[measaint]

hi everybody,

We are synthesizing this product and during the process we ran it through column of silica to get rid of unreacted reactants.
Now we have the solvent mixture with our product. Solvent mixture is hexane/ethyl acetate. we need to remove it completely . we tried rotavapor...kept it for three days on the rotavapor...we could not try freeze drying..due to the eutectic points of the mixture.
Do we have a method of crystallization for the mixture (juss random guesses) ?

Kindly help in this regard
saint

[sjb]

Ethyl acetate and hexane should come off pretty easily under vacuo - what kind of vacuum are you pulling? Are you sure that your compound is not a liquid? Does NMR or similar show any impurities?

[measaint]

We are using a Labconco ...even we thought tht it might be evaporator...as these solvents have pretty low boiling points..but it wont come off.
Do you have any method to crytallize out the product in such cases?

Saint

[Squirmy]

In my experience, ethyl acetate can be much more difficult to remove than one would expect from its boiling point. I don't know if you'd ever get it all off with a rotavap vacuum without using azeotropes. I usually just put my stuff on high vac to remove the last traces. Keep going until it reaches a constant mass.