Organic Chemistry 6 Flashcards
formula for benzene
C6H6
how are the 6 carbons in benzene arranged?
in a ring structure
how many electrons does each carbon have in its outermost shell
4
what happens to the 3 of the 4 electrons in carbon’s outer shell
form sigma bonds
3 sigma bonds formed by carbon’s electrons
2 formed between each carbon atom
1 between carbon and hydrogen
what shape do these electrons give benzene
planar hexagonal ring
where is the 1 electron that is left
in a p orbital
describe what happens to the p orbitals
the lobes of these p orbitals fuse to form a single ring of charge above and below the sigma bond skeleton. these are pi bonds. electrons can move around - delocalised
what does the delocalisation of electrons cause
causes bonds in benzene to be similar and makes the molecule unexpectedly stable
what are the bonds in benzene
not single and not double, but an intermediate between the two
which type of reaction would benzene typically undergo?
substitution reactions
what would one might expect to be benzene’s usual reaction type and why
addition reactions as it is unsaturated
is benzene a polar or non-polar molecule and why?
non-polar as the centres of positivity coincide
is benzene soluble in water and why
no as it is non-polar and does not form hydrogen bonds with water
what did benzene used to be used for and why not anymore
as an organic solvent but no longer as it is carcinogenic
what is now used in benzene’s place as an organic solvent
methylbenzene
some aromatic pharmaceuticals
aspirin, morphine, paracetamol, penecillin
aromatic dye
napthalene
some aromatic narcotics
heroin and cocaine
aromatic insecticide
DDT
aromatic disinfectant
TCP
aromatic material
terylene is a type of polyester
aromatic indicator
phenolphthalein
some aromatic fragrant oils
menthol and clove oil
EXTRACTION OF CLOVE OIL
main constituent of clove oil
eugenol
EXTRACTION OF CLOVE OIL
principle of steam distillation
when two immiscible liquids are together, their boiling point is lower than either of the two pure compounds alone
EXTRACTION OF CLOVE OIL
2 immiscible liquids
oil and water
EXTRACTION OF CLOVE OIL
if you did not mix with water
would have to bring cloves up to the oil’s boiling point and would char the clove and would become impossible to extract the oil
eugenol
top
OH
eugenol
first right C
OCH3
eugenol bottom
C-H
C-H
H-C-H
EXTRACTION OF CLOVE OIL
if oil doesn’t form a separate layer
solvent extraction
droplet dispersed - emulsion
organic solvent dissolves oil and then separated from water using separating funnel
organic solvent evaporates off
EXTRACTION OF CLOVE OIL
safety precaution
wear gloves as oil can burn the skin
EXTRACTION OF CLOVE OIL
first step
add water to steam generator
EXTRACTION OF CLOVE OIL
explain the safety tube
placed in the steam generator, bottom should be well below level of water. water topped up regularly. relieves pressure, avoids build up of steam and explosion
EXTRACTION OF CLOVE OIL
where do you put the cloves
in the pear shaped flask with some water
EXTRACTION OF CLOVE OIL
cloves are in
bunsen burner turned on and steam allowed to pass through for 40 minutes
EXTRACTION OF CLOVE OIL
what happens to the clove oil emulsion
passed through the condenser to the receiver (separating funnel)
EXTRACTION OF CLOVE OIL
describe the emulsion
milky colour
EXTRACTION OF CLOVE OIL
what happens to emulsion
allowed to cool
EXTRACTION OF CLOVE OIL
what is added to emulsion
organic solvent e.g.cyclohexane added and contents of separating funnel shaken vigorously
EXTRACTION OF CLOVE OIL
before separating emulsion
invert the funnel and tap to release pressure
EXTRACTION OF CLOVE OIL
how do you extract
draw off the clear aqueous lower layer into a beaker labelled aqueous and repeat the process many times with the organic layer
EXTRACTION OF CLOVE OIL
why do you repeat many times
to maximise the yield of oil collected
EXTRACTION OF CLOVE OIL
where do you then place the organic layer
in a beaker, it may contain some water
EXTRACTION OF CLOVE OIL
what do you add to the organic layer in the beaker and how much? what happens?
add enough anhydrous sodium sulfate so that it no longer clumps together
it should appear to settle as a dry powder when all of the water has been removed from the clove oil
EXTRACTION OF CLOVE OIL
after adding anhydrous sodium sulfate
swirl flask and filter to remove drying agent, rinse with cyclohexane to maximise yield of oil
EXTRACTION OF CLOVE OIL
last step
the cyclohexane solvent was allowed to evaporate off from the filtrate in a warm place or desiccator. This leaves the clove oil behind, measure its volume.
