Q: What is the major product when phenylmagnesium bromide reacts with methyloxirane (propylene oxide) followed by acid workup?

$$\mathrm{1\text{-}Phenyl\text{-}2\text{-}propanol}$$\ (racemic)$

Question 1

Which of the following statements best explains why Grignard reagents must be prepared and used under anhydrous conditions?

Accepted Answer

Grignard reagents are strong bases and react rapidly with water to form alkanes, destroying the reagent.

Question 2

Which of the following organohalides would NOT be suitable for the preparation of a Grignard reagent?

Accepted Answer

4-Bromo-1-pentanol

Question 3

What is the product of the reaction between butylmagnesium bromide and ethylene oxide followed by aqueous acid workup?

Accepted Answer

$$\mathrm{1	ext{-}Hexanol}$$

Question 4

Which of the following best describes the role of ether in the preparation of Grignard reagents?

Accepted Answer

Ether acts as a solvent and Lewis base, coordinating to magnesium and stabilizing the reagent.

Question 5

Which of the following sequences would best accomplish the transformation of 1-bromocyclohexene to 1-methylcyclohexene?

Accepted Answer

Treat with lithium dimethylcopper

Question 6

What is the major product when phenylmagnesium bromide reacts with methyloxirane (propylene oxide) followed by acid workup?

Accepted Answer

$$\mathrm{1	ext{-}Phenyl	ext{-}2	ext{-}propanol}$$\ (racemic)$

Question 7

Which of the following best describes the hybridization and electronic structure of a carbene?

Accepted Answer

sp2 hybridized with one lone pair and an empty 2p orbital

Question 8

Which of the following statements about the Simmons-Smith reaction is correct?

Accepted Answer

It uses diiodomethane and zinc-copper couple to generate a carbenoid that reacts stereospecifically with alkenes.

Question 9

Which of the following best explains why Gilman reagents (lithium diorganocopper) are useful in organic synthesis?

Accepted Answer

They enable the coupling of two alkyl halides to form new C–C bonds, especially with primary and vinylic halides.

Question 10

Which of the following is the correct order of increasing acidity (lower to higher pKa) for the following compounds: water, alcohol, carboxylic acid?

Accepted Answer

Water \u003c Alcohol \u003c Carboxylic acid

Question 11

A student attempts to prepare an organolithium reagent from 4-bromo-1-pentanol and lithium metal in pentane. What is the most likely outcome?

Accepted Answer

The alcohol group will react with the organolithium reagent, destroying it.

Question 12

Which of the following best describes the stereochemistry of the addition of dichlorocarbene to a cis-alkene?

Accepted Answer

The product is a cis-dichlorocyclopropane.

Question 13

Which of the following best explains why organolithium reagents must be handled under an inert atmosphere?

Accepted Answer

They are highly reactive with atmospheric oxygen and moisture.

Question 14

What is the product of the following reaction sequence: 1-chlorobutane + 2 Li (pentane) → product?

Accepted Answer

$$\mathrm{Butyllithium}$$

Question 15

Which of the following is a correct retrosynthetic disconnection for the preparation of 2,7-dimethyloctane from 1-bromo-3-methylbutane using only this compound as the carbon source?

Accepted Answer

Couple two equivalents of 1-bromo-3-methylbutane via a Gilman reagent.

Question 16

Which of the following best describes the mechanism of the Simmons-Smith reaction?

Accepted Answer

It is a concerted, stereospecific addition of a carbenoid to an alkene.

Question 17

Which of the following is a real-world application of organometallic reagents in medicine?

Accepted Answer

They are used to synthesize pharmaceutical intermediates via C–C bond formation.

Question 18

Which of the following best explains why dichlorocarbene is more stable and selective than methylene?

Accepted Answer

Resonance stabilization with the lone pairs on chlorine satisfies the electron deficiency on carbon.

Question 19

Which of the following is the correct product for the reaction of (Z)-3-hexene with dichlorocarbene generated from chloroform and potassium tert-butoxide?

Accepted Answer

$$\mathrm{cis	ext{-}1,1	ext{-}Dichloro	ext{-}2,3	ext{-}diethylcyclopropane}$$

Organometallic Compounds and Carbenes in Organic Synthesis

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