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Chemistry Forums for Students => Organic Chemistry Forum => Organic Chemistry Forum for Graduate Students and Professionals => Topic started by: nan on June 08, 2007, 06:29:49 PM

Title: What do you guys put on your schlenk line to protect your pump
Post by: nan on June 08, 2007, 06:29:49 PM

Some folks hook a drierite and NaOH pallets to the line, does anyone have a general guideline of these things. Thanks a million

Title: Re: What do you guys put on your schlenk line to protect your pump
Post by: ATMyller on June 12, 2007, 07:19:56 AM

Drying agent (http://en.wikipedia.org/wiki/Drying_agent) prevents water from entering the pump. It is helpful to put a small layer of the more expensive indicating Drierite toward the inner and outer ends of drying tube to provide warning (blue to red) that the agent is nearly exhausted and should be replaced. KOH would give slightly better protection than NaOH againts water, but neither protect from organic solvents.

I personally favour cold trap immersed in liquid nitrogen since it removes even organic solvents, but tends to clog up if used for long times.

Title: Re: What do you guys put on your schlenk line to protect your pump
Post by: kiwi on June 12, 2007, 08:05:46 AM

the KOH/NaOH is there to protect the pump from volatile acidic fumes, like HCl, TFA etc. If these get into the oil of your pump, its in big trouble. I don't specifically dry my lines going into the pump either, the liquid N2 trap does that.
Some people do put drierite or silica beads in-line on their inert gas line however. Again not me, i think it does more harm than good.

Title: Re: What do you guys put on your schlenk line to protect your pump
Post by: hmx9123 on June 13, 2007, 11:50:34 AM

I use a liquid nitrogen trap; if it's really bad (TFA, acetonitrile, etc.), I use a double trap. 

Top pic is of my hood at UCB.  Note the two traps on the left and the two mercury bubblers on the right.
Second pic is a closeup version of the same.

Title: Re: What do you guys put on your schlenk line to protect your pump
Post by: kiwi on June 13, 2007, 05:24:30 PM

nice setup, whats with the all-glass tubing leading to the traps? it looks a bit unwieldy. i have my trap connected to the manifold with vacuum hose, and the trap sitting on the floor beside the pump. frees up a lot of space in the hood. but then again it's a rare day for me when the schlenk tubes have to come out, i get away with roundbottoms and septa.

Title: Re: What do you guys put on your schlenk line to protect your pump
Post by: hmx9123 on June 14, 2007, 11:21:56 AM

Most of my stuff is air-sensitive.  The glass tubing leading to the traps is one less connection to make and thus one less source of leaks.

Title: Re: What do you guys put on your schlenk line to protect your pump
Post by: nan on June 19, 2007, 04:41:24 PM

Thank you folks, and I'm sure it's not only benefited me. Thank you again