Organic Synthesis
Chemistry: Cambridge International A Level, topic 3.10.2
Introduction to Synthesis
For organic synthesis, chemists must map out a route of reactions that will lead to the desired product and start from the starting materials.
Organic synthesis
- If we want to synthesize a molecule, we must find reaction routes that will allow us to convert starting materials into the desired product.
- After finding possible synthesis routes, we must make sure the route is the best it can be by considering:
- Effect on the environment.
- Type of solvent used.
- Percentage yield.
- Percentage atom economy.
Steps in synthesis
- Each synthetic route is made up of a series of reaction steps.
- Each reaction step typically involves:
- Carrying out the reaction.
- Separating the desired product.
- Purifying the desired product.
Importance
- Creating synthetic routes is incredibly important in science.
- It helps us design and produce medicines.
- It also helps us reduce the waste and the hazards whilst producing such chemicals.
Improving Synthesis
There are many ways in which we can make a synthetic route better. This involves maximising the desired products and minimising the side products.
Type of solvent
- The type of solvent used is very important.
- Where possible, it is ideal to have solvent-free reactions or reactions that are carried out in water.
- If we reduce the use of solvents, it will reduce both the possible hazards and the wastage.
Percentage yield
- The percentage yield is the ratio percentage of the actual yield obtained compared to the theoretical yield from calculations.
Percentage atom economy
- The percentage atom economy is the percentage of reactant atoms that are transformed into the desired product.
- E.g. if all the reactants are used to make one desired product, with no side-products or bi-products in the equation, the atom economy is 100%.
- As soon as there are waste products in the equation, the atom economy decreases.
Maximising percentages
- We can optimise the percentage yield and atom economy through:
- Selecting reactions with no bi-products.
- Selecting synthetic routes with fewer steps.