Question

Which of the following are products when an alcohol is added to a carboxylic acid in the presence of a strong acid? I. water II. ester III. aldehyde A. I only B. II only C. I and II only D. I and III only

Short answer

C. I and II only

Step-by-step solution

Understanding Esterification

The reaction between an alcohol and a carboxylic acid in the presence of a strong acid is known as esterification. This process typically produces an ester and water.

Identifying the Products

In an esterification reaction, the alcohol and carboxylic acid react to form an ester and water. No aldehyde is formed in this reaction.

Comparing Options

Look at the options given: I. water, II. ester, III. aldehyde. Based on the reaction, the correct products are water (I) and ester (II).

Choosing the Correct Answer

The correct answer is C. I and II only, because both water and ester are produced in the reaction.

Key concepts

carboxylic acid

Carboxylic acids are organic compounds that contain a carboxyl group, which is represented by the functional group \(-COOH\). These acids are typically weak acids but play a crucial role in various chemical reactions. They are commonly used in esterification reactions.
Carboxylic acids have properties that make them reactive with alcohols, especially when in the presence of a catalyst. Their structure consists of a carbonyl group (C=O) attached to a hydroxyl group (OH).

Examples of carboxylic acids include acetic acid, which is found in vinegar, and citric acid, found in citrus fruits. Understanding the properties of carboxylic acids is key to mastering esterification reactions.

alcohol

Alcohols are organic compounds characterized by the presence of one or more hydroxyl (-OH) groups attached to a carbon atom. These compounds are crucial in various organic reactions, including esterification.
Alcohols react with carboxylic acids to form esters and water in the presence of a strong acid catalyst. The general structure of an alcohol consists of an alkyl group (a chain of carbon atoms) bonded to a hydroxyl group.

Common examples of alcohols include ethanol, methanol, and butanol. These compounds vary in their reactivity based on the number of carbon atoms and the position of the hydroxyl group. In esterification, the hydroxyl group of the alcohol reacts with the carboxyl group of the carboxylic acid.

strong acid catalyst

A strong acid catalyst is an essential component in the esterification reaction. It speeds up the reaction between the alcohol and the carboxylic acid without being consumed in the process. Commonly used strong acids include sulfuric acid (H2SO4) and hydrochloric acid (HCl).
The catalyst works by protonating the carboxyl group of the carboxylic acid, making it more electrophilic and thus more reactive toward the nucleophilic alcohol. This protonation step is crucial to initiate the reaction and ensure it proceeds efficiently.

Without the strong acid catalyst, the reaction would be very slow or might not occur at all. The catalyst ensures the formation of the ester and water as products.

ester and water production

Esterification results in the production of an ester and water. This reaction occurs when a carboxylic acid reacts with an alcohol in the presence of a strong acid catalyst.
Esters are characterized by the functional group \(-COO-\), which links the carbon atom of the carboxylic acid to the oxygen atom of the alcohol. They usually have pleasant, fruity aromas and are used in fragrances and flavorings.

In addition to the ester, water is also produced. This happens as the hydroxyl group from the carboxylic acid combines with the hydrogen atom from the alcohol's hydroxyl group during the reaction. The balanced chemical equation for the esterification reaction looks like this:

\[ \text{R-COOH} + \text{R'-OH} \rightarrow \text{R-COOR'} + \text{H}_2\text{O} \]

Understanding this equation is key to grasping the basic product outcomes of the esterification process.