Esters, fats and oils, emulsions

• How is an ester made

  By reacting an alcohol with a carboxylic acid
• Ending of an ester

  1st part- alcohol with -yl

  2nd part- carboxylic acid with -oate

  e.g. methyl ethanoate made from methanol and ethanoic acid
• Functional group of an ester

  Ester link

  
• Esterification


  The reaction of an alcohol with a carboxylic acid to produce an ester and water.

  It is a condensation reaction and reversible
• Properties of esters

  - non-polar

  - can be volatile. An issue with this is that it leads to high concentrations of esters in the air
• Uses of esters


  - flavourings

  - fragrances

  - industrial solvents
• How to break down an ester

  Hydrolysis. Uses water. Alcohol and carboxylic acid produced.
• Properties of fats and oils

  - example of esters

  - concentrated source of energy compared to carbohydrates

  - provide essential fatty acids

  - necessary to transport and store fat soluble vitamins
• Sources of fats and oils

  - animal (butter)

  - vegetable (olive oil)

  - marine (fish oil)
• Fats and oils are formed when .... and ... react

  Glycerol

  3 chain long carboxylic acids (fatty acids)

  Water is produced for each fatty acid (condensation reaction)

  
• Properties of glycerol

  3 hydroxyl groups means that glycerol is very viscous and had high mp/bp due to presence of hydrogen bonds
• Fats and oils contain glycerol combined with fatty acids in the ratio


  glycerol: fatty acids

  1:3
• Difference between fats and oils

  oils are liquid at room temperature

  fats are solid at room temperature

  => different intermolecular forces of attraction
• Fats are (saturated/unsaturated)


  saturated (single C-C)

  drawn as shown

  
• Oils are (saturated/ unsaturated)

  unsaturated (double (C=C)

  drawn as shown

  
• Why fats have high mp/bp

  high saturation => close packaging of molecules => increases number of interactions => attraction stronger => higher mp/bp needed
• Why oils have low mp/bp

  unsaturated C=C => distorts shape => prevents close packaging => less interactions => attraction is weaker => lower mp/bp needed
• How to harden oils

  Hydrogenation reaction

  They are able to pack more closely together

  
• Emulsifiers

  prevent immiscible liquids separating into layers

  formed by reaction between glycerol and 1 or 2 fatty acids

  Hydroxyl groups are hydrophobic, so mix with water (polar)

  Long C chain is hydrophilic, so mix with oil (non-polar)

  
• Emulsifier diagram