Titanium butoxide
{{chembox
| Watchedfields = changed
| verifiedrevid =
| ImageFile = Structural formula of titanium tetrabutoxide.svg
| ImageCaption = gas phase structure
| ImageSize = 280
| SystematicName =
| IUPACName = Titanium(IV) butoxide
| OtherNames = Titanium(IV) butoxide, titanium n-butoxide, titanium tetrakis(butoxide), butyl titanate, tetrabutoxy titanium, titanium tetrabutoxide, tetrabutoxytitanium, tetrabutyltitanate, tetrabutyl orthotitanate, titanium tetrabutanolate, TYZOR TBT
| Section1 = {{Chembox Identifiers
| CASNo = 5593-70-4
| PubChem = 21801
| ChemSpiderID = 13836735
| InChI=1S/4C4H9O.Ti/c4*1-2-3-4-5;/h4*2-4H2,1H3;/q4*-1;+4
| InChIKey= YHWCPXVTRSHPNY-UHFFFAOYSA-N
| SMILES = CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-].[Ti+4]
| EINECS = 227-006-8
| UNII = FJS8Q2MX9I
| UNNumber = 2920
}}
| Section2 = {{Chembox Properties
| Formula = C16H36O4Ti
| MolarMass = 340.32164
| Appearance = COLORLESS TO LIGHT-YELLOW LIQUID
| SolubleOther = most organic solvents except ketones
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| Section4 = {{Chembox Thermochemistry
| HeatCapacity = 711 J/(mol·K)
| Entropy =
| DeltaGf =
| DeltaHc =
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| Section7 = {{Chembox Hazards
| LD50 = 3122 mg/kg (rat, oral) and 180 mg/kg (mouse, intravenal).
}}
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Titanium butoxide is a metal alkoxide with the formula Ti(OBu)4 (Bu = –CH2CH2CH2CH3). It is a colorless odorless liquid although aged samples can appear yellowish. Owing to hydrolysis, samples have a weak alcohol-like odor. It is soluble in many organic solvents. Decomposition in water is not hazardous, and therefore titanium butoxide is often used as a liquid source of titanium dioxide, which allows deposition of TiO2 coatings of various shapes and sizes down to the nanoscale.
Titanium butoxide is often used to prepare titanium oxide materials and catalysts.{{cite journal |doi=10.1002/anie.201906056 |title=Enhanced Electrocatalytic N2 Reduction via Partial Anion Substitution in Titanium Oxide–Carbon Composites |date=2019 |last1=Qin |first1=Qing |last2=Zhao |first2=Yun |last3=Schmallegger |first3=Max |last4=Heil |first4=Tobias |last5=Schmidt |first5=Johannes |last6=Walczak |first6=Ralf |last7=Gescheidt-Demner |first7=Georg |last8=Jiao |first8=Haijun |last9=Oschatz |first9=Martin |journal=Angewandte Chemie International Edition |volume=58 |issue=37 |pages=13101–13106 |pmid=31257671 |hdl=21.11116/0000-0004-023B-8 |s2cid=195760017 |hdl-access=free }}{{cite journal |doi=10.1021/ja302846n |title=Synergetic Effect of MoS2 and Graphene as Cocatalysts for Enhanced Photocatalytic H2 Production Activity of TiO2 Nanoparticles |date=2012 |last1=Xiang |first1=Quanjun |last2=Yu |first2=Jiaguo |last3=Jaroniec |first3=Mietek |journal=Journal of the American Chemical Society |volume=134 |issue=15 |pages=6575–6578 |pmid=22458309 }}{{citation needed|date=March 2024}}
Structure and synthesis
Image:Titanium 4 Ethoxide WIKI.png (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.{{citation needed|date=December 2023}}
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.{{Citation needed|date=March 2024}}
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 the overall process can be summarized with this balanced equation.
:Ti(OBu)4 + 2 H2O → TiO2 + 4 HOBu
Diverse oxo-alkoxo intermediates have been trapped and characterized.{{cite journal |doi=10.1039/b103398k |title=Mechanistic Aspects of the Hydrolysis and Condensation of Titanium Alkoxides Complexed by Tripodal Ligands|date=2001 |last1=Weymann-Schildknetch |first1=Sandrine |last2=Henry |first2=Marc |journal=Journal of the Chemical Society, Dalton Transactions |issue=16 |pages=2425–2428 }}
Pyrolysis also affords the dioxide:
:Ti(OBu)4 → TiO2 + 2 Bu2O
Titanium butoxide 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.{{cite journal|doi=10.1007/BF00905301|title=Reactions of organocyclosiloxanes with tetrabutyl orthotitanate|volume=11|issue=5|date=1962|pages=776–779|issn=0568-5230|journal=Bulletin of the Academy of Sciences of the USSR Division of Chemical Science|author=K. A. Andrianov |author2=Sh. V. Pichkhadze |author3=V. V. Komarova |author4=Ts. N. Vardosanidze }}
File:Chiral TiO2 nanofibers 2.jpg (top) and TEM (bottom) images of chiral TiO2 nanofibers produced by depositing titanium butoxide on carbon nanofibers. Carbon was removed by heating in air.]]
Safety
LD50 is 3122 mg/kg (rat, oral) and 180 mg/kg (mouse, intravenal).{{cn|date=October 2023}}
Titanium butoxide is a corrosive, flammable liquid which reacts violently with oxidizing materials. It is incompatible with sulfuric and nitric acids, inorganic hydroxides and peroxides, bases, amines, amides, isocyanates and boranes. It is irritating to skin and eyes, and causes nausea and vomiting if swallowed. LD50 is 3122 mg/kg (rat, oral) and 180 mg/kg (mouse, intravenal); flash point is 77 °C.
When heated it emits irritating fumes, which form explosive mixtures with air at concentrations above 2 vol%.{{citation needed|date=March 2024}}