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Author: Subject: Separation of Nitroethane from Methoxy-2-propanol
SamuelLFraction
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[*] posted on 27-4-2018 at 15:43
Separation of Nitroethane from Methoxy-2-propanol


Finally I have managed to find an OTC source of EtNO2, no more endless and expensive work ups! Well.. hopefully.

The msds for this compound concludes that it is comprised of three chemical components. DCM, methoxyisopropanol and of course Nitroethane. The DCM will be easy enough to separate via simple distillation due to the large difference in BP, however, the methoxyisopropanol not so much. After a quick read up about M2P, the BP is in a ballpark of 117-121. With Nitroethane being ca. 112... well i need not ramble any more.

Does anyone have any further information about methoxyisopropanol, such as solubility or even if M2P forms an azeotrope with Nitroethane? All I can seem to find is rather unhelpful. I was hoping someone may know as I am thinking of azeotropic distillation with n Heptane or perhaps Isopropanol. As far as I can read up that drops the BP of EtNO2 to 89 or 82 respectively. I don’t know a lot about the nitronate salt but perhaps this may be a better way of separation.

Please excuse my stupidity, there is a thread posted by drzdude asking exactly the same question... Doh! Could a mod merge this into that? Sorry!

[Edited on 27-4-2018 by SamuelLFraction]

[Edited on 28-4-2018 by SamuelLFraction]
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Tsjerk
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[*] posted on 28-4-2018 at 09:29


There is a methoxy-2-propanol - water azeotrope boiling at 96,5 degrees Celsius, which would bring your boiling points almost 20 degrees apart. Excess water would still boil 14 degrees below nitroethane. Sounds quite feasible if you can do fractional distillation.

https://www.parchem.com/chemical-supplier-distributor/1-meth...
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[*] posted on 28-4-2018 at 10:16


Adding water may well create a ternary azeotrope.

Could the ether be hydrolysed to the alcohols?
Proplyene glycol has a much higher BPt and methanol a much lower one compared to Methoxy-2-propanol.
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SamuelLFraction
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[*] posted on 28-4-2018 at 12:21


Thank you Tsjerk for the info on M2P. Now that it’s confirmed to have an azeotrope with water, it makes things a little dicey as nitroethane also forms an azeotrope with water, of which BP is 87.2 degrees. If the M2P water azeotrope is 96.5, then I feel that even with fractional distillation this difference is not enough with my small fractionating column.

Unionised, I agree with your speculation about it forming a ternary azeotrope as they both are azeotropic with water. It seems to form azeotropes with many solvents so I wouldn’t brush aside the idea of it being possible.
https://www.angus.com/literature/downloaddoc?fileName=ANGUS_...

If possible to hydrolyse, of which is a fantastic idea in theory, methanol does not form any azeotrope with nitroethane which is handy and propylene glycol I am unsure of.
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[*] posted on 28-4-2018 at 13:14


I missed the azeotrope between water and nitroethane boiling at 87 degrees. If that is true; what is the problem? Then distill this azeotrope.

The difference between normal distillation and fractional distillation is the amount of glass between the boiling liquid and the start of the distillate being captured. Don't you have some glass adapters you can put in between? 8 degrees separation is doable if you take your time. I did a separation of two liquids 20 degrees apart in a short path.
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SamuelLFraction
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[*] posted on 28-4-2018 at 13:47


The problem being if a ternary azeotrope is formed between water, M2P and Nitroethane. Of course that is pure speculation and by no means guaranteed. I suppose (assuming no ternary azeotrope) like you said distill the azeotrope of Nitroethane and water with perhaps two or three fractionating columns vertically, with a ca. 70/30 w/w ratio respectively with this azeotrope, MgSO4 may be used to dry up the water from the azeotropic distillate. This would be no problem, you are right.
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[*] posted on 28-4-2018 at 15:48


Considering the lengths you seem to be going to get nitroethane, let's just say I have hunch that you'll be wanting it for a Henry-type reaction with something containing a benzaldehyde skeleton, am I right? Now, ask yourself this: could methoxy-2-propanol work as a solvent for a Henry-type reaction? And if so, do you even need to separate them?



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SamuelLFraction
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[*] posted on 29-4-2018 at 00:48


At this point in time Melgar the challenge is in the ability to selectively separate these two compounds. I myself am the type of person who likes to learn actively and due to the unwritten nature of Methoxy-2-Propanol it makes it that much more challenging and interesting to learn how the compound acts.

In short Melgar, yes I want to separate them.
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[*] posted on 29-4-2018 at 05:38


Nitroethane forms a Azeotrope with 75% Toluene, boiling @106.2 °C.
Methoxy-2-Propanol also forms a Azeotrope with 20% Toluene,
but the only Data I found was on pubs.acs.org and I dont have Access to the Text...


[Edited on 29-4-2018 by Amoled]
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[*] posted on 29-4-2018 at 05:48


I would go for the binary azeotrope with water, if that works and comes over at 87 degrees; no problem, easy peacy. If a ternary comes over, maybe you can oxidize the M2P alcohol to the carboxylic and wash it away with a bit of alkaline water. I would go for a concentrated alkaline as nitroethane is quite soluble in plain water (4,5g / 100ml). Also for this reason; throw in some brine before you separate your nitroethane/water layers.

[Edited on 29-4-2018 by Tsjerk]
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SamuelLFraction
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[*] posted on 29-4-2018 at 08:11


Amoled, thanks for the information, I hate how they subject you to ridiculous payments. Perhaps someone else here has access and could relay some information if they’re feeling nice! :) it would be really nice to log down everything about M2P in a nice orderly manner for any future references.

Tsjerk I’ll be performing the separation as soon as I get time to; I’ll make sure to post here as soon as I receive results for clarification on azeotropes and their weights etc. How would one go about oxidising a secondary alcohol to carboxylic acid? Please forigve me for my ignorance but I thought it was not possible to do this.

[Edited on 29-4-2018 by SamuelLFraction]

[Edited on 29-4-2018 by SamuelLFraction]




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[*] posted on 29-4-2018 at 09:21


Quote: Originally posted by Tsjerk  
maybe you can oxidize the M2P alcohol to the carboxylic

[Edited on 29-4-2018 by Tsjerk]

Maybe not. It's a secondary alcohol so getting it past the ketone stage may be tricky.
However the ketone will have a different boiling point etc so it may be a step forward.
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[*] posted on 29-4-2018 at 10:46


Unforunately oxidation to Methoxy 2 Propanone is not beneficial as the BP actually drops to 118 :(



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[*] posted on 29-4-2018 at 11:22


Purely unsubstantiated idea, but would coordination to Zn work? I can imagine anhydrous ZnCl2 coordinating to the alcohol and, more weakly, to the ether. Maybe addition of this followed by distillation could give better results?

[Edited on 29-4-2018 by Eddygp]




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[*] posted on 29-4-2018 at 12:05


A secondary alcohol will not oxidize to a carboxylic... nope.

For literature excess: go to sci-hub.tw and enter your DOI of interest
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[*] posted on 29-4-2018 at 12:10


Quote: Originally posted by Eddygp  
Purely unsubstantiated idea, but would coordination to Zn work? I can imagine anhydrous ZnCl2 coordinating to the alcohol and, more weakly, to the ether. Maybe addition of this followed by distillation could give better results?

[Edited on 29-4-2018 by Eddygp]

It might work, but I'd be wary of mixing heavy metals into nitro compounds then heating.
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[*] posted on 29-4-2018 at 14:44


Tsjerk I don’t know how I haven’t come across that proxy before but thank you very much for that link.

Although it was of no benefit in this situation, with regards to the idea of oxidising M2P whilst in presence of Nitroethane is a no go. Nitroethane is not compatible with any oxidising agents. Just wanted to make that clear; prevention is better than cure.




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[*] posted on 29-4-2018 at 19:04


It might be worth exploring drying agents that may be complexed by the compound you want to remove. Certain drying agents are reported to complex with things like alcohols and amines, making them not suitable as drying agents for those compounds. In this case, you may be able to leverage that by adding, say, CaCl2 to your mixture and having it complex the alcohol. Then you could filter off the solids and have your mixture enriched in EtNO2.

https://erowid.org/archive/rhodium/chemistry/equipment/dryin...
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[*] posted on 29-4-2018 at 22:27


The before mentioned File:

https://www.mediafire.com/file/r810elhdzl0dedu/1-Methoxy-2-p...

I hope its useful, there are several Azeotropes of 1-Methoxy-2-Propanol and 2-Butoxy-Ethanol listed.
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[*] posted on 30-4-2018 at 04:13


Quote: Originally posted by SamuelLFraction  
Although it was of no benefit in this situation, with regards to the idea of oxidising M2P whilst in presence of Nitroethane is a no go. Nitroethane is not compatible with any oxidising agents. Just wanted to make that clear; prevention is better than cure.


Why wouldn't it be? The nitrogen atom is fully oxidized already, the rest of the molecule is just aliphatic carbon. You could run into problems with the acidic alpha C-H, but in neutral or acidic environments that shouldn't be a problem. Nitro ethane can be synthesized by permanganate oxidation of ethyl amine.
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[*] posted on 30-4-2018 at 05:14


Any chance the nitroethane contained could be converted to a nitronate salt with sodium or potassium hydroxide, then crystallized out by the addition of a less polar solvent? I'm not sure about converting it back to the nitroalkane, though, just tossing out the idea.
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[*] posted on 30-4-2018 at 09:49


Quote: Originally posted by Tsjerk  
Why wouldn't it be? The nitrogen atom is fully oxidized already, the rest of the molecule is just aliphatic carbon. You could run into problems with the acidic alpha C-H, but in neutral or acidic environments that shouldn't be a problem. Nitro ethane can be synthesized by permanganate oxidation of ethyl amine.

Yep. Even manganese heptoxide doesn't react with it.

The propylene glycol ether would be extracted into a sulfuric acid solution, no? Or into a water layer?




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[*] posted on 30-4-2018 at 14:04


Quote: Originally posted by Tsjerk  
Quote: Originally posted by SamuelLFraction  
Although it was of no benefit in this situation, with regards to the idea of oxidising M2P whilst in presence of Nitroethane is a no go. Nitroethane is not compatible with any oxidising agents. Just wanted to make that clear; prevention is better than cure.


Why wouldn't it be? The nitrogen atom is fully oxidized already, the rest of the molecule is just aliphatic carbon. You could run into problems with the acidic alpha C-H, but in neutral or acidic environments that shouldn't be a problem. Nitro ethane can be synthesized by permanganate oxidation of ethyl amine.


http://nj.gov/health/eoh/rtkweb/documents/fs/1373.pdf Page 6 on Hazards data on the right hand side, why does this source suggest it is not compatible then? My apologies for stating incorrect information I just decided to take that source’s word for it without even thinking really. Pehaps it is in relation to formation of shock sensitive salts.




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[*] posted on 30-4-2018 at 15:41


What happens when you add water? Possibly with some more or different organic solvent?

[Edited on 30-4-2018 by S.C. Wack]




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[*] posted on 1-5-2018 at 02:54


Quote:
http://nj.gov/health/eoh/rtkweb/documents/fs/1373.pdf Page 6 on Hazards data on the right hand side, why does this source suggest it is not compatible then? My apologies for stating incorrect information I just decided to take that source’s word for it without even thinking really. Pehaps it is in relation to formation of shock sensitive salts.


That is a safety sheet, as nitro-ethane can act as an oxidizer as well as a reductor, they just state it is not compatible with oxidizers and reducers (see the hydrocarbon listed there as well).

[Edited on 1-5-2018 by Tsjerk]

[Edited on 1-5-2018 by Tsjerk]

[Edited on 1-5-2018 by Tsjerk]
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