Carboxylic acids and esters Flashcards
What are carboxylic acids?
They contain the carboxyl functional group -COOH.
To name them you find and name the longest alkaline chain, take off the ‘e’ and add ‘-oic acid’. They are always found at the end of a molecule.
Why are carboxylic weak acids?
In water they partially dissociate into a carboxylate ion and a H+ ion.
How do carboxylic acids form salts, carbon dioxide and water?
They react with carbonates containing CO3^2- ion).
How are esters produced from carboxylic acids?
Carboxylic acids and alcohols react (heated), in the presence of a strong acid catalyst to give esters.
What are esters?
They are organic compounds containing -COOH- group.
Outline the esterification reaction (condensation reaction) to form esters:
(The reaction were carboxylic acid and alcohol heat using concentrated sulfuric acid as the acid catalyst).
What are common uses of esters?
- They have a sweet smell making them very useful in perfumes and flavor foods and drinks.
- They are polar liquids so lots of polar organic compounds will dissolve in them and due to their low boiling points, they evaporate easily from mixtures making them good solvents in glues and printing inks.
- They are used in plasticizers- added to plastics during polymerization to make plastic more flexible.
What are the two types of hydrolysis to form alcohols?
- Acid hydrolysis.
- Base hydrolysis.
Describe fats and oils as esters:
Fatty acids are long carboxylic acids and combine with glycerol (propane-1,2,3-triol) to make esters. The fatty acids can be saturated or unsaturated.
- Animal fats have mainly saturated hydrocarbon chains; fit together increasing van Der Waals forces between them so you need higher temperatures to melt them (solid at RT).
- Vegetable oils have unsaturated hydrocarbon chains meaning they don’t pack well decreasing van Der Waals forces so they’re easier to melt (liquids at RT).
How can oils and fats be hydrolyzed to make glycerol, soap and fatty acids?
You can hydrolyze oils and fats by heating them with sodium hydroxide which produces a soap.
What’s biodiesel?
It is a mixture of methyl esters of long-chain carboxylic acids which are produced by converting vegetable oils using methanol and potassium hydroxide as the catalyst.
