Elrik - 14-1-2019 at 22:13
I never got to use a dean-stark in college, I've only seen them used on youtube. To date I've only seen them used with no insulation of any kind, and
I'm curious why this is.
That distance of glass seems a significant heat loss source prior to where it should be condensing. Is the practical difference between insulating and
not simply not big enough to bother with? Is there some other reason they are not insulated? Are youtubers simply doing it wrong [like they generally
do with fractional distillation].
I'm looking forward to using one in an attempt to make 2-(4-isobutylphenyl)propionamide, via thermal dehydration, for an experiment series and this
detail struck me as odd when I mentally noted the need for denim lagging strips and realized I've never seen one insulated.
Sigmatropic - 14-1-2019 at 22:34
I usually insulate mine but as with other distillations I think you need to choose the right size dean-stark and thus headspace volume with the amount
of solvent you have and also heat it to a very vigorous reflux.
I've seen colleagues set some up without insulation and the next day still nothing collected, not sure what they were trying to do, but I doubt he
wanted an air cooled condensor.
Elrik - 15-1-2019 at 13:28
Thanks 
I assumed the answer would indeed be to insulate, I've just learned to second guess myself when everyone I see goes against my assumptions.
Perhaps I should make an exception in that policy for when viewing youtube 
TheOtherKindOfDoc - 15-1-2019 at 23:37
When it comes to youtube I think a lot of content creators avoid insulation to better show the process. It is harder to see what is happening if the
glass is covered with aluminium foil or something.
XeonTheMGPony - 16-1-2019 at 03:39
all so it just comes down to your needs, do you get better separating properties at low or high temp, so on.
Dr.Bob - 16-1-2019 at 06:26
Insulating the Dean Stark helps it work much better. A vacuum jacketed one is ideal, but just wrapping it is fiberglass and aluminum foil does fine.
It will make the system work much better. Also, fill the trap with solvent before starting, so that you don't boil the flask too dry when
starting, if you have a small flask. They take a lot of time to work, most reactions with a DS I run overnight to get them to go to completion.