carboxylic acids and esters Flashcards
what are the physical properties of carboxylic acids
OH bond forms hydrogen bonds this means they have relatively high MP and BP compared to similar sized alkanes
the COOH group is very soluble in water due to hydrogen bonding, but hydrocarbon chain of a carboxylic acid is insoluble and so doesnt dissolve in water
wether a carboxylic acid is soluble depends on length of the carbon chain
how do you name an ester
the first part of the name comes from the chain attached to the O with a single bond
the second part of the name needs to come from the chain which the c=o bond
e.g ethyl propanoate
how do you form an ester
reacting a carboxylic acid with an alcohol
the reaction uses a conc H2SO4 catalyst
the reaction is reversible
water is always the by product
heat under reflux is the condition
hydrolysis meaning
breaking a bond using water
how can you make an ester an alcohol and carboxylic acid
hydrolyse them by breaking the ester link
theres two methods
acid catalysed hydrolysis
base catalysed hydrolysis
acid catalysed hydrolysis to form alchol and RCOOH
conditions
why is it hard to get a high yield
room temp using a strong acid catalyst
its hard to get a high yield of alcohol and carboxylic as its a equilibrium reaction
base catalysed hydrolysis
catalyst
describe the process in 4 points
warm aqueous NaOH
one the RCOOH forms it reacts with NaOH
this forms the salt of acid
this increases the yeild as it shifts the position of the equilibrium to the right
it also means if the carboxylic acid is the desired product this method is not appropriate as the salt forms instead
uses of esters
animal fats
vegetable oils
fatty acids.
describe acid hydrolysis to form carboxylic acids and glycerol
tri-esters from fats and oils can be hydrolysed in acidic conditions to form the constituent RCOOH and glycerol
describe base hydrolysis to form RCOOH salts and glycerol
tri-esters from fats and oils can be hydrolysed in alkaline conditions to form the constituent carboxylic acid salts and glycerol
what can carboxylic acids salts be used as and how do they work
SOAP
polar head of molecule dissolve in water
non polar tail of molecule dissolves into oil and grease
what is biodiesel
a mixture of methyl esters
how do you create biodiesel
the fatty acids formed from the hydrolysis of triesters can be used to create biodiesel
the fatty acid which is formed is used to create a new ester using methanol
name some uses of esters
plasticisers
perfumes
name an acid anhydride where the two R groups are the same (2 carbons)
ethanoic anhydride
