Duff - 11-5-2020 at 05:40
Can anyone recommend a good manufacturer for Schlenk lines and flasks? There is a big difference between the prices from manufacturers like ChemGlass
and Laboy, and I am not sure what additional quality I would get if I spent $9000 with ChemGlass vs. $500 with Laboy.
Dr.Bob - 11-5-2020 at 13:02
If you are in the US, it will arrive in one piece from Chemglass in a few days. It might arrive from Laboy sometime. I would find a used good
manifold in the US, from Ebay or one of the used labware places. The flasks are much less critical, they can much better survive the shipping from
China. You can also sometimes find new Chemglass items cheaper from some distributors or online sellers. Chinese stopcocks are not always very
good, so getting a good vacuum is tougher. Maybe even find a local glassblower if you can, that sometimes works, if they can repair or fix one from
Ebay.
Sulaiman - 11-5-2020 at 13:36
for hobby use you could consider one or two of these instead ?
https://www.ebay.co.uk/itm/14-23-19-26-24-29-29-32-Joint-T-T...
or
https://www.ebay.co.uk/itm/24-40-3-Way-Glass-Vacuum-Flow-Con...
or similar.
You would need flasks with 2 (or more) necks or a Claisen adapter.
Bmoore55 - 11-5-2020 at 14:00
I have tried the Laboy flasks in the past and I have noticed a significant difference in the ability to be shipped without damage and a tendency to
have the glass crack with moderate use. If you are doing any kind of inert chem and you are cycling vacuum and inert gas I would go with the best
glassware you can get. Glassware that cracks and fails when you are dealing with a vacuum can result in a big problem. You can sometimes find good
quality used flasks on eBay.
Chemetix - 11-5-2020 at 16:21
I'd say go to a local glass blower and get what you want. Chinese glass is cheap and you'll pay for it. The taps can leak and the glass is thin.
The main chunk of the price of a Schlenk is the taps. The glassblower will often have to buy them for around $50 to $80 each, then it's the
fabrication time.
I've posted few I have done recently and you can see the extras that can be added or the customisation that you get with a glassblower.
The coloured bracing is one of those little details that makes it a true custom piece of work.
[Edited on 12-5-2020 by Chemetix]
Dr.Bob - 11-5-2020 at 18:26
Chemitix, those are nice ones.
I will note that for true Schlenk work with highly air and water sensitive compounds, PTFE stopcocks will not work well enough, as they don't sell
well enought for high vacuum work or keep out all oxygen and water, unless you really work at it. For real airfree work you really need high vacuum
stopcocks made of glass, at least that was what I found years ago. I did some then, and had a tough time until I got the right stuff. Some
compounds will decomp with even 1ppm oxygen or water. Now, for many tasks like lithiation, Grignards, etc, a simple manifold will do, but for
Grubbs, Ni(COD)2, some weird chiral catalysts, some organometallics, super pyrophorics, and many others, any trace of air or moisture will turn it
into crap. just depends on what you are planning. I have even had some chiral reactions (especially catalytic ones) that just gave crap results as
soon as everything was not perfect. Now I try to avoid those, but that is not always possible.
Chemetix - 11-5-2020 at 19:27
"PTFE stopcocks will not work well enough,..."
Dr Bob I generally agree here, I offer some high vaccuum taps that are rated to 10^-6 Torr, but the researchers ask for the taps they prefer and suit
the work they are doing. The one on display here are what was ordered by the customer.