Esters Flashcards
hydrolysis is
the breaking up of a compound by water into two compounds
when naming esters,
-the first word comes from :
-the second word comes from:
in all the naming structure will look like this:
- first word: the alkyl group joined to O
- second word: alkyl group joined to C
alkyl alkanoate
name the following:
1) HCOOCH3
2) CH3COOCH3
3) HCOOCH2CH3
4) CH3COOCH2CH3
5) CH3COOCH2CH2CH3
1) methyl methanoate
2) methyl ethanoate
3) ethyl methanoate
4) ethyl ethanoate
5) propyl ethanoate
physical properties of esters:
- colourless liquids
- relatively low melting and boiling points
- insoluble in water
- they smell (have pleasant smells)
why are esters insoluble in water?
all the hydrogen atoms in the compound are bonded to carbon atoms, so hydrogen bonding is impossible
pentyl ethanoate, CH3COOCH2CH2CH2CH2CH3, smells of
pears
3-methylbutyl ethanoate smells of
bananas
methyl butanoate smells of
apples
write the equation for the reaction of ethanoic acid with ethanol (this is reversible)
CH3COOH + CH3CH2OH ⇌ CH3COOCH2CH3 + H2O
-the reversible arrow shows the hydrolysis of ethyl ethanoate
we can catalyse the hydrolysis of an ester by adding ………. acid
sulphuric acid in warm conditions
method for the hydrolysis of an ester:
add equal volumes of water and the ester, with a few drops of sulphuric acid and place in hot water bath
we can also use an alkali, ………………….. to hydrolyse an ester, but this produces a…………………salt instead of a carboxylic acid. here the reaction goes to………………..
- aqueous sodium hydroxide
- carboxylate salt instead of a carboxylic acid
- the reaction goes to completion
the equation showing the hydrolysis of methyl propanoate with aqueous sodium hydroxide is:
CH3CH2COOCH3 + NaOH → CH3CH2COO- + Na+ + CH3OH
we can convert the carboxylate salt to a carboxylic acid by adding
a dilute acid
the equation showing the conversion of the carboxylate ion CH3CH2COO- into a carboxylic acid is:
CH3CH2COO + H+ → CH3CH2COOH
