C7.2 Esters Flashcards
- What is the functional group for esters?
‘-COO-‘
- What family are esters in?
-organic chemicals
- What produces esters?
- carboxylic acids react with alcohols, in the presence of a strong acid catalyst (e.g. concentrated sulphuric acid), to produce esters
- [esterification]
- What type of reaction is esterification?
-a reversible reaction
- What smells do esters have?
-esters have distinctive smells- pleasant
- What are esters responsible for?
-the smells and flavours of fruits
- What are examples of the uses of esters?
-food flavourings, solvents, plasticizers, perfumes
- What is the use of an ester as FOOD FLAVOURINGS?
-in sweets etc. because of sweet smell and taste
- What is the use of an ester as SOLVENTS?
-for paint, ink, glue, nail varnish remover
- What is the use of an ester as PLASTICIZERS?
-added to plastics to make them more flexible
- What is the use of an ester as PERFUMES?
-sweet smelling and volatile so it can evaporate easily so can be smelled)
- What is an example of an ester made form from a carboxylic acid and an alcohol?
-ethyl ethanoate
- What are the techniques used to make a liquid ester?
1- heating under reflux
2- distillation
3- purification by treatment with reagents in a tap funnel
4- drying
- What are the reasons for HEATING UNDER REFLUX to make a liquid ester?
-heating a mixture speeds up the reaction; can’t use Bunsen burner or will catch fire before it reacts
- What is the process of HEATING UNDER REFLUX to make a liquid ester?
-mixture is gently heated in a flask fitted with a condenser which catches vapours and recycles them back into the flask, giving them time to react (refluxing)
- What are the reasons for DISTILLATION to make a liquid ester?
-separates ester from rest of mixture (unreacted alcohol, carboxylic acid, sulphuric acid, water)
- What is the process of DISTILLATION to make a liquid ester?
- mixture heated below a fractionating column
- when temp of top column= boiling point of ethyl ethanoate (ester), the liquid that flows out of condenser is collected.
- the liquid is impure ethyl ethanoate= distillate
- What are the reasons for PURIFICATION to make a liquid ester?
-to remove impurities left from distillation
- What is the process of PURIFICATION to make a liquid ester?
- distillate (liquid) is poured into tap funnel
- mixture is shaken with sodium carbonate solution= remove acidic impurities
- lower layer tapper off as ethyl ethanoate doesn’t mix with water in sodium carbonate solution
- remaining layer shaken with concentrated calcium chloride= remove thanol
- lower layer taped off and removed
- What are the reasons for DRYING to make a liquid ester?
-remove remaining water
- What is the process of DRYING to make a liquid ester?
- shake with lumps of anhydrous calcium chloride which absorbs water
- pure ethyl ethanoate can be separated from solid calcium chloride by filtration
- What are fats and oils?
- esters of glycerol and fatty acids
- mainly fatty acid chains= most properties
- What are fatty acids?
-long chain carboxylic acids (16-20 carbon atoms)
- What is glycerol?
-an alcohol
- Are fatty acids saturated or unsaturated?
- can be both
- saturated: C-C single bonds
- unsaturated: C=C double bonds
- Why do living organisms make fats and oils?
-as an energy store
- What bonds do animal fats have?
-mainly saturated hydrocarbon chains
-few C=C bonds
=normally solid at room temperature
- What bonds do vegetable oils have?
-mainly unsaturated hydrocarbon chains
-lots of C=C bonds
=normally liquid at room temperature
