Sciencemadness Discussion Board

Convert Sodium Iodide to sodium Iodate? ( Iodi'IDE' -> Iod'ATE')

LuckyWinner - 12-11-2020 at 10:18

When making Sodium Iodide from Elemental Iodine you
get a side reaction of sodium Iodate.


6NaOh + 3 I2 = 5 NaI + NaIO3 + 3H2)
or with sodium Carbonate
Na2CO3 + (3)I2 --> NaIO3 + (5)NaI + (3)CO2


Process
-------------
Elemental Iodine 10g
Sodium Hydroxide 25g
distilled water 50ml

dissolbe NaOh in distilled water,
heat solution until hot but not boiling,
then add iodine under mag stirring.

reaction is finished when a white precipitate is
forming at the bottom of the flask.

solution should be yellow with white precipitate
of side product 'Sodium Iodate NaIO3'

turn off heat and let cool down to room temp.

(*if no precipitate formed too much water is present
which needs to be boiled down.)

filter solids 'Sodium Iodate' and boil down filtrate
to get sodium iodide (8.8g).

OR if you got a furnace place solution
after precipitation occurred into a furnance
at min 425C ,
'Iodate is removed by heating strongly: NaIO3 === > NaI + 3/2 O2. '
then recrystallize in water to get pure sodium iodide.


source: ChemExperimentalist
https://youtu.be/7vZOJRPnY8M
http://www.sciencemadness.org/talk/viewthread.php?tid=17635#...
http://www.sciencemadness.org/talk/viewthread.php?tid=17635#...



questions
-------------
1)will this work as written?
since I have no use for sodium Iodate.

2)are there any OTC conversions of sodium Iodate to Sodium Iodide if there is no furnace around?

3) For how long should you heat the sodium Iodate + Sodium Iodide mix for in the
furnace?
I assume 450C is better cause 425C is written as melting point of sodium Iodate.

4) will there be any residual NaOh present in the sodium iodide after boiling off the water?
' Boil the mixture down and dry at above 65 degrees to get rid of the water and extract with absolute ethanol. You could redissolve in water and neutralize any NaOH with HCl or HI if you worry about the NaOH.

You only have to dissolve iodine in hot NaOH untill the purple color doesn't disappear anymore, then add a bit more NaOH untill color disappears, boil down, dry, extract with ethanol, dry, redissolve, neutralize NaOH, dry.'


[Edited on 12-11-2020 by LuckyWinner]

[Edited on 12-11-2020 by LuckyWinner]

njl - 12-11-2020 at 10:36

If you don't want iodate then the SM thread that you linked has an OTC procedure for both NaI and IO3- --> I-


"Na2SO3 + S --> Na2S2O3
Na2S2O3 + I2 --> Na2S2O6 + (2)NaI"


"Elemental iodine can be reduced to iodide by reaction with thiosulfate."

and

"Sodium bisulfite (not bisulfate) can reduce iodate to iodide."

LuckyWinner - 12-11-2020 at 11:10

Quote: Originally posted by njl  
If you don't want iodate then the SM thread that you linked has an OTC procedure for both NaI and IO3- --> I-


"Na2SO3 + S --> Na2S2O3
Na2S2O3 + I2 --> Na2S2O6 + (2)NaI"


"Elemental iodine can be reduced to iodide by reaction with thiosulfate."

and

"Sodium bisulfite (not bisulfate) can reduce iodate to iodide."


ok
you forgot to add the (2) before the Na, now I got it...
(2)Na2S2O3 + I2 --> Na2S2O6 + (2)NaI


that means
1 mol iodine is added to 2 mol Sodium thiosulfate
in min amount of water and mixed.
once solution turns white the reaction is finished?

then boil off water and extract NaI with absolute ethanol.
evaporate and you are left with pure NaI?

cant find any concrete data about a reaction like this?

no sodium Iodate formed ?


Sodium dithionite
Chemical formula: Na2S2O4
Solubility: slightly soluble in alcohol‎
Solubility in water: 18.2 g/100 mL (anhydrous, ...
CAS Number: 7775-14-6


NaI
SOLUBILITY (G/100 CC SOLVENT): 184 G IN WATER @ 25 °C; 302 G IN WATER @ 100 °C; 42.57 G IN ALCOHOL @ 25 °C; 39.9 G IN ACETONE @ 25 °C

Bedlasky - 12-11-2020 at 11:15

Quote: Originally posted by njl  
If you don't want iodate then the SM thread that you linked has an OTC procedure for both NaI and IO3- --> I-


"Na2SO3 + S --> Na2S2O3
Na2S2O3 + I2 --> Na2S2O6 + (2)NaI"


"Elemental iodine can be reduced to iodide by reaction with thiosulfate."

and

"Sodium bisulfite (not bisulfate) can reduce iodate to iodide."


This isn't correct. Iodine reacts with thiosulphate to form iodide and TETRAthionate.

2Na2S2O3 + I2 --> Na2S4O6 + 2NaI

LuckyWinner - 12-11-2020 at 11:26

quote wikipedia
https://en.wikipedia.org/wiki/Sodium_tetrathionate
Quote:

Sodium tetrathionate is formed by the oxidation of sodium thiosulfate (Na2S2O3), e.g. by the action of iodine:.[2]

2 Na2S2O3 + I2 → Na2S4O6 + 2 NaI

The reaction is signaled by the decoloration of iodine. This reaction is the basis of iodometric titrations.



https://pubchem.ncbi.nlm.nih.gov/compound/203055#section=Dep...

there is no data about solubility, how should this be separated from he NaI?


what is the proper clean procedure to make NaI with this method?

Bedlasky - 12-11-2020 at 12:47

https://en.wikipedia.org/wiki/Sodium_tetrathionate

It have quite low solubility, most of tetrathionate will crystallize first.

Iodide can be also made by reaction of iodine with oxalate in the presence of UV light (sun as source of UV is good enough).

I2 + C2O42- --> 2I- + CO2

[Edited on 12-11-2020 by Bedlasky]

LuckyWinner - 13-11-2020 at 04:10

i found this patent
https://www.freepatentsonline.com/2439720.html
Quote:
Sodium tetrathionate dihydrate (Na2S4O6.2H20) which is the ordinary crystalline form of this salt, is commonly prepared-by the- interaction of-sodium thiosulfate and iodine in concentrated aqueous solution, the tetrathionate being -precipitated from the reaction mixture by the addition-of alcohol. Inasmuch as-sodiumriodide -(which is formed as a by-product during the reaction) is among the impurities known to interfere with the stability of dry sodium tetrathionate, it is obvious that the salt as first obtained must be further purified. It has been found impossible to obtain satisfactory purification by simple washing with ordinary 95 per cent ethyl alcohol even though sodium iodide is very soluble in this solvent, probably because the crystals of sodium tetrathionate as obtained are quite dense and frequently relatively large in size, making it impossible for the alcohol to leach out the impurity occluded within the crystals. According to the teaching of the prior art, this purification of the salt is best carried out by dissolving the crystals in water and recrystallizing upon the addition of alcohol. Such a purification results in a large loss of yield, particularly if it must be repeated a second time.


Quote:

As a part of the present invention, it has been found that if the crude dihydrate crystals as isolated from the reaction mixture are first washed several times with 95 per cent ethyl alcohol, which may conveniently be done on a Biichner funnel, to remove mechanically adhering aqueous liquid, then freed from excess solvent by brief suction, and then treated in a flask with a relatively large I volume of substantially anhydrous ethyl alcohol, the relatively dense dihydrate crystals gradually lose their form and swell to many times their former bulk, frequently stiffening the whole mixture to a non-pouring paste. The powder ob0 tained by filtering and drying such a mixture is light and fluffy; has a much smaller particle size, and is substantially less hydrated than the original dihydrate-crystals. Further, the powder thus obtained is-found to be substantially free of sodium iodide; and any last traces thereof may be further removed by continued washing with alcohol


Quote:

A quantity of sodium tetrathionate dihydrate is prepared in any convenient fashion, such as by the interaction of 410 grams of sodium thiosulfate dissolved in 180 cubic centimeters of water with 200 grams of iodine suspended in 30 cubic centimeters of water and 100 grams of ice, taking care that there is at all times an excess of iodine throughout the reaction mixture, and then precipitating the crystalline dihydrate salt by two liters of alcohol. After cooling and settling, the crystals are filtered and sucked reasonably dry.

They are then washed wahdith several successive portions of 95 per cent ethanol and finally with several portions of absolute alcohol, and they are then sucked quite dry on the filter. The crystals are then transferred to a dry flask and allowed to stand under 500 cubic centimeters of anhydrous ethanol with occasional shaking or stirring. In a short while the crystals are observed to settle more slowly and finally to begin to set to a paste. At this point another 500 cc. portion of absolute ethanol is added to produce a thin slurry, this treatment being repeated later in the process if necessary. After standing overnight, the finely powdered product is filtered, washed further with anhydrous ethanol on the funnel, if desired, and then dried in a vacuum desiccator. After grinding the granulations formed in drying, the thoroughly dried powder is ready to be filled into ampules, or to be used for any other purpose desired. This powder is instantly soluble in water.


well this should make clean sodium tetrathionate but will
the NaI be contaminated with some sodium tetrathionate
since there will be several 95% ethanol water washes which should
contaminate the NaI ethanol washes.

I can not find any data about the solubility of sodium tetrathionate in acetone,...

would dissolving the NaI in dry acetone and filtering it (if sodium tetrathionate is insoluable in dry acetone) be sufficient to get very pure NaI?


that means mix
sodium thiosulphate
water
iodine , suspended in water + ice

till it turns white then filter out sodium thiosulfate in buchner.
collect water containing NaI and evaporate water.
scrape up NaI crystals with tetrathionate impurities and dissolve in dry acetone.

buchner separate tetrathionate sediments and squirt some dry acetone over it,
evaporate acetone to get pure NaI.