Synthesis 7

Question 1

How can carboxylic acids be prepared

Answer 1

1. Oxidisation of alcohols and aldehydes

2. Hydrolysis of esters, amides and nitriles

Question 2

Describe how carboxylic acids are prepared through oxidation

Answer 2

Primary alcohols and aldehydes can be oxidised to carboxylic acids
Copper oxide, acidified dichromate, acidified permanganate = oxidising agents the 2 acidified need heating under reflux

Question 3

Describe how carboxylic acids are prepared through hydrolysis of ester

Answer 3

Water is catalyst

Ester +water —> carboxylic acid + alcohol

Question 4

P what is needed for carboxylic acids to be prepared through hydrolysis of amides

Answer 4

Acid or base catalyst required

Question 5

Describe how carboxylic acids are prepared through hydrolysis of nitriles

Answer 5

Dilute hydrochloride acid catalyst

Nitrile ( C triple N)

Question 6

For hydrolysis of esters and amines into carboxylic acids how can you shift the equilibrium to the right

Answer 6

By using a base
This would mean that a salt is formed removing it from the equilibrium
Equilibrium then shifts right to dissociate more of the ester or amine

Question 7

What are the 4 reactions of carboxylic acid

Answer 7

1. Salt formation by reacting with metal
2. Condensation to form ester
3. Amide link formation ( C0NH)
4. Reduction to primary alcohol

Question 8

Describe salt formation reaction using carboxylic acids

Answer 8

React with metals to produce a salt and H2
Also react with bases such as ;
metal hydroxides to form a salt + H2O
metal carbonates to from salt + CO2 + H2O

Question 9

Describe amide link formation reaction using carboxylic acids

Answer 9

1. Carboxylic acid + ammonia = ammonium salts then Ammonium salts —heated-> amides
2. Carboxylic acid + amines —> amides
   Reaction via salt which when heated = amide

Question 10

What is an amine and how is it classified

Answer 10

An ammonia where hydrogen atoms replaced by alkyl groups

Classified by no. of alkyl groups attached to nitrogen

Question 11

How are amines named

Answer 11

By listing the alkyl groups attached to nitrogen (alphabetically) followed by the word amine
Eg. Ethyl methyl propyl amine
Methyl propyl amine

Question 12

Amine properties

Answer 12

Polar N~H bonds with ability to H bond between amine molecules as well as amine +water
Only primary and secondary amines can H bond cause tertiary has no N~H
Due to H bonding present bpt higher than alkanes
All water soluble but increase Alkyl group length = decrease solubility

Question 13

Amines are weak bases, what are some reactions with them

Answer 13

1. Water. Water soluble Amines produce weak alkaline solution
2. Acid. Amines can react with mineral or carboxylic acids to produce salts