Question

Give the isomers of the esters having the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\).

Short answer

The two isomer structures for the molecular formula \(C_4H_8O_2\) forming esters are Methyl ethanoate (Methyl acetate) and Ethyl methanoate (Ethyl formate). Each has a variety in chain length and carbonyl group positioning.

Step-by-step solution

Identify the Isomers based on the Molecular Formula

Having \(C_4H_8O_2\) as formula, one can determine that there should be 4 carbon atoms, 8 hydrogen atoms, and 2 oxygen atoms in the structure. As esters generally have the formula \(RCOO-R'\), an Isomer of an ester of this formula will have one oxygen in a carbonyl group \(-C=O\) and another oxygen connecting two carbon atoms, depicting the hydrocarbon chains in \(RCOO-R'\). These chains can vary in length and position to depict different isomers.

Draw the Isomers

There are two possible isomers fitting the provided molecular formula \(C_4H_8O_2\) and also fitting the ester pattern of \(RCOO-R'\). \n1. Methyl ethanoate (Methyl acetate): Here, R group is an ethyl group (2 carbons) and R' group is a methyl group (1 carbon). The carbonyl group is adjacent to the ethyl group. \n2. Ethyl methanoate (Ethyl formate): In this case, R group is a methyl group (1 carbon) and R' group is an ethyl group (2 carbons). The carbonyl group is adjacent to the methyl group.

Verify the Structures

After drawing the two isomers, verifying that each isomer is following the molecular formula \(C_4H_8O_2\) and the ester structure pattern \(RCOO-R'\) is important. This confirms that these are true isomers of the provided ester molecular structure.

Key concepts

Molecular Formula

Understanding the molecular formula is essential when studying organic chemistry. It tells us the exact number of each type of atom present in a molecule. In our case, the molecular formula is (C_4H_8O_2). This indicates that any compound with this formula will have four carbon atoms, eight hydrogen atoms, and two oxygen atoms.

But, a molecular formula doesn't reveal the arrangement of those atoms, which is where molecular structure and isomerism come into play. Isomers can have the same molecular formula but different structures, leading to different physical and chemical properties. Identifying all the possible structures, as has been done with esters in the exercise, demonstrates the variety of compounds that can come from the same simple formula.

Structural Isomerism

A key concept in organic chemistry is structural isomerism. Structural isomers are molecules with the same molecular formula but different arrangements of atoms. They can have different chemical properties and can be functionally quite diverse. For the molecular formula (C_4H_8O_2), we already learned that multiple esters can be formed.

When dealing with esters, the variation often comes from the different ways of arranging the carbon chain and where the carbonyl group is placed. The length of the carbon chains attached to either side of the ester linkage, (O-C=O), can vary. In the given exercise solution, the two esters drawn are structural isomers of each other, differing by the position of the carbonyl group and carbon chains.

Organic Chemistry

In the realm of organic chemistry, we focus on the study of carbon-containing compounds and their structures, properties, and reactions. It includes a wide variety of compounds, from simple molecules like methane (CH4) to complex structures like carbohydrates, proteins, and esters.

The two isomers identified in our exercise, methyl ethanoate and ethyl methanoate, are classic examples from organic chemistry, each featuring the common elements of esters: the alkyl or aryl group denoted as R, the carbonyl group (C=O), and the single oxygen (O) linking it to another carbon chain.

Carbonyl Group

Central to many organic compounds, including esters, is the carbonyl group. This functional group plays a crucial role in the behavior of the compound and is characterized by a carbon atom double-bonded to an oxygen atom (-C=O).

In esters, the carbonyl group is found next to an oxygen atom that is also bonded to a carbon chain. The positioning of this group is key to creating different esters and contributes to isomerism. The carbonyl's placement affects the compound's polarity, reactivity, and how it interacts with other molecules. Hence, understanding the behavior of this group helps in predicting the properties of the esters formed.