Acid and Acid chloride separation by GC

Chromatography Forum: GC Archives: Acid and Acid chloride separation by GC
Top of pagePrevious messageNext messageBottom of pageLink to this message  By Bhaskar on Sunday, December 14, 2003 - 10:31 pm:

Can any body suggest me a GC method to separate acids and acid chlorides?

Thanks in advance.

BhaskarReddy


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Monday, December 15, 2003 - 02:31 am:

Acid chlorides are very reactive. I'd derivatise them with a primary amine or such like first. The raw acids should not react.
John


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Anonymous on Wednesday, December 17, 2003 - 10:59 am:

Diethylamine is a good one to use. Add some toluene to dilute sample and absorb heat of reaction. Filter off the amine hydrochloride if it precipitates. If the acids to not elute well derivatise a second time with BSTFA


Top of pagePrevious messageNext messageBottom of pageLink to this message  By Reini on Tuesday, December 30, 2003 - 05:19 am:

We analyze since 20 years acid chlorides (C1 - C9)without derivatisation. We have a XY-1301 phase, id 0.53mm. Important is the use of a syringe with a platin needle and a wolfram plunger to order by Hamilton. It needs some expirience by the handling.
Good luck
Reini


Top of pagePrevious messageNext messageBottom of pageLink to this message  By mmm on Monday, August 2, 2004 - 11:56 am:

I wondered if any could expand on the idea of analyzing acid chlorides without derivitization.Two of the impurities we are looking at derivitize into the same tri-ester.We have also tried normal phase HPLC (the main component is an anhydride)but response factor is unpredictable.This is espicially true for the main component.As the purity gets higher from 98%-99% the main component practically disappears.I was using a silica column, but will try a CN column to avoid any possible reaction with the silica.
Any information on a GC or LC method would be helpful.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By chromatographer1 on Tuesday, August 3, 2004 - 05:51 am:

GC is not recommended for underivatized analysis unless you have a VERY inert injection port and column. The acid chlorides will react with any, repeat ANY, silanol available or other reactive material in your system.

It can be done but only after carefully deactivating your system. Of course, we won't discuss the atmospheric water in your syringe and handling problems of the acid chloride.

Or you can:

Make a propyl ester of the acid chloride to separate it from the free acid impurities and the methyl ester starting material, 37C overnight in anhydrous ether and n-propanol. Inject directly.


Top of pagePrevious messageNext messageBottom of pageLink to this message  By A.Mouse on Tuesday, August 3, 2004 - 06:39 pm:

well, I am not sure... I would think that it can be solved with the correct combination of packing material, frits and column. There are completely organic (and unreactive) packings available for GC, the frits and the column wall can also be constructed of unreactive materials.
Of course, the simpler solution may very well be to get around the problem, as the previous post suggested.


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