11/5 Flashcards
what happens to the oxygen in the carbonyl of an acetal formation
the oxygen is removed as a byproduct of water
what is the nucleophile in acid catalyzed acetal formation
an alcohol
what are the three ways to get a acetal formation to favor the products?
by using an alcohol as the solvent
-this provides more reactants which causes equilibrium to shift toward the products
By removing water as it is formed with a drying agent
-this removes the product concentration and causes the equilibrium to shift towards the products
Azeotropic distillation
-you distill alcohol and water to shift the reaction towards the products
what is the purpose of ethylene glycol
it creates a cyclic acetal which acts as a protecting group and prevents the carbonyl from reacting
what happens when we try to form an acetal from a base catalyzed mechanism?
you only form the hemiacetal, it stops there because the OH cannot be protonated to form a good leaving group
if we want to protect an alcohol in a reaction, what should we use and make?
use a Silyl protecting group (TBSCl) to create OTBS
if you only want one part of the starting material to react, how do you prevent the ketone/aldehydee from reacting if present?
use ethylene glycol to make a protecting group
do esters react to form acetals?
no, only ketones and esters
how do you remove a protecting acetal group
with hydrolysis in H30+
if you react an aldehyde or ketone with water, what is the product
hydrate
if you react a aldehyde or ketone with an alchohol, what is the product
acetal
if you react a primary amine with a ketone or aldehyde, what is the result
an imine
if you react a secondary amine with a ketone or aldehyde, what is the result
an enamine
what type of reaction is imine formation
nucleophilic addition
when creating an imine, how do we form OH into h20, a good leaving group
we do a proton transfer
what is the first step in the formation of an enamine? how does this differ from the formation of an imine
the secondary amine attacks the carbonyl,
in imine formation, the carbonyl is first protonated
whats the second step of enamine formation
a proton transfer occurs onto the oxygen
how do enamines and imines differ in their formation
enamines come from secondary amines which do not have a proton to deprotonate directly while imines do, this causes an alpha hydrogen to be taken to form a double bond
what proton is taken in enamine formation
the alpha hydrogen to form an alkene
