Question

Draw the backbone structure of the amide formed by reacting hexylamine with ethanoic acid.

Short answer

The amide backbone is CH₃CONHC₆H₁₃.

Step-by-step solution

Identify the Reactants

To draw the backbone structure of the amide, first identify the reactants involved: hexylamine and ethanoic acid. Hexylamine is an amine with the formula C₆H₁₃NH₂, and ethanoic acid (also known as acetic acid) has the formula CH₃COOH.

Understand Amide Formation

Amides are formed when an amine reacts with a carboxylic acid. Specifically, the -NH₂ group from the amine reacts with the -COOH group from the acid, leading to the formation of an amide bond (peptide bond). During this reaction, a molecule of water (H₂O) is released.

Identify the Structural Elements

To draw the structure, identify the key groups: the NH portion from the amine and the CO portion from the acid. These will form the amide linkage (C=O)-NH) when combined.

Construct the Backbone

Start by forming the amide bond. Write the carbonyl group (C=O) from ethanoic acid. Next, write the NH group from the hexylamine adjacent to it. This forms the backbone linkage of amides: C=O-NH.

Complete the Structure with Carbon Chains

Attach the appropriate carbon chains. The carbonyl carbon (from ethanoic acid) remains attached to the methyl group CH₃, originating from ethanoic acid's structure. Attach the six-carbon hexyl group C₆H₁₃ from hexylamine to the nitrogen. Therefore, the full backbone structure is CH₃CONHC₆H₁₃.

Key concepts

Hexylamine

Hexylamine is a type of amine. Amines are organic compounds derived from ammonia, where one or more hydrogen atoms are replaced by hydrocarbon chains, which are often represented as R groups. In hexylamine's case, the formula is written as \( \text{C}_6\text{H}_{13}\text{NH}_2 \). This indicates that it has a six-carbon chain (hexyl group) attaching to the amine group \( \text{NH}_2 \).
The structure allows hexylamine to participate actively in chemical reactions since the nitrogen atom in the amine group has a lone pair of electrons. These electrons make hexylamine a nucleophile, meaning it can donate them to other molecules, often resulting in the formation of new bonds.

• Hexylamine is a clear example of primary amines, where the amine group is directly connected to a single carbon chain.
• This organic compound is often used in chemical synthesis, taking part in forming more complex structures like amides.

Understanding hexylamine's role in the reaction is crucial because it's this -NH2 group that will ultimately bond with other molecules like ethanoic acid to form amides.

Ethanoic Acid

Ethanoic acid, more commonly known as acetic acid, is a simple carboxylic acid with the chemical formula \( \text{CH}_3\text{COOH} \). This compound should not only sound familiar due to its presence in everyday vinegar, but also for its importance in organic chemistry.
In ethanoic acid:

• The -COOH group is known as the carboxyl group.
• This group is quite reactive due to the double bond between the carbon and the oxygen atom \( (C=O) \), making the acid prone to participate in reactions like amide formation.

The reactivity of the carboxyl group makes ethanoic acid a good reactant for forming amides. Ethanoic acid is an essential building block in organic synthesis, used widely in biology and chemistry for creating more complex molecules.

Peptide Bond

A peptide bond is a type of amide bond formed between the carboxyl group of one molecule and the amino group of another. It is a central bond in biochemistry, especially within proteins.
When hexylamine and ethanoic acid interact, a reaction occurs between the amine group \( (-\text{NH}_2) \) of hexylamine and the carboxyl group \( (-\text{COOH}) \) of ethanoic acid to create a new amide linkage. The process releases a water molecule \( \text{H}_2\text{O} \):

• The -OH group from the carboxylic acid and the -H from the amine are removed.
• This leaves room for the nitrogen of hexylamine to form a bond with the carbonyl carbon of ethanoic acid.

This bond is also commonly termed as a peptide linkage, especially within lengthy chains like proteins. Its formation and stability are fundamental to the structure and function of proteins in living organisms.

Amide Structure

An amide structure is characterized by the linkage between a carbonyl group and an amine group, which can be represented as \( \text{RCONHR'} \). This structure arises when a carboxylic acid and an amine undergo a condensation reaction, resulting in water removal, forming the amide bridge. The structural formula for the amide formed from hexylamine and ethanoic acid is \( \text{CH}_3\text{CONHC}_6\text{H}_{13} \).
Let's break down this structure further:

• The carbonyl group \( (C=O) \) from the ethanoic acid is linked to the amine group \( (NH) \) from the hexylamine.
• The ethanoic acid contributes its methyl group \( \text{CH}_3 \), part of its initial structure, creating the first part of the chain.
• Hexylamine contributes its long carbon chain \( \text{C}_6\text{H}_{13} \), adding to the nitrogen's connectivity in the amide linkage.

Amide structures are integral not only in industrial chemistry but also in biological systems, due to their strong and stable bonds. These form the backbone of protein chains, and thus understanding their formation and representation can be essential for various fields of study.