Question 1

Which of the following best describes the role of sodium amide ($$\mathrm{$$NaNH_2$$}) in $$the synthesis of 2-bromopentane from acetylene?

Accepted Answer

It deprotonates acetylene to generate an acetylide anion for nucleophilic substitution.

Question 2

In the retrosynthetic analysis for the preparation of 5-methyl-1-hexanol from acetylene, which step introduces the methyl group at the 5-position?

Accepted Answer

Alkylation with 3-bromopentane ($$\mathrm{CH_3CH(CH_2$)_2Br})$$

Question 3

What is the product of the hydroboration-oxidation of 5-methyl-1-hexene?

Accepted Answer

5-Methyl-1-hexanol

Question 4

Which reagent is used to selectively reduce an alkyne to a cis-alkene in the synthesis routes described?

Accepted Answer

Lindlar catalyst

Question 5

During the synthesis of 2-bromopentane from acetylene, which reaction mechanism is involved in the addition of HBr to 1-pentene?

Accepted Answer

Markovnikov electrophilic addition

Question 6

Which of the following sequences correctly represents the order of reactions in the synthesis of 2-bromopentane from acetylene?

Accepted Answer

Alkylation, Reduction, Hydrohalogenation

Question 7

In the synthesis of 5-methyl-1-hexanol, what is the purpose of using $$\mathrm{BH_3$}$$ followed by $$\mathrm{H_2O_2}$$ and $$\mathrm{NaOH}$$?

Accepted Answer

To convert the alkene to an alcohol via anti-Markovnikov addition

Question 8

Which intermediate is formed immediately after the alkylation of acetylene with 1-bromopropane ($$\mathrm{CH_3CH_2CH_2Br}) in $$the synthesis of 2-bromopentane?

Accepted Answer

1-Pentyne

Question 9

A student attempts to synthesize 2-bromopentane from acetylene but skips the reduction step. What is the most likely product after the addition of HBr?

Accepted Answer

2-Bromopentyne

Question 10

Which of the following statements about retrosynthetic analysis is most accurate based on the synthesis routes provided?

Accepted Answer

It involves breaking down complex molecules into simpler starting materials by reversing known reactions.

Question 11

In the context of the provided syntheses, what is the main advantage of using acetylene as a starting material?

Accepted Answer

It is highly reactive and can be easily converted into a variety of carbon skeletons via alkylation.

Question 12

Which of the following best explains why Lindlar catalyst is used instead of a typical hydrogenation catalyst in these syntheses?

Accepted Answer

Lindlar catalyst selectively reduces alkynes to cis-alkenes without further reduction to alkanes.

Question 13

If a student uses $$\mathrm{$$NaNH_2$$}$$ and then reacts acetylene with $$\mathrm{CH_3CH_2CH_2Br}$$, what is the major organic product?

Accepted Answer

1-Pentyne

Question 14

Which of the following is the correct IUPAC name for the product formed after hydroboration-oxidation of 5-methyl-1-hexene?

Accepted Answer

5-Methyl-1-hexanol

Question 15

A chemist wants to synthesize a terminal alcohol from an alkyne. Which sequence of reactions would be most appropriate?

Accepted Answer

Hydroboration-oxidation

Question 16

Which of the following is a key difference between the hydroboration-oxidation and acid-catalyzed hydration of alkenes?

Accepted Answer

Hydroboration-oxidation gives anti-Markovnikov alcohols, while acid-catalyzed hydration gives Markovnikov alcohols.

Question 17

In the synthesis of 2-bromopentane, which carbon atom does the bromine atom attach to after the addition of HBr to 1-pentene?

Accepted Answer

The second carbon atom (C-2)

Question 18

Which of the following best describes the function of THF (tetrahydrofuran) in the alkylation step of these syntheses?

Accepted Answer

It acts as a polar aprotic solvent, stabilizing the acetylide anion.

Question 19

A student wants to synthesize 5-methyl-1-hexanol but accidentally uses $$\mathrm{CH_3CH_2Br}$$ instead of $$\mathrm{CH_3CH(CH_2$)_2Br} in $$the alkylation step. What is the most likely product after completing all steps?

Accepted Answer

3-Methyl-1-pentanol

Organic Synthesis: Retrosynthetic Analysis and Synthesis Routes from Acetylene

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