Question 1

Which of the following best describes the functional group present in alcohols?

Accepted Answer

A hydroxy group ($$-OH)$$

Question 2

Which statement correctly defines reduction in organic chemistry?

Accepted Answer

Reduction is the addition of hydrogens, addition of electrons, or removal of oxygens.

Question 3

What is the product when a ketone is reduced by sodium borohydride ($$\mathrm{Na^+BH_4$^-}$$)?

Accepted Answer

A secondary alcohol

Question 4

Which of the following reagents can be used to reduce an aldehyde to a primary alcohol?

Accepted Answer

$$\mathrm{Na^+BH_4$^-} ($$sodium borohydride)

Question 5

Why can't tertiary alcohols be synthesized by the reduction of ketones or aldehydes using $$\mathrm{Na^+BH_4$^-} or$$ $$\mathrm{Li^+$$AlH_4$$^-}$$?

Accepted Answer

Because the reduction of ketones and aldehydes only yields primary or secondary alcohols.

Question 6

In the reduction of a carbonyl compound using $$\mathrm{Na^+BH_4$^-}$$, what is the source of the proton that ultimately forms the alcohol?

Accepted Answer

The alcohol solvent (e.g., $$\mathrm{CH_3OH})$$

Question 7

Which statement best describes the mechanism of $$\mathrm{Na^+BH_4$^-}$$ reduction of aldehydes?

Accepted Answer

It is a concerted, termolecular process with simultaneous hydride and proton addition.

Question 8

What is the main limitation of using $$\mathrm{Na^+BH_4$^-}$$ and $$\mathrm{Li^+$$AlH_4$$^-}$$ for alcohol synthesis?

Accepted Answer

They only produce primary and secondary alcohols, with no increase in carbon number.

Question 9

Which organometallic reagent is commonly known as a Grignard reagent?

Accepted Answer

$$\mathrm{CH_3MgBr} ($$methylmagnesium bromide)

Question 10

What is the role of organometallic reagents such as $$\mathrm{R-MgX} in $$the synthesis of alcohols?

Accepted Answer

They act as nucleophiles, forming new C–C bonds and increasing the carbon number.

Question 11

When a Grignard reagent ($$\mathrm{R-MgX}) $$reacts with formaldehyde ($$\mathrm{CH_2O}$$), what is the product after aqueous work-up?

Accepted Answer

A primary alcohol

Question 12

Which of the following best explains the concept of 'umpolung' in organometallic chemistry?

Accepted Answer

It refers to the reversal of the polarity of a functional group, making a normally electrophilic carbon nucleophilic.

Question 13

A student attempts to synthesize a tertiary alcohol by reacting a Grignard reagent with a ketone. Which of the following correctly describes the outcome?

Accepted Answer

A tertiary alcohol will be formed after aqueous work-up.

Question 14

Which of the following reactions will increase the number of carbon atoms in the final alcohol product?

Accepted Answer

Reaction of a Grignard reagent with an aldehyde

Question 15

Which of the following is a correct IUPAC name for the alcohol shown below?

A cyclopentane ring with an OH group attached to carbon 1 and a methyl group attached to carbon 2.

Accepted Answer

2-methylcyclopentan-1-ol

Question 16

Which of the following statements about Grignard reagents is FALSE?

Accepted Answer

They can be used to reduce aldehydes to primary alcohols without increasing the carbon number.

Question 17

A chemist wants to synthesize cyclohexanol from cyclohexanone. Which reagent should be used?

Accepted Answer

$$\mathrm{Na^+BH_4$^-} in $$methanol

Question 18

Which of the following best describes the difference between the mechanisms of $$\mathrm{Na^+BH_4$^-}$$ and $$\mathrm{Li^+$$AlH_4$$^-}$$ reductions?

Accepted Answer

$$\mathrm{Na^+BH_4$^-}$$ reduction is concerted, while $$\mathrm{Li^+$$AlH_4$$^-} is $$stepwise.

Question 19

Which of the following is a correct description of the product formed when $$\mathrm{CH_3MgBr}$$ reacts with cyclohexanone followed by aqueous work-up?

Accepted Answer

2-methylcyclohexanol (a tertiary alcohol)

Alcohols: Structure, Synthesis by Reduction, and Organometallic Reagents

Guida di studio - Domande di pratica

Study guide - Flashcard