Sciencemadness Discussion Board

Can MgSO4 be used as a drying agent for MeI?

Tkuze - 20-7-2019 at 15:47

I need to synthesize methyl iodide for methylation of a carboxylic acid to the corresponding methyl ester. I dont have CaCl2, but i do have MgSO4 and Na2SO4. Can these anhydrous salts be used to dry the methyl iodide instead of the CaCl2?

TGSpecialist1 - 20-7-2019 at 21:31

Yes.

Metacelsus - 21-7-2019 at 03:14

Yes. The potential reaction to form dimethyl sulfate is actually more favorable in the reverse direction (notably, MeI can be prepared from dimethyl sulfate + iodide salt)

Off topic, but is there a reason a simple Fischer esterification wouldn't work? I guess if the compound is acid sensitive that would be a no-go.

CharlieA - 21-7-2019 at 16:55

I don't understand what dimethyl sulfate has to do with it?
Yes, anhydrous MgSO4 or anhydrous Na2SO4 are commonly used as drying agents (especially since MgSO4, Epsom salts, is readily available and inexpensive).

Amos - 21-7-2019 at 18:37

What on earth are you making a methyl ester of that requires you to use such an expensive, hard-to-prepare, and sought-after reagent like methyl iodide?

morganbw - 21-7-2019 at 21:03

Take care with the methyl iodide, its boiling point is pretty low.
Useful though.

draculic acid69 - 22-7-2019 at 04:26

Not exactly hard to prepare I'd say.

Tsjerk - 22-7-2019 at 08:25

Quote: Originally posted by Amos  
What on earth are you making a methyl ester of that requires you to use such an expensive, hard-to-prepare, and sought-after reagent like methyl iodide?


Something that doesn't like acid catalysts I guess.

Tkuze - 22-7-2019 at 13:17

Its required to make a methy ester, then directly react with concentrated ammonia and ammonium chloride to form an amide. This is for a project in which the reagent is used to make novel 2-[(diphenylmethyl)sulfinyl] acetamides from the correspondonding carboxylic acid.
Thanks for the help. I only see CaCl2 being used and I have plenty of other drying agents.

Tsjerk - 22-7-2019 at 13:48

Pfff, in that case I wouldn't dare to say other agents would be fine. I can only say sulfates are fine as long as you don't try to dry small alcohols. Either you have few references or there is a reason to use CaCl2.

Tkuze - 22-7-2019 at 18:26

I agree, there are many other ways of performing this reaction, but there is only one reference in all of scifinder referencing this series of compounds and their synthesis. The goal is to replicate their results exactly to have a good handle on the chemistry and keep the results consistent. This is essentially our means of making a control, then we will expand on the library of compounds they created.

Tkuze - 22-7-2019 at 18:31

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3041981/