Addition, Elimination & Substitution - Organic Reactions & Mechanisms (8.2) Flashcards
What is an addition reaction?
Two molecules are joined together to form one product
What is an elimination reaction?
A small molecule is removed from a larger molecule
What is a substitution reaction?
One part of the molecule is swapped for another group
What is a condensation reaction?
Two molecules join together forming the desired product & another small molecule
What type of bond is involved in an addition reaction?
Double bond
Name 3 types of addition reactions
- Hydrogenation
- Hydration
- Halogenation
What is hydrogenation used to synthesise?
Margarine
What is hydration used to synthesise?
Alcohol
What is halogenation used to synthesise?
Haloalkanes
What are the conditions required for hydrogenation?
- High temp
- Ni catalyst
What are the conditions required for hydration?
- High temp & pressure
- Steam
- Strong acid catalyst
What are the conditions required for halogenation?
Room temperature
How can you test for the presence of alkenes?
An addition reaction using bromine water - bromine adds across the double bond
Orange -> colourless
What happens in addition polymerisation?
- During polymerisation an alkene undergoes an addition reaction with itself to form a very long hydrocarbon chain
- The double bond in the monomer (alkene) opens up, joining the monomers together to make a polymer
What conditions are required for polymerisation?
- Heat
- Catalyst
Give the 2 types of elimination reactions
- Dehydration
- Elimination
What is removed in dehydration?
Water
What is commonly removed from an elimination reaction?
HX - hydrogen halide
What are the conditions of a dehydration reaction?
reflux (boil)
w/ a concentrated acid catalyst
What are the conditions of an elimination reaction when haloalkanes are the reactant?
Reflux (boil)
w/ a base in ethanol
Name the reaction:
Alkane-> Alkene
Cracking
Name the reaction:
Alkene -> Alkane
Hydrogenation
Name the reaction:
Alkene -> Haloalkane
Addition
Name the reaction:
Haloalkane -> Alkene
Elimination
Name the reaction:
Alkene -> Alcohol
Hydration
Name the reaction:
Alcohol -> Alkene
dehydration
Give the 3 types of substitution reactions
- Free radical substitution
- Hydrolysis
- Halogenation
What type of substitution reaction is this:
Alkane -> Haloalkane
Free radical substitution
What molecule is involved in a hydrolysis?
Water
What is synthesised in a halogenation reaction?
Haloalkane
What conditions are required in free radical substitution?
UV light
What conditions are required in hydrolysis?
Room temperature
What conditions are required for halogenation?
Room temperature
How can you test for haloalkanes?
- Warm the suspected haloalkane gently in water & add silver nitrate
- The free halide ion react w/ the silver ions to give a coloured precipitate
How can you test for alcohols?
- Add phosphorus pentachloride to an alcohol
- White misty fumes of HCl will be released
- Universal indicator paper turns red (acidic fumes)
