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Author Topic: Decomposition of DMF  (Read 1688 times)

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vikram

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Decomposition of DMF
« on: October 05, 2018, 08:35:24 PM »

I am quite unsure about decomposition temperature of DMF (into CO and dimethylamine).Some sources say just upon heating and some other are like above 350 °C.Do anyone have clear idea?

Thanks in advance :)
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Enthalpy

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Re: Decomposition of DMF
« Reply #1 on: October 09, 2018, 02:45:05 AM »

At least the boiling point of +153°C mentions no decomposition.
One source tells +350°C there
http://www.inchem.org/documents/hsg/hsg/hsg043.htm

Why shouldn't you try yourself? Take a monoxide detector, heat, observe.

I wonder how sensitive the decomposition is to other compounds, impurities and trace pollutants.
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wildfyr

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Re: Decomposition of DMF
« Reply #2 on: October 09, 2018, 03:03:36 AM »

Every sample of DMF I've ever encountered in my life contained at least trace dimethylamine. DMF itself (and DMSO for that matter) do not smell strongly, but the decomposition products (dimethyl amine and dimethyl sulfide) are compounds we are evolved to smell at ppb levels.

Enthalpy, getting it to that temperature requires a high-pressure bomb reactor...
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vikram

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Re: Decomposition of DMF
« Reply #3 on: October 09, 2018, 03:20:10 PM »

Thanks wildfire and enthalpy for your inputs:)
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clarkstill

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Re: Decomposition of DMF
« Reply #4 on: December 05, 2018, 09:23:49 PM »

But the decomposition is acid and base-catalysed, so that temperature might be quite a lot lower under whatever reaction conditions you are using. For example, we saw quite a bit of dimethylamine when doing a NaH reaction in DMF at 100 C.
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zarhym

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Re: Decomposition of DMF
« Reply #5 on: December 07, 2018, 08:37:30 PM »

DMAc is a substitution of DMF for higher temperature reaction.
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BobfromNC

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Re: Decomposition of DMF
« Reply #6 on: December 18, 2018, 08:56:53 AM »

I have run many reactions of DMF at reflux overnight, and there has never been a sign of any real amount of decomp. in them at the BP for 16+ hours.   But as stated, there is almost always a smell of DiMeNH2 in it, so there must be some small equilibrium to the decomp. at RT.    But it is fine for high temps.   If DMF or DMA is not ideal, NMP is the best thing, as it is nearly impossible to decomp, even with conc H2SO4 in it.
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Babcock_Hall

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Re: Decomposition of DMF
« Reply #7 on: December 18, 2018, 09:23:46 AM »

BobFromNC,

I am not familiar with two of your abbreviations, DMA and NMP.
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wildfyr

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Re: Decomposition of DMF
« Reply #8 on: December 18, 2018, 11:16:11 AM »

DMA is Dimethyl acetamide and NMP is N methyl pyrrolidone. Both are polar aprotic high boiling solvents of the same ilk as DMF. DMA is toxic, NMP is generally not I believe.
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