Sciencemadness Discussion Board

Condensation with Nitromethane

kamal - 15-4-2006 at 21:53

Hi friends !

I'm trying condensation of 3-acetoxy benzaldehyde with Nitromethane as under.

OHC-Ph-OCOCH3 + CH3NO2 = CH(OH)CH2NO2-Ph-OCOCH3.

Can anyone pls suggest me how to perform this reaction ? :o

Awaiting your suggetions !!




kmorendha :cool:

PainKilla - 16-4-2006 at 07:51

I don't mean to be rude but searching "nitromethane condensation benzaldehyde" on google brings up MANY results on the first page that are absolutely relevant to your question.

I won't be so kind to provide the links though ;). Refluxing your benzaldehyde and nitromethane has always worked for the people that I don't know (don't forget the catalyst). You could also try the Henry reaction. Both work well.

Good luck.

[Edited on 16-4-2006 by PainKilla]

garage chemist - 16-4-2006 at 07:59

I've prepared unsubstituted ß- nitrostyrene from straight benzaldehyde and nitromethane, via the cold method:

The benzaldehyde and a slight excess of nitromethane are dissolved in methanol and cooled with a salt ice- bath.
Under strong stirring, a methanolic KOH solution (same molar amount as the benzaldehyde, plus a bit of excess) is added dropwise over the course of one hour. The temperature must never be allowed to rise over 5°C.
The mix is then poured into an excess of icecold 15% HCl, the nitrostyrene separates as faintly yellow powder. It is filtered at the pump, dried and recrystallized from petrolether to yield beautiful long thin yellow needles, with a faint cinnamon smell.

However, for the acetoxybenzaldehyde, this method might not be suitable because the basic conditions might break the ester linkage.

Nicodem - 16-4-2006 at 09:39

He is asking about making the 1-(3-acetoxyphenyl)-2-nitroethanol and not the nitrostyrene (this would be clearer if the equation would not be wrong).
The classical Henry condensation, like garage chemist described it, might work even though KOH is used, since its concentration is never rally high and the temperature is low. There are also literature examples where triethylamine is used which should be enough weak to prevent any hydrolysis of the sensitive phenyl acetate link.
But Kamal, why don't you search Beilstein/SciFinder yourself?

Sergei_Eisenstein - 16-4-2006 at 10:24

Quote:
Originally posted by Nicodem
But Kamal, why don't you search Beilstein/SciFinder yourself?



Quite hard when the structure is wrong :D

Main issue here, next to avoiding hydrolysis of the acetate, is the elimination of water. This occurs readily as the resulting nitrostyrene is stabilized. There are a few bases that are good for stopping the reaction at the nitro-alcohol stage. More information can be found in The Nitro Group in Organic Synthesis, which is available as an e-book on several websites.

1-(3-acetoxyphenyl)-2-nitroethanol

kamal - 17-4-2006 at 05:02

Yes Nicodem !

You're right. I want to make 1-(3-acetoxyphenyl)-2-nitroethanol & NOT the styrene derivative.

But I'm still confused to adopt experimental conditions for this.

I read somewhere that just stirring the aldehyde & nitromethane in eq. molar proportions in presence if a small qty. of solution of NaHCO3/Na2CO3 or org. base so that the condensation product would be fall out as reaction goes, but unfortunately I did not get like this...........

What do you all think ?

By the way, I'm quite unknown to use beilstein/scifinder online ! Can you give me some more info about its usage ?




[Edited on 17-4-2006 by kamal]

Nitromethane & Benzaldehyde

trynerror - 3-9-2015 at 19:36

garage chemist:

I've prepared unsubstituted ß- nitrostyrene from straight benzaldehyde and nitromethane, via the cold method:

The benzaldehyde and a slight excess of nitromethane are dissolved in methanol and cooled with a salt ice- bath.
Under strong stirring, a methanolic KOH solution (same molar amount as the benzaldehyde, plus a bit of excess) is added dropwise over the course of one hour. The temperature must never be allowed to rise over 5°C.
The mix is then poured into an excess of icecold 15% HCl, the nitrostyrene separates as faintly yellow powder. It is filtered at the pump, dried and recrystallized from petrolether to yield beautiful long thin yellow needles, with a faint cinnamon smell.

However, for the acetoxybenzaldehyde, this method might not be suitable because the basic conditions might break the ester linkage.


I done same up to stage before crystallization and had the same color and smell when you do with Nitroethane!!!?

now any idea what's the different? it looks to me same smell of tear gas like and orange like color. the only things I done different was adding KOH as solid half of benz (which is 10ml) in this example.


any expert idea about this?

Thanks

[Edited on 4-9-2015 by trynerror]

I already know that nitromethane makes substitute

trynerror - 4-9-2015 at 17:46

I already know that nitromethane makes substitute but really have no idea what that means by substitute Phenylalanine.

trynerror - 6-9-2015 at 22:45

Ok, I done another try ... firstly don't know how come garage chemist ended up beautiful long thin yellow needles as mine showed up more like yellow powdery cake, even after washing with Ethanol still same shape and pale yellow but not sharp neither long or any to what garage chemist done. the only things was different was I used dry KOH rather than using liquid. in fact I add only 3g to 5g KOH on the solution and in almost 3 to 5 dosage. can say done this reaction at least 3 times in last couple of days but always same result. also I did not recrystallized with HCL as he did and only after reaction finished it become like solid in room temperature.

I'm not agree with what's written here and so far what is see is totally is different. that's why I asked such a question above.

Tsjerk - 7-9-2015 at 06:53

Maybe you should do as Garage Chemist describes before you ''don't agree''. I can see two reasons why you don't get the same results, one of which I'm 99% sure is the reason.

Thx

trynerror - 7-9-2015 at 21:28

Quote: Originally posted by Tsjerk  
Maybe you should do as Garage Chemist describes before you ''don't agree''. I can see two reasons why you don't get the same results, one of which I'm 99% sure is the reason.


looks like this forum is not for mute chemist! anyway it's now evening so most likely I will do another try tonight and make sure to get some photo and put the result of both reactions.

to make it clear that I did not used any of those web documented and ref. and the way I used it my own way I done with try n error. I say by tomorrow around same time I post result. and they not similar true! smell and odor changed after a while, the one with ethan cause even burn on face skin and eyes full of tears but the methane one only initially strong odor but faint after a while reaction done.

Thx

CuReUS - 8-9-2015 at 09:30

finally a synthesis question:D.Thank god for small favors
I gave it some thought and came up with 3 solutions(arranged in increasing order of craziness)

1.using sterically hindered base like TEA as nicodem suggested.maybe bulky metal alkoxides could be used(Al-tert butoxide).Your idea of using a weak base like K2CO3 is not wrong,that idea is used in aldol condensation to prevent the dehydration step.

2.using a solvent that dissolves the reactants but not the product(the nitro-hydroxy or nitroxy;) ) so that furthur dehydration is prevented.I don't think distillation will work as the boiling point of nitroxy will be more than that of the nitroalkene.)

3.An important point in the synthesis is to prevent the hydrolysis of the ester.So why not do the nitroaldol on 3-hydroxybenzaldehyde and then esterify it.The phenolic OH should be more acidic than the secondary OH(but there is a nitro next to it,so I am not sure) and should selectively esterify.

trynerror - 8-9-2015 at 19:28

Quote: Originally posted by CuReUS  
finally a synthesis question:D.Thank god for small favors
I gave it some thought and came up with 3 solutions(arranged in increasing order of craziness)

1.using sterically hindered base like TEA as nicodem suggested.maybe bulky metal alkoxides could be used(Al-tert butoxide).Your idea of using a weak base like K2CO3 is not wrong,that idea is used in aldol condensation to prevent the dehydration step.

2.using a solvent that dissolves the reactants but not the product(the nitro-hydroxy or nitroxy;) ) so that furthur dehydration is prevented.I don't think distillation will work as the boiling point of nitroxy will be more than that of the nitroalkene.)

3.An important point in the synthesis is to prevent the hydrolysis of the ester.So why not do the nitroaldol on 3-hydroxybenzaldehyde and then esterify it.The phenolic OH should be more acidic than the secondary OH(but there is a nitro next to it,so I am not sure) and should selectively esterify.


no offense taken, I don't understand so appreciate if you explain simple what is it and what's called the final products.
as promised I done the experiment and upload whole file. no copyright neither anything else and anyone welcome to modify and make it like those standard you put in here as I did not check or spell check and only wrote what passed on my mind and thought while doing it.

good luck but for god sake tell me:
1 - what's the final products name I make? or any scientific name for it ..
2 - what's the usage as I do usually dump them, in fact I just did to test if I my procedure work for 10% to 20% better yield of nitroethane made by French dessigne guy.

and here is the file

trynerror - 8-9-2015 at 19:29

the file

Attachment: procedure.rar (4.4MB)
This file has been downloaded 621 times

UC235 - 8-9-2015 at 19:32

Do this website a favor and drink your reaction mixture.

trynerror - 8-9-2015 at 19:34

don't know what you mean, but had difficulty in uploading file, I see it's fine now.

trynerror - 8-9-2015 at 22:08

come on I just want to know what garage chemist means by unsubstituted ß- nitrostyrene :( so far cost me hours of doing something that I have no idea what's it and was main question and still no one say any word!?

where's that Nicodem guy I know he's expert and I've been reading most of his reply since last 7 years.

trynerror - 11-9-2015 at 21:40

Ok all goru(s) I find some ref on Vogel 3rd IV,129 pages 721 after, I know it's called now and thx for not having any comment. most likely your knowledge had a wrong reaction with your sense of ... ;)

Thx again and good luck