Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: jjjj21 on August 28, 2020, 06:35:54 PM
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I am trying to synthesize Tris(2,4,6-triisopropylphenyl)phosphine (Tipp3P). I have no experience on phosphine chemistry except few days before I synthesize Mes3P. This synthesis went quite well and was able to recrystallise it from EtOH. For Tipp3P, however, I was following this protocol (doi.org/10.1021/ja027493n (http://doi.org/10.1021/ja027493n)) and in the last step I'm not able to recrystallise the phosphine from oil (added an image). Even, I tried other solvents like dry EtOH, EtOH/hexane mixture, but oil stays as it is. Has anyone has experience in such kind of synthesis? I checked the crude 31P-NMR, it showed single peak which corresponds to my phosphine but the 1H-NMR was black forest. Please help me!
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Do a hot crystallization from ethanol. Water may assist the recrystallization! Cool it down if that doesn't work, and use a stir bar if you see two layers because the solvent and oil must be thoroughly mixed. Use a two neck RBF with teflon (1.5-2x turn) which is as good as vacuum grease ~80% of the time (U can measure if you don't believe me)
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Do you have access to a sonicator? The last few compounds (not phosphines mind) that I made should have been solids but they were oils because solvent was trapped in it despite being under vacuum. I suspended my compounds in either MeOH or MeCN (specific to the compounds Im working on) and put them in the sonicator for an hour, and voila, solid.
Try adding 10 mL ethanol per gram of product and putting the rbf in the sonicator for a while, see if that does anything. Worse comes to worse, you vac off the ethanol