chemist1243
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Diethylamine hydrochloride - Success!
Recently, I asked a question about the synthesis of diethylamine hydrochloride. It was recommended that I not store it in a salt, but after my
distillation colum broke, and just for fun, I’ve decided to go with making diethylamine hydrochloride by hydrolysis of DEET with NaOH, and then
acidification of the mixture with HCl, and then boiling off the liquid to get a solid, which is mostly DEA hydrochloride, with a little salt. It is in
fact not a gummy residue, because there was a point where no more precipitate would fall out, so I killed the heat and filtered the liquid off(which I
will boil down completely to get more DEA out), to reveal diethylamine hydrochloride. It smells a lot like prescription medicine/diethylether/acetone.
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G-Coupled
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Hey - that's pretty good. Nicely done. 
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Boffis
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I don't understand your description of your method but are you sure you have got the diethylamine hydrochloride? firstly it has to be isolated from
the reaction mixture from which it distils are the reaction proceeds and collected in HCl solution, then evaporated down. My initial crop of crystals
were pale golden brown but odourless. They required a second distillation to obtain them pure white. There is nothing wrong with storing the
hydrochloride salt, it is perfectly stable but rather deliquescent (absorbs moisture until it turns to a liquid).
Secondly, from your description your product is not diethylamine hydrochloride but a mixture of sodium chloride and m-toluic acid. Your DEA has become
the angels share as it will have boiled off without distillation and collection.
Thirdly, what is wrong with the previous thread? Why start a new one?
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Pumukli
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Why do you think it is "mostly diethylamine hydrochloride"?
You still have the other half of the starting DEET molecule in your mixture! It is the m-toluic-acid part! Actually, for each mol diethylamine-hcl
there is an equivalent ammount of this acid. Taking into account their respective molar masses you can't really say "mostly diethylamine-hcl". (110
g/mol, 136 g/mol)
To be more exact, your reaction mixture may contain 44% diethylamine-hcl AT MOST. It probably contains much less because you did not distilled off the
amine but neutralized the solution and evaporated the water. There's probably a fair ammount of NaCl in that mixture too. 18-20% may not be
unrealistic, so the "mostly diethylamine-hcl" is probably a mixture of various compounds and MAY contain 25% diethylamine-hcl - if you are lucky! 
(Even a few percent of the amine smell "wonderful", so the smell of the mass is not really counts.)
Before you think I'm too rude with you: it is nothing personal! I really like that you decided to do this hydrolysis reaction because it was a long
standing "gray area reaction" for most of us on this board. I try to point out the mistakes in the hope you can learn from them. Because they are so
basic errors and I fell victim of errors like these when I started to mess with chemistry too.
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chemist1243
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Quote: Originally posted by Pumukli  | Why do you think it is "mostly diethylamine hydrochloride"?
You still have the other half of the starting DEET molecule in your mixture! It is the m-toluic-acid part! Actually, for each mol diethylamine-hcl
there is an equivalent ammount of this acid. Taking into account their respective molar masses you can't really say "mostly diethylamine-hcl". (110
g/mol, 136 g/mol)
To be more exact, your reaction mixture may contain 44% diethylamine-hcl AT MOST. It probably contains much less because you did not distilled off the
amine but neutralized the solution and evaporated the water. There's probably a fair ammount of NaCl in that mixture too. 18-20% may not be
unrealistic, so the "mostly diethylamine-hcl" is probably a mixture of various compounds and MAY contain 25% diethylamine-hcl - if you are lucky!
(Even a few percent of the amine smell "wonderful", so the smell of the mass is not really counts.)
Before you think I'm too rude with you: it is nothing personal! I really like that you decided to do this hydrolysis reaction because it was a long
standing "gray area reaction" for most of us on this board. I try to point out the mistakes in the hope you can learn from them. Because they are so
basic errors and I fell victim of errors like these when I started to mess with chemistry too.
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Okay, so let’s say what I have here is 25% DEA HCl(at best). I think there is a way to over come this.
Do you think that if I treated the salt with ethanolic NaOH solution, maybe I could get a mix of freebase diethylamine in ethanol, which could then be
decanted off and stored? This is similar to a video I watched by chem player, where he did the same with hydrazine sulphate to get the freebase
hydrazine and ethanol.
I can see scaling this up a bit to get more diethylamine. It should also be noted that I only used 25% DEET, so it’s understandable that what I have
is really only around 10-15%.
This isn’t the most efficient method, and definatly not nearly as efficient as the method Boffis uses, but I love to “play” around with
different method to see what I can get to work.
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Boffis
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I echo Pumukli's comments and likewise do not wish to be seen as harsh but from the limited amount of actual experimental description you have
provided it sounds like all liberated amine would have been lost and depending on the ratio of NaOH to DEET you used in your original reaction you
will end up with a mixture of sodium chloride and m-toluic acid. These are easily separated since m-toluic acid is practically insoluble in cold
water.
As I recalled to you earlier I am working on a write up for the pre-pub section and it is nearly complete. In this work I have covered not only the
hydrolysis but also the recovery and purification of the components which is fairly involved and needs attention to detail. The recovery of pure
m-toluic acid is only about 70% because there are impurities that are difficult to separate once they have built up to significant level. The recovery
of pure free diethylamine was about 80%.
When making posts it worth spending a little bit more time to describe in greater detail your results/question/data etc so that other members can make
sensible comments as we can't mind read .
[Edited on 24-11-2019 by Boffis]
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chemist1243
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177ml of 25% DEET was mixed well with 20ml of 75% MeOH (inside of an appropriate bottle with cap). The mixture immediately formed two separate layers.
Added to this was 20g of NaOH, which was shaken in very well. The whole mixture was heated via external hot water bath (40* C) for 1 hour, and then
shaken well once more. The cap was screwed on extra tight, and then the mixture was allowed to sit, in the closed bottle, at room temperature, for 2
days. Over this two-day period, the bottle was shaken very well once every hour, to allow the separate layers to interact fully with each other. A
slightly fishy odor was observed.
After two days, the mixture was refluxed at 50* C for 1 hour. After this, the mixture turned from yellow, to very, very deep yellow, though it had not
become homogeneous yet.
Anyways, a separatory funnel was attached to the only neck on a 1-liter RB flask which contained the refluxed DEET mixture. (I should note at this
point the fishy smell began to get very strong). All joints were sealed very tightly. The flask was sitting in an ice bath hopefully condense any
dimethylamine vapors.
Next, I added 100ml of 31.45% HCl solution to the separatory funnel. The stopcock was turned very slightly, so that the HCl dripped onto the mixture
at a steady, medium pace. Immediately, a white loom of DEA HCl formed, but because of the well-sealed joints, none escaped. I allowed the loom to
“sink” back down unto the mixture until no more foggy cloud was observed. This was repeated until the mixture dropped to a PH of around 4-5.
Good measure, I let the mix sit in the ice bath for an additional 10 minutes to let the rest of the residual fog die down. This mix was transferred to
a 500ml beaker. I used a rubber band to secure a bag over the top of the beaker to prevent any vapors from escaping.
After this whole procedure, I asked for advice in another thread on how to recover my DEA HCl, and your replies made me changed my mind, and I set out
to freebase it again and then fractionally distill of the amine. Of course, like most good things, my plan crumpled to pieces due to my own conscious
actions-more on that later.
Anyways, I decided to start by converting the salt back into a freebase. I did this under the exact same circumstances as I did when salting the
amine, only this time it was done via drop wise addition of saturated NaOH solution until a PH of 9-10 was achieved. I set up my distillation setup
and just as I was about the add the mixture, I was alerted that it was scheduled to rain within the next hour, so I quickly gathered up my setup as
quickly as possible, only forgetting one very important piece of equipment, which was my long path distillation Colum. I figured it would be fine
outside as long as it was safe in its container. This would’ve been the case-had I drained the water out of the Colum before leaving it! Being
November, the cold weather froze the water in the jacket of the Colum, and the glass contracted around this frozen water, cracking it.
In a desperate attempt to make this work while still getting my DEA, I devised a new plan. I would convert my DEA into a salt once more, and then boil
the liquid off. Hopefully, the DEA HCl would precipitate out, allowing me to reacted it with an alcoholic alkaline solution to get a mixture of DEA
and some alcohol.
So once again, I set out to salt it, using the EXACT same method as before, only this time, the upper layer of the solution became an orange red
color, and a white precipitate, which I presumed was NaCl, began to fall out of solution. This mixture was then boiled down, and a very large amount
of fine, brownish, fruity/chemical smelling precipitate fell out of solution when the liquid amount dropped to a level around 40ml of remaining liquid
left. The precipitate was filtered out, leaving dark reddish goop behind, which I will analyze. It you want pics, ill be sure to provide some you.
I hope this clears up any questions about how I obtained the solid wet mass you see in the photo I attached.
[Edited on 24-11-2019 by chemist1243]
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PirateDocBrown
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Why do you not do an extraction with an immiscable organic solvent? (Make some 1,4 dioxane, or distill some starter fluid for ether. Never handle
amines in halogenated solvents.)
Why do you let it stand for 2 days (!) before reflux? Surely reflux would provide much faster reaction as well as the ability for the reactants to
comingle.
[Edited on 11/25/19 by PirateDocBrown]
Phlogiston manufacturer/supplier.
For all your phlogiston needs.
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chemist1243
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| Quote: Originally posted by PirateDocBrown | Why do you not do an extraction with an immiscable organic solvent? (Make some 1,4 dioxane, or distill some starter fluid for ether. Never handle
amines in halogenated solvents.)
Why do you let it stand for 2 days (!) before reflux? Surely reflux would provide much faster reaction as well as the ability for the reactants to
comingle.
[Edited on 11/25/19 by PirateDocBrown] |
i guess diethyl ether could work, but unfortunately, my colum is broke atm. i was planning to recover some diethyl ether from starting fluid soon, but
i guess thats gonna have to wait for a new colum.
as for me waiting 2 days? its been a very wet and cold november where i live. i dont have a fumehood, so i have to go outside for most distillations,
which at this time of the year is rare due to such poor weather conditions.
a 55*C reflux for like 5 hours shouldve done it, but ill take what i can get. thats mostly why i refluxed the daylight out of it as soon as i could
for as long as i could
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monolithic
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| Quote: Originally posted by chemist1243 | | Quote: Originally posted by PirateDocBrown | Why do you not do an extraction with an immiscable organic solvent? (Make some 1,4 dioxane, or distill some starter fluid for ether. Never handle
amines in halogenated solvents.)
Why do you let it stand for 2 days (!) before reflux? Surely reflux would provide much faster reaction as well as the ability for the reactants to
comingle.
[Edited on 11/25/19 by PirateDocBrown] |
i guess diethyl ether could work, but unfortunately, my colum is broke atm. i was planning to recover some diethyl ether from starting fluid soon, but
i guess thats gonna have to wait for a new colum.
as for me waiting 2 days? its been a very wet and cold november where i live. i dont have a fumehood, so i have to go outside for most distillations,
which at this time of the year is rare due to such poor weather conditions.
a 55*C reflux for like 5 hours shouldve done it, but ill take what i can get. thats mostly why i refluxed the daylight out of it as soon as i could
for as long as i could |
You don't need a fume hood to do distillations, unless you're working with something particularly noxious or otherwise hazardous to health. Place some
tubing on the vacuum take off adapter and lead it out of a nearby window. I've done hundreds of distillations like this with all sorts of organic
solvents, and even azeotropic HCl.
[Edited on 11-25-2019 by monolithic]
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Boffis
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Without knowning what the other 75% of the original preparation was its hard to say what you have made but I can't see how you separated the toluic
acid or toluate salt. When you added the acid the copious white precipitate is almost certainly toluic acid. This should have been filtered off or it
will simply dissolve again when you make it alkaline. You don't need a complex fractional distillation system to distil off the amine, particularly if
you are preparing the hydrochloride salt. The fact that you are still getting orange colours and ppts when you add NaOH or acid means that you haven't
got pure amine.
Also how did you add hydrochloric acid from a separating funnel if the system was "well sealed"? You have to have a vent somewhere in the system.
Further more, my experiments found that only very slight hydroysis occurred at 100 C with aqueous NaOH alone that's why I used ethylene glycol and KOH
for the hydrolysis and then collected the amine as it distilled off. Even at these temperature (about 160 C) hydrolysis was slow and took many hours.
A little water appears to be essential at least at the beginning of the reaction.
I suggest you think about your experiment design more carefully before you start playing with chemicals. When I design an experiment I will write down
my proposed procedure and then I usually conduct it on a 1g scale first. Then taking into account anything I have learned from the first experiment I
will try again at say 1 or 5g scale and so on until I am confident I can carry it out succesfully and safely at the required scale. For instance in
another thread I described the preparation of chlorophenol-sulphonic acid dye intermediates, before I launched into mixing 100g of phenol with 70-80g
of sulphuryl chloride I carried out 5 separate experiments at increasing scale BEFORE my preparation run so that I knew what to expect in the way of
exothermc reactions and how to work up the reaction mixture. This not only save you from wasting expensive chemical it may also save you from an early
grave!
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PirateDocBrown
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That brings up another good point. Why use an impure starting material, when you don't have to? 100% DEET is readily available, OTC and online.
Phlogiston manufacturer/supplier.
For all your phlogiston needs.
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Boffis
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I was unable to find 100% DEET locally but 95% was easy to come by. The main impurities seem to be lime oil (fragrance), dodecanol or some similar
high boil point alcohol and good old ethanol, what proportion these make up is not stated but the last I thought would boil off, the dodecanol is
inert to the reaction and the amount of lime oil too small to care about .
[Edited on 26-11-2019 by Boffis]
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monolithic
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Are there any over the counter compounds that can be hydrolyzed to yield n-methylethan-1-amine? I did some searching but I'm not finding much.
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Pumukli
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Monolithic: I doubt if it was. Such assymetric amin is harder to manufacture than say dimethyl- or diethyl-amine and for most porpuses the symmetrical
varieties are satisfactory. I've never came across any compounds or goods that used such methyl-ethyl-amine.
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monolithic
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| Quote: Originally posted by Pumukli | | Monolithic: I doubt if it was. Such assymetric amin is harder to manufacture than say dimethyl- or diethyl-amine and for most porpuses the symmetrical
varieties are satisfactory. I've never came across any compounds or goods that used such methyl-ethyl-amine. |
That's a shame. I don't think there are any accessible laboratory preparations of it, either, only industrial methods.
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Boffis
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@ monolithic, there is a recently resurrected thread with an old link to a paper that describes the use of sodium saccharin in a two stage reaction
that allow the preparation of asymmetric amines by condensing an alkyl halide with the ionised imino group in saccharin, partial hydrolysis to break
the imino ring and then a second alkyl halide followed by hydrolysis of the sulphonamide. I can't remember which thread but was fairly recent.
Ah found it:
http://www.sciencemadness.org/talk/viewthread.php?tid=19483#...
[Edited on 27-11-2019 by Boffis]
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chemist1243
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| Quote: Originally posted by monolithic | | Quote: Originally posted by chemist1243 | | Quote: Originally posted by PirateDocBrown | Why do you not do an extraction with an immiscable organic solvent? (Make some 1,4 dioxane, or distill some starter fluid for ether. Never handle
amines in halogenated solvents.)
Why do you let it stand for 2 days (!) before reflux? Surely reflux would provide much faster reaction as well as the ability for the reactants to
comingle.
[Edited on 11/25/19 by PirateDocBrown] |
i guess diethyl ether could work, but unfortunately, my colum is broke atm. i was planning to recover some diethyl ether from starting fluid soon, but
i guess thats gonna have to wait for a new colum.
as for me waiting 2 days? its been a very wet and cold november where i live. i dont have a fumehood, so i have to go outside for most distillations,
which at this time of the year is rare due to such poor weather conditions.
a 55*C reflux for like 5 hours shouldve done it, but ill take what i can get. thats mostly why i refluxed the daylight out of it as soon as i could
for as long as i could |
You don't need a fume hood to do distillations, unless you're working with something particularly noxious or otherwise hazardous to health. Place some
tubing on the vacuum take off adapter and lead it out of a nearby window. I've done hundreds of distillations like this with all sorts of organic
solvents, and even azeotropic HCl.
[Edited on 11-25-2019 by monolithic] |
are you sure? ive hear diethyl ether is pretty trickybecause it crawls along surfaces until it reaches ignition sources. same with diethylamine.
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chemist1243
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| Quote: Originally posted by Boffis | Without knowning what the other 75% of the original preparation was its hard to say what you have made but I can't see how you separated the toluic
acid or toluate salt. When you added the acid the copious white precipitate is almost certainly toluic acid. This should have been filtered off or it
will simply dissolve again when you make it alkaline. You don't need a complex fractional distillation system to distil off the amine, particularly if
you are preparing the hydrochloride salt. The fact that you are still getting orange colours and ppts when you add NaOH or acid means that you haven't
got pure amine.
Also how did you add hydrochloric acid from a separating funnel if the system was "well sealed"? You have to have a vent somewhere in the system.
Further more, my experiments found that only very slight hydroysis occurred at 100 C with aqueous NaOH alone that's why I used ethylene glycol and KOH
for the hydrolysis and then collected the amine as it distilled off. Even at these temperature (about 160 C) hydrolysis was slow and took many hours.
A little water appears to be essential at least at the beginning of the reaction.
I suggest you think about your experiment design more carefully before you start playing with chemicals. When I design an experiment I will write down
my proposed procedure and then I usually conduct it on a 1g scale first. Then taking into account anything I have learned from the first experiment I
will try again at say 1 or 5g scale and so on until I am confident I can carry it out succesfully and safely at the required scale. For instance in
another thread I described the preparation of chlorophenol-sulphonic acid dye intermediates, before I launched into mixing 100g of phenol with 70-80g
of sulphuryl chloride I carried out 5 separate experiments at increasing scale BEFORE my preparation run so that I knew what to expect in the way of
exothermc reactions and how to work up the reaction mixture. This not only save you from wasting expensive chemical it may also save you from an early
grave! |
my plan was articulated in an ordered fasion, but the procedure was obviously not. i only posted what i did from start to finish, not what i had
planned to do. ill try again sometime when the weather is more...predictable. right now i currently a experiencing 60mph winds so everything outside
is a no-go at the moment.
i do believe that purer starting material would work, but figured that according to the MSDS, since what wasnt DEET in the 25% stuff was mostly
ethanol, it wouldnt hurt as long as i scaled down the material amounts in my original procedure by 75%, i would be fine, but as is the case i guess i
was wrong. im taking all of your suggestions from here and using them to formulate a hopefully better plan. thanks for all the help, this thread got
alot bigger than i originally intended.
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chemist1243
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so, as a quick recap of what i have learned(correct me if im wrong), this is all information that will help me greatly in deveolping a method of doing
this.
1: For each mole of diethylamine HCl obtained from the hydrolysis, there will also be one mole of toluic acid.
2: Distilling off diethylamine results in higher yield than just boiling off the liquid until I get a solid.
3: It is best to conduct the experiment on a small scale (such as 1g) to see if it works before trying to do larger amounts.
4: Only very slight hydrolysis occurs when using NaOH at 100 C.
5: Using a solvent with a high boiling point(such as ethylene glycol) at a
high temperature, as well as using KOH instead instead of NaOH results in more complete hydrolysis than the former method.
6: Distilling off the amine as it forms instead of refluxing will save a lot of amine which otherwise would just escape from the mixture.
7: If I need help Its better to use the original thread than opening a whole new can of worms with another one.
[Edited on 27-11-2019 by chemist1243]
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chemist1243
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| Quote: Originally posted by Boffis | Without knowning what the other 75% of the original preparation was its hard to say what you have made but I can't see how you separated the toluic
acid or toluate salt. When you added the acid the copious white precipitate is almost certainly toluic acid. This should have been filtered off or it
will simply dissolve again when you make it alkaline. You don't need a complex fractional distillation system to distil off the amine, particularly if
you are preparing the hydrochloride salt. The fact that you are still getting orange colours and ppts when you add NaOH or acid means that you haven't
got pure amine.
Also how did you add hydrochloric acid from a separating funnel if the system was "well sealed"? You have to have a vent somewhere in the system.
Further more, my experiments found that only very slight hydroysis occurred at 100 C with aqueous NaOH alone that's why I used ethylene glycol and KOH
for the hydrolysis and then collected the amine as it distilled off. Even at these temperature (about 160 C) hydrolysis was slow and took many hours.
A little water appears to be essential at least at the beginning of the reaction.
I suggest you think about your experiment design more carefully before you start playing with chemicals. When I design an experiment I will write down
my proposed procedure and then I usually conduct it on a 1g scale first. Then taking into account anything I have learned from the first experiment I
will try again at say 1 or 5g scale and so on until I am confident I can carry it out succesfully and safely at the required scale. For instance in
another thread I described the preparation of chlorophenol-sulphonic acid dye intermediates, before I launched into mixing 100g of phenol with 70-80g
of sulphuryl chloride I carried out 5 separate experiments at increasing scale BEFORE my preparation run so that I knew what to expect in the way of
exothermc reactions and how to work up the reaction mixture. This not only save you from wasting expensive chemical it may also save you from an early
grave! |
you say that even at tempatures around 160 C in an enviorment of KOH, that the hydrolysis still takes many hours to complete.
if you're willing to say, how many hours?
as a side note, i was wondering what your thoughts were on acid hydrolysis instead of base hydrolysis. i considered it a long time ago but couldnt
find anything on it so i decided to focus on base hydrolysis.
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monolithic
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| Quote: Originally posted by chemist1243 |
are you sure? ive hear diethyl ether is pretty trickybecause it crawls along surfaces until it reaches ignition sources. same with diethylamine.
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Unless your ground glass joints are severely defective, the only possible path for the fumes is through the take off adapter... which will travel
through the hose and out the window.
Boffis, very interesting, will take a look.
[Edited on 11-27-2019 by monolithic]
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chemist1243
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| Quote: Originally posted by monolithic | | Quote: Originally posted by chemist1243 |
are you sure? ive hear diethyl ether is pretty trickybecause it crawls along surfaces until it reaches ignition sources. same with diethylamine.
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Unless your ground glass joints are severely defective, the only possible path for the fumes is through the take off adapter... which will travel
through the hose and out the window.
Boffis, very interesting, will take a look.
[Edited on 11-27-2019 by monolithic] |
hmm. does it matter weather the window is above you or below you? i would imagine if it was above than the air from the outside would just get sucked
back in through the take off adapter because it is lower pressure than where the other end of the tube is(if the setup is truly sealed well)
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DavidJR
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Uhh... what? Why would it be at a lower pressure?
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chemist1243
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wait nevermind....im thinking about this like a water siphon. i forgot that for the apmosphere, air pressure decreases as altitude increases.
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