Compounds


Compounds

The +4 oxidation state dominates in titanium chemistry, but compounds in the +3 oxidation state are also common. Because of this high oxidation state, many titanium compounds have a high degree of covalent bonding.

Although titanium metal is relatively uncommon, due to the cost of extraction, titanium dioxide (also called titanium(IV), titanium white, or even titania) is cheap, nontoxic, readily available in bulk, and very widely used as a white pigment in paint, enamel, lacquer, plastic and construction cement. TiO2 powder is chemically inert, resists fading in sunlight, and is very opaque: this allows it to impart a pure and brilliant white colour to the brown or gray chemicals that form the majority of household plastics. In nature, this compound is found in the minerals anatase, brookite, and rutile.

Paint made with titanium dioxide does well in severe temperatures, is somewhat self-cleaning, and stands up to marine environments. Pure titanium dioxide has a very high index of refraction and an optical dispersion higher than diamond. Star sapphires and rubies get their asterism from the titanium dioxide present in them. Titanates are compounds made with titanium dioxide. Barium titanate has piezoelectric properties, thus making it possible to use it as a transducer in the interconversion of sound and electricity. Esters of titanium are formed by the reaction of alcohols and titanium tetrachloride and are used to waterproof fabrics.

Titanium nitride is often used to coat cutting tools, such as drill bits. It also finds use as a gold-coloured decorative finish, and as a barrier metal in semiconductor fabrication.

Titanium(IV) chloride (titanium tetrachloride, TiCl4, sometimes called "Tickle") is a colourless, weakly acidic liquid which is used as an intermediate in the manufacture of titanium(IV) oxide for paint. It is widely used in organic chemistry as a Lewis acid, for example in the Mukaiyama aldol condensation. Titanium also forms a lower chloride, titanium(III) chloride (TiCl3), which is used as a reducing agent.

Titanocene dichloride is an important catalyst for carbon-carbon bond formation. Titanium isopropoxide is used for Sharpless epoxidation. Other compounds include; Titanium bromide (used in metallurgy, superalloys, and high-temperature electrical wiring and coatings) and titanium carbide (found in high-temperature cutting tools and coatings).