They do not fully dissociate only the H on the carboxyl group does
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Dissociation of a carboxylic acid
Carboxylic acid ⇌ Carboxylate ion + H⁺
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Reaction of a carboxylic acid and alchohol
Forms ester
O-H on carboxyl swaps with R-O on alcohol to form an ester and water (condensation reaction)
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Ester Functional Group
R -- C = O
|
O -- R
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Naming Esters
Alkyl group (methyl, ethyl propyl) comes from the alcohol and is the R group that is single bonded to only one O
The carboxylate (anoate) group comes from the carboxylic acid as does its name (ethanoic acid --> ethanoate)
Any extra groups such as methyl
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Uses of Esters
Esters have a sweet smell and so can be used in perfumes and are also used to flavour sweets and drinks
They are also polar so many polar organic compounds will dissolve in them. Combined with their low boiling points they can be good solvents in glues an
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Hydrolysis of esters
Esters can be hydrolysed to form alcohols through acid hydrolysis or base hydrolysis
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Acid Hydrolysis
The ester reacts with water in a dilute acid under reflux to form a carboxylic acid of the carboxylate group and an alcohol of the carbonyl group
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Base Hydrolysis
The ester reacts with an OH⁻ ion under reflux to form a carboxylate ion from the carboxylate group and an alcohol from the carbonyl group
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Fats and oils
Esters formed from a glycerol (propane-1,2,3-triol) backbone and 3 fatty acid chains linked by an ester bond
Can be saturated (no double bond) or unsaturated (double bond present)
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Animal fats vs Plant oils
Animal fats tend to be saturated to fit neatly for storage. This leads to more VDW intermolecular forces giving a higher melting point so they are solid at room temperature
Plant oils are unsaturated so have less VDW forces and a lower melting point so a
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Hydrolysis of Oils and Fats
Oils and Fats can be hydrolysed to form Glycerol, soap and fatty acids
This can be done by heating with NaOH to form propane-1,2,3-triol and a sodium salt/soap
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Biodiesel
Mixture of Methyl Esters formed from fatty acids
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Formation of biodiesel
Biodiesel can be formed by adding vegetable oils to methanol and a KOH catalyst
This will form propane-1,2,3-triol and 3 methyl esters from the fatty acids of the oil
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Other cards in this set
Card 2
Front
They do not fully dissociate only the H on the carboxyl group does
Back
Why are carboxylic acids weak acids
Card 3
Front
Carboxylic acid ⇌ Carboxylate ion + H⁺
Back
Card 4
Front
Forms ester
O-H on carboxyl swaps with R-O on alcohol to form an ester and water (condensation reaction)
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