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Metacelsus
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Question about paraformaldehyde and imines
Can paraformaldehyde be used to form imines?
Specifically, I'm thinking about the reaction with ethylamine to form N-methylethanimine.
If not, is there another form of formaldehyde I could use?
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Random
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acid salts quick question
Does monosodium citrate react with trisodium citrate to form two amounts of disodium citrate?
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bfesser
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Yes. Equilibrium. Next time, post in the right place. Spamming Beginnings out of laziness is unacceptable, and I may move such
posts to Detritus.
[Edited on 1.1.14 by bfesser]
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bfesser
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Threads Merged
1-1-2014 at 11:05 |
Nicodem
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Quote: Originally posted by Cheddite Cheese  | Can paraformaldehyde be used to form imines?
Specifically, I'm thinking about the reaction with ethylamine to form N-methylethanimine.
If not, is there another form of formaldehyde I could use? |
The condensation of ethylamine with (para)formaldehyde does not give N-methylethanimine. You need acetaldehyde and methylamine for that.
The condensation of primary amines with formaldehyde normally gives the corresponding 1,3,5-trialkyl-hexahydro-s-triazines. The reaction with
paraformaldehyde gives the same product, just much more slowly.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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DubaiAmateurRocketry
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Does hydrated sodium sulfate dissolve in Ethanol or methanol ?
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elementcollector1
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Not sure whether to post this in Bad days in the lab or with glassware? or here... so I'll post it here.
I recently received a vacuum gauge. However, it is currently at 4.5 inches Hg despite not being connected to anything. How do I fix this?
[Edited on 1-3-2014 by elementcollector1]
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DubaiAmateurRocketry
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Whats the easiest way to measure the visousity of a liquid ? the answer does not havet to be perfect.
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Zyklon-A
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http://www.wikihow.com/Measure-Viscosity
(I have not tried this method myself yet.)
[Edited on 7-1-2014 by Zyklonb]
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DubaiAmateurRocketry
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Is there a method I heard that you put a drop on a flat board like object, and then place this thing at an angle, and it will flow down, the time it
takes to cover what ever distance is its visousity. I dont know what is that called..
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bfesser
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No, DubaiAmateurRocketry, that is not a valid way of measuring viscosity—it would be more of a measure of <a
href="https://en.wikipedia.org/wiki/Adhesion" target="_blank">adhesion</a> <img src="../scipics/_wiki.png" /> than <a
href="https://en.wikipedia.org/wiki/Viscosity" target="_blank">viscosity</a> <img src="../scipics/_wiki.png" />. <a
href="https://en.wikipedia.org/wiki/Viscometer" target="_blank">Viscometers</a> <img src="../scipics/_wiki.png" /> and stopwatches are
readily and cheaply available on eBay. Also, please don't use this thread as a substitute for a simple <a
href="http://lmgtfy.com/?q=measure+viscosity" target="_blank">Google</a> <img src="../scipics/_ext.png" /> or literature search.
[Edited on 7.1.14 by bfesser]
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alexleyenda
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When something is soluble in Ethanol, can I assume it will also be soluble in methanol? Same question for insoluble?
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DraconicAcid
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The solubility of a solute in methanol will differ quantitatively from that in ethanol, but not by much (for most solutes).
Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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Zyklon-A
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I have a question, I guess.
I was producing H2 this morning, via reaction of Al with HCl(aq), in a test tube, (for another reaction), however something strange happened, I put a
cork (an actual cork not a rubber stopper) on the tube, and then the H2 caught on fire, not a big deal of course, but it was random.
I want to know why it caught fire, that has never happened to my before.
The tube was warm (from the reaction), but not hot, the cork caught on fire too, thus keeping the flame alive.
I blowed it out but it caught fire again, and again, I think 4-5 times.
Does anyone know why it did that? Perhaps the cork acts as a catalyst of some kind, I know Pt catalyzes the reaction of H2 and O2, maybe this does as
well?
For the record, I tried it again but it failed to work.
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elementcollector1
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H2 usually burns with an invisible flame - are you sure something else wasn't catching fire somehow?
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Zyklon-A
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Like I said, the cork did catch on fire, but it was the H2 that initiated the reaction.
[Edited on 8-1-2014 by Zyklonb]
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Mailinmypocket
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Did the cork pop out of the tube when this event took place? When you were blowing it out and it was continuously reigniting, was this due to the
burning cork still being on the tube? Hydrogen usually burns with a pop and doesn't reignite itself if generated in a test tube and lit while being
generated.
Let's just say the cork was a catalyst in some parallel universe, it should be able to cause the same thing to happen again if repeated. The fact that
it did not makes me wonder what else was around or going on, it's very hard to imagine how this would happen by reading your post!
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alexleyenda
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To me it sounds like your cork stopper was contaminated by some kind of catalyst. Also it could help to describe a bit more how it happened. Was the
stopper made with an hole and connected to tubing or was it a solid stopper. Did you put it during the reaction or after just to contain the hydrogen?
By the way H2's flame is very easy to see if something else burns around it ( like cork for example ) ! It also often comes with a noise when it
ignites and the heat and the distortion of the air it causes is also easy to detect.
[Edited on 8-1-2014 by alexleyenda]
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Metacelsus
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My guess: static electricity. Can you provide more detail on how the hydrogen reignited? Did the cork serve as a sort of pilot light?
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Zyklon-A
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| Quote: Originally posted by Mailinmypocket | Did the cork pop out of the tube when this event took place? When you were blowing it out and it was continuously reigniting, was this due to the
burning cork still being on the tube? Hydrogen usually burns with a pop and doesn't reignite itself if generated in a test tube and lit while being
generated.
Let's just say the cork was a catalyst in some parallel universe, it should be able to cause the same thing to happen again if repeated. The fact that
it did not makes me wonder what else was around or going on, it's very hard to imagine how this would happen by reading your post!
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Yes the cork did pop out, the first time it hit the roof, the other times there was not enough H2 to hit the roof, but it did pop up.
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Zyklon-A
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Yes, that's exactly my guess, but as for the first time....
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Zyklon-A
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The cork was solid, also there was pressure building up in the tube, I'm starting to doubt that a catalyst is the cause, I think it may be static
electricity, as Cheddite Cheese stated. I'm not sure though.
Edit: Ok, I tried it again, and it happened again!
Can someone else try it too, maybe my cork is special?
This is so weird, LOL.
[Edited on 8-1-2014 by Zyklonb]
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alexleyenda
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I don't know why you would put a solid stopper on an ongoing gas producing reaction :p but anyways my guess would be that with the pressure, a bit of
H2 escapes really quickly around the stopper and the friction creates enough heat to ignite the H2. Another theory, this one is quite mad but who
knows: There is H2 and O2 in the flask, pressure builds up, the 2 H2 + O2 ---> 2 H2O reaction is favorised as 2 moles of gas takes less place than
3 moles of gas so even if the flask is only warm it ignites to counterbalance the pressure.
[Edited on 8-1-2014 by alexleyenda]
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elementcollector1
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^Not likely. At STP, a mole of gas is 22.4 liters. The average test tube is about 10-20 mL, so you do the math. There is much more hydrogen than
oxygen, and as far as I know only the stoichiometric mixture is prone to spontaneous explosion.
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alexleyenda
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Yeah I was just talking about the mole ratio and I know that in normal conditions it would not happen but as it is under pressure, maybe .. ! Anyways
as I said this is a mad theory, I don't really think it is right but hey I would give it a try, you could maybe try it with a rubber stopper to see if
it works. If it doesnt then there are good chances it is because of the pressure.
[Edited on 8-1-2014 by alexleyenda]
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Zyklon-A
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I think a nonstoichiometric mixture could at least ignite, (From Wikipedia: ''Hydrogen is easily ignited, as it is flammable over a wide range of
concentrations in air, so that the test does not rely on having an exact mixing ratio.'') Obviously there is some 02 in there. I don't think that the
pressure in the tube could ignite it though, it happening twice at different times rules out static electricity, I think.
Edit: tried a rubber stopper, nothing happened.
[Edited on 8-1-2014 by Zyklonb]
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