3.3.9 - carboxylic acids and derivatives - Chemistry Alevel

Carboxylic acid - type of acid

Weak acid

Carboxylic acid - BP reason

Carboxylic acids have high BPs as you can get more extensive hydrogen bonding in carboxylic acids due to the C=O bond. [Two bond together:

C=O:||||||𝛿+H-O-C ]

Carboxylic acid and acid reactions - Potassium hydroxide

ROOH + K-OH → ROO-K + H₂O

(H from ROOH substituted and potassium potassium R-anoate produced)

Carboxylic acid and acid reactions - Sodium carbonate

2ROOH + Na₂CO₃ → 2ROONa + CO₂ + H₂O

(H from ROOH substituted and potassium sodium R-anoate produced)

Carboxylic acid and acid reactions - Sodium hydrogencarbonate

ROOH + NaHCO₃ → ROONa + CO₂ + H₂O

(H from ROOH substituted and potassium sodium R-anoate produced)

Carboxylic acid - general test

Universal indicator turns red.

Carboxylic acid - specific test

React with sodium carbonate OR sodium hydrogencarbonate to PRODUCE effervescence as CO₂ is released.

Esterification - definition

The reaction between carboxylic acids and alcohols to form esters.

Uses of esters

Food flavourings/Solvents/Plasticisers

Plasticiser - definition

They are incorporated into plastics to improve flexibility.

Carboxylic acid to carboxylate salt - reaction

C' ACID [+ NaOH] → C'LATE SALT

C' ACID ← C'LATE SALT [+ HCl]

[reversible]

What are vegetable oils and animal fats?

Esters of propane-1,2,3-triol (glycerol). Esters formed this way are known as triglycerides.

Are fats & oils soluble in water?

No as they have very long non-polar carbon chains.

Oil - state/MP

Oils are liquids and have a lower MP.

Fat - state/MP

Fats are solids and have a Higher MP.

Why - fats & oils MP

There are stronger van Der Waals forces in fats as the permanent kink in the cis form (typically oils) means.

Leaving group - definition

The part of the molecule that is eliminated

Acylation reactions - nucleophiles

Each nucleophile has N OR O which both have a lone pair of e⁻s. The molecules can be thought of as Nu-H and an acid-by-product of HCl is formed.

Naming salts/ionic compound

Base/positive ion named 1st

Acylation acyl chlorides - mechanism

Nucleophilic addition-elimination

Which is preferred for synthesis of esters/aspirin

Ethanoic anhydride is preferred

Why is _______ preferred for synthesis of esters/aspirin

Ethanoic anhydride is cheaper, less corrosive, less vulnerable to hydrolysis, less hazardous to use as it doesn't produce corrosive fumes of HCl as a by-product than ethanol chloride