6 - Equations and Calculations - Atom Economy

What are reaction pathways?

The ways reactions happen

Why are reaction pathways with high atom economies good (2 reasons)?

Cost

• Using the smallest possible amount of reactants saves money

Waste

• A higher atom economy means that less waste is produced.

What does an atom economy reaction indicate?

• The atom economy of a reaction indicates how efficient the chemical reaction is at incorporating the reactants into the desired product

What does an atom economy specifically measure?

It measures the percentage of reactant atoms that end up in the final desired product, rather than by-products

What do reactions with 100% atom economy convert all reactants into?

Converts all reactant atoms into the desired product.

What do reactions with lower atom economies generate?

More waste

What is the formula for calculating atom economy?

Its a percentage, so, times by 100

What does the equation do?

Formula essentially compares the mass of the desired product to the total mass of all reactants.

What does the value obtained tell you about the efficiency?

The higher the percentage, the more efficient the reaction is at converting reactants to the desired product

What are the 2 key points about atom economy?

1 - Its based on the balanced chemical equation, so make sure to use the correct mole ratios

2 - Atom economy gives no indication of the percentage yield or losses during processing

What are the 2 reaction types that are explored in common atom economy calculations?

1 - Addition reactions

2 - Substitution reactions

What do addition reactions involve?

These involve 2 reactants combining to form a single product.

What do substitution reactions involve?

These involve some atoms being substituted between reactants, generating at least 2 products- the desired product and an unavoidable by-product.

1 - Addition reactions: What is the usual atom economy that these reactions end up with?

100% atom economy: because all reactant atoms end up in the desired product

1 - Substitution reactions: What is the usual atom economy that these reactions end up with?

Less than 100%: there’s a desired product but a by-product is produced as waste

What are the 2 factors considered when we talk about the importance of high atom economy?

1 - Environmental

2 - Economic

Environmental: What is the importance of high atom economy?

Reactions with higher atom economies are more sustainable and better for the environment

Environmental: Why are high atom economy reactions better for the environment?

• Less waste is generated, reducing disposal impacts

• Raw materials are used more efficiently, preserving limited resources

• Less energy intensive conditions are often required

Economic: What is the importance of high atom economy?

It has financial advantages

Economic: What are the advantages of high atom economy?

• Reduces cost for separating products from waste

• Lower raw material demands decreases expenses

• Energy costs for heating and pressurising reactions are minimised

Considering the 2 factors of the importance of high atom economy reactions, what do companies aim to do?

They aim to develop chemical processes with the highest atom economy wherever possible to maximise sustainability and profits