PAG 6 Synthesis of an organic solid Flashcards
what is recrystallisation for?
to purify a solid organic compound
outline how to recrystallise
dissolve in MINIMUM volume of hot solvent
cool until crystals form
filter under reduced pressure using a Buchner funnel
leave to dry
what are the properties of a solvent needed for recrystallisation?
solid needs to be soluble when hot
and insoluble when cold
when are insoluble impurities removed during recrystallisation?
when the hot solution is filtered
insoluble impurities cannot dissolve
what is the test for phenols?
add Fe 3+ ions and violet solution forms
add Br2 water and white ppt forms
what method can be used to TEST purity?
obtain the melting point and compare with known values
what would the melting point look like with an impure compound?
a range of values
what would the melting point look like with a pure compound?
a single value
how can you separate liquid impurities from a solid organic product?
filter under reduced pressure
outline filtration under reduced pressure
use a buchner funnel with filter paper
add reaction mixture to the funnel
reduced pressure caused by the vacuum will suck the liquid out which separates from the solids which are left in the filter paper
diagram for filtration under pressure
outline melting point determination
put solid into capillary tube
put capillary tube into melting point apparatus
obtain value for melting point and compare with known values
