[wool]

Acetyl chloride plus ethanol or methanol is as far as I've heard a very good and easy method to prepare somewhat anhydrous hydrochloric acid. Now I was wondering how concentrated a solution of HCl you can prepare safely with this method? Is it possibly to use 1:1 molar ratio of ethanol/methanol to acetyl chloride to get a highly concentrated HCl solution in methyl/ethyl acetate?

I.e mix approximately 20 mL methanol with 35 mL acetyl chloride to get a ~9M solution of HCl in methyl acetate.

[lavoisier]

I don't know if your stoichiometry is right, however there are at least two things you must consider if you attempt that:
1. this reaction will evolve a LOT of heat
2. have you checked how soluble HCl is in EtOAc? Because you might even manage to generate tons of HCl, but if your solvent can't take it, the acid will just fly away (and dissolve your face, presumably).

As far as I'm aware, when you use AcCl to make HCl, you generally use a strong eccess of alcohol so that the alcohol can dissolve the HCl.
In some special cases you can even add the AcCl to a mixture of alcohol and the product you want to react with HCl. There are industrial processes using that.

[kiwi]

if you want strong anhydrous HCl in a solvent, you can just generate HCl gas (eg. NaCl + conc H2SO4) and bubble it into the solvent you want for a while. This works well with ether, i normally put a drying trap of more H2SO4 in the line before the gas goes to the ether.