Reflux apparatus understanding

[Rajini]

Hello All,
I have a doubt in reflux apparatus. Usually when we heat some solvents in a glass flask it may evaporate..and this vapour is cooled by reflux condensor and again go in to boiling solvent. So on heating the amount of solvent wont decrease or decompose. What I want to know is whether the flask is closed or left open to atmosphere while heating?
Regards, Rajini.

 

[Bystander]

the flask is closed or left open to atmosphere while heating?

Ordinarily, NOT ALWAYS.

 

[ManiacaLaugh]

It is very seldom a good idea to heat a completely sealed apparatus, as pressure can build up and cause it to explode. If your reactants are water sensitive, a drying tube can be placed on top of the condenser to eliminate moisture, and if they are oxygen sensitive the apparatus would need to have a stream of inert gas supplied, or be run inside a glove box.

 

[Rajini]

Hello Bystander,ManiacaLaugh,
Thanks for your reply. My reactants are oxygen sensitive. Also I cannot heat inside a glovebox/bag! So plan to pass continuously an inert gas (Ar) while heating (30 to 60 min of heating around 250 celsius is enough for my case).
Regards, Rajini.

 

[Borek]

So plan to pass continuously an inert gas

Depending on how sensitive your reactants are, you may want to use an oxygen scrubber with vanadium(II) chloride solution.