GOD
(Hive Addict) 07-22-02 01:29 No 335575 |
Pyridoxine -> Pyridine | Bookmark | ||||||
Post 215902 (Rhodium: "Re: OTC Pyridine & Acetic Anhydride", Chemicals & Equipment) , Rhodium states a simple decarboxylation to make pyridine out of pyridoxine. Swim couldnt find a writeup on Rhodiums site, or here. Any suggestions for a non-chemist? thank you. i FEEL funny. |
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SPISSHAK (Hive Bee) 07-22-02 05:55 No 335630 |
Yes there is a good route | Bookmark | ||||||
One of our Russian friends, diafrag, posted a decarboxylation scheme of nicotinic acid using nicotinic acid and Calcium oxide in a 1/1.2 ratio and heating to 320 degess for 1.5 hours. What I don't understand is the exact mechanism, e.g the carboxylic acid of pyridine here reacts with CaO and common sense would tell you that water is a by-product and the calcium salt of the carboxylic acid. Now, how does an ester like this give off CO2 and donate hydrogen to the aromatic ring of the now pyridine when hydrogen was diplaced in the acid/base reaction? here is the posts regarding that.Diafrag (ChemLover) 05-27-02 06:12 No 314749 demethylation Delete bookmark Reply Demethylation of 3-methoxy-4,5-dioxyphenylethylamine by heating with conc. HCl in a closed ampoule. K. Hahn, Ber., 71, 2141 (1938) someone can try to find that. and i've just scanned an article about purification of nicotinic acid by sublimation and decarboxylation it to pyridine by 1,5 hours of heating it at 320°C with CaO 1:1.2 in an ampoule. Diafrag (ChemLover) 05-27-02 13:13 No 314880 decarboxylation Bookmark Reply the authors of this article had only 6 mg of nicotinic acid they've obtained from some bacteriums and they had to purify it and decarboxylate it to obtain pyridine and prove that it was nicotinic acid. so after sublimating they put their 6 mg of acid and CaO in a ratio 1:1.2 in an ampoule, soldered it and then made a neck in the middle of it. then they bent this ampoule on it's neck about 45°. then they put the whole ampoule in a sand bath, gradually increased temp. of the bath to 320°C and maintained it for 1.5 hours. then, working with forceps they took the empty bent side of the ampoule and waited for drops to appear in it. then heating was turned off but the aumpule was standing in a bath for 30 min more. then they broke the ampoule and got 86-90% of pyridine. so they decarboxylated acid and distilled the product in one ampoule. soon i'll post this in russian at my webpage and you will be able to see pictures http://www.chemlover.narod.ru/articles/a So, can somebody possibly explain the mechanism here? Another thing, I don't know how well babelfish works to translate foreign documents, but I saw an interesting thing at fry's electronics. It was an infrared pen that you can scan forein documents, plug into the usb port of your computer, and use the downloaded dictionaries from thier website to translate it with. The pen costs around $200.00 But if I had the money I'd buy it and offer translating services to all of you. |
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sYnThOmAtIc (Hive Bee) 07-22-02 05:55 No 335631 |
Eheheh, I was reading the label on this powerade ... | Bookmark | ||||||
Eheheh, I was reading the label on this powerade I was drinking the other day and saw pyridoxine.hcl on the label and wondered if this was related to pyidine (cause of the name) so that it may be isolated for some microwave chem experimentation. ANd shit what do you know! Ok lets lee artificial sweetener form coke can lead to methamphetamine precursors and powerade energy juice a useful chemical in many synths. Hmm what fucked up food additives we have these days. |
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SPISSHAK (Hive Bee) 07-22-02 08:59 No 335690 |
let's see | Bookmark | ||||||
If I can't answer this, I heard that the by-product is a dimer of pyridine, and just maybe it isn't an acid base reaction in the brownstead-lowry sense because no water is around to promote ionic disassociation? |
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GED (Hive Addict) 07-22-02 12:11 No 335737 |
Vitamin Confusion | Bookmark | ||||||
Between this thread and thread number Post 215008 (Eeyoredonkey: "OTC Pyridine & Acetic Anhydride", Chemicals & Equipment) 4 different vitamins appear to have been mentioned, as though they were the same thing. Just for the record------ niacin, nicotinic acid = Vitamin B3 pyridoxine (hcl) = Vitamin B6 pantothenic acid = Vitamin B5 cobalamin = Vitamin B12 Anyone who can find a valuable use for kilos of out of date bulk Pyridoxine hcl (B6), please make suggestions. MadMax Post 218782 (MaDMAx: "Re: OTC Pyridine & Acetic Anhydride", Chemicals & Equipment) "Pyridoxine doesn't have anything to be decarboxylated." |
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SPISSHAK (Hive Bee) 07-22-02 17:31 No 335799 |
why your right that's why I just say nicotinic | Bookmark | ||||||
acid, anyone know a mechanism for this? |
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GOD (Hive Addict) 07-22-02 19:51 No 335826 |
Spisshack, wait your turn- havent awnsered my ?yet | Bookmark | ||||||
whoever awnsers, could you please bee specific, I origionally asked about pyridoxene hcl. Rhodium...there appears to bee a difference in opinion between you and MaDMAx regarding this. i FEEL funny. |
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blondie (Hive Bee) 07-23-02 01:18 No 335942 |
pyridoxine | Bookmark | ||||||
At least according to chemfinder there is no carboxylic group on pyridoxine. Foxy2 found a ref for decarboxylating nicotinic acid which is 3 Pyridine carboxylic acid. see Post 223562 (foxy2: "Re: pyridine from decarboxylation of niacin?", Chemistry Discourse) |
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SPISSHAK (Hive Bee) 07-25-02 15:42 No 336928 |
do you think | Bookmark | ||||||
the other method will work with calcium oxide? |
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SPISSHAK (Hive Bee) 09-03-02 00:22 No 351965 |
Anyone have chemweb account? | Bookmark | ||||||
Get the full article and post it as a reply to this beilstien abstract? It should clear up a lot of questions about the transition states, and thermodynamics of a Calcium nicotinate salt decraboxylation. A Study on Solid State Thermal Decomposition Characteristics of Some Metallo-organic Compounds. Part-I : Dehydration and Decarboxylation of Hydrated Calcium Salts of Pyridine Monocarboxylic Acids AUTHORS Ghosh, S.; Ray, S. K.; Ray, P. K.; Bandyopadhyay, T. K. SOURCE J.Indian Chem.Soc. 1982, 59: 9 1034-1037 DOCUMENT TYPE Journal CODEN JICSAH LANGUAGE EN CNR 5860857 ABSTRACT Solid stete dehydration of hydrated calcium salts of picolinic acid, nicotinic acid and isonicitinic acid and subsequent decarboxylation of the corresponding anhydrous salts have been studied by simultaneous TG, DTA and DTG techniques.From the analysis of the TG,DTA and DTG traces for the dehydration of the hydrated salts, the thermal stability order of the hydrates have been found to be Ca(pic)2*H2O > Ca(isoNic)2*4H2O > Ca(Nic)2*3H2O.But the trend observed in the decarboxylation process is Ca(Nic)2 > Ca(isoNic)2 > Ca(pic)2.Thermal parameters like activation energy, enthalpy change and order of reaction for each process have been computed by standard methods.An attempt has been made to correlate the trend in the thermal stability of the anhydrous salts towards decarboxylation with their molecular structure. COPYRIGHT Copyright © 1988-2001, Beilstein Institut für Literatur der Organischen Chemie licenced to Beilstein Chemiedaten und Software GmbH and Beilstein Informationssysteme GmbH. All rights reserved. |
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SPISSHAK (Hive Bee) 09-05-02 07:19 No 352903 |
Puuullllesssee! | Bookmark | ||||||
Pretty please, with a cherry on top, and sugar all around? |
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weedar (Verbose Viking) 09-05-02 17:23 No 353019 |
I'm working on it! | Bookmark | ||||||
I tried finding it earlier today,with no luck..All I found is the abstract,just give me some time.. Edit:Anyone who feels like telling me how I can get the whole journal instead of just the abstract,please tell me?I have a chemweb account,isn't that enough?I can't even find the entire articel.. Weedar Me fail English?That's unpossible! |
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Rhodium (Chief Bee) 09-05-02 18:29 No 353032 |
The Journal of the Indian Chemical Society is not ... | Bookmark | ||||||
The Journal of the Indian Chemical Society is not available online, so you will have to go to your nearest University Library to make a copy of that article. |
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SPISSHAK (Hive Bee) 09-05-02 21:41 No 353110 |
Well thank you | Bookmark | ||||||
For your effort anyhow fellows. |
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weedar (Verbose Viking) 09-06-02 13:39 No 353434 |
Tomorrow | Bookmark | ||||||
I might visit my local university library tomorrow(Saturday) so if no-one else posts the article I'll try getting it.. Weedar Me fail English?That's unpossible! |
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weedar (Verbose Viking) 09-14-02 22:09 No 356334 |
J. Ind. Chem. Soc.:Decarboxylation of pyridine (Rated as: excellent) |
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J. Ind. Chem. Soc.:Decarboxylation of pyridine Sorry for taking so much time,I've been busy,but I really don't have an excuse,here it is: Part-I: Dehydration and Decarboxylation of Hydrated Calcium Salts of Pyridine Monocarboxylic Acids
I'm supposed to put two tables here,but I'm having some trouble,will post them later.. Solid state thermal decomposition of the salts of aromatic or heterocyclic acids has received little attention from the kinetic point of view. Most of the workers, who studied the thermal decomposition of the salts of organic acids (mostly aliphatic acids) in the solid state, used the maximum point method4-6 and the Freeman-Carrol method7 for the determination of the kinetic parameters. In the present work we have utilised Horowitz and Metzger's method, an analytical technique which utilises a single TG plot to determine the pertinent Arrhenius parameters and reaction order. The values obtained by the application of this method have been verified by the Coats and Redfern8 method wherever possible. We have utilised the DIA curves for the evalution of enthlpy changes for the dehydration as well as decarboxylation processes. The single step dehydration of calcium nicotinate trihydrate and the calcium isonicotinate tetrahydrate indicated that all the water molecules in the nicotinate trihydrate are similarly bound and such is also the case with the water molecules in the calcium isonicotinate tetrahydrate. A single endotherm in each of the DTA curves definitely points to the accuracy of the above conclusion. In the single step dehydration of all the three hydrates represented by the general equation in Table 1, the activation energies and enthalpy changes of dehydration are in order picolinate > isonicotinate > nicotinate. This difference in thermal stabilities of the hydrates may be attributed to the differences in the mode of binding of the water molecules in the crystals of the three different pyridine monocarboxylates. It may thus be concluded that the water molecules in calcium picolinate are more firmly bound than those in isonicotinate and nicotinate and the water molecules in the calcium isonicotinate are held more stronlgy in comparison to those present in the calcium nicotinate. In the decarboxylation of the anhydrous salts represented by equations given in Table 2, the activation energy follows the order nicotinate > isonicotinate > picolinate. The enthalpy change in the decarboxylation process also follows the same order. It may be concluded from the data in Table 2 that the thermal stabilities of the carboxylates follow the order nicotinate > isonicotinate > picolinate. This trend is quite logical as the negatively charged carboxylate ion has a + I effect8 and hence releases electrons with a consequent increase of electron density on the ring carbon atom which, if present in a benzene ring, would have stabilized the ring carbon-carboxyl carbon bond. But in the present case, as the ring is a heterocyclic ring, the nitrogen atom being much more electronegative than carbon, would change the situation significantly and we find that unlike benzene, electron density distribution in the pyridine ring9 is as follows: 0.95 /----\ 0.85 / \ 0.82 \ / 1.58 \____/ Due to the ortho-para orienting influence of the carboxylate ion the positions ortho and para to the ring carbon containing the carboxylate ion will have greater electron density and in the case of calcium picolinate, where the electronegative nitrogen atom is present in the position ortho to the ring carbon containing the carboxylate ion, it conveniently draws away this excess electron cloud towars itself and consequently reduces the electron cloud accumulated on the adjacent ring carbon atom considerably. It thus weakens the ring carbon-carboxylate carbon bond to a significant extent making it comparatively thermolabile. In the case of the 4-picolinate anion, the enhanced electron density in the position para with respect to the carboxylate ion is accomodated on the nitrogen atom as a result of which the 4-carbon atom is relieved of some of its electron cloud acquired from the carboxylate anion and results the weakening of the ring carbon-carboxyl carbon bond and consequently induces thermolability. But overall destabilisation effect is greater in 2-picolinate than in 4-picolinate due to the closeness of the ring nitrogen to the carboxylate substituet in the former and makes the 4-picolinate thermally more stable than the 2-picolinate compound. In the case of the 3-picolinate, the ortho-para orienting carboxyate ion would again result in electron enrichment in the ortho and para positions leaving the meta position unaffected. Thus, the increased electron density on the ring carbon atom containing the carboxylate ion is not decreased in this case. This leads to the stabilisation of the ring carbon-carboxyl bond when compared to the 2- and 4-picolinates and makes the 3-picolinate thermally stabler than the other two. Thus, the thermal stability order nicotinate > isonicotinate > picolinate, observed in this study, is quite in accordance with the theoretical principles. References 1. K. Sano, Sci. Rep. tohuku, Imp. Univ., 1st Ser., 1936, 24, 719. 2. H. H. Horowitz and G. M. Metzger, Anal. Chem., 1963, 35, 1464. 3. A. W. Coates and J. P. Redfern, Nature, 1964, 201, 68 4. K. Akita and M. Kase, J. Polymer Sci., 1967, A1, 833. 5. J. H. Flynn and L. A. Wall, J. Res. Nat. Bur. Stand., 1966, 70A, 487 6. R. M. Fuoss, I. D. Salver and H. S. Wilson, J. Polymer Sci., 1964, A2, 3147 7. E. S. Freeman and B. Carrol, J. Phys. Chem. Ithaca, 1959, 62, 394 8. J. March, "Advanced Organic Chemistry: Reactions, Machanisms and Structure", McGraw-Hill, 1968, p. 21. 9. I. L. Finar, "Organic Chemistry", ELBS and Longmans, Green, 1964, Vol 1, p. 760. Sorry,I'll have to post the 2 missing tables tomorrow,I won't bee posting the two Figures,doubt they are useful and my photocopies aren't very good.BTW,SPISSHAK,you owe me $1.5 Weedar Me fail English?That's unpossible! |
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weedar (Verbose Viking) 09-15-02 23:39 No 356654 |
Missing Tables | Bookmark | ||||||
Trying hard to make the rows align with the columns,I give up,hope you all can understand it though,or tip me off how I can post tables with the Board software(psst Lilienthal!).. Reaction | Initiation | Peak |Completion| Loss in wt. % | EACT | Delta-H | Order of | | temp.°C | temp.°C | temp.°C | Calcd. Found | Kcal/mole | Kcal/mole | reaction | Ca(C6H4NO2)2.3H2O -> Ca(C6H4NO2)2+3H2O 39 90 120 15.97 16 15.55 46.37 1 Calcium nicotinate hydrate Ca(C6H4NO2)2.4H2O -> Ca(C6H4NO2)2+4H2O 82 130 215 20.22 20 22.96 62.07 1 Calcium isonicotinate tetrahydrate Ca(C6H4NO2)2.H2O -> Ca(C6H4NO2)2+H2O 160 193 240 5.96 5.88 52.13 26.24 1 Calcium picolinate monohydrate Table 2 have the exact same names of the columns in Table 1.. Ca(C6H4NO2)2 -> CaCO3 + products 432 560 622 64.78 60.84 76.14 166.3 1 Calcium nicotinate Ca(C6H4NO2)2 -> CaCO3 + products 385 486 620 64.78 64.83 50.85 44.46 1 Calcium isonicotinate Ca(C6H4NO2)2 -> CaCO3 + products 380 442 540 64.78 65.38 14.86 20.37 1 Calcium picolinate Me fail English?That's unpossible! |
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