7782-68-5 Usage
Uses
Used in Analytical Chemistry:
Iodic acid is used as a strong oxidizing agent in analytical chemistry laboratories. Its strong oxidizing properties make it suitable for redox titrations and standardizing solutions of both weak and strong bases using indicators such as methyl red or methyl orange.
Used in Salt Fortification:
Iodic acid is used as a key starting material to synthesize sodium or potassium iodate, which is then used to increase the iodine content of salt. This helps prevent iodine deficiency disorders and promotes overall health.
Used in Pharmaceutical Industry:
Iodic acid is used in the synthesis of various pharmaceutical compounds, such as iodine-containing drugs and contrast agents for medical imaging.
Used in Water Treatment:
Iodic acid can be used in water treatment processes to oxidize and remove contaminants, such as iron and manganese, from water supplies.
Used in Textile Industry:
Iodic acid is used in the textile industry for dyeing and printing processes, as it can act as a mordant to improve the colorfastness of dyes on fabrics.
Preparation
Iodic acid may be prepared by the reaction of sulfuric acid with barium iodate. The solution is filtered to remove barium sulfate and then crystallized to obtain iodic acid:
Ba(IO3)2 + H2SO4 → BaSO4 + 2HIO3
It also may be produced by oxidation of iodine with concentrated nitric acid:
3I2 + 10HNO3 → 6HIO3 + 10NO + 2H2O
Also, iodic acid may be obtained by oxidation of iodine with chlorine in dilute acidic solutions:
I2 + 5Cl2 + 6H2O → 2HIO3 + 10HCl
Another method of preparation involves oxidation of iodine with hydrogen peroxide:
I2 + 5H2O2 → 2HIO3 + 4H2O
It also may be prepared by treating hypoiodous acid with a base:
3HIO + 2OHˉ → HIO3 + 2H2O + Iˉ
Hypoiodous acid may be obtained by alkaline hydrolysis of iodine at pH 12:
I2 + H2O → HIO + H+ + Iˉ
Iodic acid dehydrates to iodine pentaoxide when heated at 180°C:
2HIO3 → I2H5 + H2O
Iodic acid is a relatively weak monoprotic acid, the Ka value at 25°C is 1.6 x 10–1. Several species have been detected in concentrated aqueous solutions, which include IO3ˉ, H+, HIO3, (HIO3)2 and (HIO3)3. Its solution turns blue litmus red and then bleaches the litmus paper because of its strong oxidizing properties.
When heated with potassium iodate, potassium hydrogen iodate is formed:
HIO3 + KIO3 → KH(IO3)2
An aqueous solution of iodic acid is a strong oxidizing agent. It liberates iodine from iodides:
IO3ˉ + 5Iˉ + 6H+ → 3I2 + 3H2O or,
HIO3 + 5HI → 3I2 + 3H2O
In an aqueous solution, iodic acid oxidizes hydrogen sulfide to sulfur:
2HIO3 + 5H2S → I2 + 6H2O + 5S
The solid iodic acid reacts vigorously with sulfur, phosphorus and other nonmetals.
Preparation
Iodic acid may be prepared by the reaction of sulfuric acid with bariumiodate. The solution is filtered to remove barium sulfate and then crystallizedto obtain iodic acid:
Ba(IO3)2 + H2SO4 → BaSO4 + 2HIO3
It also may be produced by oxidation of iodine with concentrated nitric acid:
3I2 + 10HNO3 → 6HIO3 + 10NO + 2H2O
Also, iodic acid may be obtained by oxidation of iodine with chlorine in diluteacidic solutions:
I2 + 5Cl2 + 6H2O → 2HIO3 + 10HCl
Another method of preparation involves oxidation of iodine with hydrogenperoxide:
I2 + 5H2O2 → 2HIO3 + 4H2O
It also may be prepared by treating hypoiodous acid with a base:
3HIO + 2OHˉ → HIO3 + 2H2O + Iˉ
Hypoiodous acid may be obtained by alkaline hydrolysis of iodine at pH 12:
I2 + H2O → HIO + H+ + Iˉ
Iodic acid dehydrates to iodine pentaoxide when heated at 180°C:
2HIO3 → I2H5 + H2O
Iodic acid is a relatively weak monoprotic acid, the Ka value at 25°C is 1.6x10-1. Several species have been detected in concentrated aqueous solutions,which include IO3-, H+, HIO3, (HIO3)2 and (HIO3)3. Its solution turns blue lit-mus red and then bleaches the litmus paper because of its strong oxidizingproperties.
When heated with potassium iodate, potassium hydrogen iodate is formed:
HIO3 + KIO3 → KH(IO3)2
An aqueous solution of iodic acid is a strong oxidizing agent. It liberates iodine from iodides:
IO3ˉ + 5Iˉ + 6H+ → 3I2 + 3H2O or, HIO3 + 5HI → 3I2 + 3H2O
In an aqueous solution, iodic acid oxidizes hydrogen sulfide to sulfur:
2HIO3 + 5H2S → I2 + 6H2O + 5S
The solid iodic acid reacts vigorously with sulfur, phosphorus and other non-metals.
Hazard
Toxic by ingestion, strong irritant to eyes
and skin.
Purification Methods
Dissolve iodic acid in the minimum volume of hot dilute HNO3, filter and evaporate in a vacuum desiccator until crystals are formed. Collect the crystals and wash them with a little cold H2O and dry them in air in the dark. It is soluble in H2O: 269g/100mL at 20o and 295g/100mL at 40o. It is soluble in dilute EtOH and darkens on exposure to light. It is converted to HIO3.I2O5 on heating at 70o, but at 220o complete conversion to HIO3 occurs. [Lamb et al. J Am Chem Soc 42 1636 1920, Bray & Caulkins J Am Chem Soc 53 44 1931.]
Check Digit Verification of cas no
The CAS Registry Mumber 7782-68-5 includes 7 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 4 digits, 7,7,8 and 2 respectively; the second part has 2 digits, 6 and 8 respectively.
Calculate Digit Verification of CAS Registry Number 7782-68:
(6*7)+(5*7)+(4*8)+(3*2)+(2*6)+(1*8)=135
135 % 10 = 5
So 7782-68-5 is a valid CAS Registry Number.
InChI:InChI=1/Hg.2HIO3/c;2*2-1(3)4/h;2*(H,2,3,4)/p-2
7782-68-5Relevant articles and documents
γ-HIO3 - A metastable, centrosymmetric polymorph of iodic acid
Fischer, Andreas,Lindsjoe, Martin
, p. 1574 - 1576 (2005)
From solutions of chromium(III) perchlorate and periodic acid, single crystals of γ-HIO3 were obtained and characterized by single-crystal X-ray diffraction, Raman spectroscopy and thermal analysis. The compound crystallizes in the orthorhombic crystal system, space group Pbca (a = 563.92, b = 611.10, c = 1507.16 pm). The structure is built up by dimers (HIO3)2, which are formed by hydrogen bonds. The crystals are metastable and transform into the stable modification, α-HIO 3, within a couple of weeks.
Kinetics of iodous acid disproportionation
Schmitz, Guy,Furrow, Stanley D.
supporting information, p. 525 - 530 (2013/07/26)
The iodous acid disproportionation is autocatalytic, and it is not easy to measure the rate constant of the step 2IO2H → IO 3- + IOH + H+ separately. Hg(II) was used previously to suppress the autocatalytic pathway, but this method presents difficulties discussed in this work. A more effective method is the use of crotonic acid, an effective IOH scavenger. It suppresses side reactions, and a purely second-order rate law is obtained. The rate constant decreases from 5 to 0.2 M-1 s-1 when the sulfuric acid concentration increases from 0.08 to 0.60 M. The observed decrease could be explained if IO 2- reacts faster than IO2H. This may have consequences for the mechanism of the oscillating Bray-Liebhafsky reaction.
Iodine(I) reagents in hydrochloric acid-catalyzed oxidative iodination of aromatic compounds by hydrogen peroxide and iodine
Bedrac, Leon,Iskra, Jernej
, p. 1243 - 1248 (2013/06/27)
Hydrochloric acid activates the oxidative iodination of aromatic compounds with the iodine- hydrogen peroxide system through the formation of an iodine(I) compound as the iodinating reagent. Activation with hydrochloric acid is more powerful than that with sulfuric acid. The formation of dichloroiodic(I) acid (HICl2) with various forms of hydrogen peroxide was followed using UV spectroscopy. The HICl2 was used as the iodinating reagent. In the preparative oxidative iodinaton of various aromatic compounds, hydrochloric acid was used in a catalytic amount and the iodine(I) reagent was formed in situ with 0.5 equiv. hydrogen peroxide and 0.5 equiv. molecular iodine. Two types of reactivity were observed in oxidative iodination with iodine(I) species catalyzed by hydrochloric acid: in the iodination of anisole 1a better yields of iodination were observed with a smaller amount of hydrochloric acid, while on the contrary 4-tert-butyltoluene 1b gave better yields of iodination upon increasing the amount of hydrochloric acid. Reactivity was further manipulated by the choice of the solvent (MeCN, trifluoroethanol, hexafluoro-2-propanol). Copyright
Conductometric and Spectrophotometric Studies on the Ionization of Iodine and Its Compounds in Chlorosulphuric Acid
Siddiqi, Z. A.,Ansari, N. A.,Aslam, M.,Lutfullah,Zaidi, S. A. A.
, p. 30 - 32 (2007/10/02)
Iodine and a few of its compounds form low valent polyatomic cations of iodine in chlorosulphuric acid medium.Conductometric redox titrations of iodine with the solutions of oxidizing agents like K2S2O8 in HSO3Cl indicate the formation of the cations I2(+) and I(+), which however, disproportionate to I3(+) and I(SO2Cl)3.Potassium iodide, iodine monochloride, iodic acid and iodine pentoxide produce reddish-brown coloured solutions characteristic of I3(+) cation.Iodine trichloride, however ionizes to yield ICl2(+).Conductometric titration of iodine against iodine trichloride in the acidic medium indicates the formation of I2Cl(+).
