Question

Draw structural formulas for the four esters with the molecular formula \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\).

Short answer

Question: Identify and name the four different esters with a molecular formula of \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\). Answer: The four different esters with a molecular formula of \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\) are Methyl acetate (HCOOCH3), Ethyl formate (HCOOCH2CH3), Ethyl acetate (CH3COOCH2CH3), and Propyl formate (HCOOCH2CH2CH3).

Step-by-step solution

Identify the possible combinations of alcohols and carboxylic acids.

To form an ester with a molecular formula of \(\mathrm{C}_{4} \mathrm{H}_{8} \mathrm{O}_{2}\), we will consider various combinations of alcohols and carboxylic acids.

Draw the structural formulas for the four different esters.

We will now draw the structural formulas for each pair of alcohol and carboxylic acid. 1. Methyl acetate: Combination: Methanol (1 carbon) + Ethanoic acid (3 carbons) Structural formula: HCOOCH3 Name: Methyl acetate +-+-+-+-+-+-+ 2. Ethyl formate: Combination: Ethanol (2 carbons) + Methanoic acid (1 carbon) Structural formula: HCOOCH2CH3 Name: Ethyl formate +-+-+-+-+-+-+ 3. Ethyl acetate: Combination: Ethanol (2 carbons) + Ethanoic acid (2 carbons) Structural formula: CH3COOCH2CH3 Name: Ethyl acetate +-+-+-+-+-+-+ 4. Propyl formate: Combination: Propanol (3 carbons) + Methanoic Acid (1 carbon) Structural formula: HCOOCH2CH2CH3 Name: Propyl formate

Key concepts

Ester Molecular Formula

Esters are a class of organic compounds that can be considered as derivatives of carboxylic acids where the hydrogen atom from the hydroxyl group is replaced by an alkyl or aryl group. But what does their molecular formula tell us? To understand esters, it’s helpful to break down their molecular formula: typically, it's represented as (CnH2nO2) for a simple, straight-chain ester.

For example, for esters with the formula \(C_4H_8O_2)\), we can deduce some key information. They have four carbon atoms, eight hydrogen atoms, and two oxygen atoms. However, the arrangement of these atoms can vary, resulting in different structures. The actual structural formula reveals the connection between these atoms and, thereby, the shape and characteristics of the molecule. Understanding the molecular formula of esters is crucial because it lays the groundwork for identifying the potential carboxylic acid and alcohol precursors used to form the ester through a condensation reaction known as esterification.

Carboxylic Acids and Alcohols

Carboxylic acids and alcohols are two essential organic compounds involved in creating esters. Carboxylic acids have the general formula \(RCO_2H)\), where R represents any alkyl or aryl group. They are characterized by their carboxyl group (−COOH), which comprises a carbonyl group (−C=O) bonded to a hydroxyl group (−OH).

Alcohols, on the other hand, have the general formula \(ROH)\), where R again stands for an alkyl or aryl group and −OH is the hydroxyl group. The size and structure of the 'R' group can alter the alcohol's properties. When an alcohol and a carboxylic acid combine in a condensation reaction (esterification), they produce an ester and water (H2O). This reaction typically requires an acid catalyst, such as sulfuric acid, to proceed. Therefore, to solve an exercise that asks for drawing the esters with a given molecular formula like \(C_4H_8O_2\), it’s critical to explore the possible pairs of alcohols and carboxylic acids that could react to form esters with this formula. Being able to identify the variables in this reaction is a key stage in mastering the chemistry of esters.

Drawing Organic Structures

Drawing organic structures is an essential skill in chemistry that enables students to visualize and understand the molecular composition and shape of organic compounds. When drawing esters from a given molecular formula, such as \(C_4H_8O_2\), it's important to consider several guidelines.

Identify the Backbone

First, identify the carbon backbone of the ester. In esters, there is a main chain derived from the carboxylic acid and a side chain derived from the alcohol. The functional group of esters, the ester linkage, is represented as −COO−. The oxygen atom double-bonded to carbon forms part of the main chain, whereas the oxygen atom single-bonded to carbon connects to the side chain.

Apply Esterification Knowledge

Second, apply your knowledge of esterification to understand how the carboxylic acid and alcohol combine. Remove a molecule of water (dehydrate) as you merge the hydroxyl (−OH) from the carboxylic acid and the hydrogen from the alcohol's hydroxyl group to form the ester linkage.

Verify Molecular Formula

Lastly, double-check that the structural formula you draw corresponds to the initial molecular formula given. For example, when constructing esters with the formula \(C_4H_8O_2\), the number of carbons, hydrogens, and oxygens must be accurately represented in your drawing. By carefully illustrating all elements and bonds, students can better grasp the physical and chemical properties of the compound in question. Practicing these steps can refine comprehension of not only esters but various organic molecules.