Question 1

Which product is formed when phenylacetylene is treated with Lindlar's catalyst and $$\mathrm{H_2$}$$?

Accepted Answer

Cis-styrene (cis-alkene)

Question 2

Which reagent(s) would you use to convert acetylene ($$\mathrm{HC \equiv CH}) to $$ethylene oxide (oxirane)?

Accepted Answer

$$1.\ \mathrm{CH_2I_2},\ Zn(Cu)\ \rightarrow\ 2.\ H_2O}$$

Question 3

Which sequence of reagents would convert acetylene to meso-2,3-butanediol?

Accepted Answer

$$1.\ \mathrm{$$KMnO_4$$},\ H_2O,\ cold}$$

Question 4

Which of the following best describes the role of Lindlar's catalyst in organic synthesis?

Accepted Answer

It selectively reduces alkynes to cis-alkenes.

Question 5

In the synthesis of muscalure from acetylene, which reaction type is primarily used to elongate the carbon chain?

Accepted Answer

Nucleophilic substitution (alkylation of acetylide anion)

Question 6

What is the product of the following reaction: $$\mathrm{HC \equiv CH}$$ treated with $$\mathrm{$$NaNH_2$$}$$ followed by $$\mathrm{CH_3CH_2Br}$$?

Accepted Answer

$$\mathrm{CH_3CH_2C \equiv CH}$$

Question 7

Which product is formed when the following compound is treated with Lindlar's catalyst: $$\mathrm{CH_3CH_2C \equiv CCH_2CH_3}$$?

Accepted Answer

$$\mathrm{CH_3CH_2CH=CHCH_2CH_3}$$\ (cis-alkene)

Question 8

Which of the following is a correct sequence for synthesizing muscalure from acetylene, two alkyl halides, and inorganic reagents?

Accepted Answer

Alkylate acetylene twice with long-chain alkyl halides using $$\mathrm{$$NaNH_2$$}$$, then hydrogenate the triple bond to a cis-alkene with Lindlar's catalyst.

Question 9

What is the stereochemistry of the alkene produced by Lindlar reduction of an internal alkyne?

Accepted Answer

Cis (Z)

Question 10

Which of the following best explains why Lindlar's catalyst produces a cis-alkene from an alkyne?

Accepted Answer

The catalyst is poisoned, allowing only syn addition of hydrogen.

Question 11

Which of the following reagents would you use to convert an alkyne to a trans-alkene?

Accepted Answer

$$\mathrm{Na}$$, liquid $$\mathrm{NH_3$}$$

Question 12

A student wants to synthesize a meso diol from acetylene. Which reagent should they use?

Accepted Answer

$$\mathrm{$$KMnO_4$$} ($$cold, dilute)

Question 13

Which of the following is the product of the Lindlar reduction of the compound shown in image 5?

Accepted Answer

A cis-alkene at the triple bond position, with all other groups unchanged

Question 14

Which of the following statements about the synthesis of muscalure is correct?

Accepted Answer

It requires two sequential alkylations of acetylide anion with long-chain alkyl halides.

Question 15

Which of the following is a necessary step in the synthesis of a terminal alkyne from acetylene?

Accepted Answer

Deprotonation with $$\mathrm{$$NaNH_2$$}$$

Organic Chemistry Study Guide: Alkyne Reactions, Synthesis, and Lindlar Reductions

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