Author Topic: A question about benzaldehyde/nitropropene  (Read 1459 times)

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  • Guest
A question about benzaldehyde/nitropropene
« on: April 18, 2003, 02:33:00 AM »
I have been dreaming lately about the electrochemical reduction of nitropropene to amphetamine.  I have been dreaming about this for the past month and a half, and I have a pretty good idea of what is going on in the reactions, but I overlooked one step in this process, and I don't have the knowledge yet to know what to do.

When changing the benzaldehyde (bought at Walmart :) to the nitropropene, the reaction is usually benzaldehyde + nitroethane + ammonium acetate or cyclohexylamine -> nitropropene.  My question is: are there any OTC ways of obtaining these chemicals, or OTC chems that can be substituted for these?  I have found sources for all chems but these.  If anyone could help me out or point me in the right direction, I would greatly appreciate it.



  • Guest
« Reply #1 on: April 18, 2003, 02:45:00 AM »
You won't find nitroethane at Walmart, it is a watched substance, but it can be synthesized, if you UTFSE and have a look at

there are several ways to accomplish this.


  • Guest
« Reply #2 on: April 18, 2003, 12:06:00 PM »
I'm crying.  All this work I've put forth to make sure everything is easier to find (not that the hive and rhodium's wouldn't cut it) and still, THIS is the response I get to see... day after day after day...

I'm beginning to get a feel for how most of the Mods (and Rhodium) must feel


  • Guest
Ever read this thread: Post 103078 , with all...
« Reply #3 on: April 18, 2003, 08:45:00 PM »
Ever read this thread:

Post 103078

(rev drone: "What can be done to improve the performance of clandestine nitroethane synth?", Chemistry Discourse)
, with all the good compendia Aurelius made?

I feel with you, Aurelius ... this must bee really depressing.

Huh, I didn't know benzaldehyde was OTC.  Isn't it supposed to bee watched as a precursor for me metthhh metttthhhhhhamphetamine?


  • Guest
Re: Huh, I didn't know benzaldehyde was OTC.
« Reply #4 on: April 18, 2003, 10:04:00 PM »

Huh, I didn't know benzaldehyde was OTC.  Isn't it supposed to bee watched as a precursor for me metthhh metttthhhhhhamphetamine?

If you search around you can find all kinds of info on it- Benzaldehyde is the primary constituent of bitter almond oil.. Easily available.



  • Guest
ambiguous question
« Reply #5 on: April 18, 2003, 10:11:00 PM »
yes, i suppose i was a bit ambiguous with my question.  i have a source for nitroethane, i was wondering what the purpose of the ammonium acetate/cyclohexylamine was in the reaction.  are they used as catalysts.  so without them, can the reaction be done without them over an extended period of time?  or are the essential to the reaction?  i have done a lot of UTFSE, and i realize that posting to the hive is an essay in criticism, but i really have looked hard for this information and found nothing.



  • Guest
They are necessary.
« Reply #6 on: April 18, 2003, 10:19:00 PM »

ammonium acetate/cyclohexylamine was in the reaction.  are they used as catalysts.  so without them, can the reaction be done without them over an extended period of time?

They work as a catalyst and are required for the reaction to work. This reaction is called a Henry Reaction, and it is essentially a base-catalyzed aldol condensation between the nitroalkane and the aldehyde. After the condensation, dehydration of the resulting nitroalcohol results in the nitroalkene, ammonium acetate and cyclohexylamine facilitate this directly.

You can however use aqueous NaOH as the base to catalyze the condensation and then complete the dehydration with aqueous HCl, I'm sure you can acquire those chemicals. Use the search engine, there are procedures for this on the Hive and on Rhodium's site.



  • Guest
« Reply #7 on: April 19, 2003, 12:36:00 AM »
Hey SpicyBrown, if this bee can't find this kind of information, what makes you think the bee can understand what you just said?  (good explaination, but a bit complicated for the beginners, it assumes to much prerequisite knowledge on the part of the beginner) 

Has anybody tried the second version SpicyBrown mentioned?  Decent yields?


  • Guest
Re: what makes you think the bee can ...
« Reply #8 on: April 19, 2003, 02:21:00 AM »

what makes you think the bee can understand what you just said?

Yea.. Good point. See, for one example Organic Syntheses, CV 1, 413 (doesn't seem to be a way to link directly to an OrgSyn entry?


In a 6-l. wide-mouthed bottle, packed in a pail with a freezing mixture of ice and salt and fitted with a mechanical stirrer, a thermometer, and a separatory funnel, are placed 305 g. (5 moles) of nitromethane (p. 401), 530 g. (5 moles) of benzaldehyde (Note 1), and 1000 cc. of methyl alcohol. A solution of sodium hydroxide is prepared by dissolving 210 g. (5.25 moles) of sodium hydroxide in approximately an equal volume of water and cooling. It is then diluted to 500 cc. with ice and water, poured into the funnel, and added with stirring to the nitromethane mixture at such a rate that the temperature is kept at 10–15° (Note 2) and (Note 3).
A bulky white precipitate forms rapidly during the addition of the alkali. The mixture gets so thick that stirring becomes difficult and it may be advisable to add 100 cc. more of methyl alcohol. After fifteen minutes' standing, the pasty mass is converted to a clear solution by the addition of 3–3.5 l. of ice water containing crushed ice (Note 4). Hydrochloric acid (made by diluting 1000 cc. of concentrated hydrochloric acid with 1500 cc. of water) is placed in a 15-l. mixing jar and the reaction mixture run into this from the separatory funnel at such a rate that the stream just fails to break into drops (Note 5). A pale yellow crystalline mass separates almost immediately as the alkaline solution comes in contact with the acid. After the stirring is stopped, the solid settles to the bottom of the jar. The major part of the cloudy liquid layer is removed by decantation, and the residue filtered by suction and washed with water until free from chlorides. This product is freed from all but a negligible amount of water by melting in a beaker immersed in hot water. Two layers are formed, and on cooling again the lower layer of nitrostyrene freezes; the water may then be poured off. The crude nitrostyrene is purified by dissolving in 420 cc. of hot ethyl alcohol (Note 6), filtering the solution into a warm suction flask to remove solid impurities, and then cooling until crystallization is complete. The yield of crude product melting at 56–58° is 650–670 g. The yield of recrystallized nitrostyrene melting sharply at 57–58° is 600–620 g. (80–83 per cent of the theoretical amount). The whole procedure, including purification, can be done in a day.

2. Notes
1. Technical benzaldehyde which had been washed with sodium carbonate solution, dried, and distilled under reduced pressure, was used in this preparation.
2. The first few cubic centimeters of sodium hydroxide solution should be added cautiously to the nitromethane mixture since, after a short induction period, there is a considerable evolution of heat and the temperature may rise from ? 10° to 30° or even higher in spite of good stirring. If necessary, this rise in temperature is easily checked by adding a handful of crushed ice directly to the mixture. After this initial reaction the rest of the alkali may be added more rapidly.
3. The condensation induced by sodium hydroxide is almost instantaneous above 10°. The procedure may be interrupted with safety after the addition of alkali, and the product will not change on standing overnight in an ice chest.
4. After the product has been dissolved in water the resulting alkaline solution is much more sensitive and should be used up as rapidly as possible and the temperature kept below 5°.
5. The alkaline solution must be added slowly to the acid, for the reverse procedure always forms an oil containing a saturated nitro alcohol. A large excess of acid at room temperature is used, conditions which facilitate the formation of the desired unsaturated nitro compound.
6. The vapors of hot solutions of nitrostyrene are very irritating to the eyes and nose, and the skin of the face is sensitive to the solid substance.

Nitroethane can be swapped in for nitromethane. There's another journal ref, can't remember it right now, that specifically details the conversion of 2,5-dimethoxybenzaldehyde yo 2,5-dimethoxy-beta-nitrostyrene using the same method; The nitrostyrene in that ref is used as an intermediate to an antibiotic...



  • Guest
Linking to Org. Syn.
« Reply #9 on: April 19, 2003, 06:21:00 PM »
(doesn't seem to be a way to link directly to an OrgSyn entry?


One way to get the appropriate URL after a search:
1) Click on the procedure entry in the search result listing.
2) Click on the title (substance being prepared) on the procedure page; this will take you to a listing of all procedures for this substance.
3) Click on the appropriate listing from #2 above and this will take you back to the procedure but with a URL on the IE address bar that is now suitable to be cut and pasted to here:


  • Guest
« Reply #10 on: April 19, 2003, 10:01:00 PM »
I'm not one for spoon feeding, but as a newbee I had a similar problem when researching on this same reaction. I think the main problem is that most of the good posts on the subject use the name of the reaction when talking about it.

The reaction you want to do is called a Knoevenagel reaction, or a slight modification version is the Henry reaction as SpicyBrown mentioned. Both are the base-catalysed condensation of a nitroalkane (nitroethane in this case) with an aldehyde (benzaldehyde in this case). Knowing to search for '(Henry or Knoevenagel) and catalyst' will provide you with a lot more useful information than simply 'nitroethane benzaldehyde', for example, because the former will return posts (46 of them in fact) by people who generally know what they're talking about, whereas the latter will give pages and pages of mainly useless information (270 posts...) from everyone who's ever asked a question about making meth from benzaldehyde and nitroethane, including you! 8)

It isn't always easy, and it's helpful to have someone point you in the right direction. As long as you're willing to learn, you'll be fine; my asking a similar question got my one and only UTFSE so far (courtesy of Barium ;D ), but once I knew what the reaction was called, searching was made much easier.


  • Guest
yes, thank you. all i needed was a point in...
« Reply #11 on: April 20, 2003, 01:18:00 AM »
yes, thank you.  all i needed was a point in the right direction, i do not wish to be spoon fed.  i am seriously interested in understanding these reactions.  TFSE and google were not much help in searching for 'nitroethane benzaldehyde' and the names of the reactions are very helpful.  thank you spicybrown and kinetic.