Question 1

Which statement best explains why the carbonyl carbon in aldehydes and ketones is susceptible to nucleophilic attack?

Accepted Answer

The carbonyl carbon is partially positive due to the electronegative oxygen, making it an electrophile.

Question 2

Which of the following carbonyl compounds is most reactive toward nucleophilic addition?

Accepted Answer

Formaldehyde

Question 3

What is the major product when methylmagnesium bromide (a Grignard reagent) reacts with acetone followed by aqueous workup?

Accepted Answer

2-methyl-2-propanol

Question 4

Why are organometallic reagents such as Grignard and organolithium compounds typically prepared in diethyl ether?

Accepted Answer

Diethyl ether prevents the reagent from reacting with water or alcohols.

Question 5

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

Accepted Answer

The nucleophile attacks the carbonyl carbon, breaking the \pi bond and forming a tetrahedral intermediate.

Question 6

Which reagent would selectively reduce an aldehyde to a primary alcohol without affecting an ester group in the same molecule?

Accepted Answer

NaBH\_4

Question 7

A student attempts to react a Grignard reagent with a molecule containing both a carbonyl and an alcohol group. What is the most likely outcome?

Accepted Answer

The Grignard reagent will be protonated by the alcohol group, destroying its nucleophilicity.

Question 8

Which of the following is the correct general reaction for the preparation of an organolithium reagent from an alkyl halide?

Accepted Answer

$$\mathrm{R-X} + 2\mathrm{Li} \rightarrow \mathrm{R-Li} + \mathrm{LiX}$$

Question 9

Which organometallic reagent is best suited for performing a 1,4-conjugate addition to an \alpha,\beta-unsaturated carbonyl compound?

Accepted Answer

Organocuprate (Gilman reagent)

Question 10

What is the product when a Gilman reagent ($$\mathrm{(CH_3$)_2CuLi}) $$reacts with 1-bromo-2-phenylethene?

Accepted Answer

(E)-1-phenylethene

Question 11

Which statement about the Wittig reaction is correct?

Accepted Answer

It replaces a carbonyl group with an alkene using a phosphonium ylide.

Question 12

Which protecting group is commonly used to protect a carbonyl group during reactions with organometallic reagents?

Accepted Answer

Acetal (formed from glycol)

Question 13

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

Accepted Answer

The nucleophile attacks the less hindered side, forming an alcohol after workup.

Question 14

Which of the following best describes the difference between 1,2- and 1,4-addition to \alpha,\beta-unsaturated carbonyls?

Accepted Answer

1,2-addition occurs at the carbonyl carbon; 1,4-addition occurs at the \beta-carbon.

Question 15

Which of the following is the correct formula for the reduction of an aldehyde to a primary alcohol using sodium borohydride?

Accepted Answer

$$\mathrm{RCHO} + \mathrm{$$NaBH_4$$} + \mathrm{H_2O} \rightarrow \mathrm{RCH_2OH}$$

Question 16

A chemist wants to synthesize a carboxylic acid from a Grignard reagent and carbon dioxide. What is the correct sequence of reactions?

Accepted Answer

Grignard reagent + CO\_2, then acid workup

Question 17

Which of the following statements about the reactivity of carbonyl compounds is true?

Accepted Answer

Aldehydes are generally more reactive than ketones because they are less sterically hindered.

Question 18

Which of the following is a correct statement about the use of protecting groups in organic synthesis?

Accepted Answer

Protecting groups temporarily mask reactive sites to prevent unwanted reactions.

Question 19

Which of the following is the correct mechanism for the formation of a hemiacetal from an aldehyde and an alcohol under acid catalysis?

Accepted Answer

Protonation of the carbonyl oxygen, followed by nucleophilic attack by the alcohol.

Organometallics and Reactions of Aldehydes & Ketones: Structure, Reactivity, and Nomenclature

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