Which method is the best to conduct the Grignard reaction?
I want to do Grignard reactions, I have two methods; classical methods (using Mg metal) and the second method by using ( Ethylmagnesium bromide soln.). Do you recommend which of them? I followed the second many times but it failed!
The second question is Does Nitrogen gas needed for both methods to condition become free of O2?
Another problem, was when I Purchased a liquid chemical (2-bromothiazole) it contains precipitate.
What are the possible causes of precipitation and are the precipitate impurities or what?
You can use the "entreinment" method, you have 1eq bromothiazole, 3eq. Mg and 2eq. Ethylenebromide. Ethylenebromide reacts rapidly with Mg and is converted to ethylene gas, this makes the Mg very reactive and reacts with the bromothiazole. If you dont have ethylenbromide (I think its listed as carcinogen) you can just use Mg and a little Iodine crystals. Its good to give it time, go for lunch and it will be ready when you get back. Dry Ether is prefered solvent, you dont need N2. The precipitate is probably no problem, very small impurity. You can also consider making a lithio-thiazole, n-BuLi, -78, dry THF, N2