Chapter 22, Problem 22.46P

Draw the product formed when pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_{\text{2}}\text{O}\right]$ is treated with each reagent. With some reagents, no reaction occurs.

a. ${\text{SOCl}}_{\text{2}}$ c. ${\text{CH}}_{\text{3}}\text{OH}$ e. ${\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\right)}_{\text{2}}\text{NH}$ (excess)

b. ${\text{H}}_2\text{O}$ d. $\text{NaCl}$ f. ${\text{CH}}_3{\text{CH}}_2{\text{NH}}_{\text{2}}$ (excess)

Interpretation Introduction

(a)

Interpretation:

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is to be drawn.

Concept introduction:

The replacement or substitution of one functional group with another functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons is known as a nucleophile. In nucleophilic acyl substitution reaction, a nucleophile takes the position of a leaving group.

Answer to Problem 22.46P

No product is formed by the treatment of pentanoic anhydride with ${\text{SOCl}}_{\text{2}}$.

Explanation of Solution

Acid anhydride do not undergo reaction with ${\text{SOCl}}_{\text{2}}$. The replacement of ${\text{RCOO}}^{-}$ group of acid anhydride with $\text{Cl}$ group does not takes place because ${\text{RCOO}}^{-}$ is a poor leaving group. Therefore, no product is formed by the treatment of pentanoic anhydride with ${\text{SOCl}}_{\text{2}}$ as shown below.

Figure 1

Conclusion

No product is formed by the treatment of pentanoic anhydride with ${\text{SOCl}}_{\text{2}}$.

Interpretation Introduction

(b)

Interpretation:

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is to be drawn.

Concept introduction:

The replacement or substitution of one functional group with another functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons is known as a nucleophile. In nucleophilic acyl substitution reaction, a nucleophile takes the position of a leaving group.

Answer to Problem 22.46P

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is,

Explanation of Solution

Acid anhydride undergoes hydrolysis on treatment with ${\text{H}}_{\text{2}}\text{O}$ and gives two alcohol molecules. Two moles of pentanoic acid are formed when pentanoic anhydride undergoes hydrolysis as shown in Figure 2.

Figure 2

Conclusion

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is shown in Figure 2.

Interpretation Introduction

(c)

Interpretation:

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is to be drawn.

Concept introduction:

The replacement or substitution of one functional group with another functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons is known as a nucleophile. In nucleophilic acyl substitution reaction, a nucleophile takes the position of a leaving group.

Answer to Problem 22.46P

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is,

Explanation of Solution

Acid anhydride on reaction with alcohol gives one mole of ester and one mole of carboxylic acid. Methyl pentanoate and pentanoic acid are formed when pentanoic anhydride is treated with methanol as shown in Figure 3.

Figure 3

Conclusion

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is shown in Figure 3.

Interpretation Introduction

(d)

Interpretation:

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is to be drawn.

Concept introduction:

The replacement or substitution of one functional group with another functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons is known as a nucleophile. In nucleophilic acyl substitution reaction, a nucleophile takes the position of a leaving group.

Answer to Problem 22.46P

No product is formed by the treatment of pentanoic anhydride with $\text{NaCl}$.

Explanation of Solution

Acid anhydride do not undergo reaction with $\text{NaCl}$. The replacement of ${\text{RCOO}}^{-}$ group of acid anhydride with $\text{Cl}$ atom does not take place because ${\text{RCOO}}^{-}$ is a poor leaving group. Therefore, no product is formed by the treatment of pentanoic anhydride with $\text{NaCl}$ as shown below.

Figure 4

Conclusion

No product is formed by the treatment of pentanoic anhydride with $\text{NaCl}$.

Interpretation Introduction

(e)

Interpretation:

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is to be drawn.

Concept introduction:

The replacement or substitution of one functional group with another functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons is known as a nucleophile. In nucleophilic acyl substitution reaction, a nucleophile takes the position of a leaving group.

Answer to Problem 22.46P

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is,

Explanation of Solution

The reaction of acid anhydride with secondary amine leads to the formation of amide. The nitrogen atom of ${\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\right)}_{\text{2}}\text{NH}$ contains lone pair of electrons. The nitrogen atom acts as a nucleophile and attacks on the electron deficient carbonyl carbon atom. The reaction between pentanoyl chloride and ${\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\right)}_{\text{2}}\text{NH}$ is shown in Figure 5.

Figure 5

Conclusion

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is shown in Figure 5.

Interpretation Introduction

(f)

Interpretation:

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is to be drawn.

Concept introduction:

The replacement or substitution of one functional group with another functional group in any chemical reaction is termed as substitution reaction. The electron rich chemical species that contains negative charge or lone pair of electrons is known as a nucleophile. In nucleophilic acyl substitution reaction, a nucleophile takes the position of a leaving group.

Answer to Problem 22.46P

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is,

Explanation of Solution

The reaction of acid anhydride with primary amine leads to the formation of amide. The nitrogen atom of ${\text{CH}}_3{\text{CH}}_2{\text{NH}}_2$ contains lone pair of electrons. The nitrogen atom acts as a nucleophile and attacks on the electron deficient carbonyl carbon atom. The reaction between pentanoyl chloride and ${\text{CH}}_3{\text{CH}}_2{\text{NH}}_2$ is shown in Figure 6.

Figure 6

Conclusion

The product formed by the treatment of pentanoic anhydride $\left[{\left({\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CO}\right)}_2\text{O}\right]$ with the given reagent is shown in Figure 6.