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Science Forum Index » Chemistry Forum » Prep of N,N-diethylarylamines?...
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| BAJJERFAN... |
 Posted: Thu May 29, 2008 11:52 am |
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Has anyone had any experience with the prep of dialkylarylamines
starting from the aniline plus triethylphosphate as described by
Billman, J Amer Chem Soc, 68, 895 (1946)? Looking most for info on
exothermic reaction using kilo quantities up to several hundred
kilos.I assume there is little danger of a reaction getting out of
hand but just want to be sure. |
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| Posted: Fri May 30, 2008 12:32 pm |
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On May 29, 2:52 pm, BAJJERFAN <BAJJER... at (no spam) aol.com>
Quote: I assume there is little danger of a reaction getting out of
hand but just want to be sure.
If your reaction is not sufficiently exothermic to necessitate cooling
at some scale of reaction then your reaction is not likely to proceed
spontaneously. The only endothermic reaction that proceed
spontaneously are entropically driven by some sort of phase change. Do
you have much experience with chemical reactions to warrant a chemical
engineering pint of view? Start with small reaction size first and
learn from your mistakes |
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| Ron Jones... |
| Posted: Fri May 30, 2008 2:23 pm |
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BAJJERFAN wrote:
Quote: Has anyone had any experience with the prep of dialkylarylamines
starting from the aniline plus triethylphosphate as described by
Billman, J Amer Chem Soc, 68, 895 (1946)? Looking most for info on
exothermic reaction using kilo quantities up to several hundred
kilos.I assume there is little danger of a reaction getting out of
hand but just want to be sure.
It can be hard to generalize - some anilines might be more reactive (or even
worse - less reactive) than others. Therefore you will not know what is the
maximum accumulation in your reaction. Without that data, you cannot say if
your addition rate is too fast, or if your cooling system could cope with
any problems. What you really need is some calorimetry run on your proposed
process. If you cannot do that yourself, then there's plenty of contractors
who could.
--
Ron Jones
Process Safety & Development Specialist
Don't repeat history, unreported chemical lab/plant near misses at
http://www.crhf.org.uk Only two things are certain: The universe and
human stupidity; and I'm not certain about the universe. ~ Albert
Einstein |
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| BAJJERFAN... |
| Posted: Sat May 31, 2008 5:40 am |
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On May 30, 5:32 pm, nico... at (no spam) hushmail.com wrote:
Quote: On May 29, 2:52 pm, BAJJERFAN <BAJJER... at (no spam) aol.com
I assume there is little danger of a reaction getting out of
hand but just want to be sure.
If your reaction is not sufficiently exothermic to necessitate cooling
at some scale of reaction then your reaction is not likely to proceed
spontaneously. The only endothermic reaction that proceed
spontaneously are entropically driven by some sort of phase change. Do
you have much experience with chemical reactions to warrant a chemical
engineering pint of view? Start with small reaction size first and
learn from your mistakes
Thanks for the info. It sounds from the procedure that one just mixes
and heats. Prolly ok on a lab scale. If it works of course scaleup is
a consideration along with price. Just trying to anticipate problems
in advance. There is also a procedure that might work which involves
heating the anhydrous arylamine hydrochloride with ethanol at elevated
temperatures, but this might limit your choice of an outside source
since not very may places have the equipment to do this on a large
scale. |
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| Ron Jones... |
| Posted: Mon Jun 02, 2008 1:56 pm |
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BAJJERFAN wrote:
Quote: On May 30, 5:32 pm, nico... at (no spam) hushmail.com wrote:
On May 29, 2:52 pm, BAJJERFAN <BAJJER... at (no spam) aol.com
I assume there is little danger of a reaction getting out of
hand but just want to be sure.
If your reaction is not sufficiently exothermic to necessitate
cooling at some scale of reaction then your reaction is not likely
to proceed spontaneously. The only endothermic reaction that proceed
spontaneously are entropically driven by some sort of phase change.
Do you have much experience with chemical reactions to warrant a
chemical engineering pint of view? Start with small reaction size
first and learn from your mistakes
Thanks for the info. It sounds from the procedure that one just mixes
and heats. Prolly ok on a lab scale. If it works of course scaleup is
a consideration along with price. Just trying to anticipate problems
in advance. There is also a procedure that might work which involves
heating the anhydrous arylamine hydrochloride with ethanol at elevated
temperatures, but this might limit your choice of an outside source
since not very may places have the equipment to do this on a large
scale.
If I had a pound for every prep I have seen that said "add all the
ingredients and cook", then I could retire now. I've seen mole preps on a
lab scale that look OK, but would cause a huge excursion on plant.
--
Ron Jones
Process Safety & Development Specialist
Don't repeat history, unreported chemical lab/plant near misses at
http://www.crhf.org.uk Only two things are certain: The universe and
human stupidity; and I'm not certain about the universe. ~ Albert
Einstein |
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