Synthesis Flashcards
(13 cards)
Chemical synthesis definition
Chemical synthesis involves the production of a chemical in a cost-efficient, safe and timely matter
Factors for choosing a pathway
- Availability and cost of reactants
- Conditions required (Temp and pressure etc.)
- Other chemicals required, including catalysts
- Side reactions that may occur producing unwanted products
Types of pathways
- Multistep process: Reactants form a product through various steps and makes intermediates along the way
- Linear pathway: A–>B–>C–>D. When a product is formed by starting with product A
- Convergent pathway: Two chemicals are made in independent reactions then combined
Principals of Green Chemistry
- Prevent Waste
- Energy efficiency
- Use a catalyst
- Reduce derivatives
- Atom Economy
- Use Safer auxiliaries
Yield
The actual amount of products that are formed in a reaction
Ways to maximise yield
- Continually supplying reactants to the mixture
- Removing products as they form
- Increase the pressure of gasses
- Use a catalyst
- Increase the S.A of reactants or the catalyst
- Increase the temperature
Habers Process
N2 + 3H2 –> 2NH3
•350-550°C
•15-35MPa
•Catalyst of iron-iron oxide fused with MgO, Al2O3 and SiO2
• These conditions give a yield 15-30%
•Recycling unused N2 and H2 ensures a yield close to 100%
Contact process
1: S + O2 –> SO2
2: 2SO2 + O2 2SO3
•450°C
•1-2 Atm
•Catalyst of V2O5
•Recycling unsed SO2 ensures a yield close to 100%
3: H2SO4 + SO3 –> H2S2O7
4: H2S2O7 + H20 –> H2SO4
Enzymes
Enzymes are biological proteins that catalyse specific reactions in living organisms. They work in very narrow temperature and pH ranges and work by a “lock and key” mechanism
Synthesis of ethanol using ethene
Ethene + Water—>(H3PO4) Ethanol
Fuels
Fuels are organic compounds containing mostly Carbon and Hydrogen
Biofuels
Biofuels are renewable and are produced from crops such as corn and wheat
Transesterfication to produce biodiesel equation
Triglyceride + Alcohol —>(OH- catalyst) Ester(Biodiesel) + Glycerol
