Q49 E - Organic Chemistry (Mcmurry)

Question

21-49 Answer Problem 21-48 for reaction of the listed reagents with methyl propanoate.

Step-by-Step Solution

Answer

1. The chemical reagent Gilman's reagent, an organo copper reagent, is $Li(ph{)}_{2}cu$. The diorganocopper reaction using Gilman's reagent produces organic esters in the usual way.
2. The reduction of an ester with Lithium aluminium hydride generates a 1° alcohol in the end.
3. As a result of the Grignard reduction, an ester is reduced to a 3° alcohol.
4. Overall, a nucleophilic acyl substitution converts an ester to carboxylic acid via an acidic catalyst.
5.   $DBE=C+1-\left(\frac{H+X-N}{2}\right)$     

       f.

      g.

      $DBE=C+1-\left(\frac{H+X-N}{2}\right)$

 

Introduction to the Concept

A chemical compound's structural formula is a graphic depiction of the molecular structure (derived by structural chemistry methods) that shows how the atoms might be organised in real three-dimensional space.

Solution Explanation

a)

It reacts with the reagents listed below in the order given. Each reaction is a typical nucleophilic acyl substitution, it should be emphasised.

$methyl propanoate+Li {\left(ph\right)}_{2}cu in ether$

Solution Explanation

b)

Primary alcohols are produced when the system reacts with lithium aluminium hydride.

The reaction is essentially a nucleophilic acyl substitution in which $Li Ae{H}_4.\mathit{\left[}L{i}^{\mathit{+}} Ae{H}_{\mathit{4}}\mathit{\right]}$  reduces an acyl carbon.

Mechanistic data are used to explain the situation.

In a typical nucleophilic acyl substitution reaction, a hydride ion H is used to reduce the acyl "The carbonyl group is added, resulting in a tetrahedral intermediate that expels the methoxide anion. 

The overall result is that ${\mathrm{OCH}}_3$ is replaced by $H^{-}$   In a second stage, $LiAe{H}_4$is used to further decrease the aldehyde, yielding the i alcohol.

Solution Explanation

c)

When a Grignard reagent, such as methyl magnesium bromide , combines with an ester, such as methyl propionate (given ester), 3° (tertiary alcohols) with two identical substituents are produced.

Using the Grignard Reagent, the reaction is basically Reduction at the acyl carbon.

Because ketones are considerably more sensitive to nucleophiles than esters, the initial stage of the nucleophilic acyl substitution yields methyl propyl ketone, which is not separated. This intermediate ketone then adds another molecule of the Grignard reagent before being hydrolyzed to 2-methyl-butan-2-ol, a reduced 3° tertiary alcohol.

Solution Explanation

d)

In this process, an ester, methyl propionate, undergoes acidic hydrolysis.

The attack of $H_3{O}^{+}$ on the acyl carbon of the starting ester initiates the hydrolysis, which is a typical nucleophilic acyl substitution reaction. Mechanistically, the methoxide anion is eliminated from the tetrahedral intermediate, resulting in propanoic acid as the resultant acid.

The reaction is essentially an acidic catalepsis because $H^{+}$ is regenerated at the end of the process.

To help with catalepsis, a few drops of $HCl$ can be added at the start.

Solution Explanation

e)

Finally, there is a reaction. The term "trans esterification" refers to an exchange of esters.

Transesterification entails a nucleophilic acyl substitution reaction that results in a partial exchange of alcoholic OR' at the acyl function.

Solution Explanation

f)

Amides are formed when esters react quickly with ammonia and amines.

An aromatic amine, aniline, causes ammonolysis via a nucleophilic aromatic substitution reaction at the acyl carbon of the supplied ester, methylpropionate, in the even process.

Through a nucleophilic acyl substitution process, ammonolysis by an amine transforms an ester to an amide.

Solution Explanation

g)

Sodium acetate is used in a nucleophilic acyl substitution that results in the creation of an acid anhydride from an organic ester.

A Nucleophilic acyl substitution process has successfully transformed an organic ester to an acid anhydride.