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9. Alkenes and Alkynes

Acetylide

9. Alkenes and Alkynes

Acetylide

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Understanding how to convert terminal alkynes to alkynides.

Understanding how to convert terminal alkynes to alkynides.

Johnny Betancourt

The mechanism of akynide synthesis.

The mechanism of akynide synthesis.

Johnny Betancourt

Using double dehydrohalogenation to perform alkynide synthesis.

Using double dehydrohalogenation to perform alkynide synthesis.

Johnny Betancourt

Predict the final product of the following reaction sequence.

Predict the final product of the following reaction sequence.

Johnny Betancourt

Practice this topic

Multiple Choice

Predict the major, organic product of the following reaction.

Textbook Question

What is the major product of the reaction of 1 mol of propyne with each of the following reagents? j. the product of part i followed by 1-chloropropane

Textbook Question

What is the major product of the reaction of 1 mol of propyne with each of the following reagents? i. sodium amide

Textbook Question

Show how you might synthesize the following compounds, using acetylene and any suitable alkyl halides as your starting materials. If the compound given cannot be synthesized by this method, explain why. a.hex-1-yne b. hex-2-yne c. hex-3-yne

Textbook Question

b. Give two sets of reactants (each set including an alkyl halide and a nucleophile) that could be used to synthesize the following alkyne: CH3CH2C≡CCH2CH2CH2CH3

Textbook Question

(•) Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.] (a)

Textbook Question

(•) Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.] (c)

Textbook Question

(••) LOOKING AHEAD Ethinylestradiol is a synthetic hormone mimic used as a contraceptive for its ability to prevent ovulation. Suggest a mechanism for the synthesis using sodium acetylide and estrone, followed by quenching with acid.

Textbook Question

Predict the product of the following acetylide alkylations. (a)

Textbook Question

Predict the product of the following acetylide alkylations. (c)

Textbook Question

Suggest reagents you might use to generate the product from the given reactant. (a)

Textbook Question

Suggest reagents you might use to generate the product from the given reactant. (c)

Textbook Question

A student provided the product of the following reactions, but made a mistake. Identify the mistake, correct the mistake, and suggest a way for the student to avoid that mistake in the future. (b)

Textbook Question

A student provided the product of the following reactions, but made a mistake. Identify the mistake, correct the mistake, and suggest a way for the student to avoid that mistake in the future. (a)

Textbook Question

(••) In Chapter 10, you learned how to make an alkyne by acetylide alkylation with a 1° haloalkane. Suggest a mechanism by which this reaction occurs.

Textbook Question

What is the product of the reaction of an ester with excess acetylide ion followed by the addition of pyridinium chloride?

Textbook Question

b. Explain why ethyne should be alkylated before, rather than after, nucleophilic addition.

Textbook Question

Suggest an acetylide ion and a carbonyl that might be used to make the following products. (a) oct-4-yn-3-ol

Textbook Question

Suggest an acetylide ion and a carbonyl that might be used to make the following products. (b) 2,6-dimethylhept-3-yn-2-ol

Textbook Question

Suggest an acetylide ion and a carbonyl that might be used to make the following products. (c) 5-phenylhex-2-yn-1-ol

Textbook Question

(•) Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]

(d) <IMAGE>

Textbook Question

(••) The introduction of elimination reactions provides a second way to synthesize alkynes in a two-step process starting with an alkene. Suggest a mechanism for both steps of this process.

<IMAGE>

Textbook Question

(•••) When the reaction scheme in Assessment 12.63 is done on a monosubstituted alkene, at least three equivalents of base are needed. Reacting the product of step 2 with D―Cl (D is an isotope of H) incorporates deuterium at the terminal carbon. Explain these two observations.

<IMAGE>

Textbook Question

Calculate for the following acid–base reactions. Which is the best base to use to deprotonate acetylene and make the acetylide anion?

(a) HO⁻ + H―C ≡ C―H ⇌ ⁻C ≡ C―H + H₂O

Textbook Question

Calculate for the following acid–base reactions. Which is the best base to use to deprotonate acetylene and make the acetylide anion?

(b) H₂N⁻ + H―C ≡ C―H ⇌ ⁻C ≡ C―H + H₃N

Textbook Question

(•) Show the products of the following acetylide alkylation reactions. [Make sure your product has the correct number of carbons.]

(b) <IMAGE>

Textbook Question

Calculate for the following acid–base reactions. Which is the best base to use to deprotonate acetylene and make the acetylide anion?

(c) <IMAGE>

Textbook Question

Suggest reagents you might use to generate the product from the given reactant.

(b) <IMAGE>

Textbook Question

A chemist is planning to synthesize 3-octyne by adding 1-bromobutane to the product obtained from the reaction of 1-butyne with sodium amide. Unfortunately, however, he forgot to order 1-butyne. How else can he prepare 3-octyne?

Textbook Question

a. Draw the product of each of the following reactions:

1. CH3CH2C≡CH→2. CH3CH2Br1. NaNH2

Textbook Question

Show how you might synthesize the following compounds, using acetylene and any suitable alkyl halides as your starting materials. If the compound given cannot be synthesized by this method, explain why.

d.4-methylhex-2-yne

e. 5-methylhex-2-yne

f. cyclodecyne

Textbook Question

a. Show how the following compounds can be prepared, using ethyne as one of the starting materials:

3. 2-methyl-3-hexyn-2-ol

Textbook Question

Why is a cumulated diene not formed in the reaction shown above?

Textbook Question

(••••) A chemist attempted to do the following acetylide alkylation reaction but was unsuccessful in several attempts, producing only the original starting materials in each case. Explain why the reaction didn't work. [We describe one way to solve this problem in Chapter 13.]

Textbook Question

Using the given starting material, any necessary inorganic reagents and catalysts, and any carbon-containing compounds with no more than three carbons, indicate how each of the following compounds can be prepared: c. CH3CH2C≡CH --> CH3CH2C≡CCH2CH3

Textbook Question

(••) Suggest a method for synthesizing the following alkynes using an alkyne and an alkyl halide. [There are two correct answers for each product.] (a)

Textbook Question

Show how you would accomplish the following synthetic transformations. Show all intermediates. (c) < of reaction>

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