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Eclectic
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Just a stray thought: Does anyone know if liquid sulfur reacts directly with calcium carbide? How about H2S and calcium carbide?
[Edited on 5-25-2009 by Eclectic]
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Nicodem
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Quote: Originally posted by Sauron  |
Recourse to Reid's book also git me a complete cirarion of the Levi paper:
T.G.Levi, Atti Accad. Lincei (5) 32. I, 560-572 (1923)
and more importantly a Chem.Abstracts citation
CA 18, 1114
which may actually be accesible. |
The entry was renumbered during the digitalization of Chemical abstracts, and it is now CA 18:8271. Here it is:
| Quote: | Dithioformic acid. Levi, T. G.. Atti della Accademia Nazionale dei Lincei, Classe di Scienze Fisiche, Matematiche e Naturali,
Rendiconti (1923), 32(i), 569-572. CODEN: AANLAW ISSN: 0001-4435. Journal language unavailable. CAN 18:8271 AN 1924:8271
CAPLUS
Abstract
L. has prepd. various derivs. of HCS2H from the K salt obtained by treating CHCl3 with K2S (cf. Cambi, C. A. 4, 1738) in alc. under definite
conditions. The Ag, HCSAg, and Pb salts, (HCS2)2Pb, were obtained as orange-yellow ppts., but could not be prepd. quite pure, owing to their insoly.
in ordinary org. solvents; both are comparatively stable; the former blackens at 95-100 and the latter at 130-5. The Zn salt is yellowish white and
the Co salt deep brownish red. The disulfide, [(HCS)2S2]x obtained as a yellowish red ppt. by cautious oxidation of the K salt in alc. by means of I,
decomps. at above 200 into CS2, H2S, C and S. |
The same paper was also published in Gazzetta Chimica Italiana which is a more common journal in the libraries:
| Quote: | | Dithioformic acid. Levi, T. G.. Gazzetta Chimica Italiana (1924), 54, 395-397. CODEN: GCITA9 ISSN: 0016-5603. Journal
language unavailable. CAN 18:18738 AN 1924:18738 CAPLUS |
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Sauron
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Thanks, Nicodem. Howeverm it is less helpful than I hopes. While stating that the rxn of CHCl3 w/ K2S in alcohol required definite conditions, it
fails to describe these, just bounces us to Cambi, CA 4 1738 - surely also now renumbered after digitization.
Can I trouble you once more, in light of this>
Every bloody paper describing use of this reagent cites Levi and not one gives prep details.
Alternative names for fithioformic acid:
thiolthionmic acid
carbodithionic acid
It apparently is prefered tautomer of initially former orthothioformic acid which like orthoformic acid has not been isolated. Well, not tautomer
since orthothioformic acid must lose H2S to for, HC(=S)SH.
Since pyrolysos>200 C breaks potassium dithioformate down to CS2, H2S, S and C, then no need for liberation of the acid, and no need for the lossy
comversion to thioformamide hydrochloride just tp pyrollize it instead. Therefore this is a two step conversion of chloroform to CS2 via KCS2H.
Gazzetta Chimica Italiana is yet another defunct jornal that Wiley boasts has been incorporated into its European Journals of Chemistry but unlike
Ber. and Ann. I have not been able to locate an index page for it at Wiley's site.
There is sporadic coverage of this journal on Internet Archive via Googlebooks. But sadly nothing after 1908.
[Edited on 25-5-2009 by Sauron]
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Sauron
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Potassium Ethyl Xanthate is pricier than I remembered, so its decomposition, while facile and efficient, is not an economical way to obtain CS2.
The conversion of chloroform to potassium dithioformate and hence to CS2 requires K2S, and therein lies the rub. The Japanese use tBuOK to make this
from H2S. tBuOK is not expensive, c.$30/mol. K2S is very air and moisture sensitive and so this is a glove box procedure. The commercial solutions of
tBuOK are too bloody expensive.
The classical prep of K2S in from the elements in liquid NH3, see Brauer.
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Nicodem
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| Quote: Originally posted by Sauron | | Thanks, Nicodem. Howeverm it is less helpful than I hopes. While stating that the rxn of CHCl3 w/ K2S in alcohol required definite conditions, it
fails to describe these, just bounces us to Cambi, CA 4 1738 - surely also now renumbered after digitization. |
I can not find that one. There is only one CA entry for Cambi as author in the years corresponding to vol. 4 of CA. In the other references of this
author I found only one mention of the reaction of Na2S with CHCl3 but the product is used in further reaction without its isolation.
| Quote: | Thiohydroxamic Acids. Cambi, Livo. Lab. Chim. Farm. R. Inst. Studi Sup., Firenze, Atti. acad. Lincei (1910), 18(I),
687-90. Journal language unavailable. CAN 4:9654 AN 1910:9654 CAPLUS
Abstract
Thiobenzohydroxamic acid, PbC(: NOH)SH, obtained by adding to an aqueous soln. of PhCS2K a soln. of NH2OH-HCl containing the equiv. amt. of K2CO3,
acidifying with dil. H2SO4 and extracting with Et2O. Its salts are obtained from the H2O soln. by evaporating to dryness in vacuo and extracting with
EtOH. Both the acid and its salts easily lose S, the free acid giving chiefly PhCN, S and H2O. Benzyl ester, PhC( : NOH)SCH2Ph, from the K salt and
PhCH2Cl in EtOH, m. 120-2; benzoyl derivative, PhC( : NOBz)SCH2Ph, from the ester and BzCl in pyridine, m. 135. Dibenzoyl derivative, PhC(:NOBz)SBz,
from the K salt in H2O with excess of BzCl and subsequent addition of NaOH, m. 90-2 : stable towards dil. HCl, even on boiling, but saponified by not
too conc. alc. KOH, partly into PhC( : NOH)SH and BzOH, but chiefly into PhC(: NOH)OH and PhCOSH.
Action of Hydrogen Sulfide on Fulminic Acid. Cambi, Livio. Milano, lab. elet. chim. r. ist. techn. sup., Gazzetta Chimica
Italiana (1911), 41(I), 166-73. CODEN: GCITA9 ISSN: 0016-5603. Journal language unavailable. CAN 5:15314 AN 1911:15314 CAPLUS
Abstract
cf. C. A., 4, 1738. When a suspension of Hg fulminate in H2O is treated in the cold with H2S, the filtered soln. gives an intense violet-blue color
with FeCl3 changing to blue on the addition of dil. HCl or H2SO4 and after standing a while, especially on heating, the soln. gives the reaction of
HSCN. With excess of NaCO3 is obtained an amorphous sodium salt, sol. in alc., which, with PhCH2Cl, gives benzyl thioformhydroxamate, C7H7SCH : NOH,
elongated prisms, m. 144-6, decomp. by boiling in the presence of HCl into C7H7SH, HCO2H and NH2OH. The same Na salt can be obtained by treating
CHCl3, in alc. with 2 mols. Na2S and, after removal of the NaCl and alc., adding NH2OH.HCl satd. with Na2CO3 to the H2O soln. of the residue. With
the heavy metals it gives amorphous ppts.: Cd, white; Pb, yellowish; Hg, yellowish; Ni, reddish brown; Co, brown; Cu, black; Ag, light yellow rapidly
blackening. The free thioformhydroxamic acid could not be isolated, as it decomp. into HSCN; the Na salt in soln. gives NH3 and when heated in the
dry state forms NaSCN. Similarly, the benzyl ester, heated with Bz2O at 80-5, gives C7H7SCN. |
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Sauron
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Many thanks. That must be it.
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watson.fawkes
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FYI. There's another drawing of the Taylor furnace in the 1921 book A course in general chemistry, p 885. This drawing looks a little more realistic. In particular, it shows a clean-out port on the bottom of the
sulfur retort. Fine coke/charcoal dust settles to the bottom, clearly.
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Sauron
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If anyone wants to know why you can't just bubble H2S into aqueous KOH to obtain K2S, the answer is
KOH + KSH equilibrates with K2S and H2O
So the anhydrous salt has to be made by union of the elements in NH3 (not convenient) or by psdding H2S into s nonsqueous solution of tBuOK (such as
in THF).
THF and tBuOH are removed and the K2S dissolved in anhydrous ethanol for reaction with chloroform.
HCS2K precipitates, ethanol and KCl are removed.
Potassium dithioformate. so simplr yet so obscure.
Incidentally Aldritch lists K2S but ONLY AVAILABLE IN JAPAN. WTF?
No one else I know of even offers it.
[Edited on 26-5-2009 by Sauron]
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Sauron
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There's a metos for preparing anhydrous K2S by adding molten KCl to liquid S. Sulfur chlorides form and volatilize, leaving K2S. Does this sound like
fun?
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len1
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That cant be right - at the melting point of KCl the S would long ago have volatalized.
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watson.fawkes
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I imagine that the molten KCl is dripped in, forming volatile and extremely reactive S vapor. I would also
guess that sulfur chlorides are a by-product.
Also, apropos of high-temperature processes. The following article is supposed to discuss a fluidized bed reactor for the production of CS2, should
the footnote be accurate: Johnson, H.S., Reactions in a fluidized coke bed with self resistive heating, Can, J. Chem. Eng., 39, 145, 1971.
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Sauron
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It's in Mellor.See attached extract, Vol II, p.623 top of page. The citation is p 628m para 2 of References,
Bemelmans, L., D.R.P. 49628, (1894)
I have not read the German patent but apparebtky the nobject was to make sulfur chlorides, and K2S is a byproduct. As for my criticisms of the process
as described by Mellor:
Mp KCl is 770 C, bp S is 444 C. I think it's a joke since K2S if formed will react with excess S to form polysulfide. Reversing the addition would be
better, but the S melt to be fluid rather than viscous would have to be at lower end of its range, and unless the KCl melt can be agitated local
excess of S is still possible. In short is seems a good way to make crappy livers of sulfur rather than nice clean well defined K2S anhydrous.
The section is pretty much a recitation of such bad methods.
Only the union of S with a solution of K in liq NH3 of all the methods mentioned will produce clean dry salt, which has to be rigirously protected
from air and oisture.
The Japanese method, H2S and tBuOK, is of course nowhere in Mellor. It is IMO more convenient, and avoids handling K. but does involve H2S.
Attachment: Pages from DjVu Document.pdf (796kB)
This file has been downloaded 671 times
[Edited on 27-5-2009 by Sauron]
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Sauron
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There is also a prep from the elements conducted between a solution of S in toluene or napthalene, and metallic K. I will have a look at this one. I
reckon if the solvent us dry and free of dissolved air amd the whole thing conducted in inert atmosphere, this could fly.
J.Locke, A.Austell, Am.Chem.Journ. 20, 592 (1898)
[Edited on 27-5-2009 by Sauron]
Attached. Unfortunately this is one of those times when Mellor got it all wrong.
[Edited on 27-5-2009 by Sauron]
Attachment: Pages from americanchemical201898balt.pdf (139kB)
This file has been downloaded 493 times
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S.C. Wack
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I want to know why, especially since all the old references say you can. This method for it and Na2S are mentioned a lot in Mellor, for instance.
Dehydration seems unchallenging.
http://dx.doi.org/10.1039/CT9007700753
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Aqueous K2S will always be an equilibrium mixture of KOH and KHS (with mainly K2S), no matter how it was prepared. Na2S is exactly the same, it's made
by saturating NaOH solution with H2S forming NaHS, then adding an equimolar amount of NaOH.
t-BuOK, come on, let's keep it affordable and OTC. CS2 preparation in a home lab becomes somewhat pointless if it requires chemicals from a chemical
supplier. If someone can buy stuff like t-BuOK readily made, he could just as easily buy CS2.
| Quote: Originally posted by Eclectic | Just a stray thought: Does anyone know if liquid sulfur reacts directly with calcium carbide? How about H2S and calcium carbide?
[Edited on 5-25-2009 by Eclectic] |
I have tried this myself, both with molten sulfur and calcium carbide, and with sulfur vapor and calcium carbide at 440°C (the carbide was put into a
Hempel column, which was connected to a flask in which sulfur was being boiled). There is no reaction at all.
H2S and calcium carbide would probably give acetylene and calcium sulfide, as H2S is a proton acid like water, an even stronger one actually, and will
protonate the acetylide anion in CaC2.
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S.C. Wack
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I am not talking about an aqueous mixture, this would be useless for the reaction with chloroform! I am talking about crystalline hydrates, of either
potassium or sodium.
[Edited on 28-5-2009 by S.C. Wack]
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Sauron
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There's a procedure for dehydrating sodium sulfate nonahydrate by vacuum dessication over H2SO4. It takes `4 days and the material still contains 4%
water. To drive that off takes high heat.
No such technique is mentioned for K2S.
The problem with Mellow on this substance is that sometimes his entries are too elliptical and either misrepresent the actual report, if you read the
original, or are ambiguous.
A case in point is the one I cited above, Locke and Austell. Mellor states they made Na2S from the elements by boiling in toluene or napthalene. I
obtained the volume 20 of Am Chem J.
The paper says they wanted and expected Na2S but insteas obtained a higher oligosulfide estimated to be Na2S3. A ;ot of unreacted Na remained.
In short the prep failed, but Mellor reported it as a success. Mellor is sometimes quicksand. In many instances, the original full trxt is well nigh
impossible to obtain soone must decide whether to rely on Mellor alone.
It IS known and reported in Mellor as well as the lit. old and new that the same reaction of the elements works fine in liq NH3 - this is also
descrived in Brauer. This produces rigorously pure white crystalline K2S quaantitatively from stoichiometric quantities of K and S. But it is
inconvenient.
Garage chemist, I am NOT advancing the reaction of tBuOK amd H2S in EtOH as a way to make K2S cheaply enough to exploit the chlorodorm reaction to
make CS2.
ou have the economical route to CS2 from S and acetylene. Be happy. There is no other unless you want to return to scaling down S + C.
S.C., it is clear that many if not all of the old methods did NOT produce inambiguous K2S, but mixtures of that with polysulfode. KSH, thiosu;fate,
KOH, carbonate etc. Preparing K2S in air will have that result regardless of method. It might be possible to isolate, quite laboroously, purer
crystalline material from such mixtures. But if you want pure unambiguous K2S colorless crystals, not yellow and with correct constants, there are
only two methods. From the elements in liq NH3, or metathesis of tBuOK and H2S in ethanol.
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Sauron
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I read the paper you cited, S.C., and saw prep of K2S.2H2O but no anhydrous materiall.
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S.C. Wack
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| Quote: Originally posted by Sauron | There's a procedure for dehydrating sodium sulfate nonahydrate by vacuum dessication over H2SO4. It takes `4 days and the material still contains 4%
water. To drive that off takes high heat.
No such technique is mentioned for K2S. |
So? There are numerous examples of dehydrations of the hydrates of both that make it clear that it is not difficult as long as air is excluded.
| Quote: Originally posted by Sauron | The problem with Mellow on this substance is that sometimes his entries are too elliptical and either misrepresent the actual report, if you read the
original, or are ambiguous.
A case in point is the one I cited above, Locke and Austell. Mellor states they made Na2S from the elements by boiling in toluene or napthalene. I
obtained the volume 20 of Am Chem J.
The paper says they wanted and expected Na2S but insteas obtained a higher oligosulfide estimated to be Na2S3. A ;ot of unreacted Na remained.
In short the prep failed, but Mellor reported it as a success. Mellor is sometimes quicksand. In many instances, the original full trxt is well nigh
impossible to obtain soone must decide whether to rely on Mellor alone. |
Jesus! All I did was mention the dudes name since he, among other sources available, gives several references, and you are familiar with the chapter
(20) apparently. None of that has anything to do with the validity of papers where the authors unambiguously state that they have monosulfide as
whichever hydrate.
For all we know, this is what whoever used with chloroform instead of a commercial sulfide.
| Quote: Originally posted by Sauron | S.C., it is clear that many if not all of the old methods did NOT produce inambiguous K2S, but mixtures of that with polysulfode. KSH, thiosu;fate,
KOH, carbonate etc.
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Says who? About what? Who says that Bloxam, for instance, is full of it?
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Sauron
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Quicksand.
The Italian papers unavailable.
So you are right, we do not know whether or not anhydrous K2S was used, or a hydrate.
My assumption is anhydrous, the Japanese method unambiguously used anhydrous K2S to prepare potassium dithioformate. Preps of K2S in liquid NH3 cited
by Mellor predate Cambi's paper and Levi's paper. C.Hugot, Compt.Rend 129, 388 (1899) so method which is still the main method for anhydrous K2S was
known a decade before Cambi and 24 years before Levi.
However, it is possible that cambi and/or Levi used a hydrate.
We simply do not have enough information to be sure.
If I did not find Mellor useful I would not be scanning his emtire series. HOWEVER he is not perfect, he makes mistakes, and is also capable of
ambiguity. My point is that the original cited texts need to ve read whenever possible. The same goes for Beilsteinm and Gmelin. All of them are
just reviews of the work of others. Vast and precious but imperfect.
[Edited on 28-5-2009 by Sauron]
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Nicodem
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| Quote: Originally posted by Sauron | However, it is possible that cambi and/or Levi used a hydrate.
We simply do not have enough information to be sure. |
As far as I understood they used ethanol as solvent in which case it is irrelevant if the sodium or potassium sulfide is hydrated or not. It is not
even important if it is sulfide or hydrogen sulfide since both nucleophiles lead to the same compound at the end (the "orthotrithioformates" are
intermediates anyway). In cases where you are in doubt it is always a good idea to check the reaction conditions, such as the solvent used, and
compare it to the up to date theory.
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Sauron
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True, but we have on one hand Levi's prep as repeated by the authors of the JCS paper cited upthread, in which the yield of potassium dithiocarbonate
was something less than 40%; and on the other hand the Japanese abstract from year 2000 which claims a high but unstated yield using K2S prepared from
H2S and tBuOK. That prep of K2S seems to be sole novel feature of the procedure. So perhaps the matter of how the K2S is prepared and whether or not
it is hydrated, is not so immaterial to the outcome of the dithioformate prep.
The Japanese also ran that reaction in alcohol, presumably ethanol.
While Na2S hydrate is cheap, and the anhydrous salt available but expensive (Alfa $5/gram in 100 g pack) potassium sulfide seems unanailable either
hydrated or anhydrous, save Aldrich which has its sale restricted to Japan only. What the hell is that all about?
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Sauron
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There's quite a bit of lit. on sodium dithioformate as source of dithioformic acid used in thiazole preps.
Nicodem suggests that in ethanpl. hydrated monosulfide ought to work fine, so Na2S.9H2O which is common ACS reagent ought to convert CHCl3 to sodium
dithioformate and thus to CS2, about 50% or more on NaCS2H basis by thermolysis.
If so we may have a whole new ball game.
Nicodem says KSH ought to work. Na2S.9H10 is $80/Kg,
NaSH is much cheaper, <$50 for 2.5 Kg and <$150 for 10 Kg.
According to a paper I post a few posts fown, KSH worksand quite exothermically so then major cost will just be the chloroform.
[Edited on 28-5-2009 by Sauron]
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Eclectic
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Hummm.....We have a procedure that needs acetylene and produces H2S, and another that needs H2S....
Might be worthwhile to see what the products are from passing H2S into a suspension of calcium carbide in ethanolic KOH.
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Eclectic
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Well you need a scrubber for the H2S produced by the acetylene process....Might as well use it to make NaSH, Na2S, KSH, or K2S in ethanol, with CaC2
possibly removing the water and making more acetylene.
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