Chapter 28 Organic Synthesis Flashcards
What type of mechanism is involved in the reaction between haloalkanes and cyanide ions?
Nucleophilic substitution
What type of reaction is involved in the reaction between carbonyl compounds and cyanide ions?
Nucleophilic addition
How do you form a carboxylic acid from nitrile?
Acid hydrolysis
What type of catalyst is used for a Friedel-Crafts reaction?
A halogen carrier (e.g. AlCl3)
How could you use a Friedel-Crafts mechanism to add a methyl group to a benzene ring?
Use a halogenoalkane and AlCl3 to create an electrophile that can attack benzene.
When purifying by recrystallisation, why is the minimum volume of hot solvent used?
So that a saturated solution is created, so that as many crystals will fall out of solution as possible when it is cooled.
Why is the solution filtered hot when purifying by recrystallisation?
To remove insoluble impurities and ensure that the crystals do not form in the filter paper.
Why is the solution cooled in an ice bath when purifying by recrystallisation?
To ensure that as many as possible fall out of solution - yield is higher
Why are the crystals washed with cold water when purifying but recrystallisation?
To remove soluble impurities
How could you separate the crystals from the reaction mixture when purifying by recrystallisation?
Filter under reduced pressure using a Büchner funnel
Why might percentage yield be below 100%? (Practical reasons)
Product is lost during filtration, drying and weighing spills, not all transferred from one piece of apparatus to the other.
Product is left dissolved in the solution - some does not crystallise. Some left on filter paper. Sample still wet.
Describe how quick fit apparatus is connected.
Grease the joints using some petroleum jelly on the inside of the joints before connecting the pieces together.
In a distillation set up, why is it necessary to have a continuous water flow around the condenser?
So that the water remains cool in order for the mixture to be distilled.
Describe a method that can be used to separated immiscible liquids.
. pour the mixture into a separating funnel and some distilled water
. Add the stopper and invert the flask to mix the mixture.
. Equalise the pressure by opening the stopper as required.
. Continue shaking until there is no ‘whistle’ sound
. To collect the water in the lower layer, open the stopper and place a beaker under the spout
. Use another beaker to collect the desired organic layer
. Shake the liquid with some drying agent
Name 2 drying agents.
Magnesium sulphate
And
Calcium chloride
