AH Chemistry - Organic Chemistry and Instrumental Analysis - (b) - Synthesis

When an organic reaction takes place, what happens?

When an organic reaction takes place, bonds in the reactant molecules are broken and bonds in the product molecules are made. The process of bond breaking is known as bond fission.

What are the two different types of bond fission?

The two different types of bond fission are:

• Homolytic

• Heterolytic

What is homolytic fission?

Homolytic fission:

• Results in the formation of two neutral radicals.

• Occurs when each atom retains one electron from the σ covalent bond and the bond breaks evenly.

• Normally occurs when non-polar covalent bonds are broken.

What do reactions involving homolytic fission tend to result in, and what does this make them unsuitable for?

Reactions involving homolytic fission tend to result in the formation of very complex mixtures of products, making them unsuitable for organic synthesis.

What is heterolytic fission?

Heterolytic fission:

• Results in the formation of two oppositely charged ions

• Occurs when one atom retains both electrons from the σ covalent bond and the bond breaks unevenly.

• Normally occurs when polar covalent bonds are broken.

What do reactions involving heterolytic fission tend to result in, and what does this make them better suited for?

Reactions involving heterolytic fission tend to result in far fewer products than reactions involving homolytic fission, and so are better suited for organic synthesis.