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Author: Subject: pyridine prep help
LoKi
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[*] posted on 27-2-2007 at 03:59
pyridine prep help


I was wondering if anyone had any ideas for a Pyridine prep. I remember reading a text saying that the general procedure for producing pyridines was the Haantz reaction? I don't remember the name off the top of my head, but I know that it gave shit other than simple pyridine. there was a variation that gave some sort of 3,5 substituted pyridine. Thats great and all but what about simple old pyridine? Would it be possible to cleave the ethers or alkyl chains or whatever it was sticking off? The pyridine ring is pretty strong if I remember correctly, so I guess you could subject it to all kinds of torture. I know, I oughta look up the reaction and be specific instead of pulling this info out my ass, but I'm tired and about to go to bed, and I think I got my point across. Apologies for typos and nonsensical ramblings. Like I said, I'm REAL tired. Anyway, any help would be greatly appreciated.



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Sauron
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[*] posted on 27-2-2007 at 10:39


I will look into this for you. Never really considered it before, pyridine being an easy chemical to buy.

Niacin (nicotinamide) is also easy to buy and you can decarboxylate it, it is pyridine-3-carboxamide.
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[*] posted on 27-2-2007 at 19:08


Conversion of niacin (nicotinamide) to pyridine sounds like an interesting synthesis for the home chemist. This presumes that one can isolate the nicotinamide in sufficient purity from the OTC niacin concoctions. It should then be readily convertible to nicotinic acid utilizing HCl.

Could the nicotinic acid then be decarboxylated to pyridine in the same way benzoic acid is decarboxylated to benzene?




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leu
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[*] posted on 27-2-2007 at 19:14


This has been discussed in detail on a site long gone from the internet. Psyloxy did most of the legwork :) It's not practical, see:

http://www.korbis-labor.de/experimente/carbonsaeuren/darstel...

1.5 g nicotinic acid and 2.5 g CaCO3, when heated to decarboxylation with a bunsen burner give 0.3 mL pyridine not worth the hassle, nicotinic acid is also quite expensive.

There's Patent DE944251:

Example 2

A solution of 200 parts 1,5-pentanedial in 800 parts 3% sulfuric acid is added, over the course of 2 h, to a boiling solution of 1100 parts crystallized Fe2(SO4)3 and 200 parts (NH4)2SO4 in 1500 parts water. Workup as in example 1 yields 82% pure pyridine.

workup as in example 1: rxn-mixture is made alkaline and the aromatic base is distilled off.

The dehydrogenation of piperidine forming pyridine can be carried out either by heating to 300° with concentrated sulphuric acid, or with nitrobenzene at 200°; or with silver acetate in acetic acid.

[Edited on 28-2-2007 by leu]

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Sauron
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[*] posted on 27-2-2007 at 19:24


A lot more people are interested in making piperidine than in making pyridine.

This includes making piperidine from pyridine (which is rather easy).
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[*] posted on 27-2-2007 at 22:43


Aldol condensation of formaldehyde with acetone(should have vrey good yield since formaldehyde is a good electrophile). Then add ammonia(conjugate addition + intramolecular cylclization) = piperdone. Reduce the carbonyl = piperidine. Looks good on paper.

[Edited on 2/28/2007 by guy]
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[*] posted on 27-2-2007 at 23:42


Piperidine

Generally you cyclize something like 5-aminopentyl bromide or similar 5-carbon backbone, it's not that tough.

However if you have a ready supply of pyridine, then reducing it with sodium in ethanol is easier. This also assumes you have a lot of sodium or can get it.

I use dilute piperidine soln for global deprotection of Fmoc peptides as it works a lot better than NMM (N-Methylmorpholine.)
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[*] posted on 28-2-2007 at 02:54


An old preparation of piperidine is by heating pentamethylenediamine hydrochloride (cadaverine); which is the result of putrefactive enzymes on lysine; ii's quite toxic in addition to being very obnoxious, but the hydrochloride salt isn't so toxic :P An alternative synthesis can be found in Ber 56 625-30 (1926):

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Sauron
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[*] posted on 28-2-2007 at 04:50


Thanks, @leu

Cadaverine is very expensive. It is classed as corrosive, nothing special is said about toxicity. Acros wants $10 a gram for it and does not have more than 25 g bottles.

On the other hand, the corresponding glycol is cheap and sold by the Kg ($66) so building the diamine from that via the dihalide would be easy.

Another related route might employ tetrahydropyran, but it is about 50% more expensive than the glycol, and being an ether will be prone to peroxide formation. The transformation to the open chain glycol would be similar to taking THF to BDO.

Incidentally these N and O saturated heterocycles sometimes do odd things.

When one of the Big Pharmas was developing Ditran as an experimental psychiatric drug they had this problem.

Ditran was a an ester of a tetrahydrofurfuryl carboxylic acid. They started with tetrahydrofurfuryl alcohol, an agricultural byproduct from Quaker Oats mostly. Made the bromide then the amine. But when this was distilled they didn't obtain the single pure tetrahydrofurfurylamine, they got a mixture of it with 3-hydroxypiperidine. The furan ring had opened, and the open chain intermediate reclosed as the six membered imine.

This observation led to the development of the 3-quinuclidinyl benzilates (BZ etc).

That piperidine ring is really very favored, chemically.

[Edited on 28-2-2007 by Sauron]
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[*] posted on 28-2-2007 at 08:14


Hmmm ... adipic acid, if you don't have a direct source then the hydrolysis of nylon-6-6 will yield it and the matching C6-diamine, convert to the diammonium salt, heat to form the cyclic amide, treat with NaOCl giving 5-amino-pentanoic acid. That should cyclicize to the amide, 6 member rings being favoured. Reduce the amide to piperidine.

Hexamethylene diamine is similar to cadaverine, maybe a bit less stinky. If you xan put together a setup to avoid the escape of the diamine and don't live well away from other people, acid hydrolysis is advisable to keep the diamine as the salt.
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[*] posted on 28-2-2007 at 09:10


I think I'll stick to Na/EtOH redn of Pyridine...

Cadaverine does sound like the Smell-O-Rama version of Jeepers Creepers. Ugh.
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[*] posted on 28-2-2007 at 10:39


I didn't realize pyridine was easy to come by. I seem to remember hearing it was watched, but not listed. The niacin decarboxylation looks interesting, I'll give it a shot and see how it goes. Fairly pure niacin should be available from several vitamin retailers. Guy- that aldol condensation sounds a lot like that Hantzsch Pyridine Synthesis that I had mentioned. Thanks so much for help, fellas.



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[*] posted on 28-2-2007 at 11:56


"watched but not listed" is just druggie paranoia. Look at all the totally irrational stuff on their lists, and ask yourself whether or not they would deliberately leave off anything they thought was significant?

These are the folks who banned Red Devil lye remember.
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[*] posted on 28-2-2007 at 12:42


Quote:
Originally posted by Sauron
These are the folks who banned Red Devil lye remember.


Which is not listed, and so a specific example of something left off the list that is thought to be significant.
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[*] posted on 28-2-2007 at 18:24


Well, then I was wrong because they haven't banned Red Devil lye, but, you can also bet your ass that there's no DEA agent lurking in every supermarket, 7-11 and hardware store checking on who buys drain cleaner.

It's ridiculous. It's a waste of manpower, and unproductive.
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[*] posted on 28-2-2007 at 18:54


Not drain cleaner but my local hardware store requires that the buyer provide his name, signature, and driver's license number when buying acetone, toluene, and another solvent that I can't remember. This is kept on a log sheet. I don't think this was inspired by the DEA but likely by the local constabulary. Ridiculousness is not a factor.



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[*] posted on 1-3-2007 at 01:43


Maybe I am old fashioned, but, if a clerk in a hardware store was arrogant enough to ask me (a paying customer, and not at all up to no good) for all that just to buy a tin of a common solvent (toluene = paint remover, acetone = degreaser) I would walk out and find another store. If the county Mounties mandated that I'd drive to a county where they still respected the privacy of honest citizens.

It IS ridiculous.

If the stuff is so hazardous to the public safety by virtue of the assholery of meth cooks, jihadis, whatever, take it off the store shelves. But if it is available to the public, OTC, then by God it is nobody's business who buys it and the gubbiment ought not to be turning counter clerks into spies and snoops.
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[*] posted on 1-3-2007 at 03:25


I'd be like suuuuuurrrrrreeeeee... put my name on the log.

After you raided 99.9% of the persons on the list, you MIGHT get one meth cook... wait though.. I'm thinking that was BEFORE the pseudoephedrine restrictions...

Those logs are useless nowadays. Pure scare tactic is all it is.
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[*] posted on 1-3-2007 at 09:25


My comment on "ridiculousness" was poorly worded. Of course it is ridiculous. What I was trying to say is that LE and the store management don't let that fact stop them.

The clerks are not arrogant. They are merely minimum wage pawns in this farce that need to keep their jobs.

I don't buy solvents at that hardware store anymore. I drive 5 miles down the road and give my business to their competitor who fortunately doesn't care to play these silly games.

And yes, Lurker, this has all been made moot by the bans on OTC pseudoephedrine anyway. It simply is just intimidation of the innocent.

[Edited on 1-3-2007 by Magpie]




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Sauron
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[*] posted on 1-3-2007 at 11:10


Of course we are all preaching to the choir.

And you are doing just what I said I'd do, go buy somewhere less nosy.

Sure the clerk is just doing what he's told. Unless the clerk is the owner, and then he's doing what he chooses, I don't think local LE can force him to do this, so it's his choice and that would make him arrogant.

Does 5 miles away get you across a county line, or out of city limits? How local is local?
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[*] posted on 1-3-2007 at 11:29


Rather than call the store management (or owner) "arrogant," I would call them politically correct wimps.

No, 5 miles is still in the city. But the owner is local, old, and crusty, and has apparently chosen not cave in to this bullshit busywork that LE wanted to foist on him.




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[*] posted on 1-3-2007 at 12:16


Okay maybe arrogant is not quite right, but, presumptuous. If I go buy a wrench the seller doesn't ark me what I want it for. All the same, tool, or supply like degreaser or paint remover. Those stores are there to sell such things and not to collect names for the Nanny State.

I have nothing at all to hide but I would go a lot farther than five miles to get away from that sort of intrusion into my privacy and I would not give that place of business one dollar of my trade, ever again, for any reason.

Good on your crusty old shopkeeper, I bet we'd see eye to eye.
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[*] posted on 1-3-2007 at 23:50


I really have nothing to hide either, but having the city's finest rummaging through my makeshift and very fragile lab is the last thing I want, which is why I would rather make my own reagents if they can't be bought at the hardware store or online. Maybe once my balls will drop and I'll try to purchase my supplies at the local chem distributor. I certainly don't want to fill out an "intended use" form or whatever they call it. Most of the things I buy, I buy only with a vague idea about what I'll use it for. I just want to try different reactions and learn the trade and gain experience. Speaking of filling out forms at stores, a law was recently passed in my state requiring strict records of psuedoephedrine, ephedrine, and PPA to be kept by all retailers. ID's are to be shown, addresses recorded, signatures, the whole nine yards. There is also a buying limit of something like 2 boxes a month. Working at a pharmacy, I hear stories about the DEA bitching like, well, a bitch, when the kids at the register don't follow their regulations to the letter. It's disgusting, and meth isn't even a problem here. I looked up the statistics, there has been ONE meth found in this county, ever. Statewide meth use and manufactor statistics are relatively low as well.



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Sauron
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[*] posted on 2-3-2007 at 03:50


However, I assume you do not feel deprived by not being able to buy ephedrine, psuedoephedrine, or PPA? I know I don't.

1. I would not stop me from doing chemistry in the slightest.

2. It would not stop me from making methamphetamine if I was so inclined, either, because there are beaucoup ways to do that which have nothing to do with ephedrine, psuedoephedrine, or PPA.

So you see, that measure ONLY affects meth cooks who were using those immediate precursors in that particular route or two.
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[*] posted on 2-3-2007 at 07:38


Quote:
Originally posted by Sauron
So you see, that measure ONLY affects meth cooks who were using those immediate precursors in that particular route or two.


Or those who actually want a decongestant. From what I hear, the replacement chemical doesn't work.
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