Thallium(I) iodide is a chemical compound with the formula TlI {\displaystyle {\ce {TlI}}} . It is unusual in being one of the few water-insoluble metal iodides , along with AgI {\displaystyle {\ce {AgI}}} , CuI {\displaystyle {\ce {CuI}}} , SnI 2 {\displaystyle {\ce {SnI2}}} , SnI 4 {\displaystyle {\ce {SnI4}}} , PbI 2 {\displaystyle {\ce {PbI2}}} and HgI 2 {\displaystyle {\ce {HgI2}}} .
14-436: TlI can be formed in aqueous solution by metathesis of any soluble thallium salt with iodide ion. It is also formed as a by-product in thallium-promoted iodination of phenols with thallium(I) acetate. Attempts to oxidise TlI to thallium(III) iodide fail, since oxidation produces thallium(I) triiodide , TlI 3 . The room temperature form of TlI is yellow and has an orthorhombic structure which can be considered to be
28-534: A distorted NaCl structure. The distorted structure is believed to be caused by favourable thallium-thallium interactions, the closest Tl-Tl distance is 383 pm. At 175 °C the yellow form transforms to a red CsCl form. This phase transition is accompanied by about two orders of magnitude jump in electrical conductivity. The CsI structure can be stabilized down to room temperature by doping TlI with other halides such as RbI, CsI, KI, AgI, TlBr and TlCl. Thus, presence of impurities might be responsible for coexistence of
42-479: Is insoluble in water. For example, the precipitation of silver chloride from a mixture of silver nitrate and cobalt hexammine chloride delivers the nitrate salt of the cobalt complex: The reactants need not be highly soluble for metathesis reactions to take place. For example barium thiocyanate forms when boiling a slurry of copper(I) thiocyanate and barium hydroxide in water: Metal complexes are alkylated via salt metathesis reactions. Illustrative
56-440: Is a common technique for exchanging counterions . The choice of reactants is guided by a solubility chart or lattice energy . HSAB theory can also be used to predict the products of a metathesis reaction. Salt metathesis is often employed to obtain salts that are soluble in organic solvents. Illustrative is the conversion of sodium perrhenate to the tetrabutylammonium salt : The tetrabutylammonium salt precipitates from
70-426: Is added to quartz and ceramic metal halide lamps that uses rare-earth halides like dysprosium , to increase their efficiency and to get the light color more close to the blackbody locus . Thallium iodide alone can be used to produces green colored metal halide lamps. Thallium(I) iodide is also used in trace amounts with NaI or CsI to produce scintillators used in radiation detectors. Natural thallium(I) iodide
84-485: Is the methylation of titanocene dichloride to give the Petasis reagent : The salt product typically precipitates from the reaction solvent. A neutralization reaction is a type of double replacement reaction. A neutralization reaction occurs when an acid reacts with an equal amount of a base . This reaction usually produces a salt. One example, hydrochloric acid reacts with disodium iron tetracarbonyl to produce
98-538: The aqueous solution. It is soluble in dichloromethane . Salt metathesis can be conducted in nonaqueous solution, illustrated by the conversion of ferrocenium tetrafluoroborate to a more lipophilic salt containing the tetrakis(pentafluorophenyl)borate anion: When the reaction is conducted in dichloromethane , the salt NaBF 4 precipitates and the B(C 6 F 5 ) 4 - salt remains in solution. Metathesis reactions can occur between two inorganic salts when one product
112-546: The cubic and orthorhombic TlI phases at ambient conditions. Under high pressure, 160 kbar, TlI becomes a metallic conductor. Nanometer-thin TlI films grown on LiF, NaCl or KBr substrates exhibit the cubic rocksalt structure. Thallium(I) iodide was initially added to mercury arc lamps to improve their performance The light produced was mainly in the blue green part of the visible light spectrum least absorbed by water, so these have been used for underwater lighting. In modern times, it
126-854: The general scheme: Typical examples are the reactions between oxysalts and binary compounds such as salts, hydrohalic acids and metal hydroxides: ab A x ( BO y ) z + xz C a D b ⟶ bx A a D z + az C x ( BO y ) b {\displaystyle {\ce {{\mathit {ab}}A_{\mathit {x}}(BO_{\mathit {y}})_{\mathit {z}}{}+{\mathit {xz}}C_{\mathit {a}}D_{\mathit {b}}{}->{\mathit {bx}}A_{\mathit {a}}D_{\mathit {z}}{}+{\mathit {az}}C_{\mathit {x}}(BO_{\mathit {y}})_{\mathit {b}}{}}}} Another classical example are
140-454: The iron dihydride: Reaction between an acid and a carbonate or bicarbonate salt yields carbonic acid , which spontaneously decomposes into carbon dioxide and water. The release of carbon dioxide gas from the reaction mixture drives the reaction to completion. For example, a common, science-fair "volcano" reaction involves the reaction of hydrochloric acid with sodium carbonate : In contrast to salt metathesis reactions, which are driven by
154-433: The reacting species can be either ionic or covalent . Classically, these reactions result in the precipitation of one product. In older literature, the term double decomposition is common. The term double decomposition is more specifically used when at least one of the substances does not dissolve in the solvent , as the ligand or ion exchange takes place in the solid state of the reactant. For example: Salt metathesis
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#1732884102398168-846: The reactions between oxysalts in solution: ab A x ( BO p ) y + xy C a ( DO q ) b ⟶ bx A a ( DO q ) y + ay C x ( BO p ) b {\displaystyle {\ce {{\mathit {ab}}A_{\mathit {x}}(BO_{\mathit {p}})_{\mathit {y}}{}+{\mathit {xy}}C_{\mathit {a}}(DO_{\mathit {q}})_{\mathit {b}}{}->{\mathit {bx}}A_{\mathit {a}}(DO_{\mathit {q}})_{\mathit {y}}{}+{\mathit {ay}}C_{\mathit {x}}(BO_{\mathit {p}})_{\mathit {b}}{}}}} The bond between
182-415: The understanding of the geochemical evolution of the planet Like all thallium compounds, thallium(I) iodide is highly toxic. Salt metathesis reaction A salt metathesis reaction is a chemical process involving the exchange of bonds between two reacting chemical species which results in the creation of products with similar or identical bonding affiliations. This reaction is represented by
196-463: Was first discovered in a naturally occurring setting in 2017 as a orthorhombic polymorph called nataliyamalikite. Small grains were found embedded in mascagnite sourced from fumaroles at Avachinsky , a volcano in Russia's Kamchatka Peninsula that can reach temperatures of 640 °C (1,184 °F). The geologists that discovered it speculate that further research into this mineral is likely to add to
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