Organic I Flashcards
What is thermal cracking and what are the conditions?
• Temperature: 1200K
• Pressure: 7000kPa
• The cracking of carbon chains to produce lots of alkenes and some alkanes
What is catalytic cracking and what are the conditions?
• Temperature: 720K
• Pressure: normal
• Zeolite catalyst
• Produces aromatic compounds
The combustion of alkanes produces…
• Carbon dioxide and water (if complete combustion)
• Carbon monoxide / carbon particulates and water (if incomplete)
What is a catalytic converter and what is it used for?
• Uses a rhodium catalyst to convert harmful products into more stable products like water and carbon dioxide
How can you identify an alkene double bond?
• Bromine water will change form orange/brown to colourless in the presence of alkenes
• This is because the double bond opens to accept the bromine atoms, becoming saturated
Alkenes can undergo… with hydrogen to produce…
What does this reaction require and what is it also called?
• Electrophilic addition
• Alkanes
• Nickel catalyst
• Hydrogenation
What is catalytic hydrogenation used for?
• The manufacture of margarine from unsaturated vegetable oils
Alkenes react with halogens to produce… via…
• Dihalogenoalkanes
• Electrophilic addition
Alkenes react with hydrogen halides to produce… via…
• Mono-substituted halogenoalkanes
• Electrophilic addition
Alkenes react with steam to form … via …
This reaction requires…
This reaction is also called a …
• Alcohols
• An Electrophilic addition reaction
• An acid catalyst
• Hydration reaction
Alkenes react with acidified potassium manganate (VII) to make a … via …
The conditions for this reaction are…
What is the colour change?
• Diol
• An addition reaction which is also an oxidation reaction (the double bond is oxidised)
• The mangantes ions must be cold, dilute and acidified
• Pale purple solution turns colourless
Name 3 common electrophiles
• HBr
• Br2
• Sulphuric acid (H2SO4)
The more stable the carbocation, the …
Therefore…
• More likely is it to form
• The major product will always be the one that is formed via the most stable carbocation intermediate possible (tertiary)
Alkenes form polymers through…
• Addition polymerisation
Waste polymers can be processed in different ways. Some can be …
• Recycled
• Used as feedstock for cracking
• Incinerated to produce energy for other industrial processes ( but this can release toxic gases which must be removed )
The rate of reaction … for halogenoalkanes as you move down the group because …
• Increases
• The greater the Mr, the lower the bond enthalpy (longer bond + less electronegative). A lower bond enthalpy means the bond can be broken more easily
Halogenoalkanes can react with aqueous alkali (soluble base) like potassium hydroxide to produce… in a … reaction
The hydroxide ion acts as a …
• Alcohols
• Nucleophilic substitution
• Nucleophile
Halogenoalkanes can react with ethanolic potassium hydroxide to produce … in an … reaction. The OH acts as a …
• An alkene
• Elimination
• Base
Outline how halogenoalkanes and silver nitrate can react
What is the role of the water?
What then happens as a result?
• Halogenoalkanes can be broken down using aqueous silver nitrate in ethanol
• The water acts as a nucleophile which breaks down the halogenoalkane, releasing the halide ions into the solution
• The halide ions then react with the silver ions from silver nitrate to form silver precipitates with different colours
In the reaction of halogenoalkanes with aqueous silver nitrate in ethanol, what are the colours of the silver precipitates and which halogenoalkane would react the fastest?
• AgCl - white precipitate
• AgBr - cream precipitate
• AgI - yellow precipitate
• Bond strength decreases with increasing Mr, so iodoalkanes would be the fastest
Halogenoalkanes can react with alcoholic ammonia to form… in a … reaction
Ammonia acts as a …
• Primary amines
• Nucleophillic substitution
• Nucleophile
Halogenoalkanes can react with alcoholic potassium cyanide to form … in a … reaction
The cyanide ion acts as a …
This reaction is useful for…
• Nitriles
• Nucleophilic substitution
• Nucleophile
• Increasing the length of carbon chains
Name 3 common Nucleophiles
• Cyanide (CN-)
• Ammonia (NH3)
• Hydroxide (OH-)
- All have lone pairs
Alcohols react with oxygen to form …
This means alcohols make good…
• Carbon dioxide and water
• Fuels as lots of energy is released
Alcohols react with halogenating agents via …
Outline what is replaced and therefore formed
• Nucleophilic substitution
• The OH group is replaced by a halogen, producing a halogenoalkane
Alcohols can react with … to make chloroalkanes
This reaction can be used as a test for…
• PCl5
• A test for alcohols because their reaction with PCl5 produces white steamy fumes that turn damp blue litmus paper red
Alcohols can react with … to make bromoalkanes
What happens in this reaction?
• 50% concentrated sulfuric acid and potassium bromide
• The potassium bromide reacts with the sulfuric acid to form HBr. This then reacts with the alcohol to make the bromoalkane
How can iodoalkanes be made from alcohols?
What is the equation of this step?
What is also a product in the final equation?
• A reaction mixture of red phosphorus with iodine is used. First, the phosphorus reacts with the iodine to produce phosphorus (III) iodine. This reacts with the alcohol to form the iodoalkane
• 2P + 3I2 —> 2PI3
• H3PO3
How can alkenes be made from alcohols ?
What reagent is needed?
• The dehydration of alcohols via an elimination (a water molecule is removed)
• Concentrated phosphoric acid
Acidified potassium dichromate means it is…
• In a solution of dilute acid like dilute sulfuric acid
How does the oxidation of primary alcohols occur?
What else is a product of this?
What else can happen?
• Potassium dichromate in dilute sulfuric acid to produce aldehydes and distillation is required to separate the aldehyde product
• Water
• When heated under reflux conditions, primary alcohols are further oxidised to carboxylic acids
How does the oxidation of secondary alcohols occur?
What else is in the products ?
• Can be oxidised in the presence of potassium dichromate (VI) with dilute sulfuric acid to produce ketones
• H2 (hydrogen)
What is observed when alcohols are oxidised with potassium dichromate (VI)?
• It is the oxidising agent, so it is reduced itself. It changes from Orange to green.
What is a test for aldehydes?
What is a positive result?
What is a negative result?
What does the solution act as ?
• Benedicts/ Fehlings solution
• When a few drops of this are added and the rest tubs is warmed, a red precipitate will form if an aldehyde is present
• If no aldehyde is present the solution will remain blue (ketones will not give a positive result)
• An oxidising agent
What is a separating funnel used for ?
• Seperating two liquids with different densities
What is distillation used for ?
• Separating liquids with different boiling points
How do you proceed with drying a compound?
What is a common example of this?
• Addition of an anhydrous salt (contains no water)
• It will absorb moisture and water present
• Sodium sulphate
(Na2SO4)
How to determine the boiling point of a compound?
• Substance is packed into thiele tube which has an inverted capillary tube in it
• Substance is heated above its boiling point and allowed to cool
• When it condenses into a liquid it will be drawn into the capillary tube and the temperature at which this change occurs is taken to be the boiling point
