iodine Chemische Eigenschaften,Einsatz,Produktion Methoden
Beschreibung
Iodine, (I), is a nonmetallic element of family seven, the halogens. It is heavy, grayish-black in color, has a characteristic odor, and is readily sublimed to a violet vapor. It has a vapor density of 4.98, which is heavier than air. It melts at 236°F (113.5°C), has a boiling point of 363°F (184°C), and is insoluble in water. Iodine is toxic by ingestion and inhalation, and is a strong irritant to eyes and skin. The TLV ceiling is 0.1 ppm in air. Iodine is used for antiseptics, germicides, x-ray contrast material, food and feed additives, water treatment, and medicinal soaps. The four-digit UN identification number for iodine is only for the compounds iodine monochloride and iodine pentafluoride, and they are 1792 and 2495, respectively. The DOT lists iodine monochloride as a Class 8 corrosive, and iodine pentafluoride carries an oxidizer and poison label. Iodine does not have an NFPA 704 designation.
Chemische Eigenschaften
Heavy, grayish-black plates or granules having a metallic luster; characteristic odor.
Readily sublimed having a violet vapor.Soluble in alcohol, carbon
disulfide, chloroform, ether, carbon tetrachloride,
glycerol, and alkaline iodide solutions; insoluble
Physikalische Eigenschaften
Iodine in its pure state is a black solid that sublimates (changes from a solid to a gas withoutgoing through a liquid state) at room temperature. It produces a deep purple vapor that is irritatingto the eyes, nose, and throat. Iodine tends to form nonmetallic diatomic molecules (I
2).It is the heaviest of the naturally occurring halogens. (Although astatine, the fifth element ingroup 17, is heavier than iodine, it is a synthetic element and does not occur in nature exceptas a very small trace.) Iodine is the least reactive of the five halogens.
Iodine’s melting point is 113.7°C, its boiling point is 184.4°C, and its density is 4.93g/cm
3.
Isotopes
There are a total of 145 isotopes of iodine. Only one (I-127) is stable andaccounts for 100% of iodine’s natural abundance on Earth. All the other 146 isotopesare radioactive with half-lives ranging from a 150 nanoseconds to 1.57×10
+7
Origin of Name
The name originates from the Greek word iodes, meaning “violet-colored,”
which is the color of iodine’s vapor.
Occurrence
Iodine is the 64th most abundant element on Earth. It occurs widely over the Earth, butnever in the elemental form and never in high concentrations.
It occurs in seawater where some species of seaweed and kelp accumulate the elementin their cells. It is also recovered from deep brine wells found in Chile, Indonesia, Japan,and Michigan, Arkansas, and Oklahoma in the United States. The iodine is recovered fromcremated ashes of seaweed. The ashes are leached with water to remove the unwanted salts.Finally, manganese dioxide (MnO
2) is added to oxidize the iodine ions (I
1-) to produceelemental diatomic iodine (I
2). The following reaction takes place: 4I
1- + MnO
2 → MnI
2 +I
2 + 2O
2-.
Chilean saltpeter [potassium nitrate (KNO
3)] has a number of impurities, includingsodium and calcium iodate. Iodine is separated from the impurities and, after being treatedchemically, finally produces diatomic iodine. Today, iodine is mostly recovered from sodiumiodate (NaIO
3) and sodium periodate (NaIO
4) obtained from Chile and Bolivia.
History
Iodine was first discovered by Barnard Courtois, a French chemist in 1811 while extracting potassium and sodium from seaweed ash. When he accidentally added sulfuric acid, a violet colored cloud evolved from the mass. The resulting gas was condensed into dark crystals-the first occurrence of observed solid iodine.Courtois analyzed them and then gave some of them to a fellow chemist, Joseph Louis Gay-Lussac, for further study.
Two years later, Gay-Lussac presented his study to the scientific community, announcing the discovery of a new element that he named "iodine," after the Greek word "ioeides" meaning violet colored.
A Swiss physician by the name of J.F. Coindet had previously used burnt sponge and seaweed for the treatment of goiter (an enlargement of the thyroid gland). This treatment had been in use since 3600 B.C., when it appeared in Chinese medical writings, as well as writings by the Greek physician Hippocrates. Upon hearing of the work of Courtois and Gay-Lussac, Coindet suspected that iodine might be the active ingredient in seaweed that cured goiter. In 1819, he successfully tested a tincture of iodine on 150 patients, significantly reducing the size of their goiter within one week. As a result of these early studies, in the 1830s the medical community started advocating for iodine supplements to decrease the occurrence of goiter.
Charakteristisch
Iodine is the least reactive of the elements in the halogen group 17. Most people associateiodine with the dark-brown color of the tincture of iodine used as an antiseptic for minor skinabrasions and cuts. A tincture is a 50% solution of iodine in alcohol. Although it is still used,iodine is no longer the antibiotic of choice for small skin wounds. Since iodine is a poisonthat kills bacteria, iodine tablets are often used by campers and others to purify water that istaken from outdoor streams.
Verwenden
Iodine is a halogen element extracted from chilean nitrate-bearing
earth or from seaweed. it functions by its presence in the thyroid
hormones. iodine deficiency is associated with goiter. sources are
potassium and cuprous iodide and potassium and calcium iodate, of
which the iodate form is preferred because of better stability. it is
used as a food supplement.
Definition
A dark-violet volatile solid element belonging to the halogens (group 17 of the periodic table). It occurs in seawater and is concentrated by various marine organisms in the form of iodides. Significant deposits also occur in the form of iodates. The element is conveniently prepared by the oxidation of iodides in acid solution (using MnO
2). Industrial methods similarly use oxidation of iodides or reduction of iodates to iodides by sulfur(IV) oxide (sulfur dioxide) followed by oxidation, depending on the source of the raw materials. Iodine and its compounds are used in chemical synthesis, photography, pharmaceuticals, and dyestuffs manufacture.
Iodine has the lowest electronegativity of the stable halogens and consequently is the least reactive. It combines only slowly with hydrogen to form hydroiodic acid, HI. Iodine also combines directly with many electropositive elements, but does so much more slowly than does bromine or chlorine. Because of the larger size of the iodine ion and the consequent low lattice energies, the iodides are generally more soluble than related bromides or chlorides. As with the other halides, iodides of Ag(I), Cu(I), Hg(I), and Pb(II) are insoluble unless complexing ions are present.
Iodine also forms a range of covalent iodides with the metalloids and non-metallic elements (this includes a vast range of organic iodides) but these are generally less thermodynamically stable and are more readily hydrolyzed than chlorine or bromine analogs.
synthetische
If extreme purification is unnecessary, commercial iodine or iodine regenerated from wastes can, according to a method described by Plotnikow, be sublimed, first over KI and then over BaO. It is then stored in ground glass containers placed in a desiccator over P2O5.
Hazard
less than pure form, it can damage the skin, eyes, and mucous membranes. Both the elementalform and its compounds (gases, liquids, or solids) are toxic if inhaled or ingested. Even indiluted form (e.g., a tincture of iodine to treat minor skin wounds), it should be used withcare.
Although a poison in high concentrations, iodine is required as a trace element in our dietsto prevent thyroid problems and mental retardation in the very young.
Industrielle Verwendung
Iodine is a purplish-black, crystalline, poisonouselementary solid, chemical symbol I, bestknown for its use as a strong antiseptic in medicine,but also used in many chemical compoundsand war gases. In tablet form it is usedfor sterilizing drinking water, and has less odorand taste than chlorine for this purpose. It isalso used in cattle feeds. Although poisonousin quantity, iodine is essential to proper cellgrowth in the human body, and is found in everycell in a normal body, with larger concentrationin the thyroid gland.
A wide range of compounds are made forelectronic and chemical uses. Iodine is also achemical reagent, used for reducing vanadiumpentoxide and zirconium oxide into highpuritymetals.
iodine Upstream-Materialien And Downstream Produkte
Upstream-Materialien
Downstream Produkte
Natriumiodat
3,5-Diiodsalicylsure
Kaliumiodid
Calciumiodid
Sodium 4-iodophenoxyacetic acid
(+)-(3R,4R)-BIS(DIPHENYLPHOSPHINO)-1-BENZYLPYRROLIDINE
Kaliumiodat
Natriumiodid
5-Bromo-3-pyridinemethanol
(R)-3-Hydroxypyrrolidine
Kaliumperiodat
Natriumperiodat
6,8,25,27-Tetrahydrobisnaphtho[2',3':6,7]indolo[2,3-c:2',3'-c']dinaphtho[2,3-i:2',3'-i']benzo[1,2-a:5,4-a']dicarbazol-5,7,9,14,19,24,26,28,33,38-decaon
(3S,4S)-(-)-1-BENZYL-3,4-BIS(DIPHENYLPHOSPHINO)PYRROLIDINE
Diiodpentaoxid
