Question 1

Which statement best explains why aldehydes are generally more reactive toward nucleophilic addition than ketones?

Accepted Answer

Aldehydes have less steric hindrance and a more electrophilic carbonyl carbon compared to ketones.

Question 2

What is the hybridization and approximate bond angle around the carbonyl carbon in aldehydes and ketones?

Accepted Answer

sp\^2 hybridized, bond angle approximately $$120^\circ$$

Question 3

Which of the following carbonyl compounds is most susceptible to nucleophilic attack?

Accepted Answer

Formaldehyde

Question 4

A Grignard reagent ($$R-MgX) $$reacts with a carbonyl compound. What is the role of the Grignard reagent in this reaction?

Accepted Answer

It acts as a nucleophile, attacking the electrophilic carbonyl carbon.

Question 5

Which reagent is most selective for reducing aldehydes and ketones, but not esters or carboxylic acids?

Accepted Answer

Sodium borohydride ($$NaBH_4)$$

Question 6

What is the product when a Grignard reagent ($$CH_3MgBr) $$reacts with formaldehyde followed by aqueous workup?

Accepted Answer

Primary alcohol ($$CH_3CH_2OH)$$

Question 7

Which organometallic reagent is commonly used for 1,4-conjugate addition to $$eta-$$unsaturated carbonyl compounds?

Accepted Answer

Gilman reagent ($$R_2CuLi)$$

Question 8

What is the major product when methylmagnesium bromide ($$CH_3MgBr) $$reacts with acetone followed by acid workup?

Accepted Answer

Tertiary alcohol ($$CH_3)_2C(OH$$)$$CH_3$$

Question 9

Why must organometallic reagents be protected from water and protic solvents during reactions?

Accepted Answer

They are highly basic and will react with protons, destroying the reagent.

Question 10

Which of the following is a correct general reaction for the preparation of an organolithium reagent?

Accepted Answer

$$R-X + 2Li \rightarrow R-Li + LiX$$

Question 11

What is the expected product when an organometallic reagent reacts with an epoxide?

Accepted Answer

An alcohol with the nucleophile added to the less hindered carbon of the epoxide

Question 12

Which statement best describes the mechanism of nucleophilic addition to a carbonyl group?

Accepted Answer

The nucleophile attacks the electrophilic carbonyl carbon, forming a tetrahedral intermediate.

Question 13

Which protecting group is commonly used to protect carbonyls during organometallic reactions and can be removed by acid hydrolysis?

Accepted Answer

Ethylene glycol forming a cyclic acetal

Question 14

What is the product of the reaction between a Wittig reagent and a ketone?

Accepted Answer

An alkene

Question 15

Which of the following best describes the role of triphenylphosphine in the Wittig reaction?

Accepted Answer

It forms the ylide intermediate necessary for alkene formation.

Question 16

Which reagent is used to oxidize primary alcohols to aldehydes without further oxidation to carboxylic acids?

Accepted Answer

Pyridinium chlorochromate (PCC)

Question 17

Which of the following is true about the reactivity of carbonyl compounds toward nucleophilic attack?

Accepted Answer

The more substituted the carbonyl carbon, the less reactive it is due to steric hindrance.

Question 18

What is the product when an organolithium reagent reacts with carbon dioxide ($$CO_2) $$followed by acid workup?

Accepted Answer

A carboxylic acid

Question 19

Which of the following statements about Gilman reagents ($$R_2CuLi) is $$correct?

Accepted Answer

They are good nucleophiles for substitution reactions with acid chlorides.

Intro to Organometallics & Reactions of Aldehydes and Ketones

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