That was a bit confusing to read
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I think dry ice lowers the temperature too much, so not only DMT will crash, but also all impurities, maybe even it freezes the naphtha? Anyways I think the advantage of a freezer there is because its just in the right temperature that will crash out most dmt (if solvent saturated enough) but not the impurities.
maybe dry ice would be something worth trying for solvents like xylene, which doesnt freeze precipitate.
Regarding naphtha evap, it might form some n-oxide if you try to speed up the evap with heat and/or a fan, but there's very little research to show how fast this happens. In my experience you can use a fan to pre-evap the naphtha and then freeze, without any significant issue with yield.
The other option is, of course, simply salting your DMT from your solvent, that way you dont have to evaporate nor freeze. Then convert the salt back to freebase (as an example, check BLAB tek which has conversion from fumarates as well as from acetates to freebase)