Question 1

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

Accepted Answer

The sp hybridized carbon in alkynes holds the negative charge more tightly due to higher s-character.

Question 2

What is the product when a terminal alkyne is treated with excess NaNH$$_2$$ followed by water?

Accepted Answer

A terminal alkyne

Question 3

Which reagent(s) would you use to selectively hydrogenate an alkyne to a cis-alkene?

Accepted Answer

Lindlar’s catalyst and H$$_2$$

Question 4

What is the major organic product when 1-hexyne is treated with 1) BH$$_3$$·THF, 2) H$$_2O$_2$$, NaOH?

Accepted Answer

Hexanal

Question 5

Which of the following best describes the mechanism of dissolving metal reduction (Birch reduction) of alkynes?

Accepted Answer

Anti addition of hydrogen atoms via a radical anion intermediate

Question 6

What is the expected product when 2-butyne is treated with excess HBr?

Accepted Answer

2,2-dibromobutane

Question 7

Which of the following statements about the hydrohalogenation of alkynes is correct?

Accepted Answer

The rate law is first order in alkyne and second order in HX: $$	ext{Rate} = k[	ext{alkyne}][	ext{HX}]^2$$

Question 8

Which of the following best describes the product(s) of ozonolysis of a terminal alkyne?

Accepted Answer

A carboxylic acid and carbon dioxide

Question 9

What is the IUPAC name for the following compound: CH$$_3C$$≡CCH$$_2CH$_3$$?

Accepted Answer

2-pentyne

Question 10

Which of the following bases can deprotonate a terminal alkyne?

Accepted Answer

NaNH$$_2$$

Question 11

A student wants to synthesize 3-hexyne from 1-butyne. Which sequence of reactions would achieve this?

Accepted Answer

1) NaNH$$_2 2) 1-$$bromopropane

Question 12

Which of the following is true regarding the halogenation of alkynes?

Accepted Answer

Addition of two equivalents of Br$$_2$$ yields a tetrahalide.

Question 13

Which of the following best describes the product of acid-catalyzed hydration of a terminal alkyne?

Accepted Answer

A ketone via Markovnikov addition

Question 14

Which of the following statements about alkylation of terminal alkynes is correct?

Accepted Answer

It proceeds via an SN2 mechanism and works best with methyl or 1º alkyl halides.

Question 15

Which of the following reagents would convert a vicinal dihalide to an alkyne?

Accepted Answer

Excess NaNH$$_2$$

Question 16

Which of the following is a common use of acetylene in industry?

Accepted Answer

As a fuel in blow torches

Question 17

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

Accepted Answer

Anti-Markovnikov addition, yielding an aldehyde

Question 18

Which of the following is the correct order of acidity (most to least acidic)?

Accepted Answer

Alkyne \u003e Alkene \u003e Alkane

Question 19

Which of the following is a synthetic alkyne used in birth control pills?

Accepted Answer

Ethynylestradiol

Question 20

Which of the following is true about the nomenclature of alkynes?

Accepted Answer

The parent chain must include the triple bond and the triple bond gets the lowest possible number.

Step-by-Step Guidance for Alkynes (Organic Chemistry, Chapter 9)

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