RU_KLO
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Thioacetamide synthesis
Im trying to find a way to make Thioacetamide with reagents that I can get. (for qualitative analysys)
I found an old article which uses Ammonium Acetate and Aluminium sulfide (which I dont have, but its seems probable to make), but its only an
abstract. I could not find the original paper.
So I ask to you, the "Organic team" to see, If you can help me to complete the missing parts for a procedure.
I do understand the risk of H2S.
here is the abstract:
Thioamides. I. Preparation of Thioamides with the Aid of Aluminium Sulphide. KARL KINDLER and FRIEDRICH FINNDORF (Ber., 1921, 54, [B], 1079--1081).-
Thioamides are prepared in good and sometiines quantitative yield by heating the requisite acid amide with aluminium sulphide and a substance
containing water of crystallisation such as sodium sulphate hexahydrate in a sealed tube; the quantities of materials are so chosen that an excess of
hydrogen sulphide is formed. Alternatively, the ammonium salt of the requisite acid.may be employed, in which case the presence of a hydrate is
unnecessary. The preparation of thiobenzamide from benzamide and acetamide from ammonium acetate is described in detail. "
So:
1) how to write the formula? Al2S3 + C2H4O2.NH3 = ?????+
C2H5NS
2) "The quantities of materials are so chosen that an excess of hydrogen sulphide is formed" I understand that Al2S3 should be in excess, how many
times? 2 times? 10 times?
3) it asks for sealed tube. How much pressure will this build? I dont like the idea of heating a flammable H2S gas under preassure. Maybe starting
small.
4) Al2S3 probably will be anhydrous. Ammonium acetate should also be anhydrous? (maybe not because the experiment asks - if not ammonium to add an
hydrate - so water is needed.
5) regarding temperature, from our wiki:
"Ammonium acetate decomposes at temperatures above 165 °C to yield acetamide:
CH3COONH4 → CH3C(O)NH2 + H2O.
so my understaning is to get to at least this temperature (150 - 200°C?)
but thioacetamide decomposes with heat
Properties
Chemical formula C2H5NS
Molar mass 75.13 g/mol
Appearance colourless crystals
Odor slight mercaptan
Density 1.319 g/cm3[2]
Melting point 115 °C (239 °F; 388 K)
Boiling point decomposes
Solubility in water good
6) and how you extract the thioacetamite from the "I dont know what else" and how to purify it.
Of course if original paper is found maybe it could answere a lot of questions.
thanks,
Go SAFE, because stupidity and bad Luck exist.
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clearly_not_atara
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Even among thioamide preparations, this one sounds particularly dangerous. H2S at high pressure? Orgsyn uses P4S10:
http://www.orgsyn.org/demo.aspx?prep=CV3P0332
[Edited on 04-20-1969 by clearly_not_atara]
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EF2000
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Quote: Originally posted by RU_KLO  |
Thioamides. I. Preparation of Thioamides with the Aid of Aluminium Sulphide. KARL KINDLER and FRIEDRICH FINNDORF (Ber., 1921, 54, [B], 1079--1081).-
Of course if original paper is found maybe it could answere a lot of questions.
thanks
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Ber.=Berichte der deutschen chemischen Gesellschaft
Fortunately, Wiley have archive of every issue and Zenodo has papers in open access.
So here's the paper: Darstellung von Thio-amiden mit Hilfe des Aluminiumsulfids. (Zur Kenntnis der Thio-amide, I.), doi:https://doi.org/10.1002/cber.19210540522
Attachment: Thio-amide Ein.pdf (119kB)
This file has been downloaded 47 times
And the second paper, also by Kindler and about thio-amides, just in case: Reduktion der Thio-amide zu primären Aminen. (Zur Kenntnis der Thioamide,
II.) doi:https://doi.org/10.1002/cber.19210540523
Attachment: Thio-amide Zwei.pdf (118kB)
This file has been downloaded 43 times
Wroom wroom
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RU_KLO
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thanks
Go SAFE, because stupidity and bad Luck exist.
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RU_KLO
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the process requires ether to extract and cristallise the products.
Can I use ethanol (absolute) to extract it? and cristallise it?
(its easier for me to get ethanol than diethyl ether) - I know that could be made from ethanol and sulfuric acid)
"Crystallise the amide from absolute diethyl ether or *benzene. Dry it at 70o in a vacuum and store it over P2O5 at 0o under nitrogen. (It develops an
obnoxious odour on storage, and absorption at 269nm decreases, hence it should be freshly recrystallised before use). [Beilstein 2 IV 565.]
It is colorless or white crystals. Mp is 113-114℃, the solubility in water is 16.3g/100ml at 25℃, ethanol 26.4g/100ml. It is slightly soluble in
benzene, ether. Their solution is quite stable at room temperature or 50-60℃, but when hydrogen ions exists, it can generate thiosulfate hydrogen
and decompose quickly. New product sometimes has mercaptan odor, slight moisture absorption
Go SAFE, because stupidity and bad Luck exist.
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clearly_not_atara
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Do not use ethanol to recrystallize.
| Quote: | | when hydrogen ions exists, it can generate thiosulfate hydrogen and decompose quickly. |
You must use an aprotic solvent.
[Edited on 04-20-1969 by clearly_not_atara]
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RU_KLO
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thanks,
Searching for aprotic solvents, found Acetone
(https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Fundamentals/Intermolecular_Forces/Polar_Protic_an
d_Aprotic_Solvents)
and from this (cannot dowload):
https://www.sciencedirect.com/science/article/abs/pii/S01677...
"Conclusion
The solubility of TAA in 15 pure solvents were determined between 272.85 K and 323.95 K by the gravimetric method under atmospheric pressure. The mole
fraction solubility in different solvents ranks as acetone > 2-butanone > methanol > 2-pentanone > ethanol > methyl acetate >
n-butanol > n-propanol > ethyl acetate > acetonitrile > isopropanol > n-pentanol > ethyl formate > isopentanol > isobutanol at
298.15 K, and the solubility profiles intersect seriously through the whole temperature range"
so its seems that Acetone could be a candidate (or missing something)?
(what makes me a little noise is that ether and benzene is in another group (NON-POLAR SOLVENTS) vs Acetonte (POLAR APROTIC SOLVENTS).
Maybe could make Chloroform . Is Chloroform Aprotic?
which one you sugest? (maybe making some Benzene...)
or dont try to reivent the wheel and follow the preparation.,i.e get ether....
[Edited on 15-3-2024 by RU_KLO]
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clearly_not_atara
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Acetone is probably fine. Some amount of condensation is probably possible. But it shouldn't affect anything.
Acetone can be a little hygroscopic, so consider drying it over magnesium sulfate before using it.
[Edited on 04-20-1969 by clearly_not_atara]
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