Chapter 16 - Organic synthesis (MODULE 4) Flashcards
What 5 pieces of equipment are part of the Quickfit apparatus
- round bottomed flask / pear shaped flask
- receiver
- screw tap adaptor
- condenser
- still head
How do we combat reactions happening at a slow rate
- what is the issue with this
- how is this problem solved
Heat the reaction mixture
- the products boil and evaporate or escape
- heating under reflux
Why is a heating mantle good when heating flammable liquids
there are no naked flames so additional layer of safety
How is reflux apparatus set up
round bottomed / pear shaped flask attached to Liebig condenser
- rubber tubing attached to condenser - water in and water out
- water in must be lower than water out
- clamp flask by neck
Why are anti bumping granules used
to allow the contents to boil smoothly
Why should condenserrs be clamped lightly when used
so they stay in place, but they are fraguke so cannot be done too hard
Why should you never put a stopper in a condenser
so that pressure can escape, else the apparatus may explode
how does a condenser work in reflux reaction
contents of flask are boiled and react
- the cold water flowing around the condenser cools it down
- vapour condenses back into the flask
How are mixtures of liquids separated
distillation
How is the apparatus for distillation set up
- pear shaped / round bottomed flask attached to still head
- out of top of still head is thermometer, side is Leibig condenser with tubing for water
- water in must be lower than water out to ensure circulation
- other end of condenser attached to receiver adaptor, which drips liquid into a flask or beaker
Why is a separate piece of apparatus used to collect the product from distillation
so that the system is not airtight
How does the distillation process work
the compound with the lowest boiling point boils first, condenses in condenser and drips into collection flask
- this repeats until all liquid has entered the flask
How do you collect only the desired product from distillation
use a flask while the reaction gets to the desired temperature
- when the mixture is 2-3 degrees below the boiling point of the desired product, switch to a different collection beaker
- when the mixture is 2-3 degrees above the boiling point of the desired product, switch collection beakers again
- there will be one beaker with the correct fraction of liquids
What are the 7 steps to purifying an organic product
- ensure tap of separating funnel is closed
- pour mixture of liquids into separating funnel, insert a stopper and invert
- allow layers to settle
- add water and see which layer increases in volume: this is the aqueous layer
- place conical flask under the separating funnel, remove stopper and open tap until lower layer has left the funnel
- place a second conical flask under the separating funnel to collect other layer.
- dispose of aqueous layer and keep organic layer
how can you remove acid impurities from a mixture
add aqueous sodium carbonate and allow gas to escape
What needs to be done to obtain a pure dry sample from the organic product from a separating funnel (5)
- use a drying agent to remove water
- leave for 10 minutes, adding more if necessary
- filter out drying agent
- repeat until organic product is colourless
- Redistil and collect fraction produced at the boiling point, the narrower the range, the better
What is organic synthesis
the process of preparing complex molecules from simple starting materials
What are the reagents and conditions for:
alkane to haloalkane
halogen and UV
What are the reagents and conditions for:
- alkene to alkane
- alkene to haloalkane
- H2 and nickel catalyst
- hydrogen halide
What are the reagents and conditions for:
- haloalkane to alcohol
- alcohol to haloalkane
- NaOH and reflux
- sodium halide and H2SO4
What are the reagents and conditions for:
- alkene to alcohol
- alcohol to alkene
- H2O and H3PO4 catalyst
- Conc. H2SO4
What are the reagents and conditions for:
- 1st alcohol to aldehyde
- 1st alcohol to carboxylic acid
- 2nd alcohol to ketone
- K2Cr2O7 + H2SO4, distil
- K2Cr2O7 + H2SO4, reflux
- K2Cr2O7 + H2SO4, reflux
What is a target molecule
The compound that is being aimed to make using organic synthesis
What is ozonolysis
breaking open a C=C bond, making 2 molecules with each C in double bond instead forming a C=O bond
