Sciencemadness Discussion Board

Triethylamine synthesis

Ramium - 20-3-2015 at 15:34

I remember reading that triethylamine can be made by the alkylation of ammonia with ethanol

This is the eqation
NH3 + 3 C2H5OH = N(C2H5)3 + 3 H20

Here is my working out of the quantities

1 mol NH3 = 17.031g
3 mol C2H5OH = 3 x 46.068g = 138.204g

Density of my ammonia = 18g/l
So for 1 mol NH3 i need 0.946 litres = 946ml

Density of 99% ethanol (i am treating it as 100%) = 79g/l
I got the density of ethanol from a website and i am not sure it is correct

3 mol C2H5OH= 1.749 litres

I would scale it down of course

Does this look right?

Should i have an excess of any of these ingredients?

Can i just mix them together or do i have to heat them or something to get them to react?



[Edited on 20-3-2015 by Ramium]

gdflp - 20-3-2015 at 15:40

Unfortunately, it's not that simple. For that reaction to work, I believe that the vapors have to be mixed, then passed over a heated catalyst, though this is a vague recollection.
(Apparently at high pressures too.) A more suitable synthesis of triethylamine in an amateur setting can be found here : http://chemistry.mdma.ch/hiveboard/chemistrydiscourse/000330...

[Edited on 3-20-2015 by gdflp]

Metacelsus - 20-3-2015 at 15:50

Ammonia doesn't react with ethanol easily. When it does, you'll get a mixture of mono, di, and trisubstituted ethylamine. I found a patent: https://www.google.com/patents/US20080194879
which uses transition metal catalysts for the reaction at 15 to 25 MPa and 170 to 230° C.

Not an easy proposition.

[Edited on 20-3-2015 by Cheddite Cheese]

Ramium - 20-3-2015 at 16:03

Thanks for your replies.i will find another method

CuReUS - 21-3-2015 at 00:48

what about an eschenweiler clark using NH3,acetaldehyde and HCOOH ?

Metacelsus - 21-3-2015 at 11:26

Why use acetaldehyde making triethylamine? Yes, it's possible, but then again triethylamine is much easier to get than acetaldehyde. I got some pretty recently from Elemental Scientific.

Ramium - 21-3-2015 at 16:23

Quote: Originally posted by CuReUS  
what about an eschenweiler clark using NH3,acetaldehyde and HCOOH ?

I don't have access to acetaldehyde sadly

Ramium - 21-3-2015 at 16:26

Quote: Originally posted by Cheddite Cheese  
Why use acetaldehyde making triethylamine? Yes, it's possible, but then again triethylamine is much easier to get than acetaldehyde. I got some pretty recently from Elemental Scientific.


I don't want to buy triethylamine I want to make it to explore the chemistry.

PHILOU Zrealone - 22-3-2015 at 13:32

@ Ramium,
Your calculations are wrong.
Density of ethanol 100% is more like 790g/L (0.79kg/L) than 79g/L!

You will get more chance at triethylamine from ammonia and CH3-CH2-X instread of ethanol.
CH3-CH2-I > CH3-CH2-Br > CH3-CH2-Cl (gaseous).
CH3-CH2-X can be easily obtained from HX/ZnX2 or H2SO4/NaX and ethanol.

papaya - 22-3-2015 at 14:46

I'm sorry if I ask this in wrong place, but what about Delepine reaction route to amines (https://en.wikipedia.org/w/index.php?title=Del%C3%A9pine_rea...), where you can use hexamethylenetetraamine instead of ammonia, isn't this more convenient than ammonia? How practical is it if I try to synthesize ethylenediamine from dichloroethane + urotropine under reflux, does this work?

Ramium - 22-3-2015 at 17:51

Quote: Originally posted by PHILOU Zrealone  
@ Ramium,
Your calculations are wrong.
Density of ethanol 100% is more like 790g/L (0.79kg/L) than 79g/L!

You will get more chance at triethylamine from ammonia and CH3-CH2-X instread of ethanol.
CH3-CH2-I > CH3-CH2-Br > CH3-CH2-Cl (gaseous).
CH3-CH2-X can be easily obtained from HX/ZnX2 or H2SO4/NaX and ethanol.
thanks
Could u please tell me what the name of CH3-CH2-x
(the thing u sugested instead of ethanol)

Steam - 22-3-2015 at 18:04

Ethyl iodide/bromide/chloride aka. chloroethane
http://en.wikipedia.org/wiki/Chloroethane

**edit** as PHI said, iodoethane is more reactive than bromoethane, which is more reactive than chloroethane.
The difficultly will be finding chloroethane... you will probably have to make it yourself. Chlorination of alcohols can be done using Thionyl Chloride or Zinc chloride. I have chlorinated benzyl alcohol before by using an excess of HCl, but you will need something a bit stronger for ethanol (benzylchloride is particularly nasty stuff- best have a a nice fume hood or where swimming goggles ;) ) It was discussed in depth in thisThread!

[Edited on 23-3-2015 by Steam]

Ramium - 22-3-2015 at 18:14

So will iodoethane react easily with ammonia to form triethylamine?

Thanks

Steam - 22-3-2015 at 18:19

Quote: Originally posted by Ramium  
So will iodoethane react easily with ammonia to form triethylamine?

Thanks


Yes, but getting/making iodoethane will be hard. I speak form experience because I have tried to synthesize iodoethane without success. ( using method 2)

https://www.erowid.org/archive/rhodium/chemistry/nitroalkane...

**edit** I suggest Starting here! https://www.youtube.com/watch?v=7Jn0z5BGpR0

[Edited on 23-3-2015 by Steam]

Ramium - 22-3-2015 at 18:31

Quote: Originally posted by Steam  
Quote: Originally posted by Ramium  
So will iodoethane react easily with ammonia to form triethylamine?

Thanks


Yes, but getting/making iodoethane will be hard. I speak form experience because I have tried to synthesize iodoethane without success. ( using method 2)

https://www.erowid.org/archive/rhodium/chemistry/nitroalkane...

**edit** I suggest Starting here! https://www.youtube.com/watch?v=7Jn0z5BGpR0

[Edited on 23-3-2015 by Steam]
thanks steam! The bromoethane in the video link u posted looked easy to make i will use that instead of iodoethane

[Edited on 23-3-2015 by Ramium]

CuReUS - 23-3-2015 at 02:04

Quote: Originally posted by Steam  
Quote: Originally posted by Ramium  
So will iodoethane react easily with ammonia to form triethylamine?

Thanks


Yes

won't you get a lot of quat ?
actually,there isn't much difference in reactivity of bromo and iodo compounds
you could say bromo is the poor man's(or in my opinion,the clever man's) reagent whereas iodo is for the rich and fussy
you could make iodoethane using finkelstein's reaction
http://en.wikipedia.org/wiki/Finkelstein_reaction
it would be better if you tried to make hunig's base instead.then you can use it for future reactions as well

[Edited on 24-3-2015 by CuReUS]

Steam - 23-3-2015 at 05:47

Nice find there CuReUs! Finkelstein is an cool name for a reaction!

I got some bromoethane and NaI, I might try to do this reaction this coming weakened!

Ramium - 26-3-2015 at 10:48

I cant find any NaBr to make the bromoethane!!!

Pool shops here don't stock NaBr or any other bromide salt. Instead there bromine tablets are 1-bromo-3-chloro-5 5- dimethylhydantion. Is there any way to convert this to NaBr?

Thanks




[Edited on 26-3-2015 by Ramium]

Ramium - 26-3-2015 at 19:11

My new plan is to use chloroethane instead.

Could i make it using this http://youtu.be/7Jn0z5BGpR0 procedure if I substituted the NaBr for NaCl?
Chloroethane is a gas so i would bubble it through an ammonia solution to yield triethylamine.

Would that work???

FedeJuninArg - 29-3-2015 at 09:58

Some time ago I wondered about that too.. I can't find the article I read but that reaction it's not possible.. I think because reactivity of Chlorine.. instead you need to add a cathalyst like zinc chloride to NaCl.. find some Zinc/Carbon batteries and add the metal (well cleaned) to the reaction flask + water to keep chlorine in solution. You can calculate the HCl excess by Redox.

With this you will prepare the HCl + cathalyst solution. Then you can add it dropwise to ethanol in a ice/water bath..

Here a ref for the reaction :

http://nepis.epa.gov/Exe/ZyNET.exe/00002EZG.txt?ZyActionD=Zy...

Good luck!

[Edited on 29-3-2015 by FedeJuninArg]

Ramium - 29-3-2015 at 11:02

Thanks!

Ramium - 6-6-2015 at 13:02

so I thought I'd come back and finish this project. I found the unbalanced equation online and I managed to balance it myself. have I balanced it correctly?

NH3 + 3 C2H5Cl = (C2H5)3N + 3 HCl

so I need

NH3 = 17.031g
C2H5Cl = 64.51 x3 = 193.53g

divide by 3

NH3 = 5.677g
C2H5Cl = 64.51g

this is my plan: pour the ammonia solution into a conical flask and attach a cork with a hole in it to the top of the conical flask. push some tubing through the hole in the cork (use glue tack to create a seal) till the end of the tubing touch's the bottom of the flask then pump the chloroethane gas through the tubing and into the flask of ammonia solution then distil out the triethylamine. do you think this would work?

my only concern is that the HCl produced in the reaction would react with the ammonia to produce ammonium chloride.

I think I'll just buy the chloroethane rather then make it.

[Edited on 6-6-2015 by Ramium]

byko3y - 6-6-2015 at 14:28

You could order the bromide salt from some other country. Of course you will need a larger batch, but if you are going to perform multiple experiments with halogenation, then you will need the bromide a lot.
You can use a regular ice for keeping hte EtCl liquid, but this way ethyl chloride would be quickly evaporating because of its high vapor pressure.
You gonna need to neutralize the HCl, because the alkylation can proceed only in non-acidic conditions. You should read the http://chemistry.mdma.ch/hiveboard/chemistrydiscourse/000330... if you haven't done this yet:
7EtNH2 + 5EtBr = 2Et3N + 4EtNH2.HBr + Et2NH.HBr
I think the best way to perform the reaction would be to add the ethyl chloride slowly together with an appropriate portion of alkali hydroxide. Acid neutralization is exothermic, so your EtCl might boil because of this if not enough cooled, leading to diminishing yields.
One very important reason why the last setup you described will not work: ethyl chloride is not soluble in water, thus it will just pass to the exit almost without reaction.
Methylamine is more volatile than triethylamine, so if you try to distill it, you will get a methylamine on exit. In case if you haven't lost your ammonia earlier.
DMSO as a solvent might work well, it is easily alkylated by methyl halides, but ethyl halides can barely react with DMSO, although if you give them a lot of time, like few weeks, then they will alkylate it. http://pubs.acs.org/doi/pdf/10.1021/jo01104a611
And you can't use acetonitrile as a solvent, because it catalyzes production of quaternary ammonium salt (overalkylation). Although, some quaternary ammonium salt could catalyze the reaction even with water as solvent, but the salt has to be prepared first.
As you might understand, the temperature of the reaction will be close to 0°C, and I'm not sure whether it will proceed in any decent rate at these conditions.
You should try to find a well developed procedure for the synthesis, because you are not capable of designing one yet.

Ramium - 6-6-2015 at 17:11

Interesting. Thanks I hadn't read that hiveboard synth.

So if I understand correctly, the precursor ethylamine can be made in this way

ETHYLAMINE HYDROCHLORIDE

75ml of ethyl bromide plus 50ml of conc ammonia are put in a 750ml glass flask. Anhydrous ethanol is added. The flask is then immediately closed with a rubber cork. Next the flask is put into an oven for 3 hours then allowed to cool .
The ethanol is then distilled off. The residue is next dissolved in a minimum amount of water and distilled with an excess of NaOH solution. The distillate is collected in a flask containing dilute hydrochloric acid. The HCl distillate mixture is then evaporated until it no lounger smells of HCl. The mixture is left to cool and after a few minutes it should solidify into a crystalline mass. This crystalline mass contains ethylamine hydrochloride and ammonium chloride.
A mixture of diethyl ether and ethanol can then be used to extract the ammonium chloride, leaving ethylamine hydrochloride.

THE CHEMISTRY

This is what I think is going on:

The ethyl bromide reacts with the ammonia:

C2H5Br + NH3 = C2H7N + HBr

hydrobromic acid reacts with ammonia:

HBr + NH3 = NH4Br

hydrochloric acid and ethylamine react when the distillate is collected in hydrochloric acid:

HCl + C2H7N = C2H5NHCl

the distillate contains NH4Br and C2H7N so the hydrochloric acid also reacts with the NH4Br:

NH4Br + HCl = NH4Cl + HBr

Is this what happens?

sorry

[Edited on 7-6-2015 by Ramium]

[Edited on 7-6-2015 by Ramium]

byko3y - 6-6-2015 at 17:59

Alkylated amines are stronger bases than non-alkylates ones, that's they will be mostly left in a solution as a salt, while less basic amines will be distilled away. However, this doesn't means that only one type of amine will be distilled, the dependence of composition is pretty complex.
In the quoted procedure, NaOH is added to the mixture, turning everything to free base.
And also NH4Br probably decomposes on distillation at atmospheric pressure, also, nobody is going to try that.

Ramium - 7-6-2015 at 03:02

I just had an idea.

Liquified ethyl chloride is poured into a conical flask. A cork with a hole in it is attached to the top of the conical flask. Tubing is push through the hole in the cork untill it touches the bottom of the conical flask. The other end of the tubing is pushed through another corked conical flask containing ammonia solution untill it's about 2 inches above the surface of the solution.

You said that the main proplem with my original plan was that ethyl chloride isn't soluble in water. So anyway, the solution of ammonia is heated gently, being VERY careful not to let the solution boil, since the solubility of ammonia in water decreases as the temperature of the water increases. Semi anhydrous ammonia gas should be given off from the solution. The gas will travel through the tubing and into the flask of ethyl chloride. No water will be present to stop the reaction.

C2H5Cl + NH3 = C2H7N + HCl

The 2 products would then react with each other.

C2H7N + HCl = C2H7N.HCl

So after the reaction I should be left with reasonably pure crystals of ethylamine hydrochloride. Right?

Does this sound possible?

I'm sorry. I know you said i should look for a well developed procedure but i think i'll learn more if i try and think it through myself.

byko3y - 7-6-2015 at 03:44

Ammonia reacts sluggishly with alkyl CHLORIDES in a neutral medium. I think it take few days, in case there's enough energy for the reaction to proceed at all. I want to remind you that the guys in the hive quote had to heat the reaction mixture.
Ammonia has solubility near 5% in chorobenzene, it might be even lower for chloroethane.
You should really consider usage of a universal solvent (DMSO, DMF, PTC), which is a well developed procedure. Also, once again, I have no idea about the temperature needed to perform the reaction.

Ramium - 7-6-2015 at 20:32

Ok how about this?

Same setup as last time except some anhydrous ethanol is poured into the flask of ethyl chloride. When the ammonia gas enters the flask of ethyl chloride and ethanol, any of the ammonia that doesn't react straight away will disolve in the ethanol and keep reacting with the ammonia over time.

Ammonia and ethyl chloride are both soluble in ethanol, so I thought it would be a good solvent to use. The flask containing the reaction mixture (ethyl chloride, ammonia, ethanol) would then be corked and heated on a hotplate for several hours.

C2H5Cl + NH3 = C2H7N + HCl

Ethyl chloride, ammonia, ethylamine and hydrochloric acid are all soluble in ethanol.

C2H7N + HCl = C2H7N.HCl

Don't know if ethylamine hydrochloride is soluble in ethanol.

But it doesn't matter because if it is insoluble, it would precipitate and could be collected by filtration. If it is soluble then the ethanol can be evaporated.

Thanks for your responses. I'm learning a lot.

byko3y - 7-6-2015 at 21:49

As far as I remember you've just explained the procedure I linked.
I don't have precise number on solubilities of those gases (and ethyl chloride probably will be a gas in your case), in case you run too much gas into reaction you might lose some yield.
ammonia solubility in absolute ethanol at 0°C : 20% (w/w)
ammonia solubility in absolute ethanol at 25°C : 16% (w/w)
I like this data.

[Edited on 8-6-2015 by byko3y]

Ramium - 8-6-2015 at 17:25

C2H5Cl + NH3 = C2H7N + HCl

so I need

ethyl chloride = 64.51g excess of 20% to ensure there is no left over ammonia which might react with the HCl produced in the reaction.
ammonia gas = 17.031g (400ml ammonia solution 42g/L concentration)

divide by 2

42g/L ammonia solution = 200ml
ethyl chloride = 32.255g plus 20% excess

based on the solubility of the chemicals I have decided to use 200ml of ethanol

once my ethyl chloride arrives in the mail I will perform the synthesis.

Chemosynthesis - 8-6-2015 at 21:30

If that is not acceptable. See JACS (1913), 35;11 p1781-3 as linked by gdflip. While the halide solubilities vary, you may consider that quaternary ammonium salts are often useful as phase transfer catalysts, so modify accordingly. Interested in seeing how things go.

[Edited on 9-6-2015 by Chemosynthesis]

Antiswat - 2-11-2015 at 02:27

hydroxides + any given ammonia salt should produce anh ammonia
calcium hydroxide would probably even work
or maybe just dump some ammonium carbonate into the EtCl, turns into CO2 and NH3 around 70*C
this could probably work out very easily if both reagents were dumped into a steel container with a screw lid and heated to around 80*C, pressure building up inside container should help reaction a slight bit too

i have before stored IPN in stainless steel container similar to this
http://ecx.images-amazon.com/images/I/71m014PIg0L._SX425_.jp...

however in freezer, but it does seem to be well airtight
maybe the CO2 building up inside could get problematic if you were to not attend the reaction for longer time