3.3.9 Carboxylic acids and derivatives Flashcards
why are carboxylic acids considered weak acids
only partially dissociate in water
what can carboxylic acids displace
carbon dioxide from carbonates
why can small carboxylic acid dissolve in water
they can form hydrogen bonds with water
why can carboxylic acids dissociate easily
they are stabilised by delocalisation making the ion more stable and more likely to form
name the products of
acid + metal (Na)
salt + hydrogen
name the products of
acid + alkali (NaOH)
salt + water
name the products of
acid + carbonate (Na2CO3)
salt + water + CO2
describe the functional group test for carboxylic acids and the positive result
react sample with solid Na2CO3 or aqueous NaHCO3
effervescence of CO2
name the products in the reversible reaction of a carboxylic acid with alcohol
ester and water
list 4 common uses of esters
solvents (polar and low b.p)
plasticisers
perfumes (pleasent smell)
food colourings
name the 2 ways used to split an ester into an alcohol
acid hydrolysis (reversible and low yield)
base hydrolysis (complete)
describe the conditions and reagents used in acid hydrolysis
heat under reflux
dilute acid, e.g. HCl (catalyst)
describe the conditions and reagents used in base hydrolysis
heat under reflux
dilute base (NaOH)
form a carboxylate ion and an alcohol
fats and oils are esters of…
glycerol and long chain carboxylic acids (fatty acids)
name the condition, reagent and product of the hydrolysis of animal fats and vegetable oil
heat
NaOH
produce soap
name the 3 products of the hydrolysis of vegetable oils and animal fats
soap, glycerol and long chain carboxylic acids (fatty acids)
what is the iupac name for glycerol
propane-1,2,3-triol
how does soap work
the polar coo- is hyrophilic and mixes with water but the long non-polar hydrocarbon chain is hydrophobic and mixes with grease, allowing water and grease to mix and be washed away
why do unsaturated hydrocarbons have lower lower melting points
chains are not straight so they can’t pack closely together and hence have weaker van der waals forces
what is biodiesal a mixture of
fatty acids made from methyl esters
how can vegetable oils be converted into biodiesal
react with methanol in the presence of strong alkali catalyst, e.g KOH
list the 4 carboxylic acid derivatives
acyl chlorides
acyid anhydrides
esters
amides or N-substituted amides
which is more reactive carboxylic acids or acyl chlorides/acid anhydrides
acyl chlorides/acid anhydrides
draw and name the mechanism for the reaction of an acid anhydride with water
nucleophilic addition elimination
1 intermediate step
2 curly arrows in step 1 and 3 curly arrows in intermediate step
carboxylic acid + HCl or ROOH formed
draw and name the mechanism for the reaction of acyl chlorides/acid anhydrides with alcohol
nucleophilic addition elimination
1 intermediate step
2 curly arrows in step 1, 3 curly arrows in 2
ester + HCl or ROOH formed
name the condition and reagent for the reaction of acyl chlorides/acid anhydrides with water
room temperature
water
name the condition and reagent for the reaction of acyl chlorides/acid anhydrides with alcohol
room temperature
ammonia
observation of the reaction of acyl chlroides with water/alcohol
steamy white fumes of HCl
draw and name the mechanism for the reaction of acetyl chloride and NH3
nucleophilic addition elimination
2 curly arrows in step1, 3 curly arrows in intermediate
form a primary amide + NH4Cl
describe the observation of NH4
white smoke
name the condition, reagent and product for the reaction of acetyl chloride with a primary amine
room temperature
primary amine, e.g CH3NH2
secondary amide or N-substituted amide
