Acylation Flashcards
ethanoyl chloride
CH3COCl
ethanoic anhydride
CH3C=O
O
CH3C=O
why are acyl chlorides so reactive
electronegative oxygen and chlorine atoms attatched to the 𝛿+ carbon make the carbon susceptible to nucleophilic attack
type of reaction acyl chlorides undergo
nucleophilic addition-elimination
why are anhydrides preferred to acyl chlorides in synthesis (4)
cheaper
less easily hydrolysed
less violent reactions
no corrosive HCl is formed
acyl chloride + water
carboxylic acid + HCl
acyl chloride + ammonia
amide + HCl
(R-C(=O)NH2)
acyl chloride + alcohol
ester + HCl
acyl chloride + amine
N-ester amide + HCl
nucleophilic addition-elimination mechanism steps
e.g. ethanoyl chloride + NH3
C=O > δ- O
: of nucleophile > δ+ C
: of O- > C-O-
H-(N)+ > (N)+
C-Cl > Cl
anhydride + water
2 carboxylic acids
anhydride + ammonia
amide + carboxylic acid
anhydride + alcohol
ester + carboxylic acid
anhydride + amine
N-ester amide + carboxylic acid
amide functional group
R(=O)NH2
salicylic acid
COOH
{o}/OH
salicylic acid + ethanoic anhydride products
COOH
{o}/OC(=O)CH3 + CH3COOH
aspirin synthesis order (6)
dissolve in min. vol. of hot solvent
hot filtration
cool and crystallise in ice
cold filtration
wash residue
dry product
during aspirin sythesis what is filtered off during hot filtration
insoluble impurities
during aspirin sythesis what is filtered off during cold filtration
soluble impurities
why is a minimum volume of hot solvent used in the preparation of aspirin
so that a saturated solution is formed making crystalisation more likely
