Diiodopentoxide

Structural formula
General
Surname	Diiodopentoxide
other names	Diiodopentaoxide Iodine pentoxide Iodine (V) oxide Iodic anhydride
Molecular formula	I 2 O 5
Brief description	white, odorless solid
External identifiers / databases
CAS number 12029-98-0 EC number 234-740-2 ECHA InfoCard 100,031,569 PubChem 159402 Wikidata Q414644
properties
Molar mass	333.81 g mol −1
Physical state	firmly
density	4.98 g cm −3 (20 ° C)
solubility	soluble in water
safety instructions
GHS labeling of hazardous substances Caution H and P phrases H: 272-315-319 P: 302 + 352-305 + 351 + 338
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Diiodopentoxide , a chemical compound of iodine and oxygen with the formula I ₂ O ₅ , is a white, crystalline powder at room temperature.

Extraction and presentation

Iodine (V) oxide is produced in two reaction stages. First, elemental iodine is reacted with fuming nitric acid at 70–80 ° C. This creates iodic acid HIO ₃ :

${\displaystyle \mathrm {3\ I_{2}+10\ HNO_{3}\longrightarrow 6\ HIO_{3}+10\ NO+2\ H_{2}O} }$

In the second step, the resulting iodic acid is dehydrated at 240–250 ° C:

${\displaystyle \mathrm {2\ HIO_{3}\longrightarrow \ I_{2}O_{5}+H_{2}O} }$

Diiodopentoxide is also formed from the elements in a glow discharge . Diiodopentoxide was first represented in 1813 by both Davy and Gay-Lussac .

properties

Diiodopentoxide forms molecular crystals of the formula O ₂ I – O – IO ₂ , which disintegrate into the elements at 275 ° C. The compound is a strong oxidizing agent, this property essentially determines its uses. It is very hygroscopic and soluble in water with regression of the iodic acid.

structure

I ₂ O ₅ crystallizes monoclinically , space group P 2 ₁ / c (space group number 14) , with the lattice parameters a = 11.04 Å , b = 5.063 Å, c = 8.135 Å and β = 107.2 °. The I-O-I angle in I ₂ O ₅ is 139.2 °. The terminal I – O distances are approximately 1.80 Å, the distances between the bridging I – O bonds are approximately 1.95 Å.

use

Diiodopentoxide is used for the quantitative determination of carbon monoxide in gas mixtures, e.g. B. in elemental and flue gas analysis, since it reacts quantitatively with carbon monoxide to form carbon dioxide and elemental iodine at room temperature .

${\displaystyle \mathrm {5\ CO+I_{2}O_{5}\rightarrow \ I_{2}+5\ CO_{2}} }$

The iodine formed can be determined by titration . Diiodopentoxide is also sometimes used as an oxidizing agent in organic chemistry. B. in the production of cyclic ketones.

Individual evidence

1. ↑ ^{a b c} Georg Brauer (ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6 , pp. 318-319.
2. ↑ ^{a b c d} data sheet di-iodine pentoxide (PDF) from Merck , accessed on March 25, 2011.
3. ^ University of Freiburg: Chemistry of Non-Metals, Chap. 4.4
4. ↑ Kari Selte, Arne Kjekshus: Iodine oxides. Part III. The crystal structure of I ₂ O ₅ . In: Acta Chemica Scandinavica. Vol. 24, 1970, ISSN  0001-5393 , pp. 1912-1914, doi : 10.3891 / acta.chem.scand.24-1912 .
5. ↑ University of Augsburg - Exhaust gas measurement: Method and information on measurement ( Memento of the original from March 4, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. 
6. ↑ Kiyoshi Yoshida, Jiro Goto, Yoshio Ban: Oxidation of Cycloalkane [b] indoles with Iodine Pentoxide (I ₂ O ₅ ). In: Chemical & Pharmaceutical Bulletin . Vol. 35, No. 12, 1987, ISSN  0009-2363 , pp. 4700-4704, doi : 10.1248 / cpb.35.4700 .