Dear all, attached is a book dealing with tips and practices in manipulating air sensitive chemicals. Under the circonstances you want to work, the best option is to work with a continuous lab flow reactor. Please check the link below. My Regards

https://doi.org/10.1021/op500290x

Dear Anthony Nolan I don't know the maximum concentration of PhMgCl in THF, but 2.0 M solutions in THF are commercially available (see attached). Please also see the link cited below in which a concentration of 3.0 M is mentioned. I hope this helps.

https://pubchem.ncbi.nlm.nih.gov/compound/Phenylmagnesium-chloride

I think you are going to handle a sensitive reaction (mainly from air) .Mainly 2M solution or 1M solution in either Ether or THF available in market . So first you see the molar concentration and then calculate which mole starting material you are going to react and it will come in gram then you can change the gram to ml and then from dry syringe (flame dry or dry from oven) you can take from bottle please from you tube you should be see the precaution during the taking the Grignard from bottle ) Calculate the THF according to the molar formula and put 1.5 :1 ratio of starting : Grignard material . As you mentioned y r going to use Phenyl magnesium chloride so mt best suggestion is that y should be use either pheny..mag..bromide or iodide because it react fast. Please wash the syringe after use other wise it will block and will be waste.

Naimish Kumar Verma Thanks for the suggestions. I have experience with n-BuLi, t-BuLi etc. These are also pyrophoric and to a lesser extent can block up needles with solid.

And PhCl is what I have to work with - I known it is not the ideal reagent, but it is what I have. I wont be using commercial Grignard reagent.

Transfer will either be into the cooled Grignard reagent, or via cannula, not syringe.

Frank T. Edelmann Naimish Kumar Verma That was an obvious thing I missed... To check the maximum strength of commercially available solutions. If 3M is available then it is a solution at r.t. That means I can have 1 mole in 330mL, and can probably run the whole thing carefully in a 1L flask.

Thanks

You can calculate according to the molar concentration of solution. Before using left PhCl at rt because at cooled condition it become solid and concentration become change so cooled at rt and when all the solution become liquid y can take either from canula or syringe depending your .But add drop wise slowly other wise side product will be formed and yield will be affected of your product.@

You can take help if you have any queries.

Naimish Kumar Verma, the objective isn't to achieve a specific perfect molarity, in this case. Rather, to produce a specific number of moles (1.00) and react all of it in the next step. I set up a reaction with 1.1 moles Mg and 1 mol PhCl today.

Indeed, I wish I had PhBr. PhCl was much more unreactive than I expected and is now sitting under N2 refluxing overnight. The ice bath was never needed. I did at least activate the Mg with some MeI, so it should now react slowly if literature is to be believed

Unfortunately, it was already getting very thick and syrupy with more than half the Mg remaining. Related reading has led me to suspect that even small concentrations of Mg(OH)2 and Mg(OR)2 can cause substantial thickening. Not a problem for commercial sources where they simply add enough ether to the neat product to give the desired concentration.

I will post here with the results for any future users. So it will be known if it works or this methodology with this starting material should be avoided.

Dear Anthony Nolan yes, it is well known that in Grignard reactions the chlorides are normally less reactive than the bromides. The corresponding fluorides are even unreactive. Why is it important for you to have such high concentrations of PhMgCl?

Dear all, attached is a book dealing with tips and practices in manipulating air sensitive chemicals. Under the circonstances you want to work, the best option is to work with a continuous lab flow reactor. Please check the link below. My Regards

https://doi.org/10.1021/op500290x

The answer to my original question would seem to be approx 2M. The overnight reflux produced some precipitate and unreacted Mg, so I added 0.1mol of extra PhCl. No further reaction. I added additional dry THF to replace losses and bring to total volume to ~500-600mL (precipitate dissolved instantly, was probably not Mg-oxygen species), the reaction resumed throughout the day and consumed all the Mg. I added additional 0.15mol Mg for overnight reflux and will filter the reaction tomorrow to obtain estimated 1.1mol PhMgCl.

Abdelkader BOUAZIZ unfortunately not everyone has access to this equipment. I am using PhCl due to limited resources. But I also believe that forced improvisation produces formidable synthetic chemists.

My reference uses commercial PhMgCl and several substituted Ar-MgBr which they made. PhBr would have been preferable but Australia has a high lead time and my lab currently has liters of PhCl and very little PhBr.

Frank T. Edelmann > Why is it important for you to have such high concentrations of PhMgCl?

The concentration need not be high, but I need a mole scale and prefer not to repeat on smaller scale. My hand is forced by local regulatory interference and I should probably leave it at that...

Thanks for the advice everyone!

Maximum is 3,0 M.

To my knowledge, 1.0 M or 2.0 M in THF is more sufficient.

Dear Anthony Nolan I think that Rossen Buyukliev is right in that 3 M solutions can be obtained, but I assume that they tend to be quite viscous. The commercially available solutions of phenylmagnesium chloride in THF are 2.0 M:

https://www.sigmaaldrich.com/catalog/product/ALDRICH/224448?lang=de®ion=DE