Carboxylic Acids

Question 1

How are carboxylic acids formed

Answer 1

Oxidation of alcohols under reflux and heat

Question 2

Are carbs weak/strong acids

Answer 2

Weak as they slightly dissociate

Question 3

Reactions with carbs

Answer 3

Weak acid forms carboxylate ion + H+
Carbonate and carb form a carboxylate salt + H2O + Co2
Base and carb form salt + H2O
Metal and carb form salt + H2

Question 4

Test for carb

Answer 4

Sodium carbonate
Positive result: fizzing

Question 5

How is an ester formed

Answer 5

Carb + alcohol ——> ester + water
Undergoes esterification which is reversible and slow
OH lost from carboxylic acid and the H lost from alcohol when combining forming a water molecule

Question 6

What does esterification need in order to take place

Answer 6

Warm and reflux with H2SO4/HCl which act as catalyst as esterification is reversible and slow

Question 7

Naming ester

Answer 7

Name the alcohol bit first then that carboxylic acid group
OH lost from carboxylic acid and the H lost from alcohol when combining forming a water molecule

Question 8

Uses of esters

Answer 8

Food colourings
Perfumes - solvent quickly evaporates
Plasticiser - make polymers more flexible

Question 9

How are lipids formed

Answer 9

Three carboxylic acids to a glycerol molecule (propan-1,2,3-triol)
They are naturally occurring esters

Question 10

Ester hydrolysis methods

Answer 10

1. Acidic
   Carb and alcohol <——> ester and water but reversible and slow
2. Alkali
   Ester ——-> carb salt and alcohol by the addition of NaOH
   This is a complete reaction, not reversible

Question 11

Conditions for saponification

Answer 11

Alkali conditions using NaOH/KOH

Question 12

What saponification produces

Answer 12

Saponification is a form of ester hydrolysis for lipids
Lipid ——> carb salt and glycerol
Boiling with KOH/NaOH

Question 13

How is biodiesel formed

Answer 13

1. Lipid is broken down with the reaction of KOH/NaOH to split into fatty acids and glycerol
2. Fatty acids react with methanol to produce three new esters

KOH acts as a catalyst and is not used up
So overall products is three new esters, glycerol and KOH
Biodiesel is potentially a carbon-neural fuel

Question 14

Mechanism for carboxylic acids and their derivatives

Answer 14

Nucleophilic addition-elimination (acylation)

Question 15

Conditions for Nucleophilic addition-elimination

Answer 15

1. Acyl chloride
2. Acid Anhydride

Question 16

Acid derivatives of carboxylic acids

Answer 16

1. Acid anhydride
2. Acyl Chloride
3. Amides

Question 17

What is the reactants usually used in nucleophilic addition-elimination

Answer 17

1. Alcohol/water
2. Amine/ammonia

Question 18

What is acylation

Answer 18

The insertion of an Acyl group into a compound

Question 19

Products from nucleophilic addition-elimination

Answer 19

Carboxylic acid
Ester
Amide
N-substituted amine - name this exactly like and ester and put n in front of the name)

Question 20

Mechanism for nucleophilic addition elimination involving alcohol/water

Answer 20

Question 21

Mechanism for nucleophilic addition elimination using amines/ammonia

Answer 21

Question 22

An additional reaction happens in nucleophilic addition elimination with amine/ammonia, what is it

Answer 22

The H+ from acid byproduct donates to another molecule of amine/ammonia