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hahas
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| Joined: 08 May 2005 |
| Posts: 27 |
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994.52 Points
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IndoleAmine
Dreamreader Deluxe
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| Joined: 09 Feb 2005 |
| Posts: 681 |
| Location: Bahamas |
18717.10 Points
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: Pyridine Synthesis
Sat May 28, 2005 12:08 pm |
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Good find! 
(btw am I just overly sensitive to it - or doesn't pyridine represent one of the worst things ever, smell-wise? Opinions highly appreciated!) |
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Lyral
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| Joined: 25 May 2005 |
| Posts: 5 |
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259.86 Points
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re: Pyridine Synthesis
Sun May 29, 2005 8:36 am |
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hahas,
Great find, infact, this is the best read I've had for a while,
Agreed that pyridine is a nasty substance, but when needed only in small amounts, and under the right safety conditions, ie, Fume hood, things shouldn't be that bad.
Thankyou to everyone that has given imput here,
Starlight, indole, nubee, secret squirrell, and hahas,
This is exactly the article that we have been looking for,
It must be made clear, as there was abit of confusion before,
that piperine, from pepper, breaks into piperidine, and piperonyl via piperic acid, which is then oxidised to piperonyl.
After spending a long haul, searching, it is just bloody fantastic to see that someone found the patent,
Well done, everyone,
Although, mein deutsch ist nich so gut, the patent, das verstere ich nicht!
Have we got a german translator, that is willing to decode this brilliant find,?
From the pictures, it looks like it is talking about methylpyridine, but i could be wrong, as my german isn't that great,
I will try and through it all into babel, and see what it spits out,
Syn
great find! |
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re: Pyridine Synthesis
Sun May 29, 2005 12:54 pm |
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I have been doing a babel fish translation of that pdf, sent in by hahas,
Damn, I wish I knew a little german,-(pun intended)
Here is some of the gobblegook that it spits out
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Babel Fish Translation Help
In English:
the rabe distortful between chinolin and it pyridinbasen let hope that in accordance with one the skraup'schen chinolinsynthese copied proceed the synthesis of pyridinebasen moglich commodity searched this task derartzu draw that he glycerin with acetamide means extracting with use of phosphorus sour anhydride as water heat up whereby it, probably only due to the empirical formulas, which emergence of pyridin expects. It erbeit however b-picoline. The fact that pyridin emergence could not was vorauszuseben, there acetamid by from more reactionswasser and phosphorus sour anhydride formed phosphorus-sour into acetic acid and ammonium phosphate split Before me tries zanoni's admits became, also I looked for the Skraup' synthesis, at least in a case, into the pyridinreihe to ubertragen being based on decomposition-wise glycerins. Out of these, out glycerin by wassereniziehnde means beside acrolein also more korper by the formula, from the unstable form acetylcarbinols, arises koune was to be taken, even if with use of schwefelsuure predominantly entsthet acrolein. These two became b-picoline according to the added pattern supply mussen if one it with ammonia and a certain condensationsmittel zusammenbrachhte. When became more letzerer sulfur-sour ammonia was angewendt, which dissociirt at hoherer temperature and supplies so the nothigen component-sound. Those tries Skraup's showed that aniline works also with presence of more uberschussiger sulfur-sour more gegenuber acrolein like a free cousin. The same applies also from ammonia, which with presence of sulfur-sour in the same way reagirt, as if work the sour only water extracting and and ammonia with the received producten became to meet. I liked therefore front spar and the effect of ammonium sulphates on glycerin besaprechen by a still so lauges continued to heat up both more korper to more ruckflusskuhler could nennenswerthe mix more basic more korper not to be received, probably desalb because the formed condensations water the achievement of hoherer temperatures, as she requires reaction, do not permit also heat up in the zugeschmolzenen pipe on 250-260 protecting 7 grant supplied only very small to mix, since beer is ershwert or prevented fur reaction the nothige dissociation the sulfate. As gunstigstes the following was found proceeded: glcyerin about 7% become English sulfur-sour in a retort, which may be gefullt only about 1/5 and is connected with a simple raid, heat up with 35-40% sulfur-sour ammonia and. Daw ammonium sulphate draws itself gradually vollig clearly up: with for instance 170c, after flussigkeit brown gefarbt itself, distillation takes place: with for instance 200c even sulfur-sour something arises ammonia with this surplus of. Those mixes the formed acroleins is one aehr small. Heating up is allmahlich made. Finally (after the temperature anf approx. 230c geatiegen are) a strong schaumen, piston contents take place now a black-brown, very dickflussige mass became. Yellowish oeltropfchen goes at the same time more uber, which are with more gruner fluorescenz loslich in alcohol. Now one interrupts the operation. The same protects about 2-3 grants. fullung if the indicated to the retort was, then the danger is missing ueberschaumens and one knows the whole attempt itself uberlassen. luftkuhlung genugt here vollstandig. The distillate is one yellowish, weakly ammoniakalisch smelling flussigkeit. This more gewohnlicher point to basen processed. The received cousin mixture (about 4% of glycerin amounting to) simmered between 05-185c, mainmixes between 110-148c. It showed the smell of the pyridinbasen and gave the hoffman'sche reaction on this Korperklasse. Within temperuturintervalls of 95-100c simmering antheil supplies a platinum double salt with platinum contents of 33.83 respectively. 33.78 %, which corresponds a gemenfe of pyridin and picolinplatinchloriddoppelsalz.
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syn
Or maybee just no translate the whole lot, just the reaction conditions and quant's
thanks in advance |
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Lyral
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| Joined: 25 May 2005 |
| Posts: 5 |
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259.86 Points
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re: Pyridine Synthesis
Sun May 29, 2005 4:09 pm |
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lol i love those babel fish texts, have you ever translated a text several times into different languages and then back? 
well, the conditions: glycerine + 35-40% ammonium sulphate (phosphate is also possible but without any increase in yield, chloride also seems to work, at least its says "chloroammonium" and i think nh4cl is meant by that, oxalate lead to a stream mainly consisting of "cyangas" which probably is HCN...)
+ 7% conc. H2SO4 --> mixed and filled into a simple distillation setup (an air-cooled retorte was used) but care is taken not to fill the flask over 1/5 of its volume because foaming will occur during the reaction
then its distilled until finally reaction temp reaches 230°C this will take appr. 2-3 hours, at this temp heating is stopped, the mixture is a black-brown viscous something at this point, the distillate is worked up to yield a mixture of bases (a/b probably) which can be further seperated by distillation, the yield of mixed bases is 4-5% calculated on glycerine  the mixture boils from 100-200°C and the main part goes over at 151-156°C (picoline, methylpyridine) but pyridine and collidine (dimethylpyridine) were also identified in the mixture
that is what the text says |
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re: Pyridine Synthesis
Sun May 29, 2005 8:39 pm |
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Thanks Lyral,
Much appreciated,
Sounds like very harsh conditions,
Thankyou very much for the translation,
Well 5% is pretty low, but the precursors are not that expensive, so if small amounts are needed, experimentation may give good results,
A member pm'd me today, and told me this:
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heated 5g of nicotinamide( 3-pyridinecarboxamide) with enough 10% Naoh based on weight of Nicotinamide to completly cover the poweder 3 fold, say 100ml
A simple reflux rig with reflux was set-up, and heated to 100c for 3 hours, where upon many different phases of reaction took place.
The pills were not purified, as this was a blind test, to see if reaction did proceed, by smell test as the means to verify product,.
Reaction went froma white milky suspension, probably filler, as nicotinamide is soluble at a rate of 500g/Litre
Next time, a good idea, would be to purify the product before commenceing!, Duh
The milky suspension quickly took on a warm brown, which quickly turned into a mass of yellow throthing, with slowing rose, and then fell,
During this time, alot of the solid material, nicotinamide, dissapeared, indicating that either the salt of nicotinic acid has now formed and beome soluable in water, or the previous has turned already into pyridine.
After 3 hours of mild boiling, the apparatus was distmantled to leave a vial, disgusting smell in the condensor and the the flash,
It was filtered leaving 50 odd mils of dark brown/black highly basic liquid, with a small bit of sediment at the botton, (the filler)
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This is all the poster gave me, but was told that he would be in touch, and report on his extraction method, which he told me involved strong basification, followed by azeotorpic distillation with toluene, caustic water, and pyridine.
The water/toluene comes off first, then the toluene followed by the pyridine.
I think that this is good news, in that fact that such a theoretical route has now been tested and been verified to work,
Excellent!
Syn |
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re: Pyridine Synthesis
Sun May 29, 2005 9:06 pm |
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I think the member was following this method
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PURPOSE:To obtain pyridine useful as an organic solvent, etc. from various kinds of pyridine compounds prepared as by-products in the process of producing a series of pyridine derivatives, by treating a pyridinecarboxylic acid amide and/or cyanopyridine in the presence of water under heating.
CONSTITUTION:A pyridinecarboxylic acid amide (e.g., picolinic acid amide, nicotinic acid amide, isonicotinic acid amide, 2,6- or 2,5-pyridinedicarboxylic acid amide, etc.) and/or cyanopyridine (e.g., 2-, 3- or 4-cyanopyridine, 2,6- or 2,5- dicyanopyridine, etc.) prepared as by-products in the process of producing a series of pyridine derivatives are treated in the pesence of water under heating at 250- 450 deg.C, preferably at 300-400 deg.C to give pyridine having high useful value industrially as a raw material for an organic solvent and chemical industry (especially agri- cultural chemical and drug).
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Although he used a base , the results seemed to be in line with this patent,
Again this is a japenese patent, and I don' expect this to be solved anytime soon,
http://l2.espacenet.com/espacenet/bnsviewer?CY=gb&LG=en&DB=EPD&PN=JP56059756&ID=JP+356059756A++I+
Have any other chemists any thoughts as to maybee the best conditions for the decarboxylation, and the amide hydrolyisis, if necessary at all?
Amide hydrolysis
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Hmm, I guess I answered my own question. Any OTC niacin should be boiled with a strong base just in case it has any niacinamide. In fact there is a general procedure in Vogel's... Amides may be hydrolysed by boiling with 10% sodium hydroxide solution to the corresponding acid (as the sodium salt). Lets see, it gives an example of another compound which is basicially boiled for 3 hours to complete the reaction, during which ammonia is given off. Since sodium nicotinate is quite soluable in water it won't precipitate, but we just boil off the water to obtain the crystals which will be mixed with NaOH, combine that with lime, mix, and heat to liberate pyridine. I am off to try that right now. To the vitamin store!
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In the previous example, the amide was base hydrolised with 10% NaOH, then continued boiling in solution , with reflux,
It would seem difficult to seperate the salt of the carbox acid, then furhter heat that with CaO, and NaOH, for another hour or so, can it be done in situ, like what the member has just said, or will his yield suffer.
The japenese patent seems to go straight from the amide to the pyridine with water, at around 300c,
I think what is called for here, is maybee a few more test reactions,
Will heating the purified nicotinamide with just Naoh at 300c for a few hours, do they same job,
Comments welcome,
syn |
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5600
: every time when i opened my cupboard the choking smell of pyridine was noticed although the bottle was properly closed.