The links below shows literature for synthesis of EMIM Ac. For small amounts the synthesis from EMIM bromide, which can be obtained by 1-methylimidazole with bromoethane, and silver acetate is the simplest synthesis (Carbohydrate Polymers(2015)121 348-354. In Green Chemistry(2015) 17(1) 231-243 a method is described in which first the methylimidazole is reacted with ethylsulfate resulting in EMIM ethylsulfate. Then the OH- form of EMIM is made by passing through a basic ion echange resin. EMIM OH is afterwards neutralized with acetic acid resulting in EMIM Ac.

www.sciencedirect.com/science/article/pii/S0167732211003382

www.rsc.org/suppdata/cc/c0/c0cc05223j/c0cc05223j.pdf

Dear Michael sir, Please send the link if you can

The Methylcarbonate route is indeed not bad, but suitable only for very small amounts.

For the ion exchange method, when removing  the water form the IL, how 'dry' did you go without running in problems with the H on the 2?

If the reaction is properly neutralised, there is normally no problem with the C2 as long as your drying method is not excessively punitive.

the H on C2 is known to be quite acidic.....i think i ran into a carbene at some moment under extensive drying

The given reference paper explains one step protocol for synthesis:

1-Methylimidazole (8.20 g, 0.1 mol), an excess of bromethyl (13.08 g,

0.12mol) and propanetriol solution of lead acetate (containing lead

acetate: 16.23 g, 0.05 mol) were added to the three-opening flask

with a reflux and stirring device at 60°C, in a constant temperature

water bath. The synthetic route was shown in Fig. 2. After 20 hours,

the solution cooled to the room temperature, and the white precipitated

was removed by suction filtration. The clear solution was

washed with pure ethyl acetate (EtOAc) (30 ml) many times. At last,

the aim product was obtained by vacuum rotary evaporation at 60°C

for 2 hours.

I thought, if we use glycerol as (solvent), how we remove this from reaction mixture?

@Tirath Raj I thought, if we use glycerol as (solvent), how we remove this from reaction mixture? ->  glycerol was removed by extraction with EtAc (solubility 9% by weight); product (IL) is insoluble in EtAc

Maybe such method is better :

EMIM+Cl-( or Br- ) + AcO-K+ -> ( tert-BuOH, soxhlet reflux) -> EMIM+ AcO- + KCl(Br) in deposit (glass frit filtering or centrifugation, rest washing with tert-BuOH, then rotary evaporation removal of tert-butanol (it can be reused)

It is green (no Pb contamination of product and waste) and probably cheap synthesis for kilo-lab quantities (maybe scalable to bulk volumes), as I suppose. Method based on solubility of potassium acetate in lower alcohols and very low solubility of potassium chloride ( and bromide in some extent). In rough estimation, next alcohol in range MeOH->EtOH->PrOH->BuOH dissolve less in 1.8 times for AcOK but in ~10 times of KCl . Maybe mixing of ethanolic solutions of EMIC and AcOK with subsequent precipitation with acetone or EtAc is suitable.

 EMIC synthesis see attachment; EtCl is available from medical vendors or from dropping of EtOH to cyanuric chloride.

https://en.wikipedia.org/wiki/Potassium_acetate

@ Michael Päch : ALDRICH site report : "Product 689041 has been discontinued. Contact Technical Service"

Alternative vendor price is not pleasant : $410/100g for US market, it should cost ~ $600 in India (+delivery and custom expences) http://www.scbt.com/datasheet-222695-1-ethyl-3-methyl-imidazolium-methyl-carbonate-solution.html

@Michael Päch : I have not found synthesis of  1-ethyl-3-methylimidazolium methylcarbonate ( for some reason named by unknown nomenclature as methocarbonate ) in cited publiction.

From my Internet I see  synthesis of 1-ethyl-3-methylimidazolium-2-carboxylate or 2-step synthesis 1-ethyl-3-methylimidazolium hydrogencarbonate  - it was really convenient precursor for various salts. Two problems are clear visible:

1) Moderate yield (~50%) = 50% waste

2) Autoclave method   - costly,  unsafe and low productive (~1g of product per 10ml of reaction vessel)

It is hard to say that such method is convenient.

@Michael Päch: Ampule method is more dangerous than autoclave, and productivity is very low  - some grams in one ampule per week! 

No doubt, methylcarbonates and hydrogen carbonates are very convenient precursors for screening of IL in a gram scale - but they are not readily available compounds for itself.

Tirath, for most of the applications as an ionic liquid you can use instead of the methyl-ethylimidazolium the mixture of 1,3-dialkylimidazolium acetates (Alk = Me, Et), it is prepared quite easily and cheap in one step from the amines, formaldehyde and glyoxal:

http://www.rsc.org/suppdata/cc/c0/c0cc05223j/c0cc05223j.pdf

Ah, sorry, I have not checked. This is by far the easiest way, anyway, especially if the ionic liquid is used as a solvent for biopolymers.

It is not a question of yields, but of purity !

I was confused with agressive and blunt downvoting (polish?) so I remove my previous messages.  

Some notes about purity issues.

Main impurity is halogen anion, this impurity is critical in electrochemistry, but for biopolymers extraction that doesn't matter (5-10 mol %). To avoid halogen contamination, alkylcarbonates and hydrogencarbonates way (as suggested by Michael Paech) is very suitable.

Nature of counter-ions in IL effect also on yields.  One of goal from my coauthors was to develop additives to non-polar paraffine oils. This problem seemed to me crazy at first. But in reality it turned out that many salts are soluble significantly. Later, I found a similar data for solubility of organic salts in hexane. Therefore, most of reported yields are not  the chemical yield but isolated yield. During extraction of impurities (with EtAc as usual) one exist substantial loss of material, although the chemical yield is close often to 100%.

From this point of view, chlorides are much better in comparison to bromides. Sodium salts are also better than potassium or lithium (for chloride salts)

Thank you all for valuable suggestions and responses.

Dear Roksana, will you explains the purity and water content in ionic liquid as prepared by above method. I would like to use for biomass application. Which need to be perfectly dry and purified. I will perform this in my laboratory. What about halide conc, present in ionic liquid? May we completely avoid it??

One another method describes using EmimBr and Ag(CH3COO)2, Which is more suitable?

 I agree with Dr. Andrei, that other ionic dialkyl ionic liquids are cheap and easy to synthesis but my foucs in on Emimoac.

@Tirath : I checked the data in Roksana's article RSC Advances, 2012, 2, 8429–8438 , it is very convenient synthesis,  the product show a high purity by elemental analysis  - the bromide content is less than 1%. It is superior method from all suggested here.

If you have money for silver acetate, you can buy simply final product without experiments. Silver acetate cost in 10 times more than EMIM acetate

Roksana Markiewicz Have you published your proposed on two-step reaction of EMIMAc synthesis? Can I have your paper about it?