Chapter 26 - Carboxylic Acids Flashcards
what are CA made from?
primary alcohols
what if there are 2 CA groups?
- dioic acid
e. g. propanedioic acid
what can the carboxyl group be attached to?
a benzene ring e.g. benzenecarboxylic acid
what is the name if an OH is attached to the CA?
add hydro- to first part of name e.g. hydrohexanoic acid
which C IS C1 in a CA?
The COOH C
Dissociation of Benzoic acid equation?
Benzoic acid (reversible ➡) Benzoate ion + H+
benzoate ion not ?
BENZONOATE
Why is a CA a weak acid?
only partially dissociates/ ionises into weak H+ ions in water
How do CAs react ?
like normal acids
Acid + metal ➡
H2 + metal salt
Acid + metal Hydroxide ➡
H20 + salt
Acid + carbonate ➡
CO2 + H2O + SALT
Acid + metal Oxide ➡
H2O + salt
ethanoic acid dissociation equation?
CH3COOH ➡(Reversible) CH3COO- + H+
⭐ Remember?
reversible arrow as CAs are weak acids
be careful w ?
charge on the metal ion
how can esters be made?
by reacting a CA w an alcohol. This rac
what is the ester FG?
-COO and it’s in the middle of the molecule
which part of the ester comes from the alcohol?
-O-
which part of the ester comes from the CA?
-C=O-
what is an ester and what does this mean?
A derivative of a CA - this means that an ester can be hydrolysed (broken down by the addition of H2O) to form a CA
How is an ester named?
- after CA
-oic acid is replaced with -oate
first part of name is from alcohol
Reagents and Conditions needed to make an Ester?
R: An alcohol
C: Reflux w H2SO4
ester prep: why is a water bath used?
for safety as ethanol and the ester are flammable
ester prep: why are anti-bumping granules added into the reflux flask?
to promote smooth boiling
ester prep: what is the role of conc H2S04?
- catalyst + dehydrating agent
as it removes the water, the equilibrium shifts forwards forming more ester
ester prep: the esterification reaction is?
reversible so after reflux there is a mixture pf r+ p in the flask
ester prep: How is the sulfuric acid removed from the products?
- add 10cm3 of aq Na2CO3 at a time until no further fizzing, this neutralises acid forming a salt that is Na2CO3
ester prep: How is the sulfuric acid removed from the products?
- add 10cm3 of aq Na2CO3 at a time until no further fizzing, this neutralises acid forming a salt that is Na2SO4
- Na2CO3 + H2SO4 ➡ Na2SO + H2O + CO2
ester prep: why are there 2 layers in the separating funnel?
organic esters are insoluble in the water and H2SO4 is aq. The ester is less dense so floats on the surface of the aq layer.
ester prep: when the ester is removed from the separating funnel, why is some anhydrous sodium sulphate added?
a small amount of H2O is always left mixed w the ester, to dry ester
ester prep: what is the last stage?
redistill the ester to remove any remaining impurities
Uses of esters: Ethyl 2-methylbutanoate?
apple
Uses of esters: butyl butanoate?
pineapple
Uses of esters: 1-methylbutyl ethanoate?
banana
(general uses of esters)?
- solvents for chemical industry
- solvent for adhesives
- flower & plant fragrances used to make perfumes
- for flavouring food
what is hydrolyiss?
the chemical break down of a substance by reaction of water
conidtions for acid hydrolyiss of an ester?
reflux the ester w dilute HCl (aq) or dilute H2SO4
equation for acid hydrolysis of ester?
Ester + water ➡ CA+ alcohol (this is the reverse of esterification)
conditions for acid hydrolysis of an ester?
reflux the ester w dilute HCl (aq) or dilute H2SO4
equation for acid hydrolysis of ester?
Ester + water (acid not written in equation) ➡ CA+ alcohol (this is the reverse of esterification)