gassing and acidity levels

[dave1234]

Just wondering when finally gassing fb/solvent (I have had some problems...but their not important here) after each gassing the solution becomes acidic, could swim make the solution more alkaline with a adding small amount of NaOH or KOH?  Does this small amount of water effect the crystalization process? I'm aware that the process should be anhydrous. If multiple gassing needed and the solution becomes acidic, is this possible or is a whole a/b extraction needed following by drying the fb/solvent before the next gassing?
I'm aware that when gassing with no problems that the gassing solution shouldn't really become that acidic but with problems it does.

[ApprenticeCook]

Why would you want to adjust the pH?
When you gas do it for a little bit then freeze, if you didnt over gas the solution after filtering out all of the crystals the NP wont be acidic, or wont be very acidic anyway....
even so the small amount of acidity will combine with the alkalinity of the freebase to produce salt, just needs to be gassed a little more to see them fall out of solution....

any water will affect the x-tal process, so just dont add anything containing water...

-AC

[Chimitant]

Always keep some freebase apart when gassing. If you went too far, just add some freebase until pH reaches the desired value. Works fine...

[dave1234]

Thanks. I thought a small amount of water would be a problem…but I was hoping it was more importantly the gas that need to be dry.
I am aware of these facts under normal but I had problems in the past. Very few crystals participated.  So long time lengths went into gassing. I assume due to no a/b conducted and trying to gas 20g of product in 800ml or greater of solvent…numerous times.
 I have now rectified these silly mistakes and swim will try gassing again under to correct conditions...can't wait.

[r2e3]

quality Chimitant!!

good    man!