carboxylic acids and esters Flashcards
why does carboxylic acid dissolve in water and upto what one?
It dissolves as it forms hydrogen bonds with water
dissolves up to and including butanoic acid
what happens if the hydrogen of the cooh is removed?
a carboxylate ion is formed
their is a negative charge over the carboxylate ion
this delocalisation makes the resulting ion more stable
how are carboxylic acids named?
the carbon in the carboxyll group is always the first carbon group
as carboxylic acids are weak what do they form when reacted with carbonates?
salt co2 and water
how do you name esters?
take the alcohol half as the alkyl group e.g ch3 =methyl
take the carboxylic acid and replace the ending with oate
descrtibe the uses of esters?
fragrance/food-nice smell
solvents- as they are polar they allow polar molecule to dissolve in.they also have a low boiling point
placticisizers
2 reactions for formation of esters
alcohol + carboxylic acid ester + h20 (reversible reaction) catalyst of conc sulphuric acid
acid anhydride + alcohol ->ester + carboxylic acid
what are the 2 types of ester hydrolysis?
acid hydrolysis
base hydrolysis
describe acid hydrolysis of ester?
reaction is completed under reflux
acid e,g sulphuric hydrochloric breaks ester down to carboxylic acid + alcohol
ester + h20 ->carboxylic acid + alcohol (acid catalyst)
describe base hydrolysis?
reaction is completed under reflux
base e.g sodium hydroxide breaks down ester to carboxyate ion + alcohol
ester+ oh- -> carboxylate ion + alcohol
what does glyderol (propan-1,2,3triol) and fatty acids (carboxylic acid) combine to make?
esters known as oils and fats
why are oils liquid at room temperature while fats are solid?
oils have unsaturated fatty acid chains(double bonds) which are not straight this means they cannot pack as closely together.hence they have weaker van der waals forces and lower boiling points
fats have saturated fatty acid chains which are straight this means they can pack closer together and have stronger wan der waals forces and a higher boiling plint
how does the hydrolysis of fats/oils produce soap?
in a base hydrolysis usually containing na it combines with carboxylate ion to form a salt which is known as soap
what is biodiesel?
biodiesel is a mixture of methyl esters and can be made from rapseed oil
what is the reaction to produces biodiesel from vegetable oil?
C3H8O3
oil (ester) + methanol -> glycerol + methyl ester (KOH catalyst)
H 3CH3OH H O
H C O C=O-R H C OH II
H C O C=O-R H C OH 3 H3CO C R
H C O C=O-R H C OH
H H