Not logged in [Login ]
 Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Nitroaldol reaction Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum

Author: Subject: Nitroaldol reaction
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

Nitroaldol reaction

EDIT: We have found the original article. For those who are interested: http://www.erowid.org/archive/rhodium/pdf/yeast.nitrostyrene... .

I was thinking of performing a nitroaldol reaction (Henry reaction) of nitroethane and benzaldehyde, using cyclohexylamine as catalyst, to yield phenyl-2-nitropropene.

I don't have much laboratory experience but I'm an avid learner (I like Clayden's organic chemistry book) and I do not underestimate safety. I built a fume hood, Strike style (i.e. with a PVC frame and thick plastic covering it).

So I found an interesting article that seems to be backed up by literature on the old Hive: https://www.erowid.org/archive/rhodium/chemistry/phenyl-2-ni... (the part by Dreamer). It references to J. Chem. Soc. Perkin Trans. 1, No. 3, pp. 501-504 (1998). Unfortunately, I was unable to get the original article (my university does not seem to have it), but luckily they (i.e. Rhodium) provided an excerpt.

Dreamer wrote:

 Quote: To 55 g (0.5mol) Benzaldehyde in a 500mL Flask were added 40 g (0.5mol) Nitroethane and 10mL Cyclohexylamine. All was refluxed for 6h on a water bath. The result were 2 layers. One orange layer at the bottom with phenyl-2-nitropropene and a clear layer at the top with cyclohexylamine and maybe a little bit (~1mL) of H2O. 50mL of H2O were added and then sucked off with a pipette until the phenyl-2-nitropropene crystallized (it crystallized when it came in contact with air in presence of 15mL H2O). I added 200mL 95% denaturated ethanol to the orange crystals. The color of the now needle-like crystals changed from orange to white-yellow. The crystals were filtered. Yield 65 g, 78% of theory.

Excerpt of J. Chem. Soc. Perkin Trans. 1, No. 3, pp. 501-504 (1998)

 Quote: Nitroethane (1.0 mL, 13.9 mmol) and cyclohexylamine (1.3 mL) were added to benzaldehyde (1.0 mL, 9.8 mmol) in glacial acetic acid (5.3 mL). The mixture was held at 100°C for 6 h, cooled and diluted with water (1 mL). The reaction mixture was cooled overnight in a water bath. The crystals formed were filtered and air dried. The crude solid was recrystallised from ethanol to give (E)-2-nitro-1-phenylprop-1-ene (0.99 g, 62%), mp 64–65°C.

Now I do not understand some aspects of these two reaction instructions, namely: the scientific article seems to heat the mixture to 100°C for 6 hours, although Dreamer claims to have heated the mixture using a water bath, and that can't be used very functional above 70°C (else it would just be slowly vaporized). These two descriptions seem contradicting. Also, the scientific article describes adding glacial acetic acid. I was not able to find a reason for this in my literature. At last I wonder if heating nitroalkyl compounds, such as nitroethane, to 100°C is very safe when working with somewhat larger quantities.

Could anyone clear some things up here for me?

[Edited on 12-6-2014 by Eisenstein]

[Edited on 12-6-2014 by Eisenstein]

[Edited on 13-6-2014 by Eisenstein]
Praxichys
International Hazard

Posts: 1022
Registered: 31-7-2013
Location: Detroit, Michigan, USA
Member Is Offline

Mood: Coprecipitated

So, you don't have laboratory experience, but you want to learn to make drugs? Oh, I see.

 Quote: Originally posted by Eisenstein Now I do not understand some aspects of these two reaction instructions, namely: the scientific article seems to heat the mixture to 100°C for 6 hours, although Dreamer claims to have heated the mixture using a water bath, and that can't be used very functional above 70°C (else it would just be slowly vaporized). These two descriptions seem contradicting. Also, the scientific article describes adding glacial acetic acid. I was not able to find a reason for this in my literature. At last I wonder if heating nitroalkyl compounds, such as nitroethane, to 100°C is very safe when working with somewhat larger quantities. Could anyone clear some things up here for me?

1. The water bath could be boiling and just topped off periodically. It is also fairly common to use various salts in water baths to reduce the evaporation rate and also increase the boiling point, as long as you have control over the temperature.

2. I don't know enough about this mechanism to guess. Someone is going to have to come up with that paper.

3. Are you worried about decomposition? Nitroethane is pretty darn stable well past its boiling point. Just mind the flammable vapor.

I suppose I don't have to mention that this preparation involves both precursors to and substances defined as "controlled" in most developed countries. Remember: It's all fun and games until Bubba from cell block F grabs you in the shower. Good luck!

Mailinmypocket
International Hazard

Posts: 1342
Registered: 12-5-2011
Member Is Offline

Mood: No Mood

Woelen JUST detritused this thread and you changed the SWIMS to "I"s and left out the story about your agoraphobia and whatnot. Nice.

http://www.sciencemadness.org/talk/viewthread.php?tid=30618
arkoma
Forum Redneck

Posts: 1232
Registered: 3-2-2014
Location: The Boondocks
Member Is Offline

Mood: Six years of Madness

No shit. Learn a little science--it might keep OTHER PEOPLE from being harmed. Obviously you do not care.

 Quote: Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Mark Twain
Praxichys
International Hazard

Posts: 1022
Registered: 31-7-2013
Location: Detroit, Michigan, USA
Member Is Offline

Mood: Coprecipitated

I might understand...

There are better ways of making money than selling drugs. The practice invariably creates more problems than it solves. I used to work with a guy who did time for possession with intent to distribute, and for that he got 5 years. I can only imagine what kind of time you'll be doing when - not if - your lab gets found out. Sooner or later, they always do.

So the question is whether you would like to spend the last days you can with your father, or watch him die from behind bars? Do you really feel the need to destroy the lives of others by feeding their addictions, just to improve life for a single person, and at a huge risk to yourself, your reputation, and the well-being of your family?

Get a second job or something. He needs you, and he depends on you. At least give him the knowledge, as he slips into the grip of Alzheimer's, that you are a good person who can do the right thing, no matter how small, than resort to... that.

You sound like a respectable, educated person. Emotions get the best of us all sometimes, often leading us to make stupid, rash, life-altering decisions. Losing a loved one is about as much hurt as you can feel. Most of us have been down that road before. Don't do it this way... it's not what he wants for his son, regardless of what the Alzheimer's says. I guarantee it.

Besides, you seem genuinely interested in chemistry. If you have a drug conviction on your record, you will never find a job in the chemical field.

And just remember... Walter White is a TV character. The real world is a lot meaner, a lot messier, and a lot more risky than they put on TV. I do not know a single person "in the biz" who hasn't been arrested/convicted or killed in less than 5 years... and as a young chemist who used to work in some low-end industrial shops, I attract these people like flies to poop.

Please. I urge you to reconsider.

Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

Woelen removed my post and I discussed this with him, he wrote:

 Quote: Hello, In the past we have had quite a few members who posted lots of low-quality posts and used term like SWIM. They were only interested in drugs, fast money, and nothing else. The policy of sciencemadness since then has become more strict. It is not prohibited to discuss psychoactive materials, but such discussions must be at a scientific level and it must be clear that there is scientific interest. So, I invite you to start a thread again. Just keep it businesslike, without SWIM and without begging, because of need of money or because of having a father, who needs care. It is that kind of things which are really frowned upon and make you look like a drugs cook, someone who just is interested in some fast money and hopes to get that money by selling homemade drugs. Also be precise and honest in what kind of compounds you want and what kind of reactants you have. If it comes to drugs, then do not expect people to help you if you keep your post vague. A professional attitude helps. Regards -- woelen

I obviously wouldn't repost this, if I hadn't discussed this with a moderator. You may call me stupid or dumb or whatever, but you should not draw conclusion of information you don't have.

[Edited on 12-6-2014 by Eisenstein]
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

Quote: Originally posted by Praxichys
So, you don't have laboratory experience, but you want to learn to make drugs? Oh, I see.

 Quote: Originally posted by Eisenstein Now I do not understand some aspects of these two reaction instructions, namely: the scientific article seems to heat the mixture to 100°C for 6 hours, although Dreamer claims to have heated the mixture using a water bath, and that can't be used very functional above 70°C (else it would just be slowly vaporized). These two descriptions seem contradicting. Also, the scientific article describes adding glacial acetic acid. I was not able to find a reason for this in my literature. At last I wonder if heating nitroalkyl compounds, such as nitroethane, to 100°C is very safe when working with somewhat larger quantities. Could anyone clear some things up here for me?

1. The water bath could be boiling and just topped off periodically. It is also fairly common to use various salts in water baths to reduce the evaporation rate and also increase the boiling point, as long as you have control over the temperature.

2. I don't know enough about this mechanism to guess. Someone is going to have to come up with that paper.

3. Are you worried about decomposition? Nitroethane is pretty darn stable well past its boiling point. Just mind the flammable vapor.

I suppose I don't have to mention that this preparation involves both precursors to and substances defined as "controlled" in most developed countries. Remember: It's all fun and games until Bubba from cell block F grabs you in the shower. Good luck!

1.
I was thinking about that, yes, but I don't think you can raise the critical evaporation point by 30 degrees by adding some salt (I'm going to research this and post back when sure, it seems interesting).

2.
Still looking. :-)

3.
Well not exactly, but as the vapor pressure increases the chances of creating a spark in my not-explosion-proof (these things are not affordable for hobbyists) extractor that let the stuff explodes rises.

Your last point made me laugh haha (in a pleasant way)! I sure as hell don't wish for Bubba to get my at block F. At least not before I finish my shower :-)!

Furthermore, I never said that I was planning on reducing P2NP to amphetamine, like all you guys imply (understandably). P2NP is legal to posses, albeit strange and suspicious. I'm not doing anything illegal, nor was I planning to do so. Please keep it on topic.

Last thing I want to add: it is very dubious to blame drug producers for the problem we are encountering today in the United States. More philosophical opinions exist on this topic and none of them is necessarily wrong. It seems to be a deficiency in the human race that where there is a demand for certain products, there will always be a suply.

EDIT:
@Praxichys,
Your last post is very honest and admirable. You seem like a good person too. I really appreciate it, I really do.

[Edited on 12-6-2014 by Eisenstein]
arkoma
Forum Redneck

Posts: 1232
Registered: 3-2-2014
Location: The Boondocks
Member Is Offline

Mood: Six years of Madness

 Quote: Originally posted by arkoma No shit. Learn a little science--it might keep OTHER PEOPLE from being harmed. Obviously you do not care.

I retract this in light of your last post. Welcome aboard, this is a wonderful site. Look for my project posts; yet I was "raided" over possibly having a meth lab. It's not a matter of "if" but WHEN. It's not 1985 anymore *sigh* LOL.

 Quote: Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Mark Twain
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

Quote: Originally posted by arkoma
 Quote: Originally posted by arkoma No shit. Learn a little science--it might keep OTHER PEOPLE from being harmed. Obviously you do not care.

I retract this in light of your last post. Welcome aboard, this is a wonderful site. Look for my project posts; yet I was "raided" over possibly having a meth lab. It's not a matter of "if" but WHEN. It's not 1985 anymore *sigh* LOL.

No problem, I appreciate the trouble you took to retract your statement.

I like chemistry a lot. I'm very active on https://chemistry.stackexchange.com/, but of course I cannot share my credentials here with you guys (just to let you know that I'm interested in more than this haha).
arkoma
Forum Redneck

Posts: 1232
Registered: 3-2-2014
Location: The Boondocks
Member Is Offline

Mood: Six years of Madness

Well, I AM an asshole at times, but I do realize that at times I also "jump to conclusions". Go read our FAQ's, check out the library and remember to UTFSE (use the fucking search engine).

And I'm going to check out stackexchange

 Quote: Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Mark Twain
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

 Quote: Originally posted by arkoma Well, I AM an asshole at times, but I do realize that at times I also "jump to conclusions". Go read our FAQ's, check out the library and remember to UTFSE (use the fucking search engine). And I'm going to check out stackexchange

Stackexchange is really nice. A lot of well educated people: loads of PhD's and even a dozen of full professors (I have spoken to many of them).

I originally came over from stack exchange (I'm actually a programmer/mathematician, organic chemistry is more like a hobby for me and just recently I though of it to make some bucks producing P2NP).

So... if anyone has programming question (or math), feel free to ask me (privately is better, because this is a chemistry forum).
arkoma
Forum Redneck

Posts: 1232
Registered: 3-2-2014
Location: The Boondocks
Member Is Offline

Mood: Six years of Madness

meh, contribute, hang out, productively post and the "powers that be" will let ya in "whimsy" where ya can/do/say anything (with manners of course)

Again, welcome aboard.

Pat

 Quote: Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Mark Twain
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

.

Now we cleared that misunderstanding. Has anyone got some ideas on the questions I posted (I'm still looking for the paper, will post it if found)?
Crowfjord
National Hazard

Posts: 390
Registered: 20-1-2013
Location: Pacific Northwest
Member Is Offline

Mood: Ever so slowly crystallizing...

This is just going off of memorized theory from college organic chemistry, but as to your second question, acid is added, I think (someone please correct me if wrong), in order to increase the rate of imine (Schiff base) formation. Also, I think acid catalysis helps to eliminate the amine in the last step, to form the nitroalkene product. As you can see from your own given examples, both ways (with or without acid) seem to work just fine, although the effectiveness seems to be fairly substrate specific, that is, dependent on the ring substitution pattern of the benzaldehyde being used.

Oh, yeah: just semantics, but the reaction we are talking about, that is amine-catalyzed with a nitroalkene as end product is known as the Knoevanagel condensation. The nitro aldol (aka Henry reaction) has a nitro alcohol as the end product. This is a very common mix-up.

[Edited on 12-6-2014 by Crowfjord]
leu
National Hazard

Posts: 368
Registered: 13-10-2005
Member Is Offline

Mood: No Mood

The article can be found on the internet:

http://www.erowid.org/archive/rhodium/pdf/yeast.nitrostyrene...

http://chemistry.mdma.ch/hiveboard/rhodium/pdf/yeast.nitrost...

and details about the mechanisms can be found in articles such as in the attached archive

Attachment: house10.zip (733kB)
This file has been downloaded 217 times

Chemistry is our Covalent Bond
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

 Quote: Originally posted by Crowfjord This is just going off of memorized theory from college organic chemistry, but as to your second question, acid is added, I think (someone please correct me if wrong), in order to increase the rate of imine (Schiff base) formation. Also, I think acid catalysis helps to eliminate the amine in the last step, to form the nitroalkene product. As you can see from your own given examples, both ways (with or without acid) seem to work just fine, although the effectiveness seems to be fairly substrate specific, that is, dependent on the ring substitution pattern of the benzaldehyde being used. Oh, yeah: just semantics, but the reaction we are talking about, that is amine-catalyzed with a nitroalkene as end product is known as the Knoevanagel condensation. The nitro aldol (aka Henry reaction) has a nitro alcohol as the end product. This is a very common mix-up. [Edited on 12-6-2014 by Crowfjord]

Yes, a beta-nitro-alcohol. No, I don't believe it is a Knoevanagel condensation, this is dehydration of an alcohol group, not a carbonyl group (I'm of course not sure though).

[Edited on 13-6-2014 by Eisenstein]
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

 Quote: Originally posted by leu The article can be found on the internet: http://www.erowid.org/archive/rhodium/pdf/yeast.nitrostyrene... http://chemistry.mdma.ch/hiveboard/rhodium/pdf/yeast.nitrost... and details about the mechanisms can be found in articles such as in the attached archive

Many thanks! I'll try to read the article, but it seems a bit above my current level and sadly not very related (it seems to explore yeast catalyzed reactions or something). Do you have any clue on the questions I posted?

[Edited on 13-6-2014 by Eisenstein]
Dr.Bob
International Hazard

Posts: 2105
Registered: 26-1-2011
Location: USA - NC
Member Is Offline

Mood: No Mood

"the scientific article seems to heat the mixture to 100°C for 6 hours, although Dreamer claims to have heated the mixture using a water bath, and that can't be used very functional above 70°C (else it would just be slowly vaporized). These two descriptions seem contradicting. "

The first article is not as well written as the second. The first say "All was refluxed for 6h on a water bath", when reflux means to boil with a condenser attached so that the reaction stays at the BP of the lowest BP component of the mixture. None of the reactants there boil below 100C, I believe, so they were really held at some temp at or below 100C, which is what the second prep says more clearly. But it is quite possible to keep water at near 100C for a while, I do it often in water baths, you just have to refill them often.

"Also, the scientific article describes adding glacial acetic acid. I was not able to find a reason for this in my literature."

Often changing the polarity of the solvent will change the reaction rate, as well as change the pH of the reaction. Acetic acid is used for both reasons in many other reactions, as well as it might help to dehydrate intermediate to the product. But often papers don't say why an additive was used, the key is that they give the specific amounts and procedure, as often it is not exactly clear why an additive is used. There are still people fighting over the exact mechanism of many reactions by giving opposite reasons why a certain chemical changes the reaction outcomes. The key to good science is stating what you did clearly; the reproducibility does not depend on a valid mechanism, only a good experimental writeup.

"At last I wonder if heating nitroalkyl compounds, such as nitroethane, to 100°C is very safe when working with somewhat larger quantities."

While nitroethane is stable, any fumes will be highly flammable, so this work should be done in a safe hood that has a non-sparking blower. The larger any experiment is scaled to, the more dangerous. Look at the number of refinery explosions which have occurred despite being run by teams of skilled chemical engineers. Having seen at least one nitromethane reaction explode in the hands of a very experienced chemist, I can safely say that no reaction with nitro compounds is without some danger and a strong need for caution.
arkoma
Forum Redneck

Posts: 1232
Registered: 3-2-2014
Location: The Boondocks
Member Is Offline

Mood: Six years of Madness

Quote:
 Quote: Originally posted by Dr.Bob The key to good science is stating what you did clearly; the reproducibility does not depend on a valid mechanism, only a good experimental writeup.

Yup. Keep a NOTEBOOK, even if ya gotta "cook the books" and keep two......one you can safely show the cops WHEN, not IF they come and a real one fer yourself.

Edit-not sure why all in a fricking quote box

[Edited on 6-13-2014 by arkoma]

 Quote: Travel is fatal to prejudice, bigotry, and narrow-mindedness, and many of our people need it sorely on these accounts. Mark Twain
Eisenstein
Harmless

Posts: 11
Registered: 12-6-2014
Member Is Offline

Mood: No Mood

 Quote: Originally posted by Dr.Bob "the scientific article seems to heat the mixture to 100°C for 6 hours, although Dreamer claims to have heated the mixture using a water bath, and that can't be used very functional above 70°C (else it would just be slowly vaporized). These two descriptions seem contradicting. " The first article is not as well written as the second. The first say "All was refluxed for 6h on a water bath", when reflux means to boil with a condenser attached so that the reaction stays at the BP of the lowest BP component of the mixture. None of the reactants there boil below 100C, I believe, so they were really held at some temp at or below 100C, which is what the second prep says more clearly. But it is quite possible to keep water at near 100C for a while, I do it often in water baths, you just have to refill them often. "Also, the scientific article describes adding glacial acetic acid. I was not able to find a reason for this in my literature." Often changing the polarity of the solvent will change the reaction rate, as well as change the pH of the reaction. Acetic acid is used for both reasons in many other reactions, as well as it might help to dehydrate intermediate to the product. But often papers don't say why an additive was used, the key is that they give the specific amounts and procedure, as often it is not exactly clear why an additive is used. There are still people fighting over the exact mechanism of many reactions by giving opposite reasons why a certain chemical changes the reaction outcomes. The key to good science is stating what you did clearly; the reproducibility does not depend on a valid mechanism, only a good experimental writeup. "At last I wonder if heating nitroalkyl compounds, such as nitroethane, to 100°C is very safe when working with somewhat larger quantities." While nitroethane is stable, any fumes will be highly flammable, so this work should be done in a safe hood that has a non-sparking blower. The larger any experiment is scaled to, the more dangerous. Look at the number of refinery explosions which have occurred despite being run by teams of skilled chemical engineers. Having seen at least one nitromethane reaction explode in the hands of a very experienced chemist, I can safely say that no reaction with nitro compounds is without some danger and a strong need for caution.

Nitroethane is indeed highly flammable. A non-sparking blower is no option, they are far above my price range (> 1000$). The catalyst, cyclohexylamine is also highly flammable. I talked to a couple of chemists and they told me that if the throughput was high enough, the concentration of the flammable compound wouldn't be high enough to form an explosive mixture. This is why it is a bit shivery to raise the temperature of the compounds in situ. Increasing the vapor pressure will increase the risk of explosion, so I'd rather reflux it at 70°C than 100°C. How is this temperature determined actually? Is it empirically observed that certain temperature have higher yield than others, or is there a theoretical base for the reflux temperature. It still is not very clear to whether I should reflux at < 70°C, or 100°C. You should note too that the reaction is refluxed, so very little nitroethane should reach the fan. This is a difficult consideration: increasing fan power will prevent built-up of vapor inside the cabinet, so decreasing explosion risk, but will also increase flow to the non-explosion-proof fan, increasing explosion risk. I appreciate your help :-) leu National Hazard Posts: 368 Registered: 13-10-2005 Member Is Offline Mood: No Mood  Quote: A non-sparking blower is no option, they are far above my price range (> 1000$).

Hopefully the problem with the search engine is fixed soon If it were working you could have easily found:

http://www.sciencemadness.org/talk/viewthread.php?tid=6707#p...

and learned more about reducing risks in the lab A lot of other safety related information has been posted over the years by various members The end results from the effort applied

Chemistry is our Covalent Bond
zed
International Hazard

Posts: 1766
Registered: 6-9-2008
Location: Great State of Jefferson, City of Portland
Member Is Offline

Mood: Semi-repentant Sith Lord

Now, the sweet reaction for forming nitropropenes, is mixing yer nitroethane and benzaldehyde, with a little butylamine and some ethanol. Then, you hold the mixture at 100 to 120 F, in the dark, absent air, for a week or so.

In your warmer climates, you might be able to run the reaction in a swimming pool. Awful lot of nitropropene, a swimming pool full, but to each his own.

Even Heisenberg would have trouble topping that. If questioned by the authorities, you could tell them you did it because you like the nice "cinnamon" smell.

Good luck getting Nitroethane!

Me? I think I can probably make Nitroethane pretty easily, by the ton. I've got an idea. Oddly enough, I feel disinclined to make any. And, I'm not going to tell you how to do it.

No good can come of it.

 Sciencemadness Discussion Board » Fundamentals » Organic Chemistry » Nitroaldol reaction Select A Forum Fundamentals   » Chemistry in General   » Organic Chemistry   » Reagents and Apparatus Acquisition   » Beginnings   » Responsible Practices   » Miscellaneous   » The Wiki Special topics   » Technochemistry   » Energetic Materials   » Biochemistry   » Radiochemistry   » Computational Models and Techniques   » Prepublication Non-chemistry   » Forum Matters   » Legal and Societal Issues   » Detritus   » Test Forum