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Author: Subject: Ethanol + Urea --> Ethyl carbamate?
khourygeo77
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[*] posted on 26-4-2019 at 10:59
Ethanol + Urea --> Ethyl carbamate?


Hello,

I want to react ethanol with urea. After searching, I realized the product would be ethyl carbamate. So I was wondering how long the reaction will take and if any catalyst is needed to make this reaction possible? Also the required temperature? reaction time?

I bought some urea as fertilizers in granules but they are tinted green. Hopefully there is nothing else added as I could remove the coloring with alcohol.

I understand the dangers of ethyl carbamate as a carcinogenic and wont eat, breathe, touch or make any skin contact possible.

So anyone has any idea?

Thanks!

[Edited on 26-4-2019 by khourygeo77]

[Edited on 26-4-2019 by khourygeo77]
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[*] posted on 26-4-2019 at 14:29


i can't find any infos apart from "ethyl carbamate is made by heating ethanol and urea together", so i say try it, just as a test.
using an excess of ethanol should make sure to consume all the urea, but i fear that the excess could react with the ethyl carbamate and remove the last -NH2, dunno.
anyway testing if it works at all should be easy, the reaction produces ammonia, the reagents at the beginning should have a neutral pH, if the solution results basic, maybe it's working (hoping is not just the urea decomposing)





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arkoma
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[*] posted on 26-4-2019 at 15:16


hmm. i have plentiful supplies of both. wikipedia says ammonia gas given off. might just try a few milliliter size reaction. been really really lazy in lab lately anyway,



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khourygeo77
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[*] posted on 26-4-2019 at 15:55


The reaction may take time, like weeks, though I am not sure. So I may not be able to know that for sure in a day :(
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[*] posted on 26-4-2019 at 18:36


ZnO is a catalyst, IIRC.



[Edited on 04-20-1969 by clearly_not_atara]
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khourygeo77
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[*] posted on 27-4-2019 at 03:48


I dont want to use catalysts. I want to find out about the reaction without any additive except maybe water

This is the information I found out with the related citations:

https://www.researchgate.net/publication/7935594_Effects_of_...

It looks like the reactions is very slow and partial in diluted form

[Edited on 27-4-2019 by khourygeo77]

[Edited on 27-4-2019 by khourygeo77]
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khourygeo77
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[*] posted on 27-4-2019 at 04:21


Also this:

http://en.cnki.com.cn/Article_en/CJFDTOTAL-SXHG200705007.htm

But I dont have the labware to perform such an experiment. Maybe I will need to keep distilling them together many times to obtain a high yield

Any idea how good ethyl carbamate would be as a solvent for rust or similar metal oxides? 1st in its melting point form and 2nd in an aqueous or alcoholic solution. I wanted to make ethyl carbamate to find this out. I know there are other solvents but I need to find the solvent capacity of ethyl carbamate. Finding out the solvent potential of a related compound can also help out in finding out its solvent capacity. (For example methanol and ethanol can almost dissolve the same things)

Thanks

[Edited on 27-4-2019 by khourygeo77]
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Morgan
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[*] posted on 27-4-2019 at 14:38


Just some tidbits/fun facts from Wiki.

"Ethyl carbamate has been used as an antineoplastic agent and for other medicinal purposes, but this application ended after it was discovered to be carcinogenic in 1943. However, Japanese usage in medical injections continued and from 1950 to 1975 an estimated 100 million 2 ml ampules of 7 to 15% solutions of ethyl carbamate were injected into patients as a co-solvent in water for dissolving water-insoluble analgesics used for post-operation pain. These doses were estimated to be at levels that are carcinogenic in mice.[3] This practice was stopped in 1975. "This regrettable medical situation appears to have involved the largest number (millions) of humans exposed to the largest doses of a pure carcinogen that is on record".[4]

"Prior to World War II, ethyl carbamate saw relatively heavy use in the treatment of multiple myeloma before it was found to be toxic, carcinogenic, and largely ineffective.[5] By US FDA regulations, ethyl carbamate has been withdrawn from pharmaceutical use. However, small quantities of ethyl carbamate are also used in laboratories as an anesthetic for animals.[6]"

"It has been shown that ethyl carbamate forms from the reaction of ethanol with urea.
This reaction occurs much faster at higher temperatures, and therefore higher concentrations of ethyl carbamate are found in beverages that are heated during processing, such as brandy, whiskey, and other distilled beverages. Additionally, heating after bottling either during shipping or in preparation will cause ethyl carbamate levels to rise further."
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[*] posted on 27-4-2019 at 14:43


*semi off topic* getting ready to go home and squeeze some high test EtOH out of a bucket of waste from lovely little yeast cells:D:D:D:D:D


will pull the 95% off the top so I have something to heat with urea tomorrow.




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[*] posted on 28-4-2019 at 02:58


Its carcinogenic property may be discovered in 1943 but I do have a pharmaceutical book printed in 1969 that still lists this compound as a treatment for various leucemias. With daily doses, for adults as well as children, etc. I'm not sure if it was used in those days, but the "knowledge" was there.

Urethane was (still is?) used as an anaesthetic in animals, I read a laboratory manual from the seventies where they routinely anaesthetised frogs by sprinkling urethane (its common name) crystals on the damp skin of the animals!
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[*] posted on 28-4-2019 at 09:08


I was curious as to what conditions are required for the reaction between ethanol or methanol and urea as all the reagents are readily available.

Apparently high temperatures (above the BP's of ethanol or methanol) are required and preferably with a catalyst (MgCl2) to reduce the reaction times to hours from days. The temperatures above the BP's would require an autoclave not a huge problem as I assume a steel CO2 bottle could be used. I assume the ammonia produced would have to be released to drive the reaction in the right direction

However I did find a US patent that suggests using only a 0.5molar excess of the alcohol with a copper acetate catalyst at atmospheric pressure and about 130C (reflux temperature) the reaction is complete in three hours. It also states that without the catalyst the reaction time would be 30 hour.

So the reaction may only require refluxing the alcohol and urea (1.5:1 molar ratio) for say two days at about 130C preferable with the temperature PID controlled if the you don't want to mind it for that long.

Here is the patent Attachment: monocarbamates-US2837561.pdf (224kB)
This file has been downloaded 26 times




i am wg48 but not on my usual pc hence the temp handle.
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[*] posted on 28-4-2019 at 12:09


Quote: Originally posted by Morgan  

"This regrettable medical situation appears to have involved the largest number (millions) of humans exposed to the largest doses of a pure carcinogen that is on record".


That rather depends on your view of vodka as a pure carcinogen.

The urethane concn was only about 10%
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[*] posted on 28-4-2019 at 14:48


Quote: Originally posted by unionised  
Quote: Originally posted by Morgan  

"This regrettable medical situation appears to have involved the largest number (millions) of humans exposed to the largest doses of a pure carcinogen that is on record".


That rather depends on your view of vodka as a pure carcinogen.

The urethane concn was only about 10%


Might as well put sunlight on the list too. There's a lot of things that can get you for sure. Some of the side effects of the drug commercials on TV seem nearly as bad as the ailments they offer to cure. And of course some can be worse.

[Edited on 28-4-2019 by Morgan]
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[*] posted on 29-4-2019 at 11:51


On my mobile. Going to try and set if I can post pictures on a moment. Yesterday morning I put 25ml denatured
EtOH (710 solvent) and one gram of urea in a 50ml beaker and started stirring. This morning I have a non soluble white crust built up. Will check when I get off work today. Still stirring.

IMG_20190429_104451.jpg - 707kBIMG_20190429_104349.jpg - 548kB




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[*] posted on 29-4-2019 at 16:28


I did some work on this forum years back making ethylene carbonate using ethylene glycol / urea. The reaction used a zinc oxide catalyst. The issue I see in translating that process to one using ethanol is that the formation of the ethylene carbonate was driven by pulling off the ammonia produced under vacuum. It was still a somewhat slow reaction, but I would think refluxing the reaction medium would help to degas ammonia and drive it forward.



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[*] posted on 29-4-2019 at 19:16


You'll have to look up Hofmann's langerem Kochen (Ber. 4, 268)...always best to start at the beginning...Beilstein mentions as a preparation that one Italian about 1892-ish gradually added equimolar NaNO2 to urea nitrate in 5 parts heated alcohol, and another apparently reproduced this before 1923.



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[*] posted on 29-4-2019 at 19:24


Used no catalyst so far, but thinking about a drop or two of H2SO4. I'm practically ancient, so carcinogens don't intimidate me LOL

Edit removed redundant picture. Stupid mobile phone.
Re edit. Mobile web throws me.
[Edited on 4-30-2019 by arkoma]



[Edited on 4-30-2019 by arkoma]




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[*] posted on 29-4-2019 at 22:47


Interestingly, ethyl carbamate itself is not a carcinogen. However, it's oxidized by CYP450 enzymes to the epoxide, which then can react with DNA. (It's similar to benzene in this respect.)



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