CHEM / A2 level

Advanced organic chemistry and synthesis

Arenes, phenols, acyl compounds, amines and amides expand functional-group chemistry. Delocalisation changes reactivity, so aromatic substitution differs from ordinary alkene addition.

Learning objectives

Explain advanced organic chemistry and synthesis using a concrete example.
Apply the worked method and justify each step.
Recognise the limitation described in the final check.

The big idea

Arenes, phenols, acyl compounds, amines and amides expand functional-group chemistry. Delocalisation changes reactivity, so aromatic substitution differs from ordinary alkene addition.

Multi-step synthesis requires compatible reagents, selective transformations and purification. Optical isomerism, condensation polymers and peptide linkages connect molecular structure with biological and material behaviour.

Worked example

What linkage joins amino-acid units in a peptide?

Follow the solution

A carboxyl group reacts with an amino group to form a peptide (amide) link, with loss of water.

Investigate and explain

Predict the worked result before calculating. Change one input, record the new result, and explain which assumptions still hold.

Related interactive model. Compare its assumptions with the explanation; it is not a complete syllabus lesson.

Open the interactive investigation

Check your understanding

1. Why does benzene commonly undergo substitution rather than simple addition?

Substitution can preserve aromatic delocalisation
It contains no electrons
Its carbon atoms have no bonds

Check the answer and reasoning

Substitution can preserve aromatic delocalisation

Addition would disrupt the stabilised delocalised ring system.

2. What linkage joins amino-acid units in a peptide?

Alkene linkage
Amide linkage
Ionic lattice

Check the answer and reasoning

Amide linkage

A carboxyl group reacts with an amino group to form a peptide (amide) link, with loss of water.

3. Are all molecules with the same formula optical isomers?

Yes
Only hydrocarbons
No

Check the answer and reasoning

Optical isomerism requires a suitable non-superimposable mirror-image relationship, not just a shared formula.