determination of acetyl chloride contents

[TK Oh]

I have searched 3 method to deternine acetyl chloride contents in the solution.
which method would give me the best result and why?
and for the other methods could you plz explain why isn't it recommended?
it is really hard to choose which method should use to get a good results.
i really appriciate for your help.


1) Titration method(titration iodine with thiosulfate)
Acetyl chloride + sulfoxide(DMSO) -> acyloxysulfonium salts + iodide -> iodine


2) GC method(silylation)
react the sample with diethylamine(70’C for 15 mins) and silylate with BSTFA

3) GC method(methanol)
add methanol to form methyl acetate and inject into GC system

column DB-wax 30*0.53*1um
Oven 40'C for 5 mins
40->230'C at 10'C/min
230'C for 7 mins
split 1:10
injector : 250'C
FID :300'C
methanol : RT 5.4 mins
methyl acetate : RT 3.78 mins

[Don_Hilton]

The method you choose depends on what you are trying to do and the quality of result you need. The first question that comes to my mind is what concentration of acetyl chloride in solution are you looking for? This may help you to rule out one method or another.

Titrations can give very good results, but are tedious if you have many samples. (unless you have an automatic titrator).

The GC method using reaction with methanol looks to be fairly easy. The reagents are not difficult to handle and it is single step sample pareparation. (You might add some pyridine to react with HCl generated by the reaction.) The question is is appropriate for the range you need, sufficiently reproducable, and are there interferences that would get in the way of reliable quantitation.

Without knowing the range of concentrations involved and the nature of the sample mixtures or matrix, one can only give some generalities.