Sciencemadness Discussion Board - What can I do with Sulphur Dioxide gas ?

What can I do with Sulphur Dioxide gas ?

Sulaiman - 18-7-2018 at 01:19

I am about to set up a smakk scale sulphur dioxide gas generator,
to reduce chloroauric acid to gold,

I shall try making a little Oleum just to see if I can do it
as I have an O₂ concentrator and some Pt

any other ideas ?

Edit : I'm thinking of sodium hydroxide as a general purpose scrubber for waste/exhaust SO₂,
I should get sodium sulphite as a by-product,
which can be used in the next SO₂ generator batch run instead of / with sodium metabisulphite.

any hints/tips/alternatives ?

[Edited on 18-7-2018 by Sulaiman]

CobaltChloride - 18-7-2018 at 05:25

There's a few interstening reactions with this gas. Firstly, it can be reduced with zinc powder to dithionite, a very interesting reducing agent.

http://www.prepchem.com/synthesis-of-sodium-dithionite/

Also, it can reduce nitrite to hydroxylamine, which is also very interesting.

http://www.prepchem.com/synthesis-of-hydroxylamine-hydrochlo... (I know this doesn't use SO2, but I think SO2 would be better in some ways as using it avoids adding additional chemicals besides the nitrite)

Scrubbing with NaOH seems to be the best option for removing this gas though.

[Edited on 18-7-2018 by CobaltChloride]

AJKOER - 18-7-2018 at 11:37

My recommendation target the creation of HSO5- (like in Oxone).

Start with SO2, water and passing air/O2 through the formed H2SO3 in the presence of a hydroxyl radical source (like by action of sunlight near to an ocean, large lake,.. on aqueous nitrite or a photo active oxide like MgO, ZnO, TiO2,..or a mix of an oxide like ZnO in the presence of dissolved N2O).

Per one source: "Rate Constants for Reactions of Inorganic Radicals in Aqueous Solution" by P. Neta and Robert E. Huie, and also this reference: https://pubs.acs.org/doi/abs/10.1021/j100143a031?journalCode... . To quote from Neta:

"3.11. Sulfite Radical
The .SO3− radical is most commonly produced by the reaction of .OH with sulfite or bisulfite.
.OH + SO3(2−) → OH− + .SO3−"

And further:
"3.13. Peroxomonosulfate Radical
The SO5.− radical is produced by the reaction of .SO3− with O2.
.SO3− + O2 → SO5.−"

Also:
"The SO5.− radical is a stronger oxidant than .SO3−, with an estimated redox potential of 1.1 V at pH 7.39. It is still quite selective in its reactions, oxidizing hydroxybenzenes at high pH rapidly but only slowly or not at all at low pH."

Now, one can convert the SO5•- to HSO5- by way of HSO3- or a transition metal:

Fe(ll)/Cu(l) + SO5•- + H+ --> Fe(lll)/Cu(ll) + HSO5- (see p. 363 at https://books.google.com/books?id=RAJMmvbfyzgC&pg=PA363&... )

Apparently, however, one of the best way to activate peroxymonosulfate (PMS) is siderite, (Fe,Mg,Ca,Mn,Zn,Co)CO3, where Fe, Mn and cobalt are the key metal ions (apparently, a trace of the toxic cobalt ions in the presence of HSO5- is capable of producing the powerful sulfate radical anion, see "COBALT/PEROXYMONOSULFATE AND RELATED OXIDIZING REAGENTS FOR WATER TREATMENT" a thesis by Georgios P. Anipsitakis, https://etd.ohiolink.edu/rws_etd/document/get/ucin1130533674... ). The ensuing advanced oxidation process can then produce both the usual sulfate radicals (see https://www.sciencedirect.com/science/article/pii/S004313540... ) and the even more powerful hydroxyl radical (see "Activation of Persulfates Using Siderite as a Source of Ferrous Ions: Sulfate Radical Production, Stoichiometric Efficiency, and Implications", at https://pubs.acs.org/doi/abs/10.1021/acssuschemeng.7b03948 ).

The siderite functions as a source of Fe2+ (think fenton with KHSO5 replacing H2O2) with the sulfate radicals as the major active radical. In place of siderite, also consider FeS2 (Fool's Gold, see for example, https://pubs.acs.org/doi/abs/10.1021/ie100740d to which I would also pump in air/O2 to expand possible reactive oxygen species creation. Further, I would suspect adding the Bravoite variation of Fool's Gold, which contains toxic nickel and cobalt, would be favorable).

Example of activation reactions with cobalt ions (which are toxic):

Co2+ + HSO5- --> Co3+ + SO4•- + OH- (2.1 from thesis)

Co3+ + HSO5- --> Co2+ + SO5•- + H+ (1.11 from thesis)

Note, the action of the sulfate radical anion, for example, on bromide (or other halogens, in reverse order of their reactivity, so the action on iodide is faster than with bromide...) proceeds as follows:

SO4•- + Br- --> SO4(2-) + •Br

•Br + •Br = Br2

•Br + Br- = •Br2-

Br2 + Br- = Br3-

Note, the sulfate radical anion is weaker than the hydroxyl radical. Hypochlorous acid activated by say cuprous creates the more powerful hydroxyl radical. In some cases, PMS is not recommended for swimming pools as it does not completely kill off problem microbes.

[Edited on 18-7-2018 by AJKOER]

Sulaiman - 18-7-2018 at 13:00

@CobaltChloride: Looks interesting, thanks.
Honestly, I doubt I'll try just yet but thanks anyway.

@AJKOER: Too radical !
I was hoping for some simple/interesting stuff,
when my brain un-melts I'll read the post again as I did not get a coherent picture on first or second reading,
but it looks like a lot of mental and physical work required
and I'm not currently in that kind of mood, but thanks anyway.

AJKOER - 18-7-2018 at 13:19

Sulaiman:

Yes the theory gets intense, but the hype on experimenting with HSO5- on SM is up there also.

Reagent friendly things like sunlight, laughing gas (available at Walmart), ZnO (easy made several ways including in a battery cell of HOCl, and a more noble metal, like a Cu/Ni coin, and a touch of sea salt), SO2 and water.

woelen - 18-7-2018 at 23:37

Another interesting one may be making SO2Cl2.
Mix equal volumes of dried Cl2 (dried with CaCl2) and dried SO2 and pass this mix over activated carbon. This makes SO2Cl2. You do not need to have exact stoichiometric ratios of gas and it also is not necessary to exclude air. Just keep everything dry. If you have excess SO2, then add extra Cl2 and once you have excess Cl2 add SO2. You hence can add the gases in an alternating fashion.
Another suitable catalyst for this reaction is camphor, instead of activated carbon.

Sulaiman - 19-7-2018 at 02:24

It would be nice to have a little SO₂Cl₂ as I already have some SOCl₂
and I will also be setting up a Cl₂ generator later as I am not satisfied with my previous Au₂Cl₆ (Dragon's Blood) synthesis.
Thanks

TalkStory - 19-7-2018 at 03:59

And if you react these 2 gases with water, you will get HCl and H2SO4. Nobody ever done this on youtube or anywhere.
I was able to find NaCl and Na2S2O7 much more easily than H2SO4, so would use them as reactants.
https://pubs.acs.org/doi/pdf/10.1021/i160061a009

Sulaiman - 19-7-2018 at 05:06

SO₂Cl₂ decomposes in water to HCl and H₂SO₄ (hydrates) so its sort of a mixed-acid-anhydride.

I've never synthesised anything from purely gas phase reactants
(other than burning gases in air)
and I am wary of the total volumes of potentially toxic gasses produced and consumed during the process of synthesising e.g. 100ml liquid SO₂Cl₂ (minimum 28 litres each of SO₂ and Cl₂)
but that should be manageable, especially if I make a more sensible 10ml only

but I don't like tiny bottles .....

clearly_not_atara - 19-7-2018 at 09:09

SO2 reacts with some aryldiazonium halides to generate the corresponding sulfonyl halides. If the arene has electron-withdrawing substituents, the corresponding sulfonyl chloride will be more electrophilic than tosyl chloride. Orgsyn demonstrates this with trifluoromethylbenzenediazonium chloride.

Actually, the p-trifluoromethylaniline might not be too hard to obtain, if you can manage to coax a nucleophilic aromatic substitution out of this:

http://en.wikipedia.org/wiki/Parachlorobenzotrifluoride

Not sure what to do next, although you may be able to generate enol sulfonates and activated amides, etc.

AJKOER - 20-7-2018 at 10:40

Here are two paths to SO3 from SO2.

First, generate singlet oxygen and let it react with SO2. The added presence of O2 should be beneficial. Source: see https://books.google.com/books?id=EvsbBQAAQBAJ&pg=PA209&... .

SO2 + O2(1P) --> SO3 + O(3P)
------------------------------------

The second method involves NO2 in a reportedly slow reaction at RT:

NO2(g) + SO2(g) --> NO(g) + SO3(g) (slow) (see https://www.chegg.com/homework-help/questions-and-answers/ni... )

which creates SO3. Interestingly, I recall a report of passing SO2 over nitrous acid (HNO2) forming SO3. Here is a quote from Atomistry.com on HNO2 acting on SO2 to quote:

"Stannous chloride is converted into stannic chloride, sulphuretted hydrogen into sulphur, sulphur dioxide into sulphur trioxide. Iodine is liberated from potassium iodide"

Also, per Wikipedia ( https://en.wikipedia.org/wiki/Nitrous_acid ), to quote:

"In anything other than very dilute, cold solutions, nitrous acid rapidly decomposes into nitrogen dioxide, nitric oxide, and water:

2 HNO2 → NO2 + NO + H2O "

With added oxygen, it is likely that passing SO2 + O2 over HNO2 forms SO3 as:

NO2(g) + SO2(g) + 1/2 O2 (g) --> (NO(g) + 1/2 O2) + SO3

NO (g) + 1/2 O2 --> NO2 (g)

Net: SO2 (g) + 1/2 O2 (g) --NO,O2,NO2--> SO3 (see p. 43 at https://mymission.lamission.edu/userdata%5Cpaziras%5CChem102... )

where I recall higher temperatures accelerate the above reaction rate. Note: acidified NaNO2 could be a source here for HNO2.

[Edited on 20-7-2018 by AJKOER]

Sulaiman - 20-7-2018 at 11:16

@AJKOER:
Have you got a reference for a reportedly fast version

preferably fun, quick and easy.

@clearly_not_atara:
I deliberately have no fluorine- or fluoride-containing reactants ... maybe one day.
I would not know how to assay or use the product

Despite my mostly negative responses

I do appreciate the suggestions

... Thanks

clearly_not_atara - 20-7-2018 at 11:42

Another thought: SO2Cl2 can be used to prepare sulfamide, SO2(NH2)2, which can then be alkylated at nitrogen to prepare symmetrical secondary amines. Hydrolysis of sulfonamides is possible with HBr in the presence of a bromine scavenger; HBr protonates and then reduces the sulfonyl group.

https://pubs.acs.org/doi/abs/10.1021/ja01111a007?journalCode...

Unsymmetrical secondary amines can also be made from the sulfamide corresponding to the primary amine, via SO2(NHR)2 + 2 R'X etc. If a cyclic product is obtained with ethylenediamine, you can even prepare the ligand N,N'-dimethylethylenediamine, which IIRC is otherwise produced by reduction of the corresponding oxamide.

That then catalyzes the condensation of acetone with nitromethane to 3-nitroisobutylene:

https://pubs.acs.org/doi/abs/10.1021/jo00373a007?journalCode...

and, with CuI, many Goldberg-type reactions, e.g.:

https://onlinelibrary.wiley.com/doi/abs/10.1002/cjoc.2013004...

[Edited on 20-7-2018 by clearly_not_atara]

AJKOER - 20-7-2018 at 12:39

Quote: Originally posted by Sulaiman

@AJKOER:
Have you got a reference for a reportedly fast version

preferably fun, quick and easy.

Despite my mostly negative responses

I do appreciate the suggestions

... Thanks

Yes, I added a Singlet oxygen path as it is fun to prepare and one see the glowing in the dark!

vmelkon - 25-7-2018 at 08:08

If you bubble SO₂ in CuSO₄ solution, I assume you get Chevreuil's salt, which is an insoluble solid and has a beautiful red color. I haven't seen many copper compounds that have a red color, except for Cu₂O.

[Edited on 25-7-2018 by vmelkon]

unionised - 25-7-2018 at 12:43

Quote: Originally posted by AJKOER

Here are two paths to SO3 from SO2.

A third would be to reduce it with sulphur. (Don't worry Ajkoer, it's probably a radical reaction)

Another option would be to dissolve it in water (not very practical but...) and then dilute it down to make 50% sulphuric acid.
Then heat that with scrap copper to get SO2
This also gives you CuSO4.
I'm told you might be able to do something interesting with that too.

Sulaiman - 25-7-2018 at 14:38

Quote: Originally posted by vmelkon

If you bubble SO₂ in CuSO₄ solution, I assume you get Chevreuil's salt, which is an insoluble solid and has a beautiful red color. I haven't seen many copper compounds that have a red color, except for Cu₂O.

Thanks, added to the list.

AJKOER - 7-8-2018 at 11:16

Just came across this, SO2 to sodium thiosulfate, to quote:

"The absorption [referring to SO2] takes place at pH 6.2 in the presence of sodium bisulfide/polysulfide to convert the sulfite to sodium thiosulfate, the formation of which controls the oxidation of sulfite to sulfate, an undesirable by-product."

Source: Sulfur Dioxide Absorption and Conversion to Sulfur. Available from: https://www.researchgate.net/publication/231300134_Sulfur_Di... [accessed Aug 07 2018].

On the prep of Na2S, see https://patents.google.com/patent/CN101337661A/en .

mackolol - 12-8-2018 at 04:03

You can make some sulphuric acid by the copper chloride process, which NurdRage presented in one of his videos. You bubble so2 to the solution of CuCl2. The CuCl2 is reduced to CuCl and and solution of so2 is oxidised to h2so4. Then you regenerate cucl to cucl2 by bubbling air through solution. The process is fully catalytic and uses only air so2 and water.