swim was doing revision lately and came up with the idea of using a solid phase extraction to remove gaak from otc pseudoephedrine pills. i havnt seen much on tfse in the stim forum about SPE.
the plan would go something like this :
performing the usual extractions and washes to obtain the p-eph.hcl mixed with the gaak.
basing this mixture to get freebase ephedrine.
now the poly(vinyl alcohol-co-vinyl acetate)( structure explained by wareamis post) has hydrophilic -oh groups enclosing its acetate groups. i wonder if it would be possible by increasing the ph to remove a h group from these oh groups???
if this is a credible situation then the polymer would have an external negative charge, ya??
under the same increased ph conditions the .hcl of the ephedrine would be removed from the molecule leaving a posative amine group, ya??
i propose passing this mixture through a column of si-oh that has also had its protons removed by solvating with a solution basic solution pH >9
the thinking is that the posative charged freebase will attach itself to the now negatively charged oxygen atoms on the si-0h
the pmma could then simply be vacuumed through the column and discarded allowing the eph to be eluted using an acidic solvent??
and then recrystallised.
this is just a quick thought and there are a few questions for more experienced bees:
1) will the increased ph alter the shape of the poly(vinyl alcohol-co-vinyl acetate)signifigantly to expose the acetate groups?
2) will the freebase be equally likely to bond to the negative o on the pmma?
3) are there any glaringly obvious flaws that i have failed to detect?
4) is this too much work for the 30mg per pill?
(i inserted this too late so it is on the bottom)
edit: poly(vinyl alcohol-co-vinyl acetate)