[zsinger]

All,
When bubbling a gas of high solubility into a solution through the inverted funnel apparatus, will I have much product loss as a result of increased SA contact, but for possibly a smaller amount of time?  I am not really looking to buy or make a gassing apparatus, as I have had SERIOUS suck-back with a simple tube, destroying my reaction.  Any anti-suckback traps, advice, pictures, etc. appreciated.  There is a good inverted funnel video on youtube which I have watched, and it appears to do what I want.

Also, my main question.  I have an azeotrope on my hands which I need to separate, (CBP: 56 C) and then the chemical itself comes over in the 30s.  Should I watch the temperature head VERY closely at the CBP, and then quickly put an ice bath on when it starts to rapidly rise, indicating the constant boiling mix is gone?  Ive dealt with positive azeotropes, just not so much with negative ones.
                -Zack
                         

[zsinger]

Or should I use steam distillation (PITA).

[discodermolide]

If the gas has high solubility in your solvent make a solution of the gas and use that, no need to constantly bubble gas.
If you are forming azeotropes try using a different solvent or try using a different purification method.

[zsinger]

I was planning on using the inverted funnel as a suckback trap during the abnormally long reflux time (18 hrs in the paper), and crystallizing product using a molar excess of HCl (aq.) at the same time (2 birds with one stone). 

I think it would be easier to deal with the Azeotrope, but I may be wrong, as I have never tried this particular method.  What might you dissolve it in to make it easier to crystalize?  I have to get this alkaloid to its HCl salt to give to my advisor so he can run the mass spec. on it.  I have my pick of solvents BTW.
                    -Zack

[discodermolide]

No idea.
You could try ethanol and add a solution of HCl in ethanol to make the hydrochloride.
Otherwise just experiment.
You don't need a salt for a mass spec.

[zsinger]

Yea….thats why I asked him why I couldn't give him the darn freebase oil……..That would be too easy!  Im sure he wanted the salt for some other reasons as well…….who knows, he's somewhat of a whack-job, but EXTREMELY brilliant.
             -Z