Analysis of Trifluoroacetylchloride

[Chandresh K. Soni]

CAn anyone suggest the best suitable GC Capillary column for the Analysis of Trifluoroacetyl Chloride and trifluoro acetic acid analysis.
Please Help me for checking the unreacted Trifluoroacetic acid in trifluoroacetyl chloride.

[chromatographer1]

FFAP thick film.

Actually I would suggest a packed column but this is not an option you indicated you would follow.

Good luck,

Rodney George

[Chandresh K. Soni]

Thanks Chromatographer-1 for your suggestion.
actually i have HP innowax column where just checked these samples but after 3-4 analysis i got some problems in my column regarding baseline. it may be due to highy acidic nature of column.
I also used the Methanol for sample preparation . Can we use this column ( HP Innowax).

[chromatographer1]

Why are you using methanol? This will form the methyl ester from the acid chloride. You could also react the free acid to the methyl ester in this exothermic reaction, ruining your analysis? The Innowax has enough basic character to affect the measurement of the free acid. I would not recommend it.

Good luck.

Rodney George

[Chandresh K. Soni]

Thanks for your Guidance.

i will try it on DBFFAP. and give u the feed back.

again thanks

[chromatographer1]

The HCl formed from your reaction will damage any column upon which it is injected .

Don't blame me, Chandresh.

best wishes,

Rodney George

[Chandresh K. Soni]

thanks for again warne to me regarding HCl.

[AICMM]

So Rodney,

The problem here is that both the chloride and the acid are going to react with methanol to form the ester, right? At that point, you could not tell them apart chromatograpically, right?

Been too long since I had to do any real chemistry!!

Best regards.

[chromatographer1]

Hi MM

The acid chloride will react with the methanol and form the Methyl ester.

But the exothermic reaction can react the free acid with the alcohol to form the ester as well.

In addition, methanol is not anhydrous. So the water in the alcohol can react with the acid chloride and form the free acid.

So if you want to test the acid chloride to determine the amount of free acid adding methanol to it is NOT the best path.

HCl is formed too, and that is not known to be kind to the phase of any column and to future analytes injected upon that column. The column should really be dedicated to the acid chloride analysis if that is done.

An expensive analysis that a packed column could do with ease and with a much lower cost. Too bad people think that packed columns no longer have any purpose and that capillary columns are always better. It ain't true.

best wishes,

Rodney George

[Chandresh K. Soni]

Is it Possible to derrivatize the sample with secondary amine to form amide , hope in that case free acid will neutralize with amine and acetyl chloride will form amide which will give me the separate peak and also suggest me the suitable Stationary Phase for packed column.

[chromatographer1]

1% SP-1000 on 60/80 Carbopack B

Fused silica lined SS tubing with SS 10µm screens (deactivated if possible)

I would suggest a 2meter but shorter or longer may be needed.

Acid chlorides can be reacted with anhydrous n-propanol.ethyl ether while the methyl ester is not affected if the methyl ester content is desired.

The free acid should separate from both esters.

best wishes,

Rodney George

[Chandresh K. Soni]

thanks rhodney for your support. i will purchase this and analyse the trifluoroacetyl chloride samples as per your sugestion.

again thanks for your support.