Write structures for the products of the following reactions involving Grignard reagents. Show the structures of both the intermediate substances and the substances obtained after hydrolysis with dilute acid. Unless otherwise specified, assume that sufficient Grignard reagent is used to cause those reactions to go to completion which occur readily at room temperatures. (a) \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{MgBr}+\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHO}\) (b) \(\mathrm{CH}_{3} \mathrm{MgI}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\) (c) \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CMgCl}+\mathrm{CO}_{2}\) (d) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{MgBr}+\mathrm{ClCO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\) (e) \(\mathrm{CH}_{3} \mathrm{Mg} 1+\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\) \((1\) mole \()\) \((1\) mole \()\) 0

Step by step solution

01

Identify the reactive sites

The Grignard reagent \(\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{MgBr}\) has a reactive site at the carbon bonded to the magnesium atom (phenyl anion). The aldehyde $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHO}$ has a carbonyl group that can react with the Grignard reagent.

02

Nucleophilic attack

The phenyl anion in the Grignard reagent acts as a strong nucleophile and attacks the electrophilic carbonyl carbon in $\mathrm{C}_{6} \mathrm{H}_{5} \mathrm{CHO}\(, forming a new C-C bond. This process generates a negatively charged alkoxide intermediate (\)\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{C}(\mathrm{OH})(\mathrm{C}_{6} \mathrm{H}_{5})$).

03

Hydrolysis with dilute acid

Upon treatment with a dilute acid, the intermediate formed in step 2 is converted to an alcohol. The alkoxide intermediate obtains a hydrogen from the acid, resulting in the final product, diphenylmethanol (\(\mathrm{C}_{6} \mathrm{H}_{5}-\mathrm{CH}(\mathrm{OH})(\mathrm{C}_{6} \mathrm{H}_{5})\)). The other reactions can be similarly broken down into steps: (b) Reaction of \(\mathrm{CH}_{3} \mathrm{MgI}\) with $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}$:

04

Identify the reactive sites

The Grignard reagent \(\mathrm{CH}_{3} \mathrm{MgI}\) has a reactive site at the carbon bonded to the magnesium atom (methyl anion). The ester $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}$ has a carbonyl group that can react with the Grignard reagent.

05

Nucleophilic attack

The methyl anion in the Grignard reagent acts as a strong nucleophile and attacks the electrophilic carbonyl carbon in $\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\(, forming a new C-C bond and causing the leaving of the ethoxy group. The resulting intermediate is a ketone, \)\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}(\mathrm{O})(\mathrm{CH}_{3})$.

06

Hydrolysis with dilute acid

Since Grignard reagents do not react with ketones under mild conditions, hydrolysis with a dilute acid does not affect the ketone, and the final product remains \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}(\mathrm{O})(\mathrm{CH}_{3})\), also known as 2-butanone. (c) Reaction of \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CMgCl}\) with \(\mathrm{CO}_{2}\):

07

Identify the reactive sites

The Grignard reagent \(\left(\mathrm{CH}_{3}\right)_{3} \mathrm{CMgCl}\) has a reactive site at the carbon bonded to the magnesium atom (tert-butyl anion). The carbon dioxide (\(\mathrm{CO}_{2}\)) has a carbonyl group that can react with the Grignard reagent.

08

Nucleophilic attack

The tert-butyl anion in the Grignard reagent acts as a strong nucleophile and attacks the electrophilic carbonyl carbon in \(\mathrm{CO}_{2}\), forming a new C-C bond. The intermediate formed has a carboxyl group, i.e., \(\left(\mathrm{CH}_{3}\right)_{3}\mathrm{C}-\mathrm{C}(\mathrm{O})(\mathrm{O}^{-})\).

09

Hydrolysis with dilute acid

Upon treatment with a dilute acid, the carboxylate group of the intermediate formed in step 2 is protonated, forming the final product, tert-butyl carboxylic acid (\(\left(\mathrm{CH}_{3}\right)_{3}\mathrm{C}-\mathrm{C}(\mathrm{O})(\mathrm{OH})\)). (d) Reaction of \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{MgBr}\) with $\mathrm{ClCO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}$:

10

Identify the reactive sites

The Grignard reagent \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{MgBr}\) has a reactive site at the carbon bonded to the magnesium atom (ethyl anion). The acid chloride $\mathrm{ClCO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}$ has a carbonyl group that can react with the Grignard reagent.

11

Nucleophilic attack

The ethyl anion in the Grignard reagent acts as a strong nucleophile and attacks the electrophilic carbonyl carbon in $\mathrm{ClCO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}\(, forming a new C-C bond and causing the leaving of the chloride group. The resulting intermediate is an ester, \)\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}(\mathrm{O})(\mathrm{O} \mathrm{C}_{2} \mathrm{H}_{5})$.

12

Hydrolysis with dilute acid

Hydrolysis with a dilute acid does not affect the ester, and the final product remains \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{C}(\mathrm{O})(\mathrm{O} \mathrm{C}_{2} \mathrm{H}_{5})\), also known as ethyl propanoate. (e) Reaction of \(\mathrm{CH}_{3} \mathrm{Mg} 1\) with $\mathrm{CH}_{3} \mathrm{COCH}_{2} \mathrm{CH}_{2} \mathrm{CO}_{2} \mathrm{C}_{2} \mathrm{H}_{5}$:

13

Identify the reactive sites

There must be an understanding error, as \(\mathrm{CH}_{3} \mathrm{Mg}1\) is not an existing Grignard reagent. Please provide a valid Grignard reagent for this reaction.

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