Question 1

Which of the following statements correctly describes the hybridization and geometry of the carbon atoms in acetylene ($$HC \equiv CH$$)?

Accepted Answer

Each carbon is $$sp$$ hybridized and has a linear geometry.

Question 2

Which of the following reagents can quantitatively deprotonate a terminal alkyne to form an acetylide ion?

Accepted Answer

$$NaNH_2$$

Question 3

What is the major organic product when 2-butyne is treated with excess $$Br_2 in$$ $$CCl_4$$?

Accepted Answer

$$CH_3C(Br)_2C(Br)_2CH_3$$

Question 4

Which of the following best describes the product(s) formed when but-1-yne is subjected to ozonolysis followed by hydrolysis?

Accepted Answer

Two carboxylic acids

Question 5

Which of the following statements about the acidity of hydrocarbons is correct?

Accepted Answer

Alkynes are more acidic than alkenes because the $$sp$$ hybridized carbon holds the negative charge more tightly.

Question 6

A terminal alkyne reacts with $$NaNH_2$$ followed by $$CH_3CH_2Br. $$What is the major product?

Accepted Answer

An internal alkyne with an ethyl group added to the terminal carbon

Question 7

Which of the following best describes the stereochemistry of the alkene product formed when an alkyne is reduced with sodium in liquid ammonia?

Accepted Answer

Trans (E) alkene via anti addition

Question 8

What is the IUPAC name for the following compound: $$CH_3CH_2C\equiv CCH_2CH_3$$?

Accepted Answer

Hex-2-yne

Question 9

Which of the following sequences would best synthesize 3-decyne from acetylene ($$HC\equiv CH$$)?

Accepted Answer

Question 10

Which of the following best describes the product of hydroboration-oxidation of a terminal alkyne?

Accepted Answer

An aldehyde via anti-Markovnikov addition

Question 11

When 1 mole of $$HBr is $$added to 1-butyne in the presence of peroxides, what is the major product?

Accepted Answer

1-Bromo-2-butene (anti-Markovnikov addition)

Question 12

Which of the following is a correct statement about the hydrogenation of alkynes using Lindlar’s catalyst?

Accepted Answer

It produces a cis-alkene via syn addition.

Question 13

Which of the following best explains why terminal alkynes are more acidic than alkenes or alkanes?

Accepted Answer

The $$sp$$ hybridized carbon in alkynes has more $$s$$ character, stabilizing the negative charge on the conjugate base.

Question 14

Which of the following is the correct product when 2-butyne is treated with dilute, neutral $$KMnO_4$$?

Accepted Answer

A diketone

Question 15

Which of the following best describes the mechanism for the alkylation of an acetylide ion with a primary alkyl halide?

Accepted Answer

SN2

Question 16

Which of the following is the correct order of acidity (most to least acidic) for the following hydrocarbons: ethyne, ethene, ethane?

Accepted Answer

Ethyne \u003e Ethene \u003e Ethane

Question 17

Which of the following best describes the product(s) when pent-2-yne is treated with hot, basic $$KMnO_4$$ followed by acid workup?

Accepted Answer

Two carboxylic acids

Question 18

Which of the following statements about the addition of $$HX ($$where $$X is a $$halogen) to alkynes is correct?

Accepted Answer

The addition is Markovnikov unless peroxides are present (for $$HBr).$$

Alkynes: Structure, Nomenclature, Properties, and Reactions

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