My setup was as follows:
All glassware is 24/40 ground glass.
All of my joints were grease sealed, and many of them clamped down.
All of it was made stable using a wall rack, jacks and clamps.
generator was a 1L erlenmeyer with a small stir bar, fitted with a pressure equalized 250mL addition funnel and a still head sitting in a salt / ice bath.
The still head's side neck was fitted with a glass thermometer adapter that had the perfect size tubing, sealed well, running into it. That tubing ran into a side neck of a 3 neck 2L RB boiling flask via a PTFE tubing adapter that screwed down to seal the tubing. The large neck of the boiling flask was fitted with a large rubber stopper with a hole in the center. I made sure that the center tube running out of this 3 neck RB boiling flask went to the bottom and the inflow tubing for this flask was kept high. The 3rd neck was stoppered with a glass stopper and clamped. I used a slightly different sized tubing, that sealed perfectly, to run out of the center rubber stopper in the boiling flask into another thermometer adapter fitted with a long glass tube. This tube was long enough to fully submerge into the IPA / rxn vessel. I stuffed a bit of steel wool into this glass tubing for lack of a gas dispersion fitting. This gas dispersion tube ran down into the center of the rxn vessel which was a 2L 2 neck RB. I also ran a PTFE stop cock adapter out of the other neck of the rxn flask into a 2N HCL bubbler which I rigged up with a filter flask. The vacuum adapter of the filter flask has a tube running up and out into a blower -> carbon filter, and vented out the roof.
I submerged the rxn vessel in a stainless steel bowl containing dry ice and acetone. This bowl was insulated with thick rags and a larger plastic outer bowl.
I did not transfer the IPA once I had gassed and weighed it. I simply added some freshly opened 3A molecular sieves, added a small amount of them, and stirred for a good hour before adding 23g iodosafrole. I left this rxn to run at RT overnight. I noticed a very slight immediate color change but not the kind of drastic one that jon describes so I know I can improve.
When I woke up the color had gone much more to yellow but still had hints of amber / golden. I knew that I had success when I added the first bit of acidic water to the freebase. In previous attempts at this, lots of golden extract material would drop or convert straight down to dark iodosafrole at this point. I saw no unreacted iodosafrole in this work up only lots of HCL going into the acid water.
I did not use a drying tube -- although I debated on using a cold condensor to grab any water vapor. I decided against it because of added dead volume and leak potential. I have attempted this with NaOH drying chambers. Those attempts failed for reasons unrelated. I checked my trap as of last evening and it still has gas in it. I thought about trying to extract more gas from my generator and trap to add to some cold IPA -- see if I could make another small batch..
I spent most of the day recrystallizing and drying a large batch of CH5N in a big 5L rb to prepare for this. I still have a few crops to claim from that I'm sure -- big beautiful flaky crystal formations from slow cooling. My area does still smell heavily of fish.
at the end of a/b extraction after ph'ing the water back up to ~12 slowly a golden / amber oil layer formed on top. I knew it was most of what I put in just from looking at it. I was working this up in a 2L sep funnel, and it was a fairly thick layer in the upper middle. I extracted with toluene, evaporated it, and weighed it.
Going to gas it tonight.
What are the advantages of gassing cold IPA over just straight gassing the Toluene containing freebase?
_Pbinteger_
