Question 1

Which of the following best describes why carbon acts as a nucleophile in organometallic compounds such as Grignard reagents?

Accepted Answer

Because the carbon is bonded to a metal that is less electronegative than carbon, making the carbon electron-rich.

Question 2

Which of the following statements about Grignard reagents is correct?

Accepted Answer

They are prepared by reacting an alkyl halide with magnesium metal in an aprotic solvent such as diethyl ether.

Question 3

Why must Grignard and organolithium reagents be handled under anhydrous (dry) conditions?

Accepted Answer

Because they react rapidly with water to form alkanes, destroying the reagent.

Question 4

Which of the following is a correct statement about the reactivity of organolithium versus Grignard reagents?

Accepted Answer

Organolithium reagents are generally more reactive than Grignard reagents due to a larger electronegativity difference between carbon and lithium.

Question 5

A student attempts to use a Grignard reagent to react with an alkyl halide. What is the most likely outcome?

Accepted Answer

No reaction will occur because Grignard reagents do not react with alkyl halides.

Question 6

Which of the following best explains why only vinylic or aryl halides are used in Suzuki and Heck coupling reactions?

Accepted Answer

Because alkyl halides with β-hydrogens undergo elimination rather than coupling.

Question 7

Which of the following is the correct general equation for the Suzuki coupling reaction?

Accepted Answer

$$ \mathrm{R{-}X} + \mathrm{R'B(OR)_2} \xrightarrow{L_2Pd,\ HO^-} \mathrm{R{-}R'} $$

Question 8

In a Heck reaction, which of the following is a key requirement for the alkene substrate to ensure regioselectivity and high yield?

Accepted Answer

The alkene should be symmetrical or have one sp2 carbon that is sterically hindered.

Question 9

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

Accepted Answer

It acts as a catalyst, cycling between oxidation states to facilitate the formation of new C–C bonds.

Question 10

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

Accepted Answer

They are prepared by reacting an organolithium compound with copper(I) iodide.

Question 11

A chemist wants to couple a primary alkyl group to a vinylic halide. Which reagent should they use for the coupling?

Accepted Answer

A Gilman reagent (organocuprate)

Question 12

Which of the following is a limitation of organocuprate coupling reactions?

Accepted Answer

The R group of the organocuprate cannot be secondary or tertiary.

Question 13

Which of the following best explains why organometallic reagents are strong bases?

Accepted Answer

The carbon-metal bond is highly polarized, making the carbon atom electron-rich and able to deprotonate even weak acids.

Question 14

Which of the following is the correct product when butyllithium reacts with water?

Accepted Answer

$$ \mathrm{C_4H_{10}}  ($$butane)

Question 15

A chemist is performing a Suzuki reaction with a vinylic bromide and an arylboronic acid. What is the expected major product?

Accepted Answer

A new C–C bond joining the vinylic and aryl groups.

Question 16

Which of the following best describes the polarity of the carbon-metal bond in organolithium and Grignard reagents?

Accepted Answer

The carbon atom carries a partial negative charge ($$ \delta^- ) $$and the metal carries a partial positive charge ($$ \delta^+ ).$$

Question 17

Which of the following is a real-world application of the Heck reaction?

Accepted Answer

Synthesis of pharmaceuticals by forming C–C bonds between aromatic rings and alkenes.

Question 18

Which of the following best explains why the Suzuki reaction requires a base such as $$ \mathrm{HO^-} $$?

Accepted Answer

The base activates the organoboron compound, facilitating the transfer of the organic group to palladium.

Question 19

Which of the following is the correct order of increasing reactivity for the following organometallic reagents: organocuprate, Grignard, organolithium?

Accepted Answer

Organocuprate \u003c Grignard \u003c Organolithium

Organometallic Compounds: Structure, Reactivity, and Coupling Reactions

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