10. Esters Flashcards
how to name esters
e.g. methanol + ethanoic acid
alcohol prefix
acid suffix/root
e.g. (CH3COO)CH3
methyl ethanoate
reagents (esterification)
carboxylic acid and alcohol
catalyst (esterification)
H2SO4
equation (esterification)
methanoic acid + methanol ->
methanoic acid + methanol -> methy methanoate + water
CH3COOH + CH3OH -> CH3COOCH3 +H2O
conditions (esterification)
heat under reflux (large ester)
destill (small ester)
products (hydrolysis of an ester)
alcohol and carboxylic acid OR carboxylate salt (depending on conditions)
formation of an acid anhydride
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carboxylic acid + carboxylic acid -> acid anhydride
CH3COOH +CH3COOH -> (CH3CO)2O
ethanoic acid + ethanoic acid -> ethanoic anhydride
why can esters be made from acid anhydride + phenol but not carboxylic acid and phenol
it is more reactive (acid anhydride)
reaction with carboxylic acid would be too slow
what do acid anhydrides react with to make esters
alcohols (including phenols)
why does acid anhydride + alcohol have a higher yield than carboxylic acid and alcohol (product ester)
acid anhydride + alcohol -> ester
not reversible
carboxylic acid + alcohol () ester
reversible
conditions (acid anhydride + alcohol)
heat gently
example of esterification (acid anhydride + alcohol)
ethanoic anhydride + methanol ->
acid anhydride + alcohol -> ester + carboxylic acid
(CH3CO)2O + CH3OH -> CH3COOCH3 + CH3COOH ethanoic anhydride + methanol -> methyl ethanoate + ethanoic acid
what is hydrolysis
chemical reaction where water breaks down another product
catalyst (hydrolysis esters under acidic conditions)
hot aq acid e.g. dilute HCl or H2SO4
conditions (hydrolysis esters under acidic conditions)
reflux
products (hydrolysis esters under acidic conditions)
carboxylic acid and alcohol
example (hydrolysis esters under acidic conditions)
propyl ethanoate + water
ester + water -> carboxylic acid + alcohol
CH3COOCH2CH2CH3 + H2O () CH3CH2COOH + CH3CH2OH
propyl methanoate + water -> propanoic acid + methanol
catalyst (hydrolysis of esters under alkaline conditions)
hot aq alkali e.g. KOH or NaOH
conditions (hydrolysis of esters under alkaline conditions)
reflux
products (hydrolysis of esters under alkaline conditions)
alcohol and carboxylate salt
equation (hydrolysis of esters under alkaline conditions)
Ethyl propanoate + sodium hydroxide ->
ester + metal hydroxide -> metal salt + alcohol
CH3CH2COOCH2CH3 + NaOH -> CH3CH2COO-Na+ + CH3CH2OH
Ethyl propanoate + sodium hydroxide -> sodium propanoate + ethanol
What is alkaline hydrolysis of esters used for (hydrolysis of esters under alkaline conditions)
to make soaps (saponification)
