Iodine

[7553-56-2] I2 (MW 253.80) InChI = 1S/I2/c1-2 InChIKey = PNDPGZBMCMUPRI-UHFFFAOYSA-N (electrophilic reagent that adds to alkenes1 and alkynes2 to give diiodides; alkenyl carboxylic acids react to give iodolactones3 and alkenyl amides lead to iodolactams;4 dehydrogenates amines5 and reacts with ketones, in the presence of base, to give α-iodo ketones;6 carboxylic acids are converted to α-iodo acid derivatives7 and carbanions react to give the substituted iodides;8 organoboranes can give alkyl iodides9 and vinylboranes lead to substituted alkenes;10 important spotting reagent for TLC analysis11) Physical Data: mp 113.6 °C; bp 185.24 °C; d 4.930 g cm−3; vapor pressure 0.31 mmHg at 25 °C. Solubility: the solubility of iodine, expressed in g/kg of solvent at 25 °C is: H2O, 0.34; benzene, 164.0; CCl4, 19.2; CHCl3, 49.7; ethyl acetate, 157; ethanol, 271.7; diethyl ether, 337.3; n-hexane, 13.2; toluene, 1875.12 Soluble glacial acetic acid; relatively insol dichloromethane. Form Supplied in: the natural abundance isotope is 127I. It is a massive bluish-black solid. When sublimed it forms near opaque, doubly refractory orthorhombic crystals that have a metallic luster. Heating iodine generates a violet-colored vapor. Commercially available in >99.5% purity, with bromine and chlorine the primary contaminants. Natural abundance iodine is diatomic, II. Preparative Methods: commercially available but can be prepared by the reaction of potassium iodide and copper(II) sulfate.13 It is also prepared by chlorination of natural brines or by treatment of brine with silver nitrate and then iron(II) iodide, followed by addition of chloride to liberate iodine.14 Purity: vacuum sublimation. Handling, Storage, and Precaution: somewhat corrosive.15 It is stored in a dark bottle or jar, at ambient temperatures. Iodine vapors have a sharp characteristic odor and they are irritating to eyes, skin, and mucous membranes (lachrymatory). Prolonged exposure should be avoided. Ingestion of large quantities can cause abdominal pain, nausea, vomiting, and diarrhea. If 2–3 g of iodine are ingested, death may occur.