Sciencemadness Discussion Board

Dimethylzinc

nelsonB - 26-9-2013 at 05:51

Hi
i have looked about the reaction of methyl iodide with zinc
to produce Dimethylzinc
since methyl iodide and Dimethylzinc have both a boiling point pretty close i was wondering if methyl iodide could be remplaced by methyl chloride in a pressure vessel that is headed with both product inside zinc and methyl chloride

DraconicAcid - 26-9-2013 at 08:53

Iodoalkanes, in my experience, tend to be a lot more reactive towards metals than chloroalkanes. When people make Grignard reagents, they usually use the bromoalkanes as a compromise between the higher reactivity of the heavier halides and the lower cost of the chlorides.

BromicAcid - 26-9-2013 at 15:44

Sigh....

Methylchloride. do you have experience with Grignard reagents? Are you familiar with how difficult it can be to get an alkyl chloride to form a Grignard? That reactivity trend should at least be a guideline here, not to mention wanting to work with methyl chloride under pressure in a reaction that generates plenty of heat.

Not just that, are you aware of just how viciously pyrophoric this material is? There is plenty of literature out there, some of it better than a century old on just this procedure, it was after all the father procedure of organometallic chemistry. There is an Org Syn prep, an oldie but a goodie that has some of the information that you are looking for. It is not just a matter of mixing these reagents, it can go well... apeshit.


http://orgsyn.org/orgsyn/prep.asp?prep=cv2p0184

Having worked with and prepared diethyl and it's little brother I can attest to the insanity of these compounds. Even in a properly outfitted lab with years of experience on your side, these little buggers will still lay in wait for that split second chance where they can take your life.

AndersHoveland - 26-9-2013 at 22:48

Quote: Originally posted by DraconicAcid  
Iodoalkanes, in my experience, tend to be a lot more reactive towards metals than chloroalkanes.

True, but in this case the ZnCl2 that forms may be able to act as a catalyst. Bromoalkanes are also very reactive.

sonogashira - 28-9-2013 at 07:02

Quote: Originally posted by nelsonB  
Hi
i have looked about the reaction of methyl iodide with zinc
to produce Dimethylzinc
since methyl iodide and Dimethylzinc have both a boiling point pretty close i was wondering if methyl iodide could be remplaced by methyl chloride in a pressure vessel that is headed with both product inside zinc and methyl chloride
Please make a video when you open the pressure vessel. :D