Sleipnir - 7-10-2009 at 13:22
because my fist trys of making triacetonamine turned out to be a disaster, i was loocking for a possible substitute and i came across
"PROXYL"-derivates (2,2,5,5-tetramethyl-1-pyrrolidinyloxy-derivates ) witch are also persistend radicals with a close resemblance to TEMPO. since it
seems that at least methyl-PROXYL (3-methyl-2,2,5,5-tetramethyl-1-pyrrolidinyloxy) an be prepared easily i was searching for infos about this compound
and it's use as a oxidations catalyst but couldn't find anything.... so does anybody have some infos about this substance especially if it's possible
to use it as a tempo substitute ?
Klute - 8-10-2009 at 12:38
Being a hindered nitroxyl radical, it seems very likely it can be used to form an oxonium salt just like TEMPO derivatives. Could you please provide a
ref for it's preparation?
Sleipnir - 10-10-2009 at 11:31
a ref is in search...
i thougt about making methyl-PROXYL from mesityl oxide and isopropylmagnesiumchloride followed by dehydration and cyclisation with ammonia to the
amine and it's oxidation to the radical with H2O2 or -probably superior- with Oxone...maybe easy was the wrong word -.-
Klute - 13-10-2009 at 19:22
You've already seen an example of such a cyclization? It might polymerise much faster than a intermolecular reaction.. You'll need very dilute
conditions..
The TAA preparation is far from optimized, but considering the very low price of the starting reagents and the simplicity of the methods not involving
gaseous ammonia, it's very easy to produce 5-10g, which is more than enough for hundred multi-miilimolar oxydations.. I really recommend distilling
the freebase after removing excess acetone/solvent, rather than going through the hydrate/salts, as it pretty hard to properly cristallize without
getting a lot of ammonium salts in the mix.. The distillation is a bit harsh, smockey, bumpy, but you get there at the end: relatively pur TAA as a
pale yellow oil.
Hey, just leave a bunch of acetone, ammonia and NH4Cl in a bottle for a week or two, remove most of the acetone, extract the organic phase, wash, dry,
remove solvent and distill.. as simple as that.. Although there is a certain amount of by products present, these won't harm the catalytic activity,
and some might actually form a nitrosyl radical themselves.. In any case, 3-10% of impurities in a catalyst used in 1% ratio to substrat is less than
the impurities present in the substrat itself most of the time!
Could you comment on your preparation of TAA? What went wrong? How do you know you didn't get any product? Which procedure did you follow?
Nicodem - 13-10-2009 at 23:06
Sleipnir, you are expected to provide references. If you don't feel like it or are too lazy to do so, you can always open threads in the Beginnings
section where not citing sources is better tolerated.
Sleipnir - 14-10-2009 at 01:56
@Klute:
i was trying two different ways of making TAA
first following the United States Patent 3959295 (http://www.freepatentsonline.com/3959295.html) using NH4Cl as a catalyst + purgeing in ammonia and the other was following G.Sosnovsky and
M.Konieczny, Synthesis, 1976, 735 using CaCl2 as a catalyst + purgeing in ammonia in both ways all i obtained was a (very) litte puddle of a thick
brownish-red liquid. it sems not to be worth the effort of distilling it since the product would be only 3-4 dropps.
@Nicodem:
it's not like i dont feel like posting refs. the problem is i didn't find any -.-
if i posted in the wrong section i apologize for that.
Nicodem - 14-10-2009 at 12:21
If you know it is called PROXYL then obviously you must have read about it somewhere? So saying that you didn't find any reference about makes little
sense. Even googling for that phrase gives several papers. If you want us to search the literature for you, you first need to motivate us. If you will
get me interested on the subject I will gladly do a SciFinder/Beilsten search for the synthesis of the compound.
Somehow, from your posts, I got the feeling that you did not read Klute's work on 4-oxo-TEMPO synthesis (TEMPO substitute?) or the related threads (Acetone and ammonia?; Functionalization of silica gel without silanes, solid supported TEMPO catalysts?).
Sleipnir - 15-10-2009 at 00:36
well the only info about using it as a oxitaions agent was found in some patents and that is exactly my problem... if made a very bad experiences with
them so i have quiet a problem taking them as a serious ref -.- (try to make quinoxalinedioxide 
). it seems that it can be used as a substitute for tempo in the oxidations-process of sugar and starch derivates as
seen in :
us patent 6831173B1
us patent 6518419
us patent 2002/0072600A1
but at least there is only the hint that tempo may be substituded by proxyl-derviates and i have a problem in relying on it...mostly it is used as a
spin-label as it can pass the blood-brain barrier
it's kind of funny that you say i didin't read TEMPO substitute? since i have used the same patent he used (US 3,959,295) but not with the
work up from the patent but with the one klute posted ^^ i only freed the amine after precipitating it.
Nicodem - 15-10-2009 at 03:48
A three step synthesis starting from methyl vinyl ketone: J. Chem. Soc., Perkin Trans. 1, 1989, 1603-1610. DOI: 10.1039/P19890001603
Via a photochemical rearrangement of a cyclic azo dioxide: Journal of Organic Chemistry, 40 (1975) 1409-1415. DOI: 10.1021/jo00898a007
Synthesis of 2,2,5,5-tetramethylpyrrolidine from triacetonamine via Favorskii rearrangement, Hoffman rearrangement and finally Wolf-Kischner
reduction:
Gazzetta Chimica Italiana, 123(8) (1993) 463-466.
Bull. Soc. Chim. France (1958) 345.
US3020288
Synthesis of 2,2,5,5-tetramethylpyrrolidine via electrophilic addition of NH3 on 2,5-dimethyl-1,5-hexadiene: US4929733
In short, I could find no reasonably useful synthesis that would be comparable to that for 4-oxo-TEMPO. Furthermore, triacetonamine seems to be the
starting material of choice to prepare 2,2,5,5-tetramethylpyrrolidine.
Sleipnir - 18-10-2009 at 07:40
sounds not very encouraging at all -.-
thank you a lot for you effort, i'm gona keep an eye on this ...but i don't have much time in the near future ...term starts tomorrow...