T_Pyro
February 13th, 2004, 02:40 PM
Iodic acid, unlike the other halogen equivalents, is quite stable, and exists as a white crystalline solid. It is a strong oxidiser, and decomposes into I, HI and O2 on heating.
Iodine crystals can directly be oxidised to iodic acid, HIO3. The method involves either oxidation of the iodine crystals by fuming nitric acid, or by ozone. There is yet another method which I came across in some laboratory procedure on the net:
"Add 22g of potassium chlorate to 90 ml of boiling water in a conical flask, followed by 8 ml of concentrated hydrochloric acid. Add, in small amounts, 20g of powdered iodine over half an hour, with shaking after each addition. When solution of iodine is complete, boil for a few minutes to destroy most of the yellow colour. Filter by suction while hot. Cool the filtrate, filter off the product which separates, and recrystallise this solid two or three times. Dry in the oven at 100oC for half an hour. If the product appears coloured, further recrystallisation is necessary."
The iodate thus formed could be converted into iodic acid by displacement by a stronger acid. The problem, however, is to stop the reaction at that stage and prevent the decomposition of the iodic acid into iodine due to the action of the acid.
I'm interested in the synthesis of Iodic acid for possible use as an oxidiser, as well as for further synthesis of other iodates (and eventually per-iodic acid, someday!). However, if the use of the iodic acid /iodate is to be as an oxidiser, it would not make any sense to use chlorates (a better oxidiser) to make iodates. Nevertheless, I'm pursuing this method purely for academic interest, and I'll post the results soon. As for the other two methods, they're beyond my reach since I do not have any fuming nitric acid at the moment... :( Has anyone tried either of the methods? if so, what were the yields like?
Some more info on iodic acid: It also has medicinal uses, apparently: "used as an astringent, caustic, disinfectant, deodorant, and intestinal antiseptic". However, I have not come across any reports of it having been used in pyrotechnic compositions of any kind.
Iodine crystals can directly be oxidised to iodic acid, HIO3. The method involves either oxidation of the iodine crystals by fuming nitric acid, or by ozone. There is yet another method which I came across in some laboratory procedure on the net:
"Add 22g of potassium chlorate to 90 ml of boiling water in a conical flask, followed by 8 ml of concentrated hydrochloric acid. Add, in small amounts, 20g of powdered iodine over half an hour, with shaking after each addition. When solution of iodine is complete, boil for a few minutes to destroy most of the yellow colour. Filter by suction while hot. Cool the filtrate, filter off the product which separates, and recrystallise this solid two or three times. Dry in the oven at 100oC for half an hour. If the product appears coloured, further recrystallisation is necessary."
The iodate thus formed could be converted into iodic acid by displacement by a stronger acid. The problem, however, is to stop the reaction at that stage and prevent the decomposition of the iodic acid into iodine due to the action of the acid.
I'm interested in the synthesis of Iodic acid for possible use as an oxidiser, as well as for further synthesis of other iodates (and eventually per-iodic acid, someday!). However, if the use of the iodic acid /iodate is to be as an oxidiser, it would not make any sense to use chlorates (a better oxidiser) to make iodates. Nevertheless, I'm pursuing this method purely for academic interest, and I'll post the results soon. As for the other two methods, they're beyond my reach since I do not have any fuming nitric acid at the moment... :( Has anyone tried either of the methods? if so, what were the yields like?
Some more info on iodic acid: It also has medicinal uses, apparently: "used as an astringent, caustic, disinfectant, deodorant, and intestinal antiseptic". However, I have not come across any reports of it having been used in pyrotechnic compositions of any kind.