Ibuprofen is a widely
used non-steroidal anti-inflammatory and analgesic drug, sold in
a variety of forms.
There are a number of ways of synthesising
ibuprofen, which used to be sold as a racemic mixture. However
the (S)-isomer is about 100 times more active than the (R)-isomer.
(S)-Ibuprofen
The separation is achieved by
using an enzyme to catalyse the hydrolysis of an ester of ibuprofen.
The enzyme acts on only one of the ester enantiomers.
The enzyme
used is lipase from candida rugosa, a fungus.
The enzyme is entrapped in the pores of a hollow fibre membrane
and the ester is delivered in the organic phase to the outside of
the membrane.
The membrane gives a high surface area of
contact between aqueous and organic phases without allowing them
to mix.
In a second membrane system ibuprofen is extracted into the aqueous
phase at higher pH. The unreacted ester remains in the organic
phase and is recycled.
The half-life of the lipase is about
30 days.
Answer
Ibuprofen deactivates the lipase.
Question
Can you think of a reason why the
concentration of ibuprofen is kept low in the reactor (by running
it at low pH)?
