C3. Ionisable Functional Groups Flashcards
Describe pH
one note
weak acids?
Weak acids vary in strength depending on extent of dissociation.
Describe Ka
-A high Ka indicates greater dissociation (stronger acid).
-A low Ka indicates less dissociation (weaker acid).
ONE NOTE
acid?
An acid is capable of donating a proton (H+).
base?
A base is capable of accepting a proton (H+)
main acids?
carboxylic acid and phenol
one note
main base?
amine and aniline
one note
conjugate pairs?
one note
Describe logP
-logP can only be applied to the uncharged form of molecules.
-Ionisation makes a big difference to lipophilicity.
-We need a slightly different metric… the partition coefficient (D).
Describe logD
-logD measures the lipophilicity of ionisable compounds.
-pH dependent
-logD7.4 is most commonly used
ie. Considers solubility at a particular pH
pKa equation?
one note
pKa analysis?
-A low pKa indicates greater dissociation (stronger acid).
-A high pKa indicates less dissociation (weaker acid).
what is pKa?
The pKa is the pH at which the group is 50% ionised
for an acid, If the pH is below the pKa…
the acid group will be more than 50% protonated
for an acid If the pH is above the pKa…
the acid group will be more than 50% deprotonated
for a base, if the pH is below the pKa…
the basic group will be more than 50% protonated
for a base if the pH is above the pKa…
the basic group will be more than 50% deprotonated
organic acid and base profile?
one note
