Carboxylic Acids
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How to name carboxylic acids
Anoic acid
What are carboxylic acids and esters with the same molecular formula
Functional group isomers
What groups to carboxylic acids contain
Carbonyl and -OH acid group
Equation for partial dissociation of ethanoic acid in water
CH3COOH + H2O double arrow to CH3COO- + H3O+
Reaction of carboxylic acids with metals
Produce CH3COO-metal+ and hydrogen gas (effervescence)
How to test for carboxylic acids
Add sodium carbonate, will be effervescence and gas will turn lime water cloudy
How can carboxylic acids be made
By oxidation of primary alcohols/aldehydes under reflux using acidified K2Cr2O7 or by hydrolysis of nitrile compounds (add dilute HCl to release acid/alkaline hydrolysis)
Can carboxylic acids form hydrogen bonds and with which groups
Yes, with their OH and CO groups
Why does solubility decrease as chain length increases
As energy released when H bonds form between carboxylic acid and water molecules not enough to overcome London forces between carboxylic acid molecules
Why do carboxylic acids have higher mps than alcohols of same mr
As can form hydrogen bonds between molecules with both CO and OH parts of functional group, requires more energy to overcome
Reaction of carboxylic acids with bases
In neutralisation reaction form salt and eg CH3COONa water
Explain acid hydrolysis to get carboxylic acid
Heat nitrile under reflux with dilute acid, get carboxylic acid and ammonium
Explain alkaline hydrolysis to get carboxylic acid
Heat nitrile under reflux with alkali eg sodium hydroxide, do not get carboxylic acid predicted as any would react with sodium hydroxide to form salt and any ammonium reacts with NaOH to form ammonia (which is also produced), get CH3COO- ion which must add dilute HCl to supply hydrogen ions and distil carboxylic acid
Reaction with bases
Neutralisation reaction as weak acids to produce salt
Process of reduction of carboxylic acids
LiAlH4 provides H:- nucleophile and are reduced to primary alcohols followed by dilute sulfuric acid to release alcohol from complex
Why is base catalysis for hydrolysis more efficient
As it is not reversible because acid formed loses its proton by reacting with excess alkali so turns into negative ion which does not react with the ammonia (which has also been deprotonated so would not react)