[jamward83]

Hey all...the only option I have available to me to dry THF is to use 3A molecular sieves. According to this paper http://ccc.chem.pitt.edu/wipf/Web/Solvent_Drying.pdf it's quite achievable (something my postdoc supervisor vehemently disagreed with!!)

One problem - I don't have an oven that will reach 300C - I do have a vac oven that will get to 200C - would this be sufficient in your opinions?

[Arkcon]

Not likely no.  I've tried to dry a variety of desiccants with a longer time at lower temperature, and it simply doesn't work.

[clarkstill]

Aldrich say 175-260C for 3A sieves

http://www.sigmaaldrich.com/chemistry/chemical-synthesis/learning-center/technical-bulletins/al-1430/molecular-sieves.html

[Babcock_Hall]

From this technical bulletin: "Regeneration in typical cyclic systems constitutes removal of the adsorbate from the molecularsieve bed by heating and purging with a carrier gas. Sufficient heat must be applied to raise the temperature of the adsorbate, the adsorbent and the vessel to vaporize the liquid and offset the heat of wetting the molecular-sieve surface. The bed temperature is critical in regeneration. Bed temperatures in the 175-260° range are usually employed for type 3A. This lower range minimizes polymerization of olefins on the molecularsieve surfaces when such materials are present in the gas. Slow heatup is recommended since most olefinic materials will be removed at minimum temperatures; 4A, 5A and 13X sieves require temperatures in the 200-315 °C range. After regeneration, a cooling period is necessary to reduce the molecularsieve temperature to within 15° of the temperature of the stream to be processed. This is most conveniently done by using the same gas stream as for heating, but with no heat input. For optimum regeneration, gas flow should be countercurrent to adsorption during the heatup cycle, and concurrent (relative to the process stream) during cooling. Alternatively, small quantities of molecular sieves may be dried in the absence of a purge gas by oven heating followed by slow cooling in a closed system, such as a desiccator."
http://www.sigmaaldrich.com/chemistry/chemical-synthesis/learning-center/technical-bulletins/al-1430/molecular-sieves.html#sthash.7EkzMEbw.dpuf

Speaking from the view of someone who does some synthesis but is not a full-time synthesis person, I find sieves somewhat frustrating.  I recently reread some of the earlier work on sieves (from Burfield and Smithers) as well as more recent work, and I was impressed by how well they work under ideal conditions.  However, I don't have any way to purge my oven with a carrier gas.  Therefore, I don't see how I can trust sieves to be as effective as they might be.  What am I missing here?