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Author: Subject: Auto-ignition temperature
Serybva
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[*] posted on 13-4-2022 at 00:30
Auto-ignition temperature


One way to make acetaldehyde is to oxidize ethanol vapors over red hot copper wire, the copper temperature is said, in a paper I found, to be around 500-600° which corresponds to "red hot" state.

However auto-ignition temperature of ethanol is 365°, so why ethanol vapors don't ignite upon contact with the copper?
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B(a)P
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[*] posted on 13-4-2022 at 02:04


Presumably you exclude oxygen from the reaction.
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Texium
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13-4-2022 at 05:39
Serybva
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[*] posted on 14-4-2022 at 04:57


Quote: Originally posted by B(a)P  
Presumably you exclude oxygen from the reaction.

Actually no, oxygen is required for the reaction to take place and there is videos on youtube that show the reaction by just suspending a red hot penny in a beaker with some ethanol in it
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unionised
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[*] posted on 14-4-2022 at 06:14


If the ratio of air to fuel vapour is far enough from ideal then you won't get ignition.

More importantly, you can do that reaction without air.

https://en.wikipedia.org/wiki/Acetaldehyde#Dehydrogenation_o...
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Serybva
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[*] posted on 15-4-2022 at 06:08


Quote: Originally posted by unionised  
If the ratio of air to fuel vapour is far enough from ideal then you won't get ignition.

More importantly, you can do that reaction without air.

https://en.wikipedia.org/wiki/Acetaldehyde#Dehydrogenation_o...

Thanks !
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reactofurnace
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[*] posted on 6-5-2022 at 06:10


Would you dissolve the acetaldehyde produced in water?
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Antiswat
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[*] posted on 27-5-2022 at 03:22


supposedly air-fuel ratio, as most fuels- acetylene and ethylene oxide excluded as they can "burn" in 100% concentration (more like, detonate sorta)

im having some ideas of coating sand or pebbles in platinum and then pumping air into EtOH/Pt catalyst, this idea i came to when another user mentioned having some Pd/C laying around
if the oxidation can happen directly- presumably at quite low temperature inside of the ethanol you could end up with an extremely safe reaction- this reaction is especially dangerous with methanol as it more oftenly ignites than ethanol, benzyl alcohol may also be oxidized like this but the boiling point makes it a more difficult operation
avoid using acetone as this will form deadly toxic ketene- a fellow chemist did run a ketene lamp without knowing anything about ketene, no windows open or anything and hes still around, but its potentially deadly scenario




~25 drops = 1mL @dH2O viscocity - STP
Truth is ever growing - but without context theres barely any such.

https://en.wikipedia.org/wiki/Solubility_table
http://www.trimen.pl/witek/calculators/stezenia.html
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