Carboxylic acids and esters Flashcards
(22 cards)
carboxylic acid functional group
=O
R - C
-O-H
naming carboxylic acid
use suffix -oic acid
carb- from carbonyl group
oxylic- from hydroxyl group
solubility of carboxylic acid
lower carboxylic acids (C1-4) are soluble in water
polar so attract water molecule
form H bonds with water from the hydroxyl group
as the size of the hydrocarbon R group increases , solubility decreases
as hydrocarbon chain= non polar
greater proportion of non polar to polar
reaction of carboxylic acid with metals
Not neutralisation but redox instead
R C =O + Na —> R C=O + 1/2 H2
- OH -o-Na+
Na replaces H
salt is named sodium blank-oate
solid dissolves
reaction of carboxylic acid with carbonate
Used as a test for carboxylic acid - phenol wont react with CO3
R C =O +NaCO3 —> R C=O +H2O + CO2
- OH -o-Na+
salt is named sodium blank-oate
fizzing observed
reaction of carboxylic acid with alkali
R C =O +NaOH —> R C=O +H2O
- OH -o-Na+
salt is named sodium blank-oate
There is no visible reaction
reaction of carboxylic acid with metal oxide
2 R C =O +Na2O —> 2 R C=O +H2O
- OH -o-Na+
salt is named sodium blank-oate
solid dissolves
ester functional group
=O
C
-O–
preparation of an ester from a carboxylic acid and an alcochol
concentrated H2SO4 and heat
esterification- condensation reaction
remove OH from the carboxylic acid and the H from the OH of the alcohol then join the molecules via the O + H2O by product
reversible reaction - low yeild
=O =O
C + HO-C —> C – O – C + H2O
-OH
Naming esters
named in 2 parts
alkyl from the alcohol named first
Alkanoate from carboxylic acid named second
Preparation of an acyl chloride from a carboxylic acid
conditions : anhydrous- completely dry
reagents : carboxylic acid (NOT aq) and SOCl2
CH3COOH + SOCl2 —> CH3COCl + SO2 + HCl
mixture is warmed gently + sep by distillation
openings in apparatus protected by drying tube containing drying agent CaCl2
Acyl chloride functional group
-COCl
Naming acyl chlorides
suffix - oyl chloride
c atom of the acyl group is always C1
then find longest C chain
reactions of acyl chlorides
highly reactive
easily converted into wide range of products
react with nucleophiles due to high delta+ charge on C atom which attracts electron pair donor
reaction of acyl chlorides with water
produces corresponding carboxylic acid + acidic HCl fumes
extremely vigorous at room temp
CH3COCl + H2O –> CH3COOH + HCl
lasso HCl instead of H2O
preparation of an ester by reacting acyl chloride with alcohol
No catalyst
reagent: acyl chloride and alcohol
more efficient than esterification as complete not reversible
CH3COCl + CH3CH2OH–> CH3COOCH2CH3 + HCl
preparation of an ester by reacting acyl chloride with phenol
No catalyst
reagent: acyl chloride and phenol
OH on phenol behaves like an alcohol
use acyl chloride as doesn’t react with carboxylic acid
CH3COCl + C6H5OH -> CH3COOC6H5 + HCl
preparation of an ester by reacting acid anhydride and an alcohol
reagents: acid anhydride and alcohol
conditions: gentle heat and anhydrous conditions
better yield than esterification because irreversible
CH3COOOCCH3 + CH3OH –> CH3COOCH3
+ CH3COOH
splits here CH3CO/OOCCH3 break 1 ester bond
OOCCH3 + H from the CH3OH to produce CH3COOH
and CH3CO + CH3O to produce the CH3COOCH3
Hydrolysis definition
breaking of a covalent bond by its reaction with water (acid or base catalysed)
acid-catalysed hydrolysis of ester
reagents: aqueous acid
conditions: heat under reflux
Breaks ester bond C-O
CH3COOCH3 + H2O <-> CH3COOH + CH3OH
produce carboxylic acid and alcohol
reversible
base-catalysed hydrolysis of ester
reagents: aqueous alkali
conditions: heat under reflux
breaks ester bond C-O
CH3COOCH3 + NaOH (aq) -> CH3COO-Na+ (aq) + CH3OH
Forms salt of carboxylic acid and alcohol
irreversible reaction
Formation of an ester from a phenol and acid anhydride
reagents: acid anhydride and phenol
conditions: anhydrous conditions
better yield than esterification because irreversible
CH3COOOCCH3 + C6H5OH –> CH3COOC5H6 + CH3COOH
splits here CH3CO/OOCCH3 break 1 ester bond
OOCCH3 + H from the C6H5OH to produce CH3COOH
and CH3CO + C6H5O to produce the CH3COOC5H6
