Iodine/potasium iodide

Sektor · Wed May 25, 2005 6:30 am

swim got hold of iodine tincture the other day (25ml), the contents of the bottle include Iodine(25g/litre) AND potassium iodide(25g/litre), does swim go about the extraction of I2 as usual? or does it need a refined extract? if some one could post the amounts (ml/g, w/e) would be also very helpfull, thanks heaps

Soap · Wed May 25, 2005 9:25 am

swim hear has several kg of potasium iodide. he mixes it hith h202 and hcl. he then has a purple liquid with soem crystals in it. what should he do to extract the iodine frome this?

loki · guinea pig

well, my personal opinion is the best way to go here is to make up a standardised KOH solution (0.5M is probably good, potassium carbonate is probably decent enuf substitute, KOH solution can be bought from hydro stores, it's the usual pH up) and titrate it into the tincture until it loses all the red colour. Then you got entirely KI. Try to avoid overshooting neutralisation, ideally the pH of the solution after titration should be neutral (this is why use a dilute base, dilute with water etc)

and then... what do you want? I am of the opinion that HI is a better iodine to get to but this mixture is a bit ick (they often put a bit of something else in these things) so in either case, evaporate off the water until you have just KI, wash it with something to get rid of the junk stuff they put in, or maybe rextal in methanol/ipa to clean it up.

from there you'd be able redissolve, titrate with conc. tartaric acid, precipitating potassium tartrate and leaving HI acid, which presumably then needs to be concentrated, after filtering. Alternatively, for I2(solid) 0.5M HCl solution and 3%H2O2 and a bit of waiting and you get I2 precipitate.

I reccommend the conversion to KI and removing the alcohol because if you just do the HCl/H2O2 conversion to I2, you can't get a certain amount of the I2 out because it dissolves in the residual alcohol, probably is a different situation with 7% tincture tho, less losses, more acid and water and peroxide used.

Elementary · Wed May 25, 2005 2:32 pm

Tritrating with a hydroxide will lead to iodoform being formed if there is alcohol in your tincture.

http://www.chemguide.co.uk/organicprops/alcohols/iodoform.html

IndoleAmine · Dreamreader Deluxe

Soap: filter them, and pat dry with tissue paper followed by air drying!? Maybe sublimation if desired? (you could remove the remainder from solution by shaking with a haloalkane like DCM, then evapping that to leave more I2...)

Soap · Fri May 27, 2005 10:47 am

thanks for the help. swim decided to take his solution filter out the crsytal and soak them in dh20. this should have removed any extra ki... he then tested it with some hcl and h202 to make sure there was no reaction. from there he filtered again and patted the crsytals dry. worked great!

loki · guinea pig

ahhh that's what that is... ugh

well, in that case, don't get tincture, get KI. takes a lot of water to dissolve the alcohol adequately to get all the i2 out

Sektor · Sat May 28, 2005 8:16 am

the iodine/potassium iodine tinct in swims parts does not say anything about other ingredients with in, so it could still contain ipa? all it says is 'iodine tincture' (weak solution on label, contents as above (first post).. swim will fuck with it anyway to see what he can see, as potasssium I is very hard to get round 'ere, and very watched too..

Soap · Sat May 28, 2005 9:11 am

sorry if there was any confusion about what swim was using. he has pure KI. he bought it off an auction site years ago by the kg. never tried iodine tincture but swim has seen large bottles of it at the brewery shop...

Sektor · Mon May 30, 2005 10:27 am

MF! swim got hold of a different brand of iodine tinct, but this shit contains same as above stated, except with the addition of ethanol and water, dosent say how much, phuck any synths for this shit? or is it the usual workup?
cheers,

bio · Working Bee

Even if not on the label standard tincture always contains K or Na Iodide. This is used because it greatly increases the I2 solubility in the solution.

DnBGirl · Tue Jun 28, 2005 1:57 pm

Yesterday I by chance found some articles how to extract iodine from KI. I never before did not heat aboust something like that. I believed it is true, because I found it on the hive archive and now I am 100% sure it is really.

Reaction, what I hope you are talking about:

2KI + H2O2 + 2HCl --> 2H2O + 2KCl + I2

It seems to be easier than extraction from iodine tincture. So why it is so infrequent? At least in my country?
And something shady. It should be potassium iodide if I translate it correctly I can buy it as medicine. Can be.

What procedure is better? I guess that with pure KI, but I dont want to be wrong.

gspot · Thu Jun 30, 2005 7:04 am

Does anybody have the writeup for using Potassium Iodide to get I2? I cant find any references that specify specific amounts. I have been using h202 and hcl with sucess but it doesn't seem like my yeild is what it should be. Anyone have specifics? Such as 100g ki disolve in XX mls h2o, etc?

loki · guinea pig

getting the KI to change into iodine is the whole point of the H2O2/HCl reaction. the HI is oxidised gently and it forms I2. when working with tincture KI is the main thing that provides the majority of the yield, diluting with water gives some extra yield of the elemental iodine already in there as well.

2spun · The Resistor

h202 avec HCL works,
on KI, try it 5grams to the lb in table salt.
swiy belives anyway. (maybe wrong) this is under electrolyses in aq.
swiy thinks.