The Vespiary

The Hive => Chemicals & Equipment => Topic started by: sYnThOmAtIc on May 15, 2004, 05:43:00 AM

Title: Which 14/20 Vigreux size?
Post by: sYnThOmAtIc on May 15, 2004, 05:43:00 AM

Okay, assuming someone wanted to distill somethings at the 3-20gram level in a 14/20 short path and 25-150grams on a normal 14/20 still setup with rotating cow and 100mm liebig. What would be the best size vigreux to have for each? Vacuum brings 250c eugenol to 65c and others around 50-55c(2.5torr?). Assuming separations will have 10c or better between boiling points. I was figuring about 25-50mm for the short path and a 75-100mm for the full size 14/20 still.

What are some of teh experts opinions too big too short? Other things to consider?

Title: destilation
Post by: hest on May 15, 2004, 01:46:00 PM

collums are alvays to short !
But with the standard vigreux at 30cm you get's desent result's. A packet one only have to bee 10-15cm long. But as long you destilate at 1dr./sek it should bee ok

Title: > with the standard vigreux at 30cm you...
Post by: Osmium on May 15, 2004, 11:13:00 PM

> with the standard vigreux at 30cm you get's desent result's.

A 30cm vigreux is way too long for a 14/20 distillation!!! That's a great way to reflux your chemicals without actually distilling it.

> A packet one only have to bee 10-15cm long.

When you want to distill only a few grams then a packed column is out of the question, unless you don't care for the yield. In case you do, get a spinning band column or something similar.

Title: Cool
Post by: sYnThOmAtIc on May 16, 2004, 08:36:00 AM

So what else would you consider to be similar to spinning band? From what I can gather from the link and this brief discription, these are quite efficient being able to separate things with a 2degree difference(well, the larger ones anyway).


 Would you care to pm me with a hint as it seems none of teh major glass makers carries what I'm looking for? I'm assuming a 2-4" column would be sufficient for a 50-150gram full size 14/20 app? It looks as though this column on this apparatus would suffice for all my needs if it were only 14/20.

http://www.chem.orst.edu/ch361-464/ch361/ch361p1.htm (http://www.chem.orst.edu/ch361-464/ch361/ch361p1.htm)

http://www.equilabcanada.com/distillationp.htm (http://www.equilabcanada.com/distillationp.htm)

High  performance,  low  cost,  Microscale  Spinning  Band  Distillation  Column  effective  in separating low-boiling liquid mixtures with volumes in the 0.5 to 5 mL range. Designed by Drs. Dana Mayo, Ronald M. Pike, and Samuel S. Butcher, authors of Microscale Organic Laboratory, John Wiley and Sons, New York, this 2.5 inch microdistillation column separates close-boiling (5-10°C) mixtures without stopcocks, utilizing a PTFE band uniquely driven by a bottom magnet. Coupled to a conventional magnet stirrer, experimental data indicate satisfactory performance at 1000 rpm. Column has been shown to achieve height equivalent/ theoretical plate values approaching 0.2 inches/plate within 90 minutes of boil-up.

(https://www.thevespiary.org/rhodium/Rhodium/hive/hiveboard/picproxie_docs/000507271-file_ajaa.jpg)

Title: > I'm assuming a 2-4" column would be...
Post by: Osmium on May 16, 2004, 05:14:00 PM

> I'm assuming a 2-4" column would be sufficient for a 50-150gram
> full size 14/20 app?

For 50-150g batches you can use an even longer vigreux column than 2-4 inches.
I've personally used 4-6 inch long vigreux columns with good results for such batch sizes.