Q: What is the correct equation for the preparation of phenylmagnesium bromide from bromobenzene?

$$\text{C}_6\text{H}_5\text{Br} + \text{Mg} \xrightarrow{\text{ether}} \text{C}_6\text{H}_5\text{MgBr}$$

Q: What is the product when ethylmagnesium bromide reacts with water?

$$\text{CH}_3\text{CH}_3 ($$ethane)

Question 1

Which of the following statements best describes the change in reactivity of carbon when 1-bromobutane is converted to butylmagnesium bromide (a Grignard reagent)?

Accepted Answer

The carbon becomes more nucleophilic due to the partial negative charge from magnesium.

Question 2

What is the correct equation for the preparation of phenylmagnesium bromide from bromobenzene?

Accepted Answer

$$	ext{C}_6	ext{H}_5	ext{Br} + 	ext{Mg} \xrightarrow{	ext{ether}} 	ext{C}_6	ext{H}_5	ext{MgBr}$$

Question 3

Which organohalide would react most rapidly with magnesium in diethyl ether to form a Grignard reagent?

Accepted Answer

1-iodobutane

Question 4

What is the percent ionic character of the C–Mg bond in a Grignard reagent, given the electronegativity difference is $$2.5 - 1.2 = 1.3$$?

Accepted Answer

$$52\%$$

Question 5

Why are Grignard reagents incompatible with starting materials containing OH, NH, SH, C≡CH, or COOH groups?

Accepted Answer

These groups contain weakly acidic protons that react with the Grignard reagent, destroying it.

Question 6

Which solvent is most commonly used for the preparation of Grignard reagents and why?

Accepted Answer

Diethyl ether, because it acts as a Lewis base and solvates the magnesium.

Question 7

What is the product when ethylmagnesium bromide reacts with water?

Accepted Answer

$$	ext{CH}_3	ext{CH}_3 ($$ethane)

Question 8

Which of the following best explains why organolithium reagents are soluble in nonpolar solvents like pentane?

Accepted Answer

They self-assemble into aggregates that present a nonpolar surface.

Question 9

A Grignard reagent reacts with an epoxide followed by aqueous workup. What is the general product?

Accepted Answer

An alcohol with two more carbons than the original Grignard reagent

Question 10

Which of the following is a correct mechanism step for the Stille coupling reaction?

Accepted Answer

Transmetallation, where the R group from the organostannane is transferred to the palladium complex

Question 11

Which of the following is a significant advantage of Suzuki coupling over Stille coupling?

Accepted Answer

Suzuki coupling produces by-products that are easily removed and uses less toxic boranes.

Question 12

What is the expected product when cyclohexanone is treated with two equivalents of methylmagnesium bromide followed by water?

Accepted Answer

1,1-dimethylcyclohexanol

Question 13

Which of the following functional groups is compatible with the preparation of a Grignard reagent from an organohalide?

Accepted Answer

Ether (R–O–R)

Question 14

Which step is generally rate-determining in the Suzuki coupling mechanism?

Accepted Answer

Transmetallation

Question 15

What is the product of the Simmons–Smith reaction when cyclohexene is treated with $$	ext{CH}_2	ext{I}_2$$ and Zn–Cu in diethyl ether?

Accepted Answer

Cyclopropylcyclohexane

Question 16

Which of the following best describes the stereospecificity of the Simmons–Smith cyclopropanation reaction?

Accepted Answer

It retains the stereochemistry of the original alkene (cis or trans).

Question 17

Which of the following is NOT a requirement for the Heck reaction?

Accepted Answer

A primary alkyl halide

Question 18

Which of the following statements about carbenes is correct?

Accepted Answer

Carbenes are short-lived intermediates with two bonds and two unshared electrons.

Question 19

In the Corey–Posner/Whitesides–House reaction, which type of organohalide gives the best results when coupled with a Gilman reagent?

Accepted Answer

Primary alkyl halide

Question 20

Which of the following is a real-world application of hydrogenolysis of cyclopropanes?

Accepted Answer

Synthesis of spongian-16-one, a sponge metabolite with anticancer properties

Organometallic Compounds: Structure, Preparation, and Reactions

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