ethyl acetoacetate

[WK]

Hi everyone
Does anyone know anything about the stability of ethyl acetoacetate in GC injector ports?
Does it break down to ethanol & the acid?
I'm using 220degC
WK

[safwatali]

Hi Wk,

Ethyl acetoacetate has a boiling point 181 C, so I think 220 C is not able to break the compound.

Do you try to separate it By GC and obtain more than one peak?

Safwatali

[xxx]

If you have an on column injector,try this and compare with a splitless injection to see if you have a major decomposition.

[WK]

Thanks for the replies Safwatali & xxx:
Safwatali - I get a few peaks at 220 and 250degC and the peak shape is not great anyway.
I tried 180 & 200degC injector ports overnight and the decomposition is much less at lower temperature - I have not quantified this yet.
Will do some more work on it soon but this info is useful now to get me by.
Regards
WK

[oscarBAL]

I never has analized that compound, but I has saw that some molecules can sufer thermal descompisition catalized by the metal of the needle, so if you have a GC with thermal rate on the injection port try to inject a low temperature, and then increas it fastly antil the temperature that you need.

[chromatographer1]

It has been over 20 years since I did a purity analysis of that chemical, but I do remember a thermal sensitivity. Of course, from its chemical structure one can see that metal contact should be avoided. Unfortunately, most syringe needles are made of metal.

I think if you call Eastman Chemical Company or Sigma/Aldrich Technical Service they will be able to give you helpful information concerning analytical testing of this chemical.

Good luck.

[Radish]

For the benefit of the chemically challenged, exactly what is it about the structure that makes contact with metal a bad thing?

[safwatali]

HI WK,

How many peaks did you obtain at 180 and 220 & the Relative percent area, and the Retention time, also, what is the column temperature?
Do you have one peak reepresents about 10% of the main peak.

Safwatali

[chromatographer1]

a remembrance

using non-polar phases seemed to give better peak shape and stability to the impurities and to the balance.

Try to keep your injector and detector temperatures below 120°C, use flow to volatilize instead of heat and minimize the amount injected neat, use isopentane or some other very volatile solvent for injection if possible.

Cold on column injection would be great. (so would a thick film methyl silicone capillary column) I did not have that option 25 years ago.