[HailoMan]

Hi,

I'm planning to use ethylenediamine and decided to look up the safety info about ethylenediamine.
Of course I went to Wikipedia to check out what it's got to say about it:

"The vapors react with moisture in humid air to form a characteristic white mist, which is extremely irritating to skin, eyes, lungs and mucus membranes. Exposure to a relatively small amount of vapor or mist by inhalation can seriously damage health and may even result in death".

, which is rather alarming....

My question is, what is the product from the reaction of water vapour with ethylenediamine? (Sorry if it is blatantly obvious. I presume being an amine it'll act an a proton acceptor, but it just seems odd seeing that it is in gas phase?!?!?)

I guess what confuses me is of how ethylenediamine is supposed to be soluble (not reactive) in water. Why then would the vapour react with moisture in humid air?

Thanks in advanced.

[kriggy]

I think It´s probably something like
R-NH₂+H₂O -> R-NH₃⁺ + OH^-

[TheUnassuming]

I don't know that its more reactive in air than in solution, it is probably a matter of exposure.  I wouldn't think it would be any more dangerous than any other volatile amine as in any case it would just form an ammonium hydroxide which is not something you want to breath. 

[Enthalpy]

From the Msds I have, it's essentially corrosive, as expected from an amine. Not carcinogenic, but potentially allergenic (depending on individual as usual).

The maximum allowable concentration in air is 10ppm; this equals the odour detection threshold by humans.
200ppm irritate human nose and are the LCLo, 400ppm are intolerable.
The vapour pressure at +20°C is 10mmHg or 13,000ppm - that would be the concentration if air above EDA were sealed. 65 times dilution bring you to 200ppm.

EDA vapour, being hygroscopic as an alkali, should react with water vapour in air to make liquid droplets of alkaline solution. But if no humidity at all were available in air, the EDA vapour woud find it in the lungs anyway.

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If someone plans a rocket fuel with high H/C ratio to avoid sooting, EDA plus guanidine looks like the best replacement for methylamine.

For rocket fuels of normal use, tertiary amines are better, since their liquid range improves. Methylating all amine functions at once is cheap. Then, heavier compounds like pentamethyl-diethylene-triamine (PMDETA) are not volatile hence not flammable. Propylamines should improve the liquid range further, if they keep the magic in farnesane and phytane.

[Enthalpy]

To make my opinion, I've looked for common compounds with similar toxic concentration and vapour pressure, and one is formaldehyde.

Though, the odour differs, the detection limit by nose and so on.