I've been working on heterocyclic compounds these last few months. A common purification step in these is distillation at low pressure. Why?
Becaue a lot of side reactions are involved that make deeply colored gooey compounds one has to distill or use chromatography to get rid of (so to
speak). So why is thisthe case? Am I right in saying this is a characteristic of heterocycles (although common with other kinds of arylamines) ?
So are these like PAH's and phenolic dyes we're making on the side?Nicodem - 1-5-2007 at 23:07
Side reactions are not characteristic just for heterocyclic chemistry but for most chemistry.Sauron - 2-5-2007 at 00:58
Absolutely. That's what short path stills, kugelrohrs etc are for. And as you say sometimes chromatography is the only way out. We used to call goop
like that "mung" (rhymes with hung). The dreaded mung. The Mung That Ate Chicago. It Came From Out of Mung. and other B-movie scifi titles.
Tars, polymers, high MW stuff. Sometimes can be very frustrating.garage chemist - 2-5-2007 at 03:12
As one does organic chemistry, one will find out lots of methods to make goop or tar out of expensive fine chemicals.
I already know how to make tar using a grignard...I am a fish - 2-5-2007 at 06:34
Quote:
Originally posted by chemrox
A common purification step in these is distillation at low pressure. Why?
Presumably to lower the boiling point of your desired product. If you require simple distillation (i.e. straightforward separation of your mixture,
without any reactions going on within it) then you will want to avoid high temperatures.
Quote:
Originally posted by Sauron
Tars, polymers, high MW stuff. Sometimes can be very frustrating.
[Edited on 2-5-2007 by I am a fish]chemrox - 2-5-2007 at 21:26
Kuglerohr will be the way to go. I can't maintain high vac with enough bubbles to avoid bumping and the holdup on my column is too much for the
amount I'm distilling. The Snyder is a lot of fun by the way... sounds like a windchime tied to a happy dog's tail. Absent a Kuglerohor maybe a
short vigeraux and a cold finger will be the way to collect it all.chemrox - 2-5-2007 at 21:28
Quote:
I already know how to make tar using a grignard...
I've made a lot of Grignards .. what's going on?
red goo still chaser
chemrox - 2-5-2007 at 21:36
I should have thought of this sooner. I need a chaser in my still pot. If my compound distills at 125/1mm could I use pump oil as a chaser? What
else comes to mind? Everything else I have boils lower or could react or both.
[Merged from new thread]
[Edited on 3-5-2007 by I am a fish]Nicodem - 2-5-2007 at 22:59
Quote:
Originally posted by chemrox
I should have thought of this sooner. I need a chaser in my still pot. If my compound distills at 125/1mm could I use pump oil as a chaser? What
else comes to mind? Everything else I have boils lower or could react or both.
[Edited on by Nicodem]I am a fish - 3-5-2007 at 02:35
Do not create new threads on exactly the same topic. If you feel as if your original thread isn't getting enough attention, then tough luck.chemrox - 7-5-2007 at 19:38
