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Baphomet
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| Quote: | Originally posted by 497
So am I right in thinking that this stuff can reduce both a double bond and a nitro group? Like maybe a nitrostyrene to phenethylamine in one step?
That would be lovely. |
Certainly seems that way (pictures in the second paper  ). In the first paper
(ketone to alcohol) the authors make the point that extra reductant should be added, and in several small increments to obtain maximum yield.
I'm wondering if it is strong enough to produce gold nanoparticles? A small test is in order 
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manimal
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| Quote: | Originally posted by Baphomet
If anyone has the full text for "Reduction of organic compounds with thiourea dioxide" I can translate it for you. |
Here is the link to the Chinese article in Youji Huaxue (Chinese Journal of Organic Chemistry). http://www.cqvip.com/qk/93463X/199802/2933582.html.
I don't know if you have to pay them for access or not. I tried registering, but it rejected every email address I typed in. I can't understand what
they're asking for because it's all Chinese to me. 
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Baphomet
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I managed to register. It forces you to have a 'strong' password and select the correct occupation & category. The article only costs 2RMB and I'd
happily pay this small sum but it requires payment through a mainland China mobile phone, which I don't have! Sorry..
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solo
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Study on reduction of organic compounds with thiourea dioxide #157
GU SHANGXIANG, YAO KALING, HOU ZIJIE and WU JIGU
Chinese Journal of Organic Chemistry 1998, 18 (2): 157-161
Abstract
Reported alcohol in alkaline aqueous solution containing thiourea dioxide nitro, carbonyl and olefinic bond to restore the role of organic compounds
to study these reaction conditions, reaction products and reaction mechanism.
NOte: this study is in Chinese ....so I hope someone can translate for you and then maybe you should post it her later.....solo
Attachment: Study on reduction of organic compounds with thiourea dioxide .pdf (308kB)
This file has been downloaded 1460 times
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Formula409
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Thank you solo. I have U2U'd Baphomet.
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497
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Have a look at this. US Patent 4610802, it talks about adding small amounts of hydrides to greatly increase thiourea dioxide's reducing power at lower pHs.
What it interesting, is it gives measured redox potentials of (fairly dilute) thiourea solutions at various pHs with and without other additives. For
example its redox potential at pH 13 is -750mV while NaBH4 is no higher than -390mV over the whole pH range, although it's concentration is much lower
(does concentration make a difference?)
How much does this tell about TDO's reducing power? Can you get an idea of what something will and won't reduce by looking at its redox potential?
[Edited on 19-2-2009 by 497]
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Nicodem
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| Quote: | Originally posted by 497
For example its redox potential at pH 13 is -750mV while NaBH4 is no higher than -390mV over the whole pH range, although it's concentration is much
lower (does concentration make a difference?)
How much does this tell about TDO's reducing power? Can you get an idea of what something will and won't reduce by looking at its redox potential?
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The redox potential of a reagent (against a standard electrode) can only tell the equilibrium constant of a redox reaction of this reagent with a
substrate when the redox potential of this substrate (against the standard electrode) is known. However, it can not tell if the reaction does indeed
occurs.
In ionic reactions, reactions on electrodes, or metal/ions reaction this information is important, because these reactions generally do indeed occur
when the redox difference allows (ions easily transfer electrons from one to the other or get them from metal surfaces). However, in organic chemistry
this information is of little value since the route a reaction will take is not only depending on the thermodynamic allowance (redox potential) but
also on the kinetics (determined by activation energy for each mechanistic possibility). And this second condition is what is most important for
predicting a reaction outcome in organic reactions. That's why studying the mechanisms and the reaction transition states is the most important thing
in organic chemistry if a student is to become a synthetic organic chemist.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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Baphomet
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Here is the first page. Anything I'm not sure about has been left verbatim so that nothing is lost in translation. For example, 'attracting the base'
is the literal translation which I guess means basic conditions are required..
| Code: |
The role of sulfur dioxide in the reduction of organic compounds.
Gu Shang Xiang, Yao Ka-Ling, Wu Ji-You
Department of Chemistry, Lanzhou University, Lanzhou 730000
Abstract:
A study of reaction conditions, reaction products and reaction mechanism for the action of sulfur dioxide containing nitro, attracting base and the olefinic bond of organic compounds
Keywords: sulfur dioxide, reduction, organic
Sulfur dioxide is a very good new reducing agent; in the textile, printing and dyeing, chemical and metallurgical industries and has a wide range of other applications.
Under alkaline conditions a sulfoxylate species can be released, with a high reduction potential, to restore a long time, to a certain extent stabilized after the reduction potential, etc., so in recent years it has been used in organic synthesis.
In this paper, that the reducing agent, containing nitro, attracts the base and the olefinic bond of the compounds to restore the role of research, discussed the reaction conditions
The impact of the reduction product and its reaction mechanism was discussed. The method is simple and easy to control with facile conditions, and a low chance of explosion.
By ketone reduction for alcohol and nitro compounds reduced to amines, it is able to obtain a high yield.
The method described here is comparible to other synthetic methods. At the same time, it can replace traditional methods for the reduction of olefins and catalytic hydrogenation reaction of olefins under more moderate temperature and pressure conditions.
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497
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Sulfur dioxide, not thiourea dioxide? I'm confused.
Still, it looks interesting, can't wait to see more.
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solo
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Topic Information
What is thiourea dioxide?
Thiourea dioxide is also called formamidine-sulfinic acid or aminoiminomethanesulfinic acid and is often abbreviated as TDO or TUD. Thiourea dioxide
is a powdered stable compound, which dissolves in water and decomposes gradually to exhibit a reducing action. But, this reaction is slow, and
particularly in an acidic to weakly alkaline region. Thiourea dioxide is stable and its reducing action is weak. Usually, thiourea dioxide dissolves
in water and produces sulfoxylic acid through formamidine-sulfinic acid. This reaction is promoted by the application of heat or in the presence of an
alkali, and a strong reducing action is thereby exhibited. TDO is useful as a reducing agent ; it reduces vat dyes, ketones to alcools and
hydrocarbons and conjugated unsaturated acids to the corresponding saturated acids. It is an excellent antioxidant in the stabilization of
percholorethylene. It is mainly used in dyeing and paper making industry stead of using sodium hydrosulphite, organic synthesis in synthetic fibre
industry, additive of polymerzation, stabilizer for polythene sensitizer of photographical emulsion.
Physical and Chemical Properties
Other Name: Formamidine sulfinic acid, Amino imino methanesulfinic acid
Appearance and Odor: White crystal powder, odorless
Formula: CH4N2SO2
Molecular weight: 108.12
Melting Point: 126℃
PH: 4(1% Solution)
CAS No.: 1758-73-2 or 4189-44-0
UN No.: 3341
Dangerous Goods Class: 4.2
Specification:
Purity: 99.%Min
Thiourea: 0.10%Max
Moisture:0.05%Max
Iron(Fe):10ppm Max
Sulphate: 0.17%Max
Packing:
500kg or 1000kg jumbo bags.
50kg fiber drums.
25kg or 50kg woven bags.
25kg kraft compound plastic bags or upon customers' demands.
Storage:
Storage in dry clean, well- ventilated condition, the warehouse temperature under 30℃ . Keep away from moisture and raining.
[Edited on 20-2-2009 by solo]
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manimal
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Am I right in ascertaining from the pictures that it can reduce benzylic ketones all the way to the hydrocarbon?
I sort of got a rough translation after installing the right fonts and copying and pasting into google translate.
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Nicodem
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Baphomet, for the beginning it would be enough if you could only translate the tittles and substrate/product columns in Table 4, with the pertaining
experimental. The rest currently does not seem particularly interesting.
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Baphomet
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Happy to help:
| Code: |
Reactant Product Reactant:TUD:NaOH Hours Temp Yield BP (lit. BP)
Cyclohexene Cyclohexane 1:2:8 8 58.0 58.0 81 (80.7)
Cyclopentene Cyclopentane 1:2:8 6 39.0 39.0 49 (49.3)
1-Hexene Hexane 1:2:8 6 55.6 55.6 68 (69)
1-Heptene 1-Heptane 1:2:8 6 54.0 54.0 98 (98.4)
1-Octene 1-Octane 1:2:8 6 46.5 46.6 124 (125.6)
1.4
Regarding Benzophenone reduction, Diphenyl methanol production rates were 14.1% and 19.3%
(Other conditions identical to table 3, and the medium alkaline as well).
When in an alkaline medium the production rate is 98.7%. This results in TUD having a
solubility dependent upon the medium in which it is used. In alkaline solution other
tautomers may be formed easily and subsequently broken down into highly reductive
SO2(-2) species:
(diagram)
Thus, TUD only has a strong reducing ability in alkaline medium.
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[Edited on 24-2-2009 by Baphomet]
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Bolt
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The reactants and products are the same! =/
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Nicodem
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Bolt: No they are not. You misread.
Baphomet, thanks a lot, but could you please also take care also of the part of the discussion talking about this reduction of olefins as well as the
experimental.
I guess "production rates" would be "yields"? Also the rest is a bit hard to understand. Is that a direct machine translation output or do you
correct/interpret it as well? It would be nice if you could interpret it in such a way as to make it more coherent. But thanks for your effort
nevertheless.
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Baphomet
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| Quote: | | Baphomet, thanks a lot, but could you please also take care also of the part of the discussion talking about this reduction of olefins as well as the
experimental. |
Sure, which page / paragraph do you want?
| Quote: | | I guess "production rates" would be "yields"? |
Yes, it says "product rates were respectively 14.1% and 19.3%" so they mean yield.
| Quote: | | Also the rest is a bit hard to understand. Is that a direct machine translation output or do you correct/interpret it as well? |
It's just my personal reading of it. The text may seem a little clumsy because I have tried to leave it as a literal translation and simply correct
the grammar. Unfortunately it is not the perfect language for scientific communication.
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Nicodem
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I would have to be able to read and understand Chinese to tell you which page or paragraph. Surely there must be a discussion where they interpret the
results shown in Table 4? This reduction of non-conjugated alkanes is so exceptional that they must have devoted some explanatory text to it. It would
also be their duty to provide a hypothesis of the mechanism, even if they did no experimental work to prove it. In short, I'm interested in anything
in there connected with their experiments on the reduction of alkenes, including the experimental part.
It is very exceptional that such a simple (nonmetalic) reducent reduces simple olefins and this would be the most accessible reagent for amateurs to
be used in such a reaction.
I understand that Chinese, a language having a totally context based meaning, is very hard to translate, particularly for scientific texts, and I
appreciate every effort you make.
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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manimal
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Here's a cleaned-up machine translation using a combination of google and altavista, and cross checking between the two. I think it's fairly accurate.
| Quote: | Olefin reduction to the alkanes is more difficult, and requires a highly alkaline solution(Table 4).
Some Alkenes have a great tendendency to polymerize, such as cyclopentene. At a temperature higher than 60C a viscous, polymer like substance forms.
Therefore, the reaction can only take place at a lower temperature, and the corresponding yield is lower.
In the TD reduction of cyclohexene, EPR study has found that this reaction system proceeds through H+ radicals, the measured g = 2.004. Note that the
reduction by TD of the olefin proceeds through the course of free radicals.
...
1.64g(.02mol) cyclohexene (homemade) is added to 5ml 95% ethanol. The molar proportions of olefin:TD:NaOH is 1:2:8. Under stirring at 80C, a solution
of TD and NaOH in 30ml water is added over the course of 1h. Stirring is continued for another 5h. At that time, a sample is taken for EPR
measurement. The reaction is allowed to continue for another 2 hr, then the mixture is cooled and extracted with ether. The extraction is fractionated
and the 80.5-81C fraction is collected, a clear colorless liquid (cyclohexane). For other reaction conditions see table. Product b.p. is basically
consistent with literature values. |
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Nicodem
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Thanks, that is exactly what I wanted. I'm glad they made an ESR experiment that confirmed the radical pathway. Very strange that nobody noticed the
potential of thiourea dioxide for radical reactions, particularly radical anion cyclisations. With the current price of sammarium(II) iodide, any
alternative would be more than welcome (and SmI2 does not even work on alkenes!).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
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Ebao-lu
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I guess the reaction with carbonyl compounds is not obligatory having a radical pathway. TUD is a 2e reductant, and 1 molecule of TUD can reduce 1
molecule of carbonyl compound directly. And in case of cyclopentene, it is realy amazing. What is the yield in the cyclohexene procedure(:sorry, did
not notice it in the table above?
[Edited on 26-2-2009 by Ebao-lu]
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Formula409
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| Quote: | Originally posted by Ebao-lu
I guess the reaction with carbonyl compounds is not obligatory having a radical pathway. TUD is a 2e reductant, and 1 molecule of TUD can reduce 1
molecule of carbonyl compound directly. And in case of cyclopentene, it is realy amazing. What is the yield in the cyclohexene procedure?
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Reactant Product Reactant:TUD:NaOH Hours Temp Yield BP (lit. BP)
Cyclohexene Cyclohexane 1:2:8 8 58.0 58.0 81 (80.7)
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Nicodem
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| Quote: | Originally posted by Ebao-lu
I guess the reaction with carbonyl compounds is not obligatory having a radical pathway. |
Indeed, it is not obligatory, but it seems a common case. Now there are already two papers (this Chinese one and the old Tetrahedron) experimentally
confirming a SET mechanism. Single electron transfers are not so rare in sulfur chemistry, there are several other cases known (like during the
oxidation of mercaptans or, after all, even the radical reaction of sulfur with alkanes at high temperatures trough homolysis of S-S bonds).
…there is a human touch of the cultist “believer” in every theorist that he must struggle against as being
unworthy of the scientist. Some of the greatest men of science have publicly repudiated a theory which earlier they hotly defended. In this lies their
scientific temper, not in the scientific defense of the theory. - Weston La Barre (Ghost Dance, 1972)
Read the The ScienceMadness Guidelines!
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Ebao-lu
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Yes, well, it must be SET then (if mentioned in papers). I imagined a mechanism, with attacking of carbonyl by sulfinic O-, then attack of OH- at
sulfur atom, and then rearrangement of the product in a 6-membered intermediate state, but realised it is also SET with anion-radical formation that i
believed first to be an alcohol.
I wonder how, i wonder why cyclohexene does not polymerise if the reaction is having a free-radical mechanism? Thats probably because it immediately
reacts with another TUD molecule, or the same +5 sulfur atom.
ps: above supposed mechanism does not explain the cyclohexene reduction, because there can not be any imaginable cyclohexene+ TUD conjugate, so there
should some another mechanism.
Also, if it is so strong reductant, why it can't reduce carbonic acid derivatives? I guess, that is only due to all carboxyl synthones ere easily
hydrolysed to COO- with base, and TUD is having also a negative charge, so they are electrostatically repulsing. But if we amend this, hope it will
work? Maybe it is possible to use some metal ions to get the anions closer (like Cu2+, Fe2+). By the way, can TUD reduce these metals to 0 state? It
will also be promising, getting nanoparticles of metals that can also be used as reducing agents
[Edited on 26-2-2009 by Ebao-lu]
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Ebao-lu
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| Quote: | When in an alkaline medium the production rate is 98.7%. This results in TUD having a
solubility dependent upon the medium in which it is used. In alkaline solution other
tautomers may be formed easily and subsequently broken down into highly reductive
SO2(-2) species: |
What are those "tautomers" mentioned above? Do they want to say, SO2(2-) is the core reducing agent, or it is only proposal? What is the mechanism
supposed in tetrahedron?
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manimal
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Quote: Originally posted by Nicodem  | | There were a couple of references where N-oxides of imines were reduced to a mixture of secondary amine and imine, but nothing about the reduction of
imines or enamines themselves. |
I would be interested in seeing those references.
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