Titanium butoxide

Titanium butoxide is an metal-organic chemical compound with the formula Ti(OBu)4 (Bu = CH2CH2CH2CH3). It is a colorless odorless liquid, although aged samples are yellowish with a weak alcohol-like odor. It is soluble in many organic solvents.[1][3] It hydrolyzes to give titanium dioxide, which allows deposition of TiO2 coatings of various shapes and sizes down to the nanoscale.[4][5]

Titanium butoxide

gas phase structure
Names
IUPAC name
titanium(4+) butan-1-olate
Other names
Titanium(IV) butoxide, titanium n-butoxide, titanium tetrakis(butoxide), butyl titanate, tetrabutoxy titanium, titanium tetrabutoxide, tetrabutoxytitanium, tetrabutyltitanate, tetrabutyl orthotitanate, titanium tetrabutanolate,[1][2] TYZOR
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.024.552
EC Number
  • 227-006-8
UNII
UN number 2920
Properties
C16H36O4Ti
Molar mass 340.32164
Odor weak alcohol-like[1]
Density 0.998 g/cm3[1]
Melting point -55 °C[1]
Boiling point 312 °C[1]
decomposes[1]
Solubility most organic solvents except ketones[1]
1.486[1]
Thermochemistry
711 J/(mol·K)[2]
Std enthalpy of
formation (ΔfH⦵298)
 -1670 kJ/mol[2]
Hazards
Lethal dose or concentration (LD, LC):
3122 mg/kg (rat, oral) and 180 mg/kg (mouse, intravenal).[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Structure and synthesis
Structure of a typical titanium alkoxide, e.g. titanium ethoxide (organic substituents removed for clarity).

Like most titanium alkoxides (exception: titanium isopropoxide), Ti(OBu)4 is not a monomer but exists as a cluster (see titanium ethoxide). Nonetheless it is often depicted as a simple monomer.

It is produced by treating titanium tetrachloride with butanol:

TiCl4 + 4 HOBu → Ti(OBu)4 + 4 HCl

The reaction requires base to proceed to completion.

Reactions

Like other titanium alkoxides, titanium butoxide exchanges alkoxide groups:

Ti(OBu)4 + HOR → Ti(OBu)3(OR) + HOBu
Ti(OBu)3(OR) + HOR → Ti(OBu)2(OR)2 + HOBu

etc. For this reason, titanium butoxide is not compatible with alcohol solvents.

Analogous to the alkoxide exchange, titanium butoxide hydrolyzes readily. The reaction details are complex, but can be summarized with this balanced equation.

Ti(OBu)4 + 2 H2O → TiO2 + 4 HOBu

Pyrolysis also affords the dioxide:

Ti(OBu)4 → TiO2 + 2 Bu2O

Reactions and hazard
leftSEM (top) and TEM (bottom) images of chiral TiO2 nanofibers produced by depositing titanium butoxide on carbon nanofibers. Carbon was removed by heating in air.[4]

Tetrabutyl orthotitanate reacts with alkylcyclosiloxanes. With ocatamethylcyclotetrasiloxane it produces dibutoxydimethylsilane, 1,5-dibutoxyhexamethyltrisiloxane, 1,7-dibutoxyoctamethyltetrasiloxane, 1,3-dibutoxytetramethyldisiloxane and polymers. With hexamethylcyclotrisiloxane it also produces dibutoxydimethylsilane.[6]

References
  1. Butyl titanate. pubchem.ncbi.nlm.nih.gov
  2. Tetrabutyl titanate. nist.gov
  3. Pohanish, Richard P.; Greene, Stanley A. (2009). Wiley Guide to Chemical Incompatibilities. John Wiley & Sons. p. 1010. ISBN 978-0-470-52330-8.
  4. Wang, Cui (2015). "Hard-templating of chiral TiO2 nanofibres with electron transition-based optical activity". Science and Technology of Advanced Materials. 16 (5): 054206. Bibcode:2015STAdM..16e4206W. doi:10.1088/1468-6996/16/5/054206. PMC 5070021. PMID 27877835.
  5. Wu, Limin; Baghdachi, Jamil (2015). Functional Polymer Coatings: Principles, Methods, and Applications. Wiley. p. 10. ISBN 978-1-118-88303-7.
  6. K. A. Andrianov, Sh. V. Pichkhadze, V. V. Komarova, Ts. N. Vardosanidze (1962). "Reactions of organocyclosiloxanes with tetrabutyl orthotitanate". Bulletin of the Academy of Sciences of the USSR Division of Chemical Science. 11 (5): 776–779. doi:10.1007/BF00905301. ISSN 0568-5230.CS1 maint: uses authors parameter (link)
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