Question

Consider the following reaction to produce methyl acetate: When this reaction is carried out with \(\mathrm{CH}_{3} \mathrm{OH}\) containing oxygen- \(18,\) the water produced does not contain oxygen-18. Explain.

Short answer

In the synthesis of methyl acetate (\( CH_{3}COOCH_{3} \)) from acetic acid (\( CH_{3}COOH \)) and methanol (\( CH_{3}OH \)), the oxygen atom in the water molecule (\( H_{2}O \)) produced comes from the acetic acid rather than the methanol containing oxygen-18. Consequently, the water produced does not contain oxygen-18 atoms.

Step-by-step solution

Write the balanced chemical equation for the reaction to produce methyl acetate

The synthesis of methyl acetate (CH3COOCH3) involves the reaction of acetic acid (CH3COOH) with methanol (CH3OH). The balanced chemical equation for this reaction is: \[ CH_{3}COOH + CH_{3}OH \rightarrow CH_{3}COOCH_{3} + H_{2}O \] Now let's analyze the sources of oxygen atoms in the water molecule produced in this reaction.

Identify the possible sources of oxygen in the water molecule

Looking at the balanced chemical equation, we can see that there are two oxygen atoms in the acetic acid molecule and one oxygen atom in the methanol molecule. In order to form water, two hydrogen atoms need to combine with one of these oxygen atoms.

Determine the source of oxygen in the water molecule

The fact that the water produced in the reaction does not contain oxygen-18 atoms implies that the oxygen atom in the water molecule does not come from the methanol (CH3OH) containing oxygen-18. Therefore, in the reaction, the oxygen atom that forms the water molecule comes from the acetic acid (CH3COOH). The oxygen atom from the CH3OH reacts with the acetic acid to form the ester bond in the product methyl acetate (CH3COOCH3).

Conclude

In conclusion, during the formation of methyl acetate, the oxygen atom in the water molecule comes from the acetic acid instead of the methanol containing oxygen-18. As a result, the water produced in this reaction does not contain oxygen-18 atoms.

Key concepts

Acetic Acid

Acetic acid is a colorless liquid with a distinctive sour taste and pungent smell, commonly known as vinegar. It plays a crucial role in the production of methyl acetate. Methyl acetate is an ester produced when acetic acid reacts with methanol in a process called esterification. This carboxylic acid contains two oxygen atoms within its molecular structure \(\text{(CH}_3\text{COOH)}\).

During the reaction to form methyl acetate, one of the oxygen atoms in acetic acid eventually forms part of the ester molecule, while the other contributes to the formation of water. This explains why the water produced in the reaction does not contain oxygen-18. In this context, acetic acid acts as a key reagent in defining the oxygen source for both the ester and the water molecule.

• A colorless liquid with a sour taste
• Key player in methyl acetate production
• Provides oxygen for water formation

Oxygen-18 Isotope

Oxygen-18 is a natural isotope of oxygen that is heavier due to the presence of two additional neutrons compared to the more common oxygen-16. It is often used in scientific experiments to trace the path of oxygen atoms during chemical reactions due to its distinct atomic mass.

In the case of producing methyl acetate, methanol labeled with oxygen-18 ( CH_3OH ) was used. This tag helps scientists determine which oxygen atoms in the final products, like water or esters, came from specific starting materials.

However, as the results show, the water produced does not contain this isotope. That indicates that the oxygen-18, originally from methanol, becomes part of the methyl acetatemolecule instead of forming water. This illustrates how isotopic labeling can be a powerful tool underlining the path and transformation of atoms in chemical reactions.

• Isotope heavier than common oxygen
• Used for tracing oxygen atoms in reactions
• Key in understanding atom transformation

Esterification

Esterification is the chemical reaction through which esters are formed. In this process, an alcohol reacts with a carboxylic acid, leading to the release of water and the creation of an ester. In the formation of methyl acetate, acetic acid ( CH_3COOH ) and methanol ( CH_3OH ) combine, resulting in an ester and water.

This transformation involves the hydroxyl group (-OH) of the carboxylic acid and the hydrogen from the alcohol forming water ( H_2O ). The remaining oxygen atom of the hydroxyl group becomes part of the ester linkage in methyl acetate. The esterification process is significant because it alters the functional groups present in each reactant to develop new chemical entities with unique properties.

• Process of forming esters
• Involves reaction between alcohol and carboxylic acid
• Releases water and creates ester linkage

Chemical Reaction Analysis

Chemical reaction analysis involves studying a chemical reaction to understand the changes substances go through. This analysis can determine the source of atoms in a product, the pathway of reactions, and the energy changes involved.

In the reaction for producing methyl acetate, scientists analyze where the oxygen in the products originates. By using isotopic labeling, such as oxygen-18 in methanol, researchers can track the path of oxygen atoms during the reaction.

For this particular reaction, the analysis reveals that methanol's oxygen does not contribute to the water formed, instead forming part of the methyl acetate. This kind of analysis is crucial in ensuring precision and understanding in synthetic reactions, especially in industrial and pharmaceutical applications.

• Examines changes during reactions
• Identifies sources of atoms in products
• Crucial for understanding reaction pathways