I been trying to prepare this reagent in situ for demethylation reactions. I used the following protocole:
In situ preparation of AlI3 A mixture of aluminum powder or foil (250 mg, 9.3 mmol) and elementary iodine (1.9 g, 15 mmol) were mixed in an inert solvent (benzene, toluene, acetonitrile, carbon disulfide, or cyclohexane, 8 ml). The mixture was stirred under reflux for about 3 h, till the purple color of iodine faded. The solution can be used directly without further purification.
From> 1. Tian, J. & Sang, D. Application of aluminum triiodide in organic synthesis. Arkivoc 2015, 446–493 (2015).
So far I tried, acetonitrile and toluene, but neither work. With dry ACN I only saw dark brown color, that never desapeares (i supposed because of I3- formation). With dry toluene I saw violete color, but again after several hours of reflux (>3h) the color persists.
I even thought that the aluminum powder I been using could be impure, so iodine was in excess, so I tried adding more aluminum powder, but no difference was observed.
It seems one of those tricky procedures. Perhaps someone who did it before can help me.
Dear Bruno Gonzalez , I sorry I never prepared the AlI3 by myself, but a quick search shows that it is a very popular experiment, even you can find multiple youtube videos where they show how to make it, basically mixing thoroughly fine iodine powder with fine aluminum powder and then adding some drops of water as initiator or catalyst, the mixture starts to burn and releasing purple vapours, and lots of light and heat, finally leaving a white powder that is the AlI3. Here you can find some information about this procedure:
https://edu.rsc.org/experiments/reacting-aluminium-and-iodine/715.article
https://www.youtube.com/watch?v=Y3kDZXP4_5A
https://www.youtube.com/watch?v=rSMMuA4QHww
If you decide to use this method, please, be careful, use the fume-hood and protect yourself and the people around.
The ref 189 from the paper by Tian & Sang, describes a more controlled version of this reaction, conducted under vacuum and by sublimating I2 and passing it through Al powder at 500-525ºC and releasing the crystalline AlI3 in a receiving flask.
Chapter Aluminum Iodide
In the following paper Zhao et al. prepared the AlI3 in solution mixing different amounts of Al and I2 in ethanol and just stirring while keeping the reaction flask into a cooling bath to keep the reaction at around 30ºC. Here is the link to their paper and the details from their procedure too:
Article Low-cost preparation of a conductive and catalytic graphene ...
"AlI3 with different concentrations was simply synthesized from I2 and Al in 100 ml ethanol under continuous stirring. The detailed experimental procedure is described as follows: 1.905 g, 3.81 g and 7.62 g I2 particles (99.8%) were mixed with 0.5 g, 1 g, and 2 g Al particles (99.9%) in 100 ml ethanol, respectively. In the following stages the mixture was continuously stirred using a magnet stirrer. During the reaction between I2 and Al in our experiment, superfluous Al particles were used. In addition, because the formation of AlI3 is a strong exothermic reaction, a bath container with ice bath was used to keep the reaction temperature at about 30 C. Because the reducing agent we used for reducing GO film was the as-prepared AlI3 solution just after synthesis, not AlI3 powders, the existence of superfluous Al particles in the solution could ensure the protection of the as-prepared AlI3 agents during the following reduction process."
Another option would be buying it directly, for instance Sigma-Aldrich is selling this reagent:
https://www.sigmaaldrich.com/catalog/product/aldrich/208493?lang=es®ion=ES
Hope it helps.
contact me via [email protected] regarding the preparation and application of this reagent, please.
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