Titanium solubility

Kol] Kolpachev, A.A., Medvedeva, N.D., Samoilov, Yu.A., Titova, LA., Effect of Iron on Titanium Solubility in Aluminium and Aluminium-Magnesium Alloys (in Russian), Tekh-nol. Legk Splavov, Nauchno-Tekh. Byull, Vses. Inst. Splavov, 8, 15-17 (1973) (Experimental, 3)... 

Anhydrous titanium dioxide is only soluble with difficulty in hot concentrated sulphuric acid dilution allows the crystallisation of a sulphate of formula T10S04.H20, but it is doubtful if the titanyl cation TiO actually exists, either in solution or the solid. Certainly [TifHjOIn] does not exist, and solutions of titanyl salts may best be considered to contain ions [Ti(0H)2(H204)] . Titanium... 

Titanium trifluoride [13470-08-17, TiF, is a blue crystalline solid that undergoes oxidation to Ti02 upon heating in air at 100°C (see Titanium compounds). In the absence of air, disproportionation occurs above 950°C to give TiF and titanium metal. TiF decomposes at 1200°C, has a density of 2.98 g/cm, and is insoluble in water but soluble in acids and alkafles. The magnetic moment is 16.2 x 10 J/T (1.75 -lB). 

Iodides. Iodides range from the completely ionic such as potassium iodide [7681-11-0] KI, to the covalent such as titanium tetraiodide [7720-83-4J, Til. Commercially, iodides are the most important class of iodine compounds. In general, these are very soluble in water and some are hygroscopic. However, some iodides such as the cuprous, lead, silver and mercurous, are insoluble. 

Most catalysts for solution processes are either completely soluble or pseudo-homogeneous all their catalyst components are introduced into the reactor as Hquids but produce soHd catalysts when combined. The early Du Pont process employed a three-component catalyst consisting of titanium tetrachloride, vanadium oxytrichloride, and triisobutjlalurninum (80,81), whereas Dow used a mixture of titanium tetrachloride and triisobutylalurninum modified with ammonia (86,87). Because processes are intrinsically suitable for the use of soluble catalysts, they were the first to accommodate highly active metallocene catalysts. Other suitable catalyst systems include heterogeneous catalysts (such as chromium-based catalysts) as well as supported and unsupported Ziegler catalysts (88—90). 

Similar to IFP s Dimersol process, the Alphabutol process uses a Ziegler-Natta type soluble catalyst based on a titanium complex, with triethyl aluminum as a co-catalyst. This soluble catalyst system avoids the isomerization of 1-butene to 2-butene and thus eliminates the need for removing the isomers from the 1-butene. The process is composed of four sections reaction, co-catalyst injection, catalyst removal, and distillation. Reaction takes place at 50—55°C and 2.4—2.8 MPa (350—400 psig) for 5—6 h. The catalyst is continuously fed to the reactor ethylene conversion is about 80—85% per pass with a selectivity to 1-butene of 93%. The catalyst is removed by vaporizing Hquid withdrawn from the reactor in two steps classical exchanger and thin-film evaporator. The purity of the butene produced with this technology is 99.90%. IFP has Hcensed this technology in areas where there is no local supply of 1-butene from other sources, such as Saudi Arabia and the Far East. 

Many metal alkoxides are soluble ia the corresponding alcohols, but magnesium alkoxides are practically insoluble. Only the distillable alkoxides, like those of alumiaum, titanium, and zirconium, are soluble ia weaMy polar solvents. The double alkoxides are soluble ia alcohol K[Li(OC2Hy)2],... 

It is carried out in the Hquid phase at 100—130°C and catalyzed by a soluble molybdenum naphthenate catalyst, also in a series of reactors with interreactor coolers. The dehydration of a-phenylethanol to styrene takes place over an acidic catalyst at about 225°C. A commercial plant (50,51) was commissioned in Spain in 1973 by Halcon International in a joint venture with Enpetrol based on these reactions, in a process that became known as the Oxirane process, owned by Oxirane Corporation, a joint venture of ARCO and Halcon International. Oxirane Corporation merged into ARCO in 1980 and this process is now generally known as the ARCO process. It is used by ARCO at its Channelview, Texas, plant and in Japan and Korea in joint ventures with local companies. A similar process was developed by Shell (52—55) and commercialized in 1979 at its Moerdijk plant in the Netherlands. The Shell process uses a heterogeneous catalyst of titanium oxide on siHca support in the epoxidation step. Another plant by Shell is under constmction in Singapore (ca 1996). 

In a second example, a cell—gelatin mixture is cross-linked with glutaraldehyde (43). When soluble enzyme is used for binding, the enzyme is first released from the cell, then recovered and concentrated. Examples of this type of immobilization include binding enzyme to a DEAE-ceUulose—titanium dioxide—polystyrene carrier (44) or absorbing enzyme onto alumina followed by cross-linking with glutaraldehyde (45,46). 

The alkaline solutions can remove water-soluble polymers in the spinning mix and inert products such as titanium dioxide. Basic treatments can also hydroly2e a certain amount of the polyester itself. For some silk-like appHcations or for producing fine denier fabrics, this basic treatment can produce a 10—30% weight loss of polyester (190,196). Certain polyesters such as anionically modified polyester can undergo more rapid weight loss than regular polyester (189). 

Hydrolysis of solutions of Ti(IV) salts leads to precipitation of a hydrated titanium dioxide. The composition and properties of this product depend critically on the precipitation conditions, including the reactant concentration, temperature, pH, and choice of the salt (46—49). At room temperature, a voluminous and gelatinous precipitate forms. This has been referred to as orthotitanic acid [20338-08-3] and has been represented by the nominal formula Ti02 2H20 (Ti(OH). The gelatinous precipitate either redissolves or peptizes to a colloidal suspension ia dilute hydrochloric or nitric acids. If the suspension is boiled, or if precipitation is from hot solutions, a less-hydrated oxide forms. This has been referred to as metatitanic acid [12026-28-7] nominal formula Ti02 H2O (TiO(OH)2). The latter precipitate is more difficult to dissolve ia acid and is only soluble ia concentrated sulfuric acid or hydrofluoric acid. 

The reactivity of titanium dioxide toward acid is dependent on the temperature to which it has been heated. Freshly precipitated titanium dioxide is soluble iu concentrated hydrochloric acid. However, titanium dioxide that has been heated to 900°C is almost iusoluble iu acids except hot concentrated sulfuric, iu which the solubiUty may be further iucreased by the addition of ammonium sulfate to raise the boiling poiut of the acid, and hydrofluoric acid. Similarly, titanium dioxide that has been calciued at 900°C is almost iusoluble iu aqueous alkahes but dissolves iu molten sodium or potassium hydroxide, carbouates, or borates. 

The Sulfate Process. A flow diagram for the sulfate process is shown in Figure 1. The strongly exothermic digestion of the dried, milled feedstock in 85—95°/ sulfuric acid converts metal oxides into soluble sulfates, primarily titanium and iron. 

It melts at 39°C and may be purified by vacuum sublimation. The Hquid boils at 233°C to give a monomeric vapor in which the Ti—Br distance is 231 pm. Titanium tetrabromide is soluble in dry chloroform, carbon tetrachloride, ether, and alcohol. Like titanium tetrachloride, TiBr forms a range of adducts with molecules such as ammonia, amines, nitrogen heterocycles, esters, and ethers. 

Titanium Tetraiodide. Titanium tetraiodide [7720-83 ] forms reddish-brown crystals, cubic at room temperature, having reported lattice parameter of either 1200 (149) or 1221 (150) pm. Til melts at 150°C, boils at 377°C, and has a density of 440(0) kg/m. It forms adducts with a number of donor molecules and undergoes substitution reactions (151). It also hydrolyzes in water and is readily soluble in nonpolar organic solvents. 

Titanium Phosphates. Titanium(III) phosphate [24704-65-2] (titanous phosphate) is a purple soHd, soluble ia dilute acid, giving relatively stable solutions. It can be prepared by adding a soluble phosphate to titanous chloride or sulfate solution and raising the pH until precipitation occurs. 

Titanium Sulfides. The titanium sulfur system has been summarized (4). Titanium subsulftde [1203-08-6] Ti2S, forms as a gray soHd of density 4600 kg/m when titanium monosulftde [12039-07-5], TiS, is heated at 1000°C with titanium ia a sealed tube. It can also be formed by heating a mixture of the two elements at 800—1000°C. The sulfide, although soluble ia concentrated hydrochloric and sulfuric acids, is iasoluble ia alkaUes. 

Titanium trisulfide [12423-80-2], TiS, a black crystalline soHd having a monoclinic stmcture and a theoretical density of 3230 kg/m, can be prepared by reaction between titanium tetrachloride vapor and H2S at 480—540°C. The reaction product is then mixed with sulfur and heated to 600°C ia a sealed tube to remove residual chlorine. Sublimatioa may be used to separate the trisulfide (390°C) from the disulfide (500°C). Titanium trisulfide, iasoluble ia hydrochloric acid but soluble ia both hot and cold sulfuric acid, reacts with concentrated nitric acid to form titanium dioxide. 

Sdanediols, eg, (CgH )2Si(OH)2 and H0Si(CgH )20Si(CgH )20H, yield four-and-six-membered rings with titanium alkoxides. Pinacols and 1,2-diols form chelates rather than polymers. The more branched the diol molecule, the more likely are its titanium derivatives to be soluble and even monomeric. 

OC-Hydroxycarboxylic Acid Complexes. Water-soluble titanium lactate complexes can be prepared by reactions of an aqueous solution of a titanium salt, such as TiCl, titanyl sulfate, or titanyl nitrate, with calcium, strontium, or barium lactate. The insoluble metal sulfate is filtered off and the filtrate neutralized using an alkaline metal hydroxide or carbonate, ammonium hydroxide, amine, or alkanolamine (78,79). Similar solutions of titanium lactate, malate, tartrate, and citrate can be produced by hydrolyzation of titanium salts, such as TiCl, in strongly (>pH 10) alkaline water isolation of the... 

Sohd, water-soluble a-hydroxycarboxyhc acid and oxaUc acid titanium complexes can be formed by reaction of the acid and a tetraaLkyl titanate in an inert solvent, such as acetone or heptane. The precipitated complex is filtered, rinsed with solvent, and dried to give an amorphous white soHd, which is water- and alcohol—water-soluble (81,82). 

Water-soluble, alkaline-stable ammonium or metal titanium malates and citrates can be formed by adding a tetraalkyl titanate to an aqueous solution of the ammonium or metal titanium malate or citrate (84). A typical formula is M TiO(citrate), where M is NH, Na, K, Ca, or Ba. 

The orange-red titanium acetylacetone chelates are soluble in common solvents. These compounds are coordinately saturated (coordination number equals 6) and thus much more resistant to hydrolysis than the parent alkoxides (coordination number 4). The alkoxy groups are the moieties removed by hydrolysis. The initial product of hydrolysis is beheved to be the bis-hydroxy bis-acetylacetone titanate, (HO)2Ti(acac)2, which oligomerizes to a... 

A family of Ti(III) derivatives roughly parallels those of Ti(IV). Titariium(III) chelates are known, eg, titanium ttisacetylacetonate [14284-96-9] prepared in benzene from titanium trichloride, acetylacetone, and ammonia (185). This deep-blue compound is soluble in benzene but insoluble in water. 

Lakes. Lakes are a special kind of color additive prepared by precipitating a soluble dye onto an approved iasoluble base or substratum. In the case of D C and Ext. D C lakes, this substratum may be alumina, blanc fixe, gloss white, clay, titanium dioxide, 2iac oxide, talc, rosia, aluminum ben2oate, calcium carbonate, or any combination of two or more of these materials. Currentiy, alumina is the only substratum approved for manufactuting FD C lakes. 

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