alcohols Flashcards
functional group
OH
general formula
Cn H2n+1 OH
naming
ol
or prefix hydroxy
H-C-H
C-C-O
angles
109.5
tetrahderal
H-O-C
angles
104.5
bent
why cant smaller alcohols dissolve in water
form hydrogen bonds with water
hydration catalyst
acid catalyst eg. phosphoric acid
hydrate alkenes
hydration conditions
aqueous
300 degrees
high pressure- expensive
hydration yield
high
only ethanol produced
purer
hydration speed and cost
faster
continuous process, so cheaper
expensive equipment
hydration- ethene
non renewable
fermentation
enzymes
starch -> sugars (to be fermented)
yeast produces enzyme to convert sugars to ethanol and CO2
fermentation conditions
lower temp- cheaper
in batches- slower
anaerobic
30-40 degrees
fermentation equation
C6H12O6 -> 2C2H5OH + CO2
fermentation product
Aqueous ethanol
fermentation cost
sugar is renewable
cheap equipment
slow, high production cost
must be purified in fractional distillation
depletes land for crops
biofuel
ethanol from fermentation can be used as biofuel
fuel from recently deceased matter
renewable
biofuel- CO2
biofuel produces CO2 when burnt, but plants absorb this while growing- carbon neutral
oxidation of primary alcohols
oxidising agent: acidified potassium dichromate , K2Cr2O7
orange to green
dichromate ion to chromium ion
oxidised to aldehydes
aldehydes further oxidised to carboxylic acids
oxidation of primary alcohols equations
ethanol + [O] -> ethanal + H2O
ethanal + [O] -> ethanoic acid + H2O
oxidisation of secondary alcohols
oxidised to ketones
reflux
acidified potassium dichromate
ketones do not oxidise easily
orange to green
oxidisation of secondary alcohols equation
alcohol + [O] -> ketone + H2O
oxidation of tertiary alcohols
do not undergo oxidation
no hydrogen atom bonded to carbon with OH group
elimination
alkenes reformed from alcohols by acid catalysed elimination reactions
alkenes used to produce addition polymers
dehydration of alcohols
