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Author: Subject: Diethylamine Synthesis
ScienceSquirrel
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[*] posted on 28-8-2008 at 08:53


Quote:
Originally posted by mbrown3391
1. Prepare a solution of 80g NaOH in 73ml H2O.
2. To this solution, add 192ml of DEET. Two layers will form.
3. While stirring, slowly add ethylene glycol to the mixture until homogeneous.
4. Add a small amount to a distillation apparatus and heat to 55 degrees C. If all goes well, add the rest and maintain 55 degrees C until boiling ceases
5. Theoretical Yield: 103.39ml Diethylamine

[Edited on 28-8-2008 by mbrown3391]


That is a recipe for a trip to A & E
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[*] posted on 28-8-2008 at 09:01


Quote:
Originally posted by ScienceSquirrel
3) You have switched ethylene glycol for propylene gycol

[Edited on 28-8-2008 by ScienceSquirrel]


PG is listed as a solvent for DEET on the MSDS. Pure PG is available on eBay. I think the inexperienced might be tempted to use antifreeze instead of going to the bother of sourcing pure EG. Antifreeze contains a lot of other stuff that might cause problems.




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[*] posted on 28-8-2008 at 09:06


But heating a solution of potassium hydroxide in propylene glycol may result in side reactions producing brown goos.

If he uses antifreeze all bets are off.

Anyway look at the scale he is thinking of trying this on.

He will have about half a litre of hot, corrosive liquid.

If that stuff decided to misbehave it could go everywhere.

[Edited on 28-8-2008 by ScienceSquirrel]
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[*] posted on 28-8-2008 at 09:14


Quote:
Originally posted by ScienceSquirrel
But heating a solution of potassium hydroxide in propylene glycol may result in side reactions producing brown goos.


I doubt it but this is all about amateur experimentalism, right? My first trial would be to heat a little NaOH in PG & see if there is any color formed.

[Edited on 28-8-2008 by Ritter]




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[*] posted on 28-8-2008 at 09:22


Quote:
Originally posted by Ritter

I doubt it but this is all about amateur experimentalism, right?
My first trial would be to heat a little NaOH in PG & see if there is any color formed.

[Edited on 28-8-2008 by Ritter]


I agree.

But his first attempt is on a semi bucket scale and he is not even thinking of investigating the solubility of sodium hydroxide in water / propylene glycol to start off with.
His starting solution of sodium hydroxide is ca 10M!
Then he is going to add 192ml of DEET, that is about £20 by my reckoning. I bought 50ml of neat DEET today for £5.
Then he is going to add propylene gylcol until it all forms a homogenous mix.
I reckon it will start to react before he gets it in the flask and his shed will fill with a cloud of diethylamine vapour.

[Edited on 28-8-2008 by ScienceSquirrel]
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[*] posted on 28-8-2008 at 09:26


Quote:
Originally posted by mbrown3391
1. Prepare a solution of 80g NaOH in 73ml H2O.
2. To this solution, add 192ml of DEET. Two layers will form.
3. While stirring, slowly add ethylene glycol to the mixture until homogeneous.
4. Add a small amount to a distillation apparatus and heat to 55 degrees C. If all goes well, add the rest and maintain 55 degrees C until boiling ceases
5. Theoretical Yield: 103.39ml Diethylamine

Start reading books! That should be the point number one in your recipe.
There are several examples in this thread that show you are still too ignorant about organic chemistry too safely conduct the hydrolysis of this amide:
1.) That you use empirical formulas instead of rational means you are completely clueless about the theory behind this reaction (or any other organic reaction).
2.) That you want to attempt the first reaction on a 1 mol scale shows how irresponsible and uncareful you are.
3.) That you believe your reaction mixture will boil at 55°C shows you are completely clueless about basic physics and physical chemistry.
4.) That you can't tell the difference between an amide and amine and furthermore believe such an benzamide can be hydrolysed at such low temperature shows you have no lab experience and no knowledge of preparative chemistry.
I could continue, but it is pointless....

Now, do you think anybody here is going to lead you step by step and risk of causing you injury? This is not the Beginnings section, so find an example of benzamide hydrolysis yourself and put it forward for discussion to bring some sense into this thread, that is developing so pathetically. For some reason you are even too lazy to check out the procedures in Vogel, Organikum or other books, some of which you could have found in our library as well.

Besides, you still did not explain why you want to hydrolyze DEET. Obviously you are more interested in diethylamine rather than the more precious m-methylbenzoic acid, which makes all this highly unusual. Diethylamine is way cheaper than DEET, unregulated and can be ordered trough any chemical reseller without troubles. If you wanted to prepare it yourself as some sort of a chalange than why have you not searched the literature first?




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[*] posted on 28-8-2008 at 09:56


Howdy Mrbrown. A few things first:

1.) NaOH v. KOH, no difference in this reaction.. both are plenty basic
2.) Hot NaOH in water will not dissolve your flask.
3.) Ethylene glycol (EG) (same stuff that you put in your car radiator) or propylene glycol only sufices to raise the boiling point of water a few degrees. It will not effect the boiling point of the amine.
4.) Ritter's suggestion to use EG/PG is to improve the solubility of DEET in the water. This is important because the water is what's actually breaking the amide bond and forming the meta-methylbenzoic acid. A research laboratory would accomplish this by use of a phase transfer catalyst (PTC), so as to not indroduce EG as a contaminant.
5.) 80g of NaOH sounds quite near to a saturated solution of NaOH. Sure.. start with this. Perhaps a little more water is easier to work with, giving you a bit of room to work with the distillation, since water will distill also.
6.) The density of DEET is very similar to that of water... hence it may not float on top, it may create an emulsion, more on this later.
7.) Small molecular weight alkylamines are more easily(safely too) handled and stored as an ammonium salt, such as the hydrochloride (HCl), which is easily converted back into the free base by preparing a basic aqueous solution of the ammonium salt and extracting into organic solvent.
8.) here are the rough procedures I might try experimenting with.

Base Hydrolysis:

I.) Prepare a solution of ~20:30 NaOH:H20 (w:v) (careful, this gets quite hot while it dissolves.. prepare it in a glass container standing in some room temperature water)
II.) Add ~1 part (v) EG (I'm not certain about this step.. may cause rxn to fail).
III.) To the aqueous NaOH add ~30 parts (v) of 100% DEET (this is ~0.2mol% relative to the base. i.e. plenty of excess NaOH). This will probably create an emulsion, and the solution may look a little bit cloudy.
IV.) Gently reflux this mixture for ~30-60min with a cold condenser (preferably <0*C).
V.) Either steam distill your diethylamine. OR partition it into organic solvent such as dichloromethane or hexane.
VI.) Acidify the distillate with slight (~1.2) molar excess of HCl and boil off the water to yield Et2NH*HCl. OR Dry the organic layer with suitable anhydrous drying agent (I like MgSO4 or Na2SO4).

*Note: for those worried about safety, see the next method. This approach to base hydrolysis would prove more difficult for the novice than dangerous.


Acid Hydrolysis (already suggested by Ritter):

I.) Reflux a solution of ~ 3:1 (v:v) DEET:HCl (30% muriatic acid is probably okay) for ~1-2hr.
II.) Cool the solution to room temperature.
III.) Extract the resulting solution with toluene (easy to get) to remove the (similar to toluene) m-methylbenzoic acid.
IV.) Boil off the water/acid in a fume hood or outdoors to yield Et2NH*HCl.
IIV.) For fun, let the toluene evaporate and hopefully you'll find your m-methylbenzoic acid left behind.

*Note: I don't believe there's anything particularly dangerous with this procedure. As always, a hot plate is preferred over a bunsen burner, toluene is flammable (DEET too), and if you get acid on yourself wash it with water immediately. HCl vapor is not particularly dangerous as it is too irritating to stay near for more than a couple seconds. Oh.. and don't eat any of your products.

My personal suggestion... start small... it's cheaper, and when it doesn't work you'll have plenty of material to try a different approach. If it works, do it again.

The acid hydrolysis method seems tame to me. Tame enough that I might say try it, and if you get zero yield... you'll atleast get a motivation to further your understanding of chemistry by continuing reading. Seems like you're on the right track. Don't get too discouraged by people flaming you for confusing "amine" and "amide"... ask the average college science student, and they won't be able to draw either one. Ask as many questions as you'd like, those willing will help.

Others: Any thoughts?

[Edited on 28-8-2008 by Arrhenius]
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[*] posted on 28-8-2008 at 10:30


Haha, censorship.. grand...
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[*] posted on 28-8-2008 at 10:47


I'm pretty sure that it is a watched substance. and I don't need the fbi at my door (i have been active in the energetic materials forum) so I don't think I will be buying diethylamine. besides, that eliminates all the fun. anyway, ill be trying this soon and ill post my results
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[*] posted on 28-8-2008 at 10:57


and I don't see why this thread should be closed. I swear there is a unique psycology behind forums. one person posts something negative, and suddenly a bunh of elitist followers start swarming around, repeating insults over and over again until no further information can get through. its unbelievavly annoying
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[*] posted on 28-8-2008 at 10:57


Quote:
Originally posted by stoichiometric_steve
close&delete this thread


There is some rubbish in this thread, but which thread does not contain some rubbish?
But there is also some good and thoughtful chemistry so I do not think closing and sending it to detritus or deletion is the right course of action.
Anyway we are promised an update when he tries an experiment....
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[*] posted on 28-8-2008 at 11:04


Quote:
Originally posted by mbrown3391
and I don't see why this thread should be closed. I swear there is a unique psycology behind forums. one person posts something negative, and suddenly a bunh of elitist followers start swarming around, repeating insults over and over again until no further information can get through. its unbelievavly annoying


That is complete rubbish.
There are a few negative comments but what do you expect?
Your original post was poor and you have done very little since to improve and you have ignored most of the advice that you were given.
Ritter, Arrhenius and myself have been the major posters in the thread and we have disagreed with each other as much as with you.
Buying 100ml of diethylamine will not bring you to the attention of the FBI or anyone else in law enforcement. The whole system of trading in chemicals would seize up completely if that sort of thing happened.
Diethylamine probabaly has dozens of uses in all sorts of products, it is a multiton bulk chemical!

[Edited on 28-8-2008 by ScienceSquirrel]
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[*] posted on 28-8-2008 at 11:19


Quote:
Originally posted by mbrown3391
I'm pretty sure that it is a watched substance. and I don't need the fbi at my door so I don't think I will be buying diethylamine.


Just because you're not paranoid doesn't mean they're not out to get you.




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[*] posted on 28-8-2008 at 11:22


stoichiometric_steve

If you are not a moderator, and you aren't, then the proper course of action if you think a thread ought to be closed or trashed is to use the REPORT function. Posting as you did is, I have been advised, improper.

Arrhenius

You are new around here. You do not have a clue as to the sort of people who are regulars on this forum. There are many here who are either professional chemists, meaning they work at chemistry for a living, or else professionally qualified chemists, meaning formally trained graduate chemists, including current MS and PhD candidates and postdocs, or retired chemists. In my case I was formally trained, worked as a RA, have been published in JOC, own patents, and am now retired. So kindly do not get on some hobbyhorse about professionals vs amateurs.

Furthermore the forum membership is highly international, and not restricted to north America and Europe. Restrictions common in USA do not necessarily apply to all other places.

Finally, you have not the slightest sense of what resources some members may have and some members may lack. There are people on this forum who are extremely well equipped and deep pocketed. There are others not so well off.

So quit making assumptions and presumptions as to what members can or can't so, can or can't buy, etc. Those are uncalled for and most of all inaccurate.

All here share a love of chemistry as a science and as a hobby. That is sufficient.




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[*] posted on 28-8-2008 at 11:22


I would not all my orriginal post poor. learly I did in fact do some of my own "legwork" as I offered 3 possible reactions and asked specific questions about them. however almost immediately people start questioning my motives(whih are irrelevant) and it eventually leads to ridiculous claims that someone who mistakes the solubility of an amide for that of an amine must be unable to hold somethbing without spilling it all over himself
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[*] posted on 28-8-2008 at 11:44


Do not search for excuses for your laziness. You did not provide a single reference and your lazy spelling is pure annoyance to the reader. All you do is taking wild guesses hoping this would incite others to do a literature search for you. This kind of behavior is only acceptable in Beginnings section where you can post questions even without checking the literature to have some basic understanding of the problem. But as you can see from what happened to this thread, such a behavior is highly destructive for those who want a serious discussion about chemistry.
You are not a new member, so no excuses. Go find a book about preparative chemistry or some paper about amide hydrolysis and find some experimental to repair this thread or else it will inevitably end up closed due to lack of progress and members flaming each other.
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[*] posted on 28-8-2008 at 12:01


first of all do not cite spelling as a represenatation of anything. it is the most tired, cliché insult around, used only when the flamer has run out of fuel. my posts have been entirely legible and I am not the only one who has made spelling mistakes.
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[*] posted on 28-8-2008 at 12:15


Sauron: I don't wish to share who I am, nor what my background or merit is. It is not your business. You wouldn't get off your pedastel if I told you anyway. I have suggested one method which anyone should be able to perform, maybe even in a test tube, or even in a 27L flask. You're making a very large stretch with what you just said. Smear away though.

And yes, I do love chemistry.

Mrbrown:
Yes, diethylamine will likely prove difficult to purchase in the West. There is constant talk, sadly, of how to obtain 'watched' or 'restricted' chemicals, but whether you'll get in trouble with the law is entirely circumstantial. For instance, the recent threat on Mr. Deebs in the Legal Matters subforum. If you had genuine interests and legal persuits in chemistry, diethylamine would still prompt prosecutors to slap some drug manufacture charges on your case. From outside the box, it looks like people are concerned about you making one certain semi-synthetic alkaloid which I've already referred too. I personally don't care what you use diethylamine for. If you can make it, and that spurs your continued interest in chemistry, then I'd say it's worth making. No one is saying you have to post your results, but I would read them.

Also, if I've made an incorrect presumption about anything pertaining to you, please PM me and let me know. I apologize in advance.

Check out this thread if you're willing to purchase some reading material. Most of the books listed will discuss alkylamines as well, but probably not a recipe.
Decent Chemistry books

To all:
I don't mind a few spelling errors so long as it's comprehensible. If a PhD chemist was posting here who didn't write perfect english, would this discredit their merit? I hope not. I don't think anyone should help Mrbrown who doesn't wish to. There is no obligation.

[Edited on 28-8-2008 by Arrhenius]

[Edited on 28-8-2008 by Arrhenius]
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[*] posted on 28-8-2008 at 12:22


I bought some DEET today and everything else is to hand so I am going to have a go at hydrolysing it this weekend.

I am not making diethylamine or its hydrochloride but I bet that I will have a few grams of shiny needles of m toluic acid by close of play on Sunday :D
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[*] posted on 28-8-2008 at 12:28


If you really want to get a source of DEA (hahaha so aptly abbreviated) then DEET is probably the best bet. Although it may be worth asking a local chemical company if they have it in stock and if they could sell it to you. I don't see why they shouldn't it's not particularly hazardous and it is fairly legitimate I can certainly think of a good number of uses for it in the hands of a private chemist!



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[*] posted on 28-8-2008 at 12:52


The posts unrelated to the topic and those inciting flame wars were removed. Use the U2U function for personal messages!
From now on only post chemistry related posts.

Quote:
Originally posted by ScienceSquirrel
I bought some DEET today and everything else is to hand so I am going to have a go at hydrolysing it this weekend.

I am not making diethylamine or its hydrochloride but I bet that I will have a few grams of shiny needles of m toluic acid by close of play on Sunday :D


You can reflux it with HCl for several hours. That should work and you don't have to use a cosolvent. I have not read the paper as I have other work now, but there is supposed to be an experimental procedure using HCl(aq) for the hydrolysis of N,N-diethyl-ortho-methylbenzamide in DOI: 10.1016/S0040-4039(00)94113-3 (you can find the Tetrahedron Letters volume 24 in References if you don't have access to the journal).
N,N-Dialkylbenzamides can also be hydrolysed with NaOH(aq) reflux - also no need for a cosolvent - but using the acid saves you from the nasty smell of diethylamine so you can do this without even using a fume hood.




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[*] posted on 28-8-2008 at 13:07


ScienceSquirrel, what kind of store did you get your DEET from?
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[*] posted on 28-8-2008 at 13:17


Quote:
Originally posted by mbrown3391
ScienceSquirrel, what kind of store did you get your DEET from?



Most pharmacists aka chemists sell 50% DEET. The rest of it is denatured alcohol and fragrance. Often the fragrance is based around citrus oils that do have a discouraging effect on insects.
Hard core travelling / camping stores that deal with people off to places with serious bug problems sell 90 - 100% DEET.
Mine is 95% DEET, the rest is denatured alcohol and a spot of citronella.
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[*] posted on 28-8-2008 at 13:19


In the UK some camping stores sell solutions of DEET as an insect repellant in spray bottles of 100mL. Now I have not seen it at 100% concentration but you may be able to find a high strength even 100% if you go to a camping store. Chances are if you search for some walking camping backpacking store online you could find high strength DEET. To be honest I haven't looked at the labels of stuff like that for a good number of years! Good hunting and keep us posted on the experiments.



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[*] posted on 28-8-2008 at 14:01


I have to admit to a compulsive label reading tendency.
I can buy most things but there is that tiny edge of subverting the system, finding something dead cheap in a shop that a chemical supplier would have done you £30 for.
Anyway 100% DEET is available quite cheap if you look around.

http://cgi.ebay.co.uk/REPEL-120ml-100-DEET-MOSQUITO-INSECT-R...
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