Question 1

Which of the following statements best explains why organolithium compounds are more reactive than Grignard reagents?

Accepted Answer

The electronegativity difference between carbon and lithium is greater than that between carbon and magnesium, making the C–Li bond more polar and reactive.

Question 2

Which of the following solvents is most appropriate for the preparation of a Grignard reagent from an alkyl bromide?

Accepted Answer

Diethyl ether

Question 3

What is the major organic product when phenylmagnesium bromide reacts with acetone followed by aqueous workup?

Accepted Answer

1-Phenyl-2-propanol

Question 4

Which of the following functional groups will react most rapidly with a Grignard reagent?

Accepted Answer

Aldehyde

Question 5

Why are organolithium and Grignard reagents incompatible with water or alcohols during their preparation?

Accepted Answer

They react with water or alcohols to form alkanes, destroying the reagent.

Question 6

Which of the following best describes the role of palladium in the Suzuki and Heck coupling reactions?

Accepted Answer

It serves as a catalyst, facilitating the formation of new C–C bonds.

Question 7

A student attempts to couple a secondary alkyl halide with an organocuprate (Gilman reagent). What is the most likely outcome?

Accepted Answer

No reaction will occur because secondary alkyl halides are not suitable for this coupling.

Question 8

Which of the following is a key requirement for a successful Suzuki coupling reaction?

Accepted Answer

A vinylic or aryl halide and an organoboron compound

Question 9

Which of the following best explains why only vinylic or aryl halides are used in Suzuki and Heck reactions, rather than alkyl halides with β-hydrogens?

Accepted Answer

Alkyl halides with β-hydrogens undergo elimination rather than coupling.

Question 10

Which of the following statements about the Heck reaction is correct?

Accepted Answer

It couples an alkene with a vinylic or aryl halide using a palladium catalyst.

Question 11

Which of the following is the correct product of the reaction between 1-bromobutane and 2 equivalents of lithium in hexane?

Accepted Answer

Butyllithium

Question 12

What is the role of THF (tetrahydrofuran) in the preparation of Grignard reagents?

Accepted Answer

It stabilizes the Grignard reagent by coordinating to magnesium.

Question 13

Which of the following best describes the reactivity of organocuprates (Gilman reagents) in coupling reactions?

Accepted Answer

They couple efficiently with primary alkyl, vinylic, and aryl halides but not with secondary or tertiary alkyl halides.

Question 14

Which of the following is a plausible reason why Grignard reagents do not react with alkyl halides?

Accepted Answer

Both Grignard reagents and alkyl halides are nucleophilic, so no reaction occurs.

Question 15

Which of the following best describes the product of the reaction between cyclohexyl bromide and magnesium in diethyl ether?

Accepted Answer

Cyclohexylmagnesium bromide

Question 16

In the Suzuki reaction, which of the following is the source of the new carbon–carbon bond?

Accepted Answer

Between the R group of the halide and the R' group of the organoboron compound

Question 17

Which of the following is a key feature of the Heck reaction mechanism?

Accepted Answer

The new C–C bond forms between two sp2-hybridized carbons.

Question 18

Which of the following statements about the polarity of the carbon–metal bond in organometallic compounds is correct?

Accepted Answer

The carbon atom is more negative when bonded to a less electronegative metal.

Question 19

Which of the following best explains why Grignard and organolithium reagents are strong bases?

Accepted Answer

The carbon–metal bond is highly polar, making the carbon atom strongly nucleophilic and basic.

Organometallic Compounds: Structure, Reactivity, and Coupling Reactions

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