11/12 Flashcards
under what mechanism do ketones and aldehydes react
nucleophilic addition
under what mechanism do carboxylic acids and derivatives react through
nucleophilic acyl substitution
why do carboxylic acids undergo nucleophilic substituion
they have a substituent that act as a good leaving group
what is the order of reactivity of carboxylic acid derivatives from greatest to least
acid halides> anhyride> thioyl ester> ester> amide
whats the least reactive carboxylic acid derivative
amide
whats the most reactive carboxylic acid derivative? why?
acid halides, halogens are good leaving groups
for the hierarchy of reactivity, can we react both down and up?
no, we can only react downhill with decreasing reactivity
why are acid chlorides useful
they can react downhill and form all other derivatives
what are the three ways to make a acid chloride with a carboxylic acid
1.) thionyl chloride SOCl2
2.) oxalyl chloride (COCl)2
3.) PCl5
what is the nucleophile in the hydrolysis of acid chlorides
water under basic conditions
what is the product of hydrolysis of acid chlorides
carboxylic acids
why do we need basic conditions for hydrolysis of acid chlorides
to deprotonate the carbonyl at the end of the reaction
when reacting an acid chloride with an alcohol, what is the product
an ester
when reacting an acid chloride with an amine NH3 what is the product
amide
when reacting an acid chloride with a carboxylate salt, what is the product
an acid anhydride
what are two methods of synthesizing acid anhydrides
1.) using carboxylic acid + acid chloride and a base like pyrimidine
2.) by reacting an acid chloride with a carboxylate salt
what does hydrolysis under acidic conditions do to a acetic anhydride
it forms 2 carboxylic acids
what are the reagents and products of a acid catalyzed fischer esterification
a carboxylic acid is reacted with an alcohol under acidic conditions to form an ester
what is the major organic product and byproducts of fischer esterification
the organic product is an ester, the byproducts are water and H+
whats the first step in the mechanism of fishcer esterification
activate the carbonyl
why do we use a proton transfer in fischer esterification
it forms a good leaving group and forms water as a byproduct
is equillibrium favored in fischer esterification?
no it is unfavorable
how can we make the fischer esterification reaction favorable
1.) use an alcohol solvent to provide excess reactants
2.) remove water using drying agents like CaCl2, NaSO4, MgSO4
what does a base promoted ester hydrolysis do? (sophonification)
cleaves the ether to form a carboxylate salt
what is a lactone
a cyclic ester
