Question

Draw the condensed structures of the compounds formed from (a) butanoic acid and methanol, (b) benzoic acid and 2-propanol, (c) propanoic acid and dimethylamine. Name the compound in each case.

Short answer

The condensed structures and names of the compounds formed are: a) CH3CH2CH2COOCH3 - Methyl butanoate b) C6H5COOCH(CH3)2 - 2-Propyl benzoate c) CH3CH2CON(CH3)2 - N,N-Dimethylpropanamide

Step-by-step solution

Identify the functional groups

Before attempting to draw the condensed structures and name the compounds, let's identify the functional groups present in each molecule. Butanoic acid has a carboxylic acid (COOH) group, and methanol has an alcohol (OH) group.

Form the ester

When a carboxylic acid reacts with an alcohol, an ester functional group is formed. Remove one hydrogen from the hydroxyl group of butanoic acid, and the hydroxyl group from methanol, and form a new bond between the oxygen atom and the carbon atom of the carboxylic acid group. This gives us the ester functional group (RCOOR') where R is the butyl group and R' is the methyl group.

Draw and name the condensed structure

The condensed structure of the resulting compound is CH3CH2CH2COOCH3. The IUPAC name of this ester compound is methyl butanoate. b) Benzoic acid and 2-Propanol

Identify the functional groups

Benzoic acid has a carboxylic acid (COOH) group, and 2-propanol has an alcohol (OH) group.

Form the ester

Once again, remove a hydrogen from the hydroxyl group of benzoic acid, and the hydroxyl group from 2-propanol, forming a new bond between the oxygen atom and the carbon atom of the carboxylic acid group to create an ester functional group.

Draw and name the condensed structure

The condensed structure of the resulting compound is C6H5COOCH(CH3)2. The IUPAC name of this ester is 2-propyl benzoate. c) Propanoic acid and Dimethylamine

Identify the functional groups

Propanoic acid has a carboxylic acid (COOH) group, and dimethylamine has an amine (NH) group.

Form the amide

When a carboxylic acid reacts with an amine, an amide functional group is formed. Remove one hydrogen from the hydroxyl group of propanoic acid, and one hydrogen from dimethylamine, and form a new bond between the nitrogen atom and the carbon atom of the carboxylic acid group. This gives us the amide functional group (RCONR'R") where R is the propyl group, R' and R" are both methyl groups.

Draw and name the condensed structure

The condensed structure of the resulting compound is CH3CH2CON(CH3)2. The IUPAC name of this amide compound is N,N-dimethylpropanamide.

Key concepts

Esterification

Esterification is a chemical reaction where a carboxylic acid and an alcohol combine to form an ester. This process is catalyzed by the presence of an acid, commonly sulfuric acid. The mechanism involves several steps:

• The acid catalyst protonates the carboxylic acid, increasing its electrophilicity.
• The alcohol attacks the carbonyl carbon, leading to the formation of a tetrahedral intermediate.
• Finally, elimination of a water molecule results in the formation of an ester product.

This specific type of reaction is crucial in many biological as well as industrial processes, including the manufacture of polymers and as an oil source in biodiesel production.

Condensed Structures

Condensed structures are a way of depicting organic molecules in a more compact form compared to Lewis structures. They maintain the important details of the molecule's structure but reduce visual clutter. For example, instead of drawing every single bond and atom explicitly, through condensed structures we can express these molecules more briefly like in this example:

• CH₃CH₂COOH becomes CH₃CH₂COOH for propanoic acid.

Understanding and reading these allows chemists to quickly grasp the molecular framework without getting distracted by too many details that are generally expected from an experienced observer.

Functional Groups

Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. They play a crucial role in the behavior of organic compounds since they can significantly alter the chemical reactivity and properties of the molecule. Here are some common examples:

• Carboxylic acid group (COOH)
• Alcohol group (OH)
• Amine group (NH or NH₂)

For instance, the carboxylic acid group can participate in esterification reactions by reacting with alcohols to form esters, which highlights their significance in organic synthesis pathways.

IUPAC Nomenclature

IUPAC Nomenclature is the standardized system for naming organic compounds. This system is widely accepted in the scientific community, ensuring that chemists speak the same language regardless of their location. IUPAC names are derived based on a set of rules that consider the type and position of functional groups, and the length and branching of carbon chains. Here are steps to give an example of how it works:

• Identify the longest carbon chain which contains the principal functional group.
• Determine the principal functional group to set the compound's suffix.
• Assign numbers to the carbon atoms, ensuring that the main functional group receives the lowest possible number.
• Name and number other substituents as prefixes in alphabetical order.

By following these steps, the molecular identity becomes clear, conveying information about the molecule's structure and reactivity.