carboxylic acids and esters Flashcards
What is the functional group of a carboxylic acid?
-COOH
What is meant by carboxylic acids are weak acids?
In water they partially dissociate into a carboxylate ion and a H+ ion
How do carboxylic acids react with carbonates?
React with carbonate to form salt, water and carbon dioxide
e.g HCOOH + NaHCO –> HCOONa + CO2 + H2O
What are the conditions and reactants for an esterification reaction?
Heat a carboxylic acid with an alcohol in the presence of a strong acid catalyst (typically conc. sulfuric acid)
What are the properties of esters?
Have a sweet smell- useful for perfumes, sweets and drinks
Polar liquids- lots of polar organic compounds will dissolve in them
Low boiling points- good solvents in glues and printing inks
Used as plasticisers- however over time the plasticiser escapes and plastic becomes more brittle
What is hydrolysis?
When a substance is split up by water
What is an acid hydrolysis reaction?
Splits the ester into an acid and an alcohol (reverse of esterification). Have to reflux the ester with dilute acid (hydrochloric or sulfuric)
What is a base hydrolysis reaction?
When you reflux the acid with a dilute alkali (e.g NaOH). OH- ions from the base react with the ester and form a carboxylate ion and an alcohol
What are animal fats and vegetable oils made from?
Made from esters of glycerol and fatty acids (long chain carboxylic acid) - triglycerides from bio.
Can be saturated or unsaturated (contain double bond)
Why are fats solid at room temp?
Mainly have saturated hydrocarbon chains so fit neatly together. This increases the van de waals forces between them, so higher temperatures are needed to melt them.
Why are oils liquids at room temperature?
Have unsaturated hydrocarbon chains- double bonds means the chains are bent and don’t pack well together so decrease the effect of the Van der waals forces so easier to melt.
What is the product formed when oils and fats are hydrolysed by base hydrolysis with sodium hydroxide?
A sodium salt that is a soap, which can then be converted back to a fatty acid by adding an acid.
How do you convert vegetable oils into biodiesel?
React with methanol using a strong alkali as a catalyst, which forms a mixture of methyl esters of long chain fatty acids
