so are you saying you pre clean with tetra and dcm before the a/b and sometimes you let it soak in the np your using for the a/b correct?It depends.
Since Geez told me the other day that boiling naptha pulled PEG nicely, along with pfed. Something which was blaring swim in the face, but he was letting tone rinses and recrystallizations deal with it.
The right thing to do (if boiling naptha was the extraction solvent) would have been to rinse in rt DCM or tetra beforehand. To both remove PEG, and to avoid a boiling solvent. Although as you said a few days back, orange will only be activated with heat AND a base.
The reason for pre-rinsing, if you decide to do them, before an A/B on pills, even though the actual A/B itself will remove them in THEORY, is to hopefully weaken the particular pills defenses.
See, an A/B should be near quantitative (100%), a pure aqueous solution of pfed.salt, should give a near quantitative migration up to the NP of pfed.fb.
But it doesn't happen that way, because of gaks, mechanical losses, human error. But mainly gaks.
So you either try to remove them, or work around them, so that they can't do what they want to do.
So then you might think, 'oh! Ill just hit it with every solvent I've got before I do the A/B', but if you do that, then you could well have lost as much, or more yield in mech. loss and human error than you would have lost if you left the gaks in.
So you need a balance. DCM or tetra are worth it.
Acetone boils remove a lot of gak, but they'll also cost you yield because it DOES dissolve pfed fb or hcl and sulfate a bit when boiling.
Best chance of a first crystallization that needs no more cleaning:
DCM or tetra rinses at rt
soak in NP you intend to extract with
A/B
Then again, there's that eudragit shit, so just play computer games for a while.
I know it's a lazy thing to say, but nevermind.