niobium - 18-10-2005 at 06:17
Hellow fellow mad scientists...
Swin has been trying to iodinate 2 compounds : 2,5-dimethoxyphenethylamine and 2,5-dimethoxyphenethylhydroxylamine.
Swin has followed the route of Barium from the hive, which is based on Synth. Comm. 32(15), 2319-24 (2002) which is posted on rhodium.
Swin has been using 1 mol eq substrate (both of them) and 1.1mol eq KI in methanol, to which was added 1.1mol eq Oxone. This mixture was left to stir
for 20 hours, after which acetic acid solution was added, the mixture defatted with dcm, extracted with ether, dried and evaporated. From both
substrates, the yield was exceptionally low giving roughly .2-.3g from 6.5g substrates. This was tried 3 times, results fairly the same each time.
A similair procedure emplying same molar quantities but instead of first adding acetic acid after 20hours the reaction mixture was first filtered and
only then acidifed, yielding again same results...
Swin is lost for opinoins, and need help.
Swin has come to the conclusion that this oxyiodination ala barium simply does not work.
Swin would like some help, if anyone knows that this infact works. If not, swin will try to first iodinate the benzaldehyde and only then to reduce it
to the amine, via silver nitrate/I2 in methanol.
your help is appreciated!
[Edited on 18-10-2005 by niobium]
Sergei_Eisenstein - 18-10-2005 at 07:56
The method indeed doesn't work as has been advocated by that author for this specific substrate.
niobium - 18-10-2005 at 13:04
So can anyone suggest a decent route for iodination? either the benzaldehyde or the amine? AgNO3 is a bit expensive.
iodination
leu - 19-10-2005 at 18:17
AgI can be synthesized from the elements at a lower price than suppliers charge. NIS is the other option. Two papers have been uploaded to the post at
Wet Dreams mentioned by solo in https://sciencemadness.org/talk/viewthread.php?tid=3007&...
THANKS!
niobium - 20-10-2005 at 08:17
Thanks! In the meantime swin found a cheap source of AgNO3
leu - 21-10-2005 at 17:50
A synthesis of silver iodide from potassium iodide and silver powder has been posted at Wet Dreams in the Inorganic Chemistry forum, it includes a zip
file with the original articles from Comptes Rendus
Cheap AgNO3
chloric1 - 22-10-2005 at 08:13
If you can obtain nitric acid or make it from nitrates you only need silver boulion for cheap silver nitrate. My cost is 10-$13 per ounce
leu - 23-10-2005 at 16:44
If you can get silver bullion and potassium iodide; you can make silver iodide by the procedure in the articles by deVille; the problem with the oxone
iodination procedure that caused this thread to be started is probably because Barium used slightly different and legal substrates in his work; for
very good reasons
wa gwan - 24-10-2005 at 11:18
leu, what relevance does the preparation of AgI have to this discussion?
leu - 24-10-2005 at 16:47
According to March, pp 704-5; iodine is too unreactive to iodinate anything but phenols. Wing-Wan Sy states in Tetrahedron Letters
34 6223-4 (1993) that silver sulfate/iodine is a facile iodination reagent for a very similar substrate. In that paper, silver
sulfate reacts with iodine to form silver iodide, as many other silver salts do in the presence of iodine, according to Normand and Cumming, Jour
Chem Soc Trans 101 1852 (1912).
[Edited on 25-10-2005 by leu]
[Edited on 25-10-2005 by leu]
Nicodem - 24-10-2005 at 23:43
AgI is not a iodinating reagent!
It is only a side product in the I2/AgNO3, I2/Ag2SO4 and other iodinations where the formation of the isoluble AgI from I2 and Ag+ is used to make
various forms of iodinating agents with the iodine as I+.
niobium - 25-10-2005 at 06:36
Nicodem thanks for clearing that up. swins thought was the same, but needed confirmation. The fact that barium posted about
2,5-dimethoxyphenethylamine iodination, for swin meant that he used that substrate. If barium used a different substrate and posted otherwise then it
is very bad, and should not be done.
Swin knows of several bees that tryed this method on the amine and were disapointed with the results, not to mention all of them lost lots of
substrate while doing this reaction.
Nicodem - 26-10-2005 at 07:27
Iodinations that involve I+ as the reactive species can not work on unprotected amines. These I+ bearing reagents have a great tendency to react with
the free amine group. Protonation is not enough protection, a full protection like the phtaloyl one is usualy used.
[Edited on 26-10-2005 by Nicodem]