Question

Write equations to show the reaction of benzoic anhydride with: (a) water, (b)ethyl alcohol, and (c) aniline.

Short answer

The reactions of benzoic anhydride with water, ethyl alcohol, and aniline are as follows: a) Hydrolysis with Water: \(C_6H_5C(=O)OC(=O)C_6H_5 + H_2O \rightarrow 2C_6H_5COOH\) b) Nucleophilic Substitution with Ethyl Alcohol: \(C_6H_5C(=O)OC(=O)C_6H_5 + C_2H_5OH \rightarrow C_6H_5COOC_2H_5 + C_6H_5COOH\) c) Nucleophilic Substitution with Aniline: \(C_6H_5C(=O)OC(=O)C_6H_5 + C_6H_5NH_2 \rightarrow C_6H_5C(=O)NH(C_6H_5) + C_6H_5COOH\)

Step-by-step solution

Reaction with Water (Hydrolysis)

When benzoic anhydride reacts with water (H2O), it undergoes hydrolysis to form two molecules of benzoic acid. Chemical equation: \(C_6H_5C(=O)OC(=O)C_6H_5 + H_2O \rightarrow 2C_6H_5COOH\)

Reaction with Ethyl Alcohol (Nucleophilic Substitution)

When benzoic anhydride reacts with ethyl alcohol (C2H5OH), it undergoes nucleophilic substitution to form ethyl benzoate and benzoic acid. Chemical equation: \(C_6H_5C(=O)OC(=O)C_6H_5 + C_2H_5OH \rightarrow C_6H_5COOC_2H_5 + C_6H_5COOH\)

Reaction with Aniline (Nucleophilic Substitution)

When benzoic anhydride reacts with aniline (C6H5NH2), it undergoes nucleophilic substitution to form N-phenylbenzamide and benzoic acid. Chemical equation: \(C_6H_5C(=O)OC(=O)C_6H_5 + C_6H_5NH_2 \rightarrow C_6H_5C(=O)NH(C_6H_5) + C_6H_5COOH\)

Key concepts

Hydrolysis of Anhydrides

Hydrolysis of anhydrides is an essential organic chemistry reaction where water breaks down an anhydride to form carboxylic acids. It involves the use of water as a reactant, making it an accessible reaction. For benzoic anhydride, hydrolysis occurs when it reacts with water, leading to the formation of two molecules of benzoic acid. This process is useful in various chemical applications:

• Production of carboxylic acids
• Biochemical processes, where water is abundant

The chemical equation for this reaction is straightforward:\[C_6H_5C(=O)OC(=O)C_6H_5 + H_2O \rightarrow 2C_6H_5COOH\]The reaction highlights the cleavage of the anhydride bond, demonstrating the simplicity and efficiency of hydrolysis in organic synthesis.

Nucleophilic Substitution

Nucleophilic substitution is a common reaction mechanism in organic chemistry where a nucleophile, an electron-rich species, substitutes a leaving group within a molecule. This reaction is crucial:

• In creating diverse compounds in pharmaceuticals
• For understanding biochemical transformations

When benzoic anhydride undergoes nucleophilic substitution with different nucleophiles such as ethyl alcohol or aniline, it results in distinct products. The nucleophile in the reaction attacks the carbonyl carbon of the anhydride, leading to a reorganization of bonds and the formation of new compounds, such as esters or amides.

Benzoic Acid

Benzoic acid is a simple aromatic carboxylic acid with the formula \(C_6H_5COOH\). It is one of the products formed from the hydrolysis of benzoic anhydride or through other organic reactions involving benzoic anhydride.
Benzoic acid is vital because:

• It is a precursor to various organic compounds
• Used as a preservative in foods and beverages

In reactions involving benzoic anhydride, it often forms as a byproduct, illustrating its stability and versatility in organic chemistry.

Ethyl Benzoate

Ethyl benzoate is an ester formed through nucleophilic substitution when benzoic anhydride reacts with ethyl alcohol. This reaction is a classic example of esterification, a conversion of an acid derivative to an ester. Ethyl benzoate has the formula \(C_6H_5COOC_2H_5\), and it's widely used in:

• Fragrance production due to its pleasant smell
• Manufacturing of solvents and intermediates in organic synthesis

The reaction can be expressed as:\[C_6H_5C(=O)OC(=O)C_6H_5 + C_2H_5OH \rightarrow C_6H_5COOC_2H_5 + C_6H_5COOH\]This showcases the adaptability of anhydrides to form useful esters when reacted with alcohols.

N-phenylbenzamide

N-phenylbenzamide is formed when benzoic anhydride reacts with aniline through nucleophilic substitution. This type of reaction involves the formation of an amide, where an amine replaces a part of the anhydride, solidifying the relationship between anhydrides and amides in organic chemistry.
The general form of the reaction is:\[C_6H_5C(=O)OC(=O)C_6H_5 + C_6H_5NH_2 \rightarrow C_6H_5C(=O)NH(C_6H_5) + C_6H_5COOH\]N-phenylbenzamide is significant in:

• Pharmaceutical synthesis, as amides are common in drug molecules
• Understanding protein structures, where amide linkages form peptides

This reaction underscores the utility of anhydrides for creating amide-based compounds.

Organic Chemistry Reactions

Organic chemistry reactions, such as hydrolysis and nucleophilic substitution, form the backbone of synthetic chemistry. These reactions help chemists create various compounds vital for different industries, from pharmaceuticals to materials science.
Key aspects of organic reactions include:

• The role of functional groups, determining the reaction pathway
• Reaction mechanisms that provide insights into molecular transformations
• Applications in designing drugs, agrochemicals, and advanced materials

Understanding the reactivity of compounds like benzoic anhydride allows chemists to not only predict products but also tailor reactions for specific outcomes, showcasing the dynamic nature of organic chemistry.