Carboxylic Acids And Esters Flashcards
What is the functional group for carboxylic acids
-COOH
How do you name carboxylic acids?
• Find and name the longest alkane chain, take off the ‘e’ and add ‘-oic acid’.
• The carboxyl group is always at the end of the molecule and it’s more important than other functional groups so number starting from this carbon
How many groups contains a carboxyl group contain? and name them
• Two
• Hydroxyl group
• Carbonyl group
Draw the displayed formula of 4-hydroxy-2-methylbutanoic acid
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Why are carboxylic acids known as weak acids and give the reaction
• in water, they partially dissociate into carboxylate ion and H+ ion
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- What products are formed when carboxylic acids react with carbonates ?
- Give the equation reaction of ethanoic acid and sodium carbonate
- Carbon dioxide
- Salt
- water
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What happens to carbon dioxide in the reaction between carboxylic acids and carbonates?
Carbon dioxide fizzes
What is formed when carboxylic acids react with alcohols and describe this reaction
• Esters are formed
• functional group of -COO- group
• Frequently heating carboxylic acids with an alcohol in the presence of a strong acid catalyst
• Esterification reaction
What is the strong acid catalyst used in an esterification reaction
Concentrated sulphuric acid
What is another word for an esterification reaction and why?
• Condensation reaction
• Releases water
Give an equation reaction of carboxylic acids and alcohols
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How is an ester named?
• First bit comes from the alcohol- alkyl group
• Second bit comes from the carboxylic acid- ‘oate’
What is the difference between the name of an ester and the displayed formula of an ester
The name is written the opposite way round the formula
How is an oate and alkyl group numbered?
• Oate- backwards
• alkyl- forwards
Give equations of how ethyl 2-methyl butanoate is formed
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Give uses of esters of esters and why they are used in the manner that they are
• Food flavourings
• Perfumes
• Solvents
• Plasticisers
• Esters have a sweet smell
Give some properties of esters
• Polar liquids
• Lots of polar organic substances will dissolve in them
• Low boiling points so they evaporate easily from mixtures
Give other uses of esters and why they are used the way that they are
• Used in glued and printing inks because they evaporate easily
• Used as plasticisers, added to plastics during polymerisation to make the plastic more flexible. The plasticiser escapes though and the lattice becomes brittle and stiff
How do esters form alcohols?
When they are hydrolysed
What is hydrolysis?
When a substance is split up by water
Why is an acid or alkali used in the hydrolysis of esters?
• It is used to speed up the reaction
What are the two types of hydrolysis of esters
• Acid hydrolysis
• Base hydrolysis
Describe acid hydrolysis
• Splits the ester into an acid and alcohol
• Reflux the ester with a dilute acid e,g hydrochloride or sulfuric
• It is a reversible reaction so lots of water is added to push equilibrium to the right
Draw the diagram formula for the reaction of ethyl ethanoate and H2O under reflux and using an acid and give the products
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• Describe the reaction of base hydrolysis
• Give a diagram of the reaction of ethyl ethanoate with an hydroxide and what products are formed
• Refluxing the ester with a dilute alkali
• E.g Sodium Hydroxide
• A carboxylate ion and alcohol is formed
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What are fats and Oils ester of?
They are esters of Glycerol and fatty acids
What are fatty acids? And how do thry form esters?
- Long chain carboxylic acids
- They combine with propan-1,2,3-triol (glycerol) to make esters
What are the two types of bonds fatty acids can possess?
- Saturated bonds (no double bonds)
- Unsaturated bonds (double bonds)
• What are most fats and oils made of?
• What are the properties of fats in humans
• What are the properties of oils?
• Most fatty acids are made from fatty acid chains
• Animal fats have mainly saturated hydrocarbon chains which lead to increasing vander waals forces between them which require higher temperatures to melt them
• Vegetable oils: have unsaturated hydrocarbons, the double bonds mean the chains are bent and don’t pack together well, decreasing the van der waals forces so they’re easier to melt and are liquids at room temperature
What products are formed when Oils and fats are hydrolysed
Glycerol, soap and fatty acids
What is a soap?
The salt of a long chain carboxylic acid
• Draw the structure of a fat
• Draw the structure of glycerol
• Give the molecular formula of sodium salt
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What is a biodiesel a mixture of? And how are they formed
• Biodiesel is a mixture of methyl esters of fatty acids
• oils must be converted to biodiesel first
• Reacting them with methanol, using potassium hydroxide as a catalyst
Give the reaction of a triester and methanol to form glycerol and a methyl ester
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Describe the bonding in the double bond of the carbonyl functional group
- The double bond in the carbonyl group compromises a S- bond and a pie bond.
- The pie bond is formed by direct overlap of orbitals between the C atom and O atoms
- The pie bond is formed by sideways overlap of p-orbitals on the carbon atom and oxygen atom. However, the carbonyl bond does not react in the same way as the double bond in an alkene because the oxygen atom is more electronegative than the carbon atom.
- This creates a dipole in the C=O bond because the bonded electrons are attracted towards the oxygen atom
Reaction of fat to form glycerol and salt
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