Acids titanium

Titanium whites resist various atmospheric contaminants such as sulfur dioxide, carbon dioxide, and hydrogen sulfide. Under normal conditions they are not readily reduced, oxidi2ed, or attacked by weak inorganic and organic acids. Titanium dioxide dissolves slightly in bases, hydrofluoric acid, and hot sulfuric acid. Owing to its chemical inertness, titanium dioxide is a nontoxic, environmentally preferred white pigment. 

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). 

Dicarboxyhc acids, eg, succinic or adipic, do not dissolve titanic acid. A phthalate has been prepared by adding acidic titanium sulfate solution to sodium phthalate solution. 

Chemicals or from Merck i Company, Inc., but can also be prepared by dissolving metallic titanium in 20% aqueous hydrochloric acid or by dissolving solid titanium trichloride in 1 M aqueous hydrochloric acid. Titanium Ill) sulfate (from BDH Chemicals Ltd.) can also be used. All... 

Anodic protection is particularly suitable for stainless steels in acids. Protection potential ranges are given in Section 2.4. Besides sulfuric acid, other media such as phosphoric acid can be considered [13,21-24]. These materials are usually stable-passive in nitric acid. On the other hand, they are not passivatable in hydrochloric acid. Titanium is also a suitable material for anodic protection due to its good passivatability. 

As Lewis acid, titanium tetrachloride, boron trifluoride or ethylaluminum dichloride is often used. The stereochemical outcome of the reaction strongly depends on the Lewis acid used. The Sakurai reaction is a relatively new carbon-carbon forming reaction, that has been developed into a useful tool for organic synthesis. ... 

It is therefore possible to determine cations such as Ca2+, Mg2+, Pb2+, and Mn2+ in the presence of the above-mentioned metals by masking with an excess of potassium or sodium cyanide. A small amount of iron may be masked by cyanide if it is first reduced to the iron(II) state by the addition of ascorbic acid. Titanium(IV), iron(III), and aluminium can be masked with triethanolamine mercury with iodide ions and aluminium, iron(III), titanium(lV), and tin(II) with ammonium fluoride (the cations of the alkaline-earth metals yield slightly soluble fluorides). 

It is possible to titrate two substances by the same titrant provided that the standard potentials of the substances being titrated, and their oxidation or reduction products, differ by about 0.2 V. Stepwise titration curves are obtained in the titration of mixtures or of substances having several oxidation states. Thus the titration of a solution containing Cr(VI), Fe(III) and V(V) by an acid titanium(III) chloride solution is an example of such a mixture in the first step Cr(VI) is reduced to Cr(III) and V(V) to V(IV) in the second step Fe(III) is reduced to Fe(II) in the third step V(IV) is reduced to V(III) chromium is evaluated by difference of the volumes of titrant used in the first and third steps. Another example is the titration of a mixture of Fe(II) and V(IV) sulphates with Ce(IV) sulphate in dilute sulphuric acid in the first step Fe(II) is oxidised to Fe(III) and in the second jump V(IV) is oxidised to V(V) the latter change is accelerated by heating the solution after oxidation of the Fe(II) ion is complete. The titration of a substance having several oxidation states is exemplified by the stepwise reduction by acid chromium(II) chloride of Cu(II) ion to the Cu(I) state and then to the metal. 

Discussion. With an acidic titanium(IV) solution hydrogen peroxide produces a yellow colour with small amounts oftitanium(up to 0.5 mg ofTiOz permL), the intensity of the colour is proportional to the amount of the element present. Comparison is usually made with standard titanium(IV) sulphate solutions a method for their preparation from potassium titanyl oxalate is described below. The hydrogen peroxide solution should be about 3 percent strength (ten volume) and the final solution should contain sulphuric acid having a concentration from about 0.75 to 1.75M in order to prevent hydrolysis to a basic sulphate and to prevent condensation to metatitanic acid. The colour intensity increases slightly with rise of temperature hence the solutions to be compared should have the same temperature, preferably 20-25 °C. 

A similar dependence of the stereoselectivity on the solvent and reaction temperature was found with the x-oxo amides 9 derived from phenylglyoxylic acid (R = C6H5) and 2-oxopropanoic acid (R = CH3) with amine F (Table 23)15. Thus, the highest selectivity was observed under chelation-controlled conditions in the presence of the Lewis acid titanium(IV) chloride. 

As Lewis acids, titanium(IV) chloride39-377-378 or titanium(IV) isopropoxide in combination with titanium(IV) chloride can be used in stoichiometric amounts40 4l. but triphenylmelhyl perchlorate or chlorotriphenylmethane with tin(II) chloride offers a mild, catalytic alternative42 46. 

Nitric Acid/Sulfuric Acid-Titanium(III) Chloride-Sodium Nitrite-N-(l-Naphthyl)-ethylenediamine... 

The preparation of imines, enamines, nitroalkenes and N-sulfonylimines proceeds via the azeotropic removal of water from the intermediate in reactions that are normally catalyzed by p-toluenesulfonic acid, titanium(IV) chloride, or montmorillonite K 10 clay. A Dean-Stark apparatus is traditionally used which requires a large excess of aromatic hydrocarbons such as benzene or toluene for azeotropic water elimination. 

Titanium is the most abundant metal in the earth crust, and is present in excess of 0.62%. It can be found as dioxy titanium and the salts of titanium acids. Titanium is capable of forming complex anions representing simple titanites. It can also be found in association with niobium, silicates, zircon and other minerals. A total of 70 titanium minerals are known, as mixtures with other minerals and also impurities. Only a few of these minerals are of any economic importance. 

Dimerisation and ester coordination restricts the number of sites available for alkoxides to two only, while maintaining a comparatively Lewis-acidic titanium centre, as needed for the reaction. In the dimer, the methine protons, alkoxide groups, and ester groups are inequivalent, but they show a rapid exchange on the H NMR timescale at room temperature, as the AG for the process is only 64 kl.mol. This process is much faster than the catalytic reaction, but due to the C2-symmetry of the tartaric esters the resulting structures of the dimers are the same. 

The establishment of the equilibrium is often accelerated by acidic or basic catalysts, for example, by strong acids (p-toluenesulfonic acid), metal oxides (antimony trioxide), Lewis acids (titanium tetrabutoxide, tin acetates or tin oc-toates), weak acid salts of alkali metals or alkaline earth metals (acetates, benzoates), or by alcoholates. 

A similar study was made on various titanium compounds. It was found that titanium dichloride diacetate and titanium dichloride di-isopropoxide produced high amounts of crystalline polyvinylisobutylether. On the other hand, the more acidic titanium tetrachloride produced more amorphous polymers. The insoluble titanium trichloride and titanium dichloride were ineffective as polymerization catalysts. The less acidic tetraisopropyltitanate and diethyltitanium dichloride were completely ineffective as catalysts. 

Natta (119) has made an excellent summary of the catalysts which produced various structures of polybutadiene. The more acidic vanadium and titanium trichloride catalysts produced large amounts of trans 1.4-polymer. Less acidic titanium iodide, cobalt, and nickel catalysts produced high amounts of cis 1.4 structure (Table 9). 

Gypsum is also obtained as a by product of various chemical processes. The main sources are from processes involving scrubbing gases evolved in burning fuels that contain sulfur, and the chemical synthesis of chemicals, such as sulfuric acid, phosphoric acid, titanium dioxide, citric acid, and organic polymers. 

Allyl silanes react with a wide variety of electrophiles, rather like the ones that react with silyl enol ethers, provided they are activated, usually by a Lewis acid. Titanium tetrachloride is widely used but other successful Lewis acids include boron trifluoride, aluminium chloride, and trim ethyls ilyl tri-flate. Electrophiles include the humble proton generated from acetic add. The regiocontrol is complete. No reaction is observed at the other end of the allylic system. All our examples are on the allyl silane we prepared earlier in the chapter. 

Phosphoric acid, titanium dioxide, steel pickling,... 

An alternative reaction, the addition of an olefinic C—H bond to C=0, is catalyzed by Lewis acidic titanium aryloxide complexes chiral binaphthol ligands give high optical yields.96... 

SYNS SULFURIC ACID, TITANIUM(4+) SALT (2 1) TITANIUM DISULFATE TITANIUM SULFATE SOLUTION (DOT)... 

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