dione.
Step 2: Ensure the reaction conditions are controlled to avoid over-oxidation or degradation of the ring structure. For example, if using KMnO₄, perform the reaction in a cold, dilute solution to selectively cleave the alkyne bond.
Step 3: After the oxidative cleavage, purify the product using techniques such as recrystallization or column chromatography to isolate cyclooctane-1,2-dione.
Step 4: Confirm the structure of cyclooctane-1,2-dione using spectroscopic methods such as NMR (nuclear magnetic resonance) and IR (infrared spectroscopy). Look for characteristic peaks corresponding to the ketone functional groups in the IR spectrum (around 1700 cm⁻¹) and the absence of alkyne signals in the NMR spectrum.
Step 5: If needed, further refine the product by repeating purification steps or adjusting reaction conditions to maximize yield and purity of cyclooctane-1,2-dione.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Cyclooctyne Structure and Reactivity

Cyclooctyne is a cyclic alkyne with a unique structure that influences its reactivity. Understanding its geometry and the presence of a triple bond is crucial for predicting how it will participate in chemical reactions, particularly in forming new bonds or undergoing transformations to synthesize other compounds.
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Dione Functional Group

A dione is a compound containing two carbonyl groups (C=O) within its structure. Recognizing how to introduce these carbonyl groups into a cyclooctane framework is essential for synthesizing cyclooctane-1,2-dione, as it involves specific reactions that can convert alkenes or alkynes into carbonyl-containing compounds.
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Synthetic Pathways and Reaction Mechanisms

Understanding synthetic pathways and reaction mechanisms is vital for planning the synthesis of complex organic molecules. This includes knowing how to manipulate functional groups, utilize reagents effectively, and follow stepwise transformations to achieve the desired product, in this case, cyclooctane-1,2-dione from cyclooctyne.
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Related Practice
Textbook Question

Using cyclooctyne 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.)

(a) cis-cyclooctene

(b) cyclooctane

(c) trans-1,2-dibromocyclooctane

Textbook Question

Using cyclooctyne 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.)

(i)

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Textbook Question

The application box in the margin of states, “The addition of an acetylide ion to a carbonyl group is used in the synthesis of ethchlorvynol, a drug used to cause drowsiness and induce sleep.” Show how you would accomplish this synthesis from acetylene and a carbonyl compound.

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Textbook Question

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

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Textbook Question

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.)

g. pentanoic acid

h. pentanal

i. undec-6-yn-5-ol

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Textbook Question

Using cyclooctyne 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.)

(h)

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