10. Esters Flashcards

1
Q

how to name esters

e.g. methanol + ethanoic acid

A

alcohol prefix
acid suffix/root
e.g. (CH3COO)CH3
methyl ethanoate

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2
Q

reagents (esterification)

A

carboxylic acid and alcohol

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3
Q

catalyst (esterification)

A

H2SO4

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4
Q

equation (esterification)

methanoic acid + methanol ->

A

methanoic acid + methanol -> methy methanoate + water

CH3COOH + CH3OH -> CH3COOCH3 +H2O

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5
Q

conditions (esterification)

A

heat under reflux (large ester)

destill (small ester)

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6
Q

products (hydrolysis of an ester)

A

alcohol and carboxylic acid OR carboxylate salt (depending on conditions)

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7
Q

formation of an acid anhydride

****

A

carboxylic acid + carboxylic acid -> acid anhydride
CH3COOH +CH3COOH -> (CH3CO)2O
ethanoic acid + ethanoic acid -> ethanoic anhydride

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8
Q

why can esters be made from acid anhydride + phenol but not carboxylic acid and phenol

A

it is more reactive (acid anhydride)

reaction with carboxylic acid would be too slow

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9
Q

what do acid anhydrides react with to make esters

A

alcohols (including phenols)

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10
Q

why does acid anhydride + alcohol have a higher yield than carboxylic acid and alcohol (product ester)

A

acid anhydride + alcohol -> ester
not reversible
carboxylic acid + alcohol () ester
reversible

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11
Q

conditions (acid anhydride + alcohol)

A

heat gently

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12
Q

example of esterification (acid anhydride + alcohol)

ethanoic anhydride + methanol ->

A

acid anhydride + alcohol -> ester + carboxylic acid

(CH3CO)2O + CH3OH -> CH3COOCH3 + CH3COOH ethanoic anhydride + methanol -> methyl ethanoate + ethanoic acid

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13
Q

what is hydrolysis

A

chemical reaction where water breaks down another product

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14
Q

catalyst (hydrolysis esters under acidic conditions)

A

hot aq acid e.g. dilute HCl or H2SO4

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15
Q

conditions (hydrolysis esters under acidic conditions)

A

reflux

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16
Q

products (hydrolysis esters under acidic conditions)

A

carboxylic acid and alcohol

17
Q

example (hydrolysis esters under acidic conditions)

propyl ethanoate + water

A

ester + water -> carboxylic acid + alcohol
CH3COOCH2CH2CH3 + H2O () CH3CH2COOH + CH3CH2OH
propyl methanoate + water -> propanoic acid + methanol

18
Q

catalyst (hydrolysis of esters under alkaline conditions)

A

hot aq alkali e.g. KOH or NaOH

19
Q

conditions (hydrolysis of esters under alkaline conditions)

A

reflux

20
Q

products (hydrolysis of esters under alkaline conditions)

A

alcohol and carboxylate salt

21
Q

equation (hydrolysis of esters under alkaline conditions)

Ethyl propanoate + sodium hydroxide ->

A

ester + metal hydroxide -> metal salt + alcohol
CH3CH2COOCH2CH3 + NaOH -> CH3CH2COO-Na+ + CH3CH2OH
Ethyl propanoate + sodium hydroxide -> sodium propanoate + ethanol

22
Q

What is alkaline hydrolysis of esters used for (hydrolysis of esters under alkaline conditions)

A

to make soaps (saponification)