carbonyls and carboxylic acids
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carbonyl functional group
C=O
colour change when oxidation occurs
orange to green
why do aldehydes and ketones react with some nucleophile?
C=O is polar
what is the characteristic mechanism for aldehydes and ketones
nucleophilic addition
nucleophile definition
electron pair donor
detecting carbonyls
• add 2,4-DNP - yellow/ orange precipitate formed
distinguishing between aldehydes and ketones
• add Tollens’ reagent - silver mirror of a carboxylic acid is formed
why do phenols not react with carbonates?
not acidic enough
what can carboxylic acids take place in?
• redox reactions - neutralisation reactions
how are carboxylate salts formed?
from redox and neutralisation reactions
what is the ion called in carboxylate salts?
carboxylate ion
draw a carboxylate ion
page 464
what do 2 ethanoic acid molecules form
ethanoic anhydride and water
draw acid anhydride
page 466
what is esterification?
reaction of an alcohol with a carboxylic acid to form an ester and water
what is hydrolysis?
chemical breakdown
what is hydrolysis?
chemical breakdown of a compound in the presence of water or in aqueous solution
what is acid hydrolysis of an ester?
reverse of esterification
how do you carry out acid hydrolysis?
• ester is heated under reflux with dilute aqueous acid - ester is broken down by water, with the acid acting as a catalyst
draw the acid hydrolysis of methyl 2-hydroxybenzoate
methyl 2-hydroxybenzoate + H20 -> 2- hydroxybenzoic acid and methanol
what sort of reaction is alkaline hydrolysis?
irreversible
what are the conditions of alkaline hydrolysis?
ester is heated under reflux with aqueous hydroxide ions
acyl chloride with alcohol forms what?
ester
draw the reaction between ethanoyl chloride and propan-1-ol
propyl ethanoate and HCl