The discovery of TiO 2 was made almost simultaneously and independently of each other by the Englishman W. Gregor and the German chemist M. G. Klaproth. W. Gregor, studying the composition of magnetic ferruginous sand (Creed, Cornwall, England, 1789), isolated a new “earth” (oxide) of an unknown metal, which he called menaken. In 1795, the German chemist Klaproth discovered a new element in the mineral rutile and named it titanium; later he established that rutile and menaken earth are oxides of the same element. The first sample of metal titanium was obtained in 1825 by J. Ya. Berzelius. A pure sample of Ti was obtained by the Dutchmen A. van Arkel and I. de Boer in 1925 by thermal decomposition of titanium iodide vapor TiI 4
Physical properties:
Titanium is a lightweight silvery-white metal. Plastic, weldable in an inert atmosphere.
It has a high viscosity and, during machining, is prone to sticking to the cutting tool, and therefore requires the application of special coatings to the tool and various lubricants.
Chemical properties:
At ordinary temperatures it is covered with a protective passivating film of oxide and is corrosion-resistant, but when crushed into powder it burns in air. Titanium dust can explode (flash point 400°C). When heated in air to 1200°C, titanium burns with the formation of oxide phases of variable composition TiO x .
Titanium is resistant to dilute solutions of many acids and alkalis (except HF, H 3 PO 4 and concentrated H 2 SO 4), however, it easily reacts even with weak acids in the presence of complexing agents, for example, with hydrofluoric acid HF forms a complex anion 2-.
When heated, titanium interacts with halogens. With nitrogen above 400°C, titanium forms nitride TiN x (x=0.58-1.00). When titanium interacts with carbon, titanium carbide TiC x (x=0.49-1.00) is formed.
Titanium absorbs hydrogen, forming compounds of variable composition TiHx. When heated, these hydrides decompose, releasing H2.
Titanium forms alloys with many metals.
In compounds, titanium exhibits oxidation states +2, +3 and +4. The most stable oxidation state is +4.
The most important connections:
Titanium dioxide, TiO 2 . White powder, yellow when heated, density 3.9-4.25 g/cm 3 . Amphoteric. In concentrated H 2 SO 4 dissolves only with prolonged heating. When fused with Na 2 CO 3 soda or K 2 CO 3 potash, TiO 2 oxide forms titanates:
TiO 2 + K 2 CO 3 = K 2 TiO 3 + CO 2
Titanium(IV) hydroxide, TiO(OH) 2 *xH 2 O, is precipitated from solutions of titanium salts; by carefully calcining it, TiO 2 oxide is obtained. Titanium(IV) hydroxide is amphoteric.
Titanium tetrachloride, TiCl 4 , under normal conditions, is a yellowish liquid that fumes strongly in air, which is explained by the strong hydrolysis of TiCl 4 by water vapor and the formation of tiny droplets of HCl and a suspension of titanium hydroxide. Boiling water hydrolyzes to titanic acid(??). Titanium(IV) chloride is characterized by the formation of addition products, for example TiCl 4 *6NH 3, TiCl 4 *8NH 3, TiCl 4 *PCl 3, etc. When titanium(IV) chloride is dissolved in HCl, complex acid H2 is formed, which is unknown in the free state; its Me 2 salts crystallize well and are stable in air.
By reducing TiCl 4 with hydrogen, aluminum, silicon, and other strong reducing agents, titanium trichloride and dichloride TiCl 3 and TiCl 2 are obtained - solid substances with strong reducing properties.
Titanium nitride- represents the interstitial phase with a wide region of homogeneity, crystals with a cubic face-centered lattice. Preparation - titanium nitriding at 1200 °C or other methods. It is used as a heat-resistant material to create wear-resistant coatings.
Application:
In the form of alloys. The metal is used in the chemical industry (reactors, pipelines, pumps), light alloys, and osteoprostheses. It is the most important structural material in aircraft, rocket, and shipbuilding.
Titanium is an alloying additive in some grades of steel.
Nitinol (nickel-titanium) is an alloy with shape memory, used in medicine and technology.
Titanium aluminides are very resistant to oxidation and heat-resistant, which in turn determined their use in aviation and automotive manufacturing as structural materials.
In the form of connections White titanium dioxide is used in paints (for example, titanium white), as well as in the production of paper and plastics. Food additive E171.
Organo-titanium compounds (eg tetrabutoxytitanium) are used as a catalyst and hardener in the chemical and paint and varnish industries.
Inorganic titanium compounds are used in the chemical electronics and fiberglass industries as additives.
Matigorov A.V.
HF Tyumen State University
Zirconium and hafnium form compounds in the +4 oxidation state; titanium is also capable of forming compounds in the +3 oxidation state.
Compounds with oxidation state +3. Titanium(III) compounds are obtained by reduction of titanium(IV) compounds. For example:
1200 ºС 650 ºС
2TiO 2 + H 2 ¾® Ti 2 O 3 + H 2 O; 2TiCl 4 + H 2 ¾® 2TiCl 3 + 2HCl
Titanium(III) compounds are purple in color. Titanium oxide is practically insoluble in water and exhibits basic properties. Oxide, chloride, Ti 3+ salts - strong reducing agents:
4Ti +3 Cl 3 + O 2 + 2H 2 O = 4Ti +4 OCl 2 + 4HCl
For titanium(III) compounds, disproportionation reactions are possible:
2Ti +3 Cl 3 (t) ¾® Ti +4 Cl 4 (g) + Ti +2 Cl 2 (t)
With further heating, titanium(II) chloride also disproportionates:
2Ti +2 Cl 2 (t) = Ti 0 (t) + Ti +4 Cl 4 (g)
Compounds with oxidation state +4. Oxides of titanium(IV), zirconium(IV) and hafnium(IV) are refractory, chemically rather inert substances. They exhibit the properties of amphoteric oxides: they react slowly with acids during prolonged boiling and interact with alkalis during fusion:
TiO 2 + 2H 2 SO 4 = Ti(SO 4) 2 + 2H 2 O;
TiO 2 + 2NaOH = Na 2 TiO 3 + H 2 O
Titanium oxide TiO 2 is most widely used; it is used as a filler in the production of paints, rubber, and plastics. Zirconium oxide ZrO 2 is used for the manufacture of refractory crucibles and plates.
Hydroxides titanium(IV), zirconium(IV) and hafnium(IV) are amorphous compounds of variable composition - EO 2 ×nH 2 O. Freshly obtained substances are quite reactive and dissolve in acids, titanium hydroxide is also soluble in alkalis. Aged sediments are extremely inert.
Halides(chlorides, bromides and iodides) Ti(IV), Zr(IV) and Hf(IV) have a molecular structure, are volatile and reactive, and are easily hydrolyzed. When heated, iodides decompose to form metals, which is used to obtain high-purity metals. For example:
TiI 4 = Ti + 2I 2
Fluorides of titanium, zirconium and hafnium are polymeric and low-reactive.
Salts elements of the titanium subgroup in the +4 oxidation state are few in number and hydrolytically unstable. Usually, when oxides or hydroxides react with acids, not intermediate salts are formed, but oxo- or hydroxo-derivatives. For example:
TiO 2 + 2H 2 SO 4 = TiOSO 4 + H 2 O; Ti(OH) 4 + 2HCl = TiOCl 2 + H 2 O
A large number of anionic complexes of titanium, zirconium and hafnium have been described. The most stable in solutions and easily formed are fluoride compounds:
EO 2 + 6HF = H 2 [EF 6 ] + 2H 2 O; EF 4 + 2KF = K 2 [EF 6 ]
Titanium and its analogues are characterized by coordination compounds in which the role of the ligand is played by the peroxide anion:
E(SO 4) 2 + H 2 O 2 = H 2 [E(O 2)(SO 4) 2 ]
In this case, solutions of titanium(IV) compounds acquire a yellow-orange color, which makes it possible to analytically detect titanium(IV) cations and hydrogen peroxide.
Hydrides (EN 2), carbides (ES), nitrides (EN), silicides (ESi 2) and borides (EV, EV 2) are compounds of variable composition, metal-like. Binary compounds have valuable properties, which allows them to be used in technology. For example, an alloy of 20% HfC and 80% TiC is one of the most refractory, m.p. 4400 ºС.
At high temperatures, titanium combines with halogens, oxygen, sulfur, nitrogen and other elements. This is the basis for the use of titanium alloys with iron ( ferrotitanium) as an additive to steel. Titanium combines with the nitrogen and oxygen present in the molten steel and thereby prevents the release of the latter when the steel solidifies - the casting is homogeneous and does not contain voids.
When combined with carbon, titanium forms carbide. From titanium and tungsten carbides with the addition of cobalt, alloys are obtained that are close to diamond in hardness.
Titanium dioxide TiO 2 is a white, refractory substance, insoluble in water and dilute acids. This is an amphoteric oxide, but both its basic and acidic properties are weakly expressed.
Found in nature as rutile(cubic system), less often in the form anatase(tetragonal system) and brookite(rhombic system). In rutile, each Ti 4+ ion is surrounded by six O 2- ions, and each O 2- ion is surrounded by three Ti 4+ ions. In the other two crystal forms, the immediate neighbors of the ions are the same.
Absolutely pure titanium dioxide is colorless. In nature, it is usually contaminated with iron oxides and is therefore colored.
Completely insoluble in water and dilute acids. In warm concentrated sulfuric acid it dissolves slowly with the possible formation titanium sulfite Ti(SO 4) 2, which, however, cannot be isolated in pure form due to the ease of its transition due to hydrolysis in titanyl sulfite(TiO)SO 4 . This salt, soluble in cold water, also hydrolyzes when heated to form H 2 SO 4 and hydrated titanium dioxide, the so-called c-titanium or metatitanic acid. The ease with which this hydrolysis occurs indicates the weak basic properties of titanium hydroxide. Titanium sulfate gives, with alkali metal sulfates (which are added to the sulfuric acid used to dissolve titanium dioxide), double salts, for example K 2, which are more resistant to hydrolysis than simple sulfates.
Alkali metal hydroxides and carbonates precipitate gelatinous hydrated titanium dioxide from sulfate solutions in the cold, the so-called L-titanic acid, which differs from β-titanic acid in its higher reactivity (for example, b-titanic acid dissolves in alkalis in which β-titanic acid is insoluble). Tetravalent titanium hydroxide, or titanic acid Ti(OH) 4 itself, cannot be isolated, in this it is similar to silicic and tin acids. L- and b-titanic acids, which are more or less dehydrated derivatives of titanium(IV) hydroxide, are completely comparable to b- and b-stannous acids.
A neutral or acidified solution of titanyl sulfate, as well as other titanium salts, is colored dark orange with hydrogen peroxide (hydrogen peroxide detection reaction). Ammonia precipitates from these solutions peroxotitanic acid H 4 TiO 5 is yellow-brown in color, having the formula Ti(OH) 3 O-OH.
TiO 2 is used in the manufacture of refractory glass, glaze, enamel, heat-resistant laboratory glassware, as well as for the preparation of white oil paint with high covering power ( titanium white).
By fusing TiO 2 with BaCO 3 one gets barium titanate BaTiO3. This salt has a very high dielectric constant and, in addition, has the ability to deform under the influence of an electric field. Barium titanate crystals are used in electrical capacitors of high capacity and small size, in ultrasonic equipment, in sound pickups, and in hydroacoustic devices.
Titanium chloride(IV) TiCl 4, obtained in the same way as SiCl 4, is a colorless liquid with a boiling point of 136? C and a melting point of -32? C, hydrolyzed by water to form TiO 2 and 4HCl. With alkali metal halides, titanium(IV) chloride gives double chlorides containing a 2- complex ion. Titanium fluoride(IV) TiF 4 is isolated in the form of a white powder with a melting point of 284? C; it also easily hydrolyzes and forms with HF hexafluorotitanium(IV) acid H 2 TiF 6, similar to hexafluorosilicic acid.
Anhydrous titanium chloride(III) TiCl 3 is obtained in the form of a purple powder by passing TiCl 4 vapor along with H 2 through a copper tube heated to approximately 700? C. In the form of an aqueous solution (purple color), it is obtained by reducing TiCl 4 in hydrochloric acid with the help of zinc or electrolytically. Titanium(III) sulfate is also obtained. Crystallizes from an aqueous solution of titanium(III) chloride violet hexahydrate TiCl 3 ?6H 2 O.
Titanium chloride(II) TiCl 2, painted black, is obtained by thermal decomposition of TiCl 3 at 700°С in a hydrogen atmosphere:
A colorless aqueous solution of this chloride quickly oxidizes in air, and it first turns purple and then becomes colorless again due to the formation of first a Ti(III) compound and then a Ti(IV) compound.
Titanium carbonitrides, oxycarbides and oxynitrides. It was found that the nature of the dependence of the dissolution of refractory interstitial phases (TIPs) - titanium carbides, nitrides and oxides - on composition correlates with a change in the degree of metallicity of Ti-Ti bonds in the TiC-TiN-TiO series, namely: with an increase in the degree of metallicity of phases in this direction their chemical resistance in HCl and H 2 SO 4 decreases, and in HNO 3 it increases. Since carbides, nitrides and titanium monoxide are characterized by complete mutual solubility, one can expect that a similar pattern will appear when their solid solutions interact with acids.
However, the information available in the literature on the dependence of the degree of dissolution of TiC x O y and TiN x O y on composition in mineral acids does not agree well with this assumption. Thus, the solubility of TiC x O y (fraction<56 мкм) в конц. HCl отсутствует вообще (20ўЄC, 6 ч и 100ўЄС, 3 ч), а в H 2 SO 4 - отсутствует при 20ўЄC (6 ч), но монотонно возрастает от 3% (TiC 0.30 O 0.78) до 10% (TiC 0.86 O 0.12) при 100ўЄC (3 ч). Степень растворения TiC x O y (фракция 15-20 мкм) в 92%-ной H 2 SO 4 (100ўЄC, 1 ч), напротив, уменьшается с ростом содержания углерода от 16% (TiC 0.34 O 0.66) до 2%(TiC 0.78 O 0.22). Степень растворения TiC x O y в конц. HCl (d= 1.19 g/cm) under the same conditions reaches 1-2%, without, however, revealing any dependence on the composition of the phase. The degree of dissolution of TiN x O y in conc. HNO 3 is low (2.5-3.0%) and does not depend on the composition of the oxynitride (20°C, 6 hours). On the other hand, the degree of dissolution of TiN x O y in HNO 3 under the same conditions varies within very wide limits: from 98% for TiC 0.88 O 0.13 to 4.5% for TiC 0.11 O 0.82. It is difficult to say anything definite about the nature of the relationship between the degree of dissolution and the composition of titanium carbonitride in hydrochloric and sulfuric acids. The degree of dissolution of TiC x O y in HCl is very low (0.3%) and does not depend on the composition of the carbonitride (60°C, 6 hours). However, in the end H 2 SO 4 it is an order of magnitude higher (3.0-6.5%) and is characterized by a minimum (2%) for a sample of composition TiC 0.67 O 0.26.
The experimental data obtained allow us to assert that the nature of the dependence of the dissolution of TiC x N y, TiC x O y and TiN x O y on the composition in HCl, H 2 SO 4 and HNO 3 is quite definite and, moreover, similar to that previously established for TiC x , TiN x and TiO x . This means that the reasons for the qualitatively different behavior of these dependences in HCl and H2SO4, on the one hand, and in HNO3, on the other, should be common to all studied compounds of the TI-C-N-O system, i.e. determined by the degree of metallicity of the Ti-Ti bond and the passivating ability of the resulting interaction products.
Lithium titanates And zinc Li 2 ZnTi 3 O 8 and Li 2 Zn 3 Ti 4 O 12 have a cubic spinel structure with a different distribution of cations over positions. It has been established that these compounds are solid lithium-conducting electrolytes. In Li 2 ZnTi 3 O 8 , lithium and titanium cations are ordered in octahedral positions in a ratio of 1:3, half of the lithium and zinc atoms are statistically distributed over tetrahedral positions: (Li 0.5 Zn 0.5)O 4 . The crystal chemical formula of Li 2 Zn 3 Ti 4 O 12 can be written as (Zn)O 4 . Based on the analysis of the IR and Raman spectra, a different method for the distribution of lithium and zinc atoms in the structure of these spinels is proposed: lithium has tetrahedral coordination, and zinc and titanium have octahedral coordination. A strong distortion of TiO 6 octahedra was also noted: for example, in Li 2 Zn 3 Ti 4 O 12 the environment of Ti 4+ ions is close to five coordination. The low ionic conductivity of these titanates at elevated temperatures is explained by the tetrahedral coordination of lithium atoms.
Using the example of halide spinels Li 2 MX 4 (M=Mg 2+ ,Mn 2+ ,Fe 2+ ; X=Cl - ,Br -) it was established that the cationic composition and the distribution of lithium atoms over positions has a strong influence on the electrical conductivity. Since there are no common edges between identical cationic positions in the spinel structure, several different positions are involved in ion transfer. High values of ionic conductivity in chloride spinels were observed as a result of disordering of the structure of compounds associated with the transition of lithium atoms at elevated temperatures from tetrahedral positions 8 A to free octahedral positions 16 With. In this case, the spinel structure turned into a NaCl-type structure. An informative method for studying the disorder of the structure of chloride spinels was the study of the Raman spectra of compounds at high temperatures.
General characteristics. History of discovery
Titanium, Ti, is a chemical element of group IV of the periodic table of elements of D. I. Mendeleev. Serial number 22, atomic weight 47.90. Consists of 5 stable isotopes; artificially radioactive isotopes have also been obtained.
In 1791, the English chemist W. Gregor found a new “earth” in the sand from the town of Menakan (England, Cornwall), which he called menakan. In 1795, the German chemist M. Clairot discovered a still unknown earth in the mineral rutile, the metal of which he called Titan [in Greek. mythology, the Titans are the children of Uranus (Heaven) and Gaia (Earth)]. In 1797, Klaproth proved the identity of this land with that discovered by W. Gregor. Pure titanium was isolated in 1910 by the American chemist Hunter by reducing titanium tetrachloride with sodium in an iron bomb.
Being in nature
Titanium is one of the most common elements in nature; its content in the earth’s crust is 0.6% (by weight). It is found mainly in the form of TiO 2 dioxide or its compounds - titanates. Over 60 minerals are known that contain titanium. It is also found in soil, animal and plant organisms. Ilmenite FeTiO 3 and rutile TiO 2 serves as the main raw material for titanium production. Smelting slags are becoming important as a source of titanium. titanium-magnetites and ilmenite.
Physical and chemical properties
Titanium exists in two states: amorphous - dark gray powder, density 3.392-3.395 g/cm 3, and crystalline, density 4.5 g/cm 3. For crystalline titanium, two modifications are known with a transition point at 885° (below 885° a stable hexagonal shape, above - a cubic one); t° pl about 1680°; t° kip above 3000°. Titanium actively absorbs gases (hydrogen, oxygen, nitrogen), which make it very fragile. Technical metal can be hot-formed. Absolutely pure metal can be rolled in the cold. In air at ordinary temperatures, titanium does not change; when heated, it forms a mixture of Ti 2 O 3 oxide and TiN nitride. In a stream of oxygen at red heat it is oxidized to TiO 2 dioxide. At high temperatures it reacts with carbon, silicon, phosphorus, sulfur, etc. Resistant to sea water, nitric acid, wet chlorine, organic acids and strong alkalis. It dissolves in sulfuric, hydrochloric and hydrofluoric acids, best of all in a mixture of HF and HNO 3. Adding an oxidizing agent to acids protects the metal from corrosion at room temperature. Quadrivalent titanium halides, with the exception of TiCl 4, are crystalline bodies, fusible and volatile in an aqueous solution, hydrolyzed, prone to the formation of complex compounds, of which potassium fluorotitanate K 2 TiF 6 is important in technology and analytical practice. Carbide TiC and nitride TiN are important metal-like substances, characterized by high hardness (titanium carbide is harder than carborundum), refractoriness (TiC, t° pl = 3140°; TiN, t° pl = 3200°) and good electrical conductivity.
Chemical element No. 22. Titanium.
The electronic formula of titanium is: 1s 2 |2s 2 2p 6 |3s 2 3p 6 3d 2 |4s 2.
The serial number of titanium in the periodic table of chemical elements D.I. Mendeleev - 22. The element number indicates the charge of the yard, therefore titanium has a nuclear charge of +22, and a nuclear mass of 47.87. Titan is in the fourth period, in a secondary subgroup. The period number indicates the number of electronic layers. The group number indicates the number of valence electrons. The side subgroup indicates that titanium belongs to the d-elements.
Titanium has two valence electrons in the s orbital of the outer layer and two valence electrons in the d orbital of the outer layer.
Quantum numbers for each valence electron:
With halogens and hydrogen, Ti(IV) forms compounds of the type TiX 4, which have sp 3 →q 4 hybridization type.
Titanium is a metal. Is the first element of the d-group. The most stable and common is Ti +4. There are also compounds with lower oxidation states - Ti 0, Ti -1, Ti +2, Ti +3, but these compounds are easily oxidized by air, water or other reagents into Ti +4. Removing four electrons requires a lot of energy, so the Ti +4 ion does not actually exist and Ti(IV) compounds usually involve covalent bonds. Ti(IV) is similar in some respects to the elements Si, Ge, Sn and Pb, especially Sn.
Properties of titanium compounds.
Titanium oxides:
Ti(IV) – TiO 2 – Titanium dioxide. It has an amphoteric character. The most stable and has the greatest practical significance.
Ti(III) – Ti 2 O 3 – titanium oxide. Has a basic character. It is stable in solution and is a strong reducing agent, like other Ti(III) compounds.
TI(II) – TiO 2 - Titanium oxide. Has a basic character. Least stable.
Titanium dioxide, TiO2, is a compound of titanium with oxygen, in which titanium is tetravalent. White powder, yellow when heated. It is found in nature mainly in the form of the mineral rutile, temperature above 1850°. Density 3.9 - 4.25 g/cm3. Practically insoluble in alkalis and acids, with the exception of HF. In concentrated H 2 SO 4 dissolves only with prolonged heating. When titanium dioxide is fused with caustic or carbonic alkalis, titanates are formed, which are easily hydrolyzed in the cold to form orthotitanic acid (or hydrate) Ti(OH) 4, which is easily soluble in acids. When standing, it turns into mstatitanoic acid (form), which has a microcrystalline structure and is soluble only in hot concentrated sulfuric and hydrofluoric acids. Most titanates are practically insoluble in water. The basic properties of titanium dioxide are more pronounced than acidic ones, but salts in which titanium is a cation are also significantly hydrolyzed with the formation of the divalent titanyl radical TiO 2 +. The latter is included in the composition of salts as a cation (for example, titanyl sulfate TiOSO 4 * 2H 2 O). Titanium dioxide is one of the most important titanium compounds and serves as a starting material for the production of other titanium compounds, as well as partially metallic titanium. It is used mainly as a mineral paint, in addition as a filler in the production of rubber and plastic metals. Included in refractory glasses, glazes, and porcelain masses. Artificial precious stones, colorless and colored, are made from it.
Titanium dioxide is insoluble in water and dilute mineral acids (except hydrofluoric acid) and dilute alkali solutions.
Slowly dissolves in concentrated sulfuric acid:
TiO 2 + 2H 2 SO 4 = Ti(SO4) 2 + 2H 2 O
With hydrogen peroxide it forms orthotitanic acid H4TiO4:
TiO 2 + 2H 2 O 2 = H 4 TiO 4
In concentrated alkali solutions:
TiO 2 + 2NaOH = Na 2 TiO 3 + H 2 O
When heated, titanium dioxide and ammonia form titanium nitride:
2TiO 2 + 2NH 3 = 2TiN + 3H 2 O + O 2
In a saturated solution of potassium bicarbonate:
TiO 2 + 2KHCO 3 = K 2 TiO 3 + H 2 O + 2CO 2
When fused with oxides, hydroxides and carbonates, titanates and double oxides are formed:
TiO 2 + BaO = BaO∙TiO 2 (BaTiO 3)
TiO 2 + BaCO 3 = BaO∙TiO2 + CO 2 (BaTiO 3)
TiO 2 + Ba(OH) 2 = BaO∙TiO 2 (BaTiO 3)
Titanium hydroxides:
H 2 TiO 3 – P.R. = 1.0∙10 -29
H 2 TiO 4 - P.R. = 3.6∙10 -17
TIO(OH) 2 - P.R. = 1.0∙10 -29
Ti(OH) 2 - P.R. = 1.0∙10 -35
Hydrooxide Ti(IV) - Ti(OH) 4 or H 4 TiO 4 - orthotitanic acid apparently does not exist at all, and the precipitate that precipitates when bases are added to solutions of Ti(IV) salts is a hydrated form of TiO 2. This substance dissolves in concentrated alkalis, and from such solutions hydrated titanates of the general formula can be isolated: M 2 TiO 3 ∙nH 2 O and M 2 Ti 2 O 5 ∙nH 2 O.
Titanium is characterized by complex formation with the corresponding hydrohalic acids and especially with their salts. The most typical are complex derivatives with the general formula Me 2 TiG 6 (where Me is a monovalent metal). They crystallize well and undergo hydrolysis much less than the original TiG 4 halides. This indicates the stability of TiG 6 complex ions in solution.
The color of titanium derivatives strongly depends on the nature of the halogen they contain:
The stability of salts of complex acids of the H 2 EG 6 type, in general, increases in the Ti-Zr-Hf series and decreases in the F-Cl-Br-I halogen series.
Derivatives of trivalent elements are more or less characteristic only of titanium. Dark purple oxide Ti 2 O 3 (mp 1820 °C) can be obtained by calcining TiO 2 to 1200 °C in a stream of hydrogen. Blue Ti 2 O 3 is formed as an intermediate product at 700-1000 ° C.
Ti 2 O 3 is practically insoluble in water. Its hydroxide is formed in the form of a dark brown precipitate when alkalis act on solutions of trivalent titanium salts. It begins to precipitate from acidic solutions at pH = 4, has only basic properties and does not dissolve in excess alkali. However, metal titanites (Li, Na, Mg, Mn) produced from HTiO 2 were obtained dry. Blue-black “titanium bronze” of the composition Na0.2TiO 2 is also known.
Titanium (III) hydroxide is easily oxidized by atmospheric oxygen. If there are no other substances capable of oxidation in the solution, hydrogen peroxide is formed simultaneously with the oxidation of Ti(OH) 3. In the presence of Ca(OH) 2 (binding H 2 O 2), the reaction proceeds according to the equation:
2Ti(OH) 3 + O 2 + 2H 2 O = 2Ti(OH) 4 + H 2 O 2
Nitrate salts Ti(OH) 3 are reduced to ammonia.
Purple TiCl 3 powder can be obtained by passing a mixture of TiCl 4 vapor with excess hydrogen through a tube heated to 650 °C. Heating causes its sublimation (with the partial formation of dimer Ti 2 Cl 6 molecules) and then dismutation according to the scheme:
2TiCl 3 = TiCl 4 + TiCl 2
It is interesting that even under normal conditions, titanium tetrachloride is gradually reduced by metallic copper, forming a black compound of the composition CuTiCl 4 (i.e. CuCl·TiCl 3).
Titanium trichloride is also formed by the action of hydrogen on TiCl 4 at the time of release (Zn + acid). In this case, the colorless solution turns purple, characteristic of Ti 3+ ions, and a crystal hydrate of the composition TiCl 3 ·6H 2 O can be isolated from it. A low-stable green crystal hydrate of the same composition is also known, released from a TiCl 3 solution saturated with HCl. The structure of both forms, as well as similar crystalline hydrates of CrCl 3, correspond to the formulas Cl 3 and Cl 2H 2 O. When standing in an open vessel, the TiCl 3 solution gradually becomes discolored due to the oxidation of Ti 3+ to Ti 4+ by atmospheric oxygen according to the reaction:
4TiCl 3 + O 2 + 2H 2 O = 4TiOCl 2 + 4HCl.
Ti3+ ion is one of the very few reducing agents that quite quickly reduce (in an acidic environment) perchlorates to chlorides. In the presence of platinum, Ti 3+ is oxidized by water (with the release of hydrogen).
Anhydrous Ti 2 (SO 4) 3 is green in color. It is insoluble in water, and its solution in dilute sulfuric acid has the violet color usual for Ti 3+ salts. From trivalent titanium sulfate, complex salts are produced, mainly of the types Me·12H 2 O (where Me is Cs or Rb) and Me (with a variable content of water of crystallization depending on the nature of the cation).
The heat of formation of TiO (mp 1750 °C) is 518 kJ/mol. It is obtained in the form of a golden-yellow compact mass by heating a compressed TiO 2 + Ti mixture in a vacuum to 1700 °C. An interesting way of its formation is the thermal decomposition (in a high vacuum at 1000 °C) of titanyl nitrile. Similar in appearance to metal, dark brown TiS is obtained by calcining TiS 2 in a stream of hydrogen (initially, sulfides of intermediate composition are formed, in particular Ti 2 S 3). TiSe, TiTe and silicide of the composition Ti 2 Si are also known.
All TiG 2 are formed by heating the corresponding TiG 3 halides without air access due to their decomposition according to the following scheme:
2TiG 3 = TiG 4 + TiG 2
At slightly higher temperatures, the TiG 2 halides themselves undergo dismutation according to the scheme: 2TiG 2 = TiG 4 + Ti
Titanium dichloride can also be obtained by reducing TiCl4 with hydrogen at 700 °C. It is highly soluble in water (and alcohol), and with liquid ammonia it gives gray ammonia TiCl 2 4NH 3 . A TiCl 2 solution can be prepared by reducing TiCl 4 with sodium amalgam. As a result of oxidation by atmospheric oxygen, the colorless TiCl 2 solution quickly turns brown, then becomes violet (Ti 3+) and, finally, becomes discolored again (Ti 4+). The black precipitate of Ti(OH) 2 obtained by the action of alkali on a TiCl 2 solution is extremely easily oxidized.
Titanium(II) hydroxide- inorganic compound titanium metal hydroxide with the formula Ti(OH) 2, black powder, insoluble in water.
Receipt
- Treatment of solutions of divalent titanium halides with alkalis:
Physical properties
Titanium(II) hydroxide forms a black precipitate that gradually becomes lighter due to decomposition.
Chemical properties
- Decomposes when stored in the presence of water:
Write a review of the article "Titanium(II) hydroxide"
Literature
- Chemical Encyclopedia / Editorial Board: Knunyants I.L. and others. - M.: Soviet Encyclopedia, 1995. - T. 4. - 639 p. - ISBN 5-82270-092-4.
- Handbook of a chemist / Editorial board: Nikolsky B.P. and others. - 3rd ed., corrected. - L.: Chemistry, 1971. - T. 2. - 1168 p.
- Ripan R., Ceteanu I. Inorganic chemistry. Chemistry of metals. - M.: Mir, 1972. - T. 2. - 871 p.
|
||||||
| This article about inorganic matter is a stub. You can help the project by adding to it. |
Excerpt characterizing Titanium(II) Hydroxide
The beauty went to her aunt, but Anna Pavlovna still kept Pierre close to her, appearing as if she had one last necessary order to make.– Isn’t she amazing? - she said to Pierre, pointing to the majestic beauty sailing away. - Et quelle tenue! [And how she holds herself!] For such a young girl and such tact, such a masterful ability to hold herself! It comes from the heart! Happy will be the one whose it will be! With her, the most unsecular husband will involuntarily occupy the most brilliant place in the world. Is not it? I just wanted to know your opinion,” and Anna Pavlovna released Pierre.
Pierre sincerely answered Anna Pavlovna in the affirmative to her question about Helen’s art of holding herself. If he ever thought about Helen, he thought specifically about her beauty and about her unusual calm ability to be silently worthy in the world.
Auntie accepted two young people into her corner, but it seemed that she wanted to hide her adoration for Helen and wanted to more express her fear of Anna Pavlovna. She looked at her niece, as if asking what she should do with these people. Moving away from them, Anna Pavlovna again touched Pierre’s sleeve with her finger and said:
- J"espere, que vous ne direz plus qu"on s"ennuie chez moi, [I hope you won’t say another time that I’m bored] - and looked at Helen.
Helen smiled with an expression that said that she did not admit the possibility that anyone could see her and not be admired. Auntie cleared her throat, swallowed her drool and said in French that she was very glad to see Helen; then she turned to Pierre with the same greeting and with the same mien. In the middle of a boring and stumbling conversation, Helen looked back at Pierre and smiled at him with that clear, beautiful smile with which she smiled at everyone. Pierre was so used to this smile, it expressed so little for him that he did not pay any attention to it. Auntie was talking at this time about the collection of snuff boxes that Pierre’s late father, Count Bezukhy, had, and showed her snuff box. Princess Helen asked to see the portrait of her aunt's husband, which was made on this snuff box.
“This was probably done by Vines,” said Pierre, naming the famous miniaturist, bending over to the table to pick up a snuffbox, and listening to the conversation at another table.
He stood up, wanting to go around, but the aunt handed the snuff box right across Helen, behind her. Helen leaned forward to make room and looked back, smiling. She was, as always at evenings, in a dress that was very open in front and back, according to the fashion of that time. Her bust, which always seemed marble to Pierre, was at such a close distance from his eyes that with his myopic eyes he involuntarily discerned the living beauty of her shoulders and neck, and so close to his lips that he had to bend down a little to touch her. He heard the warmth of her body, the smell of perfume and the creak of her corset as she moved. He did not see her marble beauty, which was one with her dress, he saw and felt all the charm of her body, which was covered only by clothes. And, once he saw this, he could not see otherwise, just as we cannot return to a deception once explained.
“So you haven’t noticed how beautiful I am until now? – Helen seemed to say. “Have you noticed that I’m a woman?” Yes, I am a woman who can belong to anyone and you too,” said her look. And at that very moment Pierre felt that Helen not only could, but had to be his wife, that it could not be otherwise.
He knew it at that moment as surely as he would have known it standing under the aisle with her. As it will be? and when? he did not know; he didn’t even know whether it would be good (he even felt that it was not good for some reason), but he knew that it would be.
Pierre lowered his eyes, raised them again and again wanted to see her as such a distant, alien beauty as he had seen her every day before; but he could no longer do this. He could not, just as a person who had previously looked in the fog at a blade of weeds and saw a tree in it, cannot, after seeing the blade of grass, again see a tree in it. She was terribly close to him. She already had power over him. And between him and her there were no longer any barriers, except for the barriers of his own will.
- Bon, je vous laisse dans votre petit coin. Je vois, que vous y etes tres bien, [Okay, I'll leave you in your corner. I see you feel good there,” said Anna Pavlovna’s voice.
And Pierre, with fear remembering whether he had done something reprehensible, blushing, looked around him. It seemed to him that everyone knew, just like him, about what happened to him.
After a while, when he approached the large circle, Anna Pavlovna said to him:
– On dit que vous embellissez votre maison de Petersbourg. [They say you are decorating your St. Petersburg house.]
(It was true: the architect said that he needed it, and Pierre, without knowing why, was decorating his huge house in St. Petersburg.)
“C"est bien, mais ne demenagez pas de chez le prince Vasile. Il est bon d"avoir un ami comme le prince,” she said, smiling at Prince Vasily. - J"en sais quelque chose. N"est ce pas? [That's good, but don't move away from Prince Vasily. It's good to have such a friend. I know something about this. Isn't that right?] And you are still so young. You need advice. Don't be angry with me for taking advantage of old women's rights. “She fell silent, as women always remain silent, expecting something after they say about their years. – If you get married, then it’s a different matter. – And she combined them into one look. Pierre did not look at Helen, and she did not look at him. But she was still terribly close to him. He mumbled something and blushed.
