6.1.3 Carboxylic Acids and Esters: Module 6: Organic Chemistry & Analysis Chemistry OCR A A Level

What is the functional group of a carboxylic acid?

-COOH (C=O and C-OH)

How do you name carboxylic acids?

-oic acid

Are carboxylic acids soluble in water? Why? What influences their solubility.

Yes. Acid group can form hydrogen bonds with water molecules.

What are the intermolecular forces in carboxylic acids?

Hydrogen bonds in solid state - very strong.

What are esters (what are they formed from)? Functional group, general formula?

Formed from carboxylic acids and alcohols.

RCOOR’ (C=O, C-O-C)

How do you name esters?

Start with the alcohol group that has replaced the hydrogen, then acid part e.g. propyl (from alcohol) ethanoate (from carboxylic acid).

What characteristic physical properties do esters have?

Volatile, pleasant fruity smells e.g. apple, pear drops.

What are some uses of esters?

Flavourings, perfumes (both for longer chains), solvents (short chains), plasticisers.

How could you distinguish carboxylic acids from other -OH containing compounds?

Add NaHCO3 , acids will produce sodium salt, water and carbon dioxide.

Write an equation for the reaction of ethanoic acid with NaOH.

CH3COOH + NaOH → H2O + CH3COO- Na+

Write an equation for the reaction of ethanoic acid with calcium oxide

2CH3COOH + CaO → (CH3COO)2 Ca + H2O

What catalyst is needed for the formation of esters from alcohols and carboxylic acids?

Concentrated strong acid. e.g. H2SO4

What catalyst is needed for the hydrolysis of esters?

Dilute strong acid. e.g. H2SO4

What is an alternative method of hydrolysis?

Base hydrolysis

What are the advantages of base hydrolysis?

Reaction goes to completion due to neutralisation by base - more product in the mixture than acid catalysed hydrolysis.

What are carboxylic acid derivatives?

Molecules that have the acyl group as part of their structure, formed from carboxylic acids.

Name two acid derivatives and give their functional groups.

Acyl chlorides: RCOCl

Acid anhydrides: RCOOCR / (RCO)2O

How do you form an acyl chloride?

React a carboxylic acids with SOCl2.

If the nucleophile is ammonia for the acylation of acyl chlorides or acid anhydrides, what are the products of the reaction?

An amide

If the nucleophile is a primary amine, what are the products of the acylation of acyl chlorides or acid anhydrides?

N-substituted amide

Write an equation for the reaction of ethanoyl chloride and methylamine.

CH3COCl + CH3NH2 → CH3CONHCH3 + CH3NH3Cl

If the nucleophile is an alcohol, what are the products of the acylation of acyl chlorides or acid anhydrides?

An ester

Write an equation for the reaction of ethanoyl chloride and ethanol.

CH3COCl + CH3CH2OH → CH3COOCH2CH + HCl

If the nucleophile is water, what are the products of the acylation of acyl chlorides or acid anhydrides?

Carboxylic acid (hydrolysis produces an ester linkage).

What is the name of this reaction (the acylation of acyl chlorides/acid anhydrides with water as a nucleophile)?

Hydrolysis

Write an equation for the reaction of ethanoyl chloride and water.

CH3COCl + H2O → CH3COOH + HCl