Titanium isopropoxide

Titanium isoproxide is a chemical compound with the formula Ti{OCH(CH₃)₂}₄. This alkoxide of titanium(IV) is used in organic synthesis and materials science.

The structures of the titanium alkoxides are often complex. Crystalline titanium methoxide is tetrameric with the molecular formula Ti₄(OCH₃)₁₆.^[1] Alkoxides derived from bulkier alcohols such isopropanol aggregate less. Titanium isoproxide is mainly a monomer in nonpolar solvents.^[2] It is a diamagnetic tetrahedral molecule.

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Preparation

It is prepared by treating titanium tetrachloride with isopropanol. Hydrogen chloride is formed as a coproduct:

TiCl₄ + 4 (CH₃)₂CHOH → Ti{OCH(CH₃)₂}₄ + 4 HCl

Properties

Titanium isoproxide reacts with water to deposit titanium dioxide:

Ti{OCH(CH₃)₂}₄ + 2 H₂O → TiO₂ + 4 (CH₃)₂CHOH

This reaction is employed in the sol-gel synthesis of TiO₂-based materials. Typically water is added to a solution of the alkoxide in an alcohol. The nature of the inorganic product is determined by the presence of additives (e.g. acetic acid), the amount of water, and the rate of mixing.

Titanium isoproxide is a component of the Sharpless epoxidation, a method for the synthesis of chiral epoxides. The compound is also used as a catalyst for the preparation of certain cyclopropanes in the Kulinkovich reaction. Prochiral thioethers are oxidized enantioselectively using catalyst derived from Ti(O-i-Pr)₄.^[3]

Naming

Titanium(IV) isopropoxide is a widely used item of commerce and has acquired many names in addition to those listed in the table. A sampling of the names include: titanium(IV) i-propoxide, isopropyl titanate, tetraisopropyl titanate, tetraisopropyl orthotitanate, titanium tetraisopropylate, orthotitanic acid tetraisopropyl ester, Isopropyl titanate(IV), titanic acid tetraisopropyl ester, isopropyltitanate, titanium(IV) isopropoxide, titanium tetraisopropoxide, iso-propyl titanate, titanium tetraisopropanolate, tetraisopropoxytitanium(IV), tetraisopropanolatotitanium, tetrakis(isopropoxy) titanium, tetraksi(isopropanolato) titanium, titanic acid isopropyl ester, titanic acid tetraisopropyl ester, titanium isopropoxide, titanium isopropylate, tetrakis(1-methylethoxy)titanium.

References

1. ^ Wright D. A.; Williams, D. A. “The Crystal and Molecular Structure of Titanium Tetramethoxide” Acta Crystallographica 1968, Volume B24, pages 1107-1114. doi:10.1107/S0567740868003766
2. ^ Bradley, D. C.; Mehrotra, R.; Rothwell, I.; Singh, A. “Alkoxo and Aryloxo Derivatives of Metals” Academic Press, San Diego, 2001. ISBN 0121241408.
3. ^ S. H. Zhao, O. Samuel, H. B. Kagan “Enantioelective Oxidation of a Sulfide:: (S)-(-)-Methyl p-Tolyl Sulfoxide” Organic Syntheses, Collected Volume 8, p.464 (1993).http://www.orgsyn.org/orgsyn/pdfs/CV8P0464.pdf