Boffis
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Substitute for piperidine in this reaction
I am trying to analysis the product of the reaction between sodium nitrite and 3-formal-2,3-dihaloacrylic acids (mucochloric acid etc). Some of these
reactions yield sodium nitromalondialdehyde (1,3,4) but the they also give salts of the isonitro form of 1,2,2-trinitropropanal (2,5) and the sodium
salt of 3-formal-3-keto-2-nitropropanoic acid (3).
In these documents it is clear that while mucobromic acid gives 35-40% yield of sodium nitromalondialdehyde mucochloric acid gives only a low 0-13%
yield. However, when I tried the Org. Synth. (4) procedure but substituting mucochloric acid for the bromo analog I got an apparent yield of 93% !!!.
Reading the Fanta et al paper (3) and the US patent (5) it is very likely that I have obtained a mixture of the compounds above and therefore this
"yield" figure is meaningless.
So... how do you analyse the product. My product is almost white -pale straw coloured and water soluble so that rules of the Na salt of
trinitropropanal (deep red). My idea is to try reacting it with hydrazine sulphate in one test (to give ultimately 4-nitropyrazole), guanidine
carbonate in another and finally a 1,2-diamine such as o-phenylenediamine in a third (to give a quinoxaline derivative). According to the literature
(6) sodium nitromalondialdehyde reacts with guanidine carbonate rapidly and in the presence of a "few drops" of piperidine almost quantitatively to
yield 2-amino-5-nitropyrimidine which being sparingly soluble precipitates. This sounds like a potential method for analysis of purity and indeed the
checkers of the Org Synth., Fanta paper (4) used it for just this purpose.
The problem, therefore, is that I don't have piperidine and while I could probably make soon from pepper extract I have several other secondary and
tertiary amines that might work. What is so special about piperidine as a catalyst? Would another secondary amine of similar pKb be suitable, perhap
morpholine or diethylamine, or even a tertiary amine such as pyridine or triethylamine work?
I also have some 2-piperidone, can this be reduced to piperidine without Pt catalysts and high pressure vessels, say with hydrazine hydrate and alkali
(I forget the name of this reaction)?
1) Hill & Torrey; American Chem. J.; 1899, v22, p89
2) Hill & Sanger; Proc. Amer. Academy of Art & Sci.; 1906 v15 p10 (This journal is available on line but I couldn't find the reference, Prof
Hill died in about 1904 so the dat may be out, see patent below).
3) Fanta et al.; J. American Chem. Soc.; 1958, v80, pp4577-4579.
4) Fanta; Org. Synth.; 195, v32, p95.
5) US 3101379
6) Hale & Brill, J. American Chem. Soc.; 1912, v34, pp82-94.
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DJF90
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Try pyrrolidine if you have it. If not it can be made from proline by decarboxylation - I think Scr0t made a thread in Prepublications on this.
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Dr.Bob
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Morpholine may also work as a replacement for piperidine. It can form enamines with aldehydes, which are very reactive, not sure if that is the
mechanism for your reaction, but that is a common use for piperidine in aldehyde reactions.
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zed
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Piperidine might be a tough "get" nowadays.
Easy to make pyridine. Might not be hard to reduce. Depends on your resources.
Have a youtube link. But, it seems like a lot of trouble, if you only need a few drops. https://www.youtube.com/watch?v=umYuJ8TwQLk
Reduction seems less odious, via hydrogenation.
https://www.sciencedirect.com/science/article/pii/S004040200...
[Edited on 7-1-2018 by zed]
[Edited on 7-1-2018 by zed]
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Boffis
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Thanks for the help guys.
I ran an experiment today using guanidine carbonate and a little morpholine but only a trace of colourless crystals formed. This reaction is supposed
to give a modest yield even without a catalyst so this seems to indicate that the original product contains very little sodium nitromalondialdehyde. I
also prepared a small amount of the Benzyl-isothiuronium salt and tomorrow I will test its melting point. I will also run a small scale reaction with
a 1,2-diamine to see if I can form a pyrazine or benzopyrazine (quinoxaline) derivative.
By the way does anyone know the name of the reduction using of ketones to alkane via the hydrazone and KOH?
Found it! Wolff Kishner reduction; but I don't think the amide (lactam) group would survive the conditions.
[Edited on 8-1-2018 by Boffis]
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Cryolite.
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The reduction of ketones to alkanes is called the Wolff-Kishner reduction. The Huang-Minlon modification is another name that you might see kicking
around for it.
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Boffis
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I tried the hydrolysis of piperine to obtain some piperidine. I used Chem Player's YT video method with a few modification, I carried it out on 5x the
scale (35g of piperine) and used 4.5 hours of refluxing. I made a few modifications as I was primarily interested in the piperidine, the yield of
which was almost quantitative as the hydrochloride. Now, how best to free base the hydrochloride? I am thinking of solid calcium hydroxide and then
distillation as the resulting calcium chloride should entrain the water.
I'll probably do a write up of the whole procedure because the larger scale offers some interesting alternatives. The yield of almost white potassium
piperinate was also excellent and the brown resin is easily washed out solid with rectified spirit.
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chemplayer...
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Awesome to hear! Would be interesting to hear the exact modifications as we were thinking of doing this again in a slightly different way (acid
hydrolysis).
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Boffis
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Write-up + pics in progress.
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Boffis
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@chemplayer, posted my write-up on the piperine hydrolysis in a new thread.
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