A reaction pathway is the series of steps or reactions needed to produce a desired chemical product. Often, there is more than one way to make the same substance, so choosing the best reaction pathway is important. The decision on which pathway to use depends on several factors.

Key Factors in Choosing a Reaction Pathway:

1. Percentage Yield: This tells us how much of the reactants are successfully turned into the desired product. A higher percentage yield means more product is made from the same amount of reactants.
2. Atom Economy: Atom economy measures how much of the reactants end up as the desired product and how much ends up as waste. A higher atom economy is better because it means less waste is produced.
3. Rate of Reaction: This is how fast the reaction happens. Faster reactions are usually preferred because they produce the product more quickly.
4. Equilibrium Position: In reversible reactions, the reaction doesn't go to completion, and the final mixture contains both reactants and products. The position of equilibrium tells us how much of the reactants are converted into products.
5. The usefulness of By-products: Sometimes, the reaction produces other substances besides the desired product. If these by-products are useful, they can be sold or used, improving the overall efficiency of the process.

Worked Example:

• Evaluating the Processes:
• Fermentation has a lower yield (15%) and a lower atom economy (51.1%) compared to the hydration of ethene, which has a yield of 95% and an atom economy of 100%.
• The rate of reaction is also much lower in fermentation. This means that, overall, the hydration of ethene is a more efficient way to produce ethanol.