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Author: Subject: Failed nitro-aldol reaction. Possible cause and fix?
zed
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[*] posted on 18-3-2019 at 17:58


In my opinion, that paper ain't kosher. It is full of typos and obvious errors.

Back in prehistoric times, I attempted the NiCl2/NaBH4 reduction of Nitropropenylbenzenes. Though to be clear, I made those attempts on substrates, that if successfully reduced, would not yield psychoactive or illegal products.

In no case, did such reductions produce amines.

Though at least some type of reduction was probably achieved, as indicated by significant de-colorization of my reaction mixture.

Most likely, reduction stopped at the oxime stage.

Easy enough to find out. It doesn't require a room full of equipment.

Filter, distill off organic solvents, acidify with aqueous HCl, and steam distill.

P2P might accumulate in your distillate.

In my neck of the woods, that ain't legal, unless you have a permit, of course.



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[*] posted on 18-3-2019 at 19:11


Thanks for the explanation @TheMasterOfTheInternet.

Why don't you make a write up here about your work with NiCl2/NaBH4 to people here try to reproduce it and check the consistency of the results and the yields?

You must have noted that the most of people here doubts NiCl2/NaBH4 can reduce completely, or at least at a reasonable yields, alpha alkyl nitrostyrenes to aryl alkylamines.

@C/J made a reference to an anonymous write up brought by @Clearly_not_atara in another thread about NaBH4/CuCl2 reduction I reproduce below. Why don't you do the same with NiCl2/NaBH4?

Amphetamine from P2NP and NaBH4-CuCl2

"With vigorous stirring, to 5ml of IPA / 1g of P2NP and 0.4 times volume of H2O in RBF was dumped 6 mol eq. of NaBH4.
Recrystallized P2NP was washed with sodium bisulfite solution, then with and water and it was then added in small portions to the mixture to minimize frothing. No external cooling applied. After all substrate was added and near-colourless solution is obtained, the solution left stirring for 30 minutes. Claisen adapter was fitted to the rbf with reflux setup and addition funnel. With one portion, 10%-mol equivalent (for the nitroalkene) of CuCl2.2H2O dissolved in IPA was added to the solution via the funnel. It was refluxed for 30 minutes. After which the remaining NaBH4 was destroyed by adding about 50% acetic acid untill the fizzing stopped and the solution was fairly acidic. With the claisen adapter still attaced, short path distillation setup was rigged and everything below 100'C was stripped. Then the solution was made basic dripping strong NaOH solution to the reaction flask and steam distilled. Additional very dilute NaOH solution was added through the addition funnel every now and then. The distillate was then made slightly acidic with H2SO4 and evaporated. Total yield after recrystallization: 80% mol wise from the P2NP due to very sloppy work"
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zed
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[*] posted on 19-3-2019 at 14:32


Quote: Originally posted by zed  
In my opinion, that paper ain't kosher. It is full of typos and obvious errors.

Back in prehistoric times, I attempted the NiCl2/NaBH4 reduction of Nitropropenylbenzenes. Though to be clear, I made those attempts on substrates, that if successfully reduced, would not yield psychoactive or illegal products.

In no case, did such reductions produce amines.

Though at least some type of reduction was probably achieved, as indicated by significant de-colorization of my reaction mixture.

Most likely, reduction stopped at the oxime stage.

Easy enough to find out. It doesn't require a room full of equipment.

Filter, distill off organic solvents, acidify with aqueous HCl, and steam distill.

P2P might accumulate in your distillate.

In my neck of the woods, that ain't legal, unless you have a permit, of course.

Note: As I recall I conducted this procedure as a hydrogenation. The premise being, that Nickel Boride formed from NaBH4/NiCl2, was acting as The hydrogenation catalyst. Ala Brown.



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[*] posted on 20-3-2019 at 09:58


Quote: Originally posted by zed  
Quote: Originally posted by zed  
In my opinion, that paper ain't kosher. It is full of typos and obvious errors.

Back in prehistoric times, I attempted the NiCl2/NaBH4 reduction of Nitropropenylbenzenes. Though to be clear, I made those attempts on substrates, that if successfully reduced, would not yield psychoactive or illegal products.

In no case, did such reductions produce amines.

Though at least some type of reduction was probably achieved, as indicated by significant de-colorization of my reaction mixture.

Most likely, reduction stopped at the oxime stage.

Easy enough to find out. It doesn't require a room full of equipment.

Filter, distill off organic solvents, acidify with aqueous HCl, and steam distill.

P2P might accumulate in your distillate.

In my neck of the woods, that ain't legal, unless you have a permit, of course.

Note: As I recall I conducted this procedure as a hydrogenation. The premise being, that Nickel Boride formed from NaBH4/NiCl2, was acting as The hydrogenation catalyst. Ala Brown.





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