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TEB
CAS Number: 97-94-9
EC Number: 202-620-9
Chemical formula: C6H15B
Molar mass: 98.00 g/mol
Triethylborane (TEB), also called triethylborine and triethylboron, is an organoborane (an organometallic compound), a near-colorless to yellowish transparent liquid with pungent ether-like odor.
Triethylborane chemical formula can be written as C6H15B, or (CH3CH2)3B, or (C2H5)3B, or Et3B.
Triethylborane (TEB), also called triethylboron, is an organoborane (a compound with a B-C bond).
Triethylborane is a colorless pyrophoric liquid.
Triethylborane chemical formula is (C2H5)3B, abbreviated Et3B.
Triethylborane is soluble in organic solvents tetrahydrofuran and hexane.
Triethylborane (Et3B) is an organoborane pyrophoric liquid.
Triethylborane is prepared on the plant scale by the reaction of AlEt3 and KBF4.
Et3B is widely used as a precursor for the preparation of reducing agents such as lithium triethylborohydride and sodium triethylborohydride.
Triethylborane can also be utilized as an initiator in radical cyclization reactions.
Triethylborane is strongly pyrophoric, igniting spontaneously in air.
Triethylborane burns intensely with a very hot flame.
The color of the flame is apple-green, which is characteristic for boron compounds.
Triethylborane fire should not be extinguished with water; a carbon dioxide or dry powder extinguisher (eg. Purple K) would be more suitable.
Triethylborane vapors may cause flash fire.
Triethylborane is soluble in tetrahydrofuran and hexane, and is not pyrophoric when in solution.
However the solution can slowly react with atmospheric moisture.
If the TEB solutions are exposed to air for prolonged time, unstable organic peroxides may form, with the presence of cationic initiators leading to polymerization.
Triethylborane is toxic to peripheral nervous system, kidneys and testes.
Triethylborane is extremely corrosive.
Some sources incorrectly refer to this chemical as tetraethylborane.
An autocatalytic cycle was found in the mechanism of autoxidation of triethylborane using density functional theory calculations.
The reaction starts with the generation of an ethyl radical via slow homolytic substitution.
Fast radical propagation then takes place through a catalytic cycle in which the ethyl radical acts as a catalyst.
Triethylborane is catalyst for allylation of aldehydes, decarboxylative C-C bond cleavage reactions, rhenium hydride / boron Lewis acid cocatalysis of alkene hydrogenations, Regioselective hydroxyalkylation of unsaturated oxime ethers.
Reactant for radical reductions of alkyl bromides with N-heterocyclic carbene boranes and synthesis of tetramethylammonium trialkylphenylborate salts with oxidation potential.
Triethylborane is a chemical compound that is used as a reagent in organic chemistry.
Triethylborane is also used to study the repair mechanism of polymer films and activation energies for radical transfer reactions.
Triethylborane has been shown to react with nitrogen atoms, forming boron and triethylborane.
This reaction occurs at low energy and the reactive site is the carbonyl group.
Triethylborane can also react with zirconium oxide, forming a boron nitride product.
TEB is a boron alkyl used in organic synthesis as an agent for stereochemical control, and as an adjuvant for Ziegler-Natta and silica-supported chromium catalysts for olefin polymerization.
General Manufacturing Information of Triethylborane:
Mixtures with triethylaluminum have been used as hypergolic igniters for rocket propulsion systems.
Because of the low volume of organoboranes and the expensive raw material that are required for manufacture, organoboranes are expensive chemical products.
Applications of Triethylborane:
Radical initiator for hydrostannylation of alkynes.
Reacts with metal enolates to give the enoxytriethylborates, useful in selective alkylation and aldol reactions.
Triethylborane is used with lithium tri-tert-butoxyaluminohydride in the reductive cleavage.
Triethylborane is used in the deoxygenation of primary and secondary alcohols.
A raw material for a wide variety of boron compounds.
Protection OH-groups in organic compounds.
Rapid gasometric determination of OH-groups in alcohols, phenols, diols, sugars and other compound.
Water content determination in crystalline, hydrates of inorganic, complex and organic salts.
Preparative dehydration of salt and sugar hydrates.
Triethylborane was used to ignite the JP-7 fuel in the Pratt & Whitney J58 turbojet/ramjet engines powering the Lockheed SR-71 Blackbird spy plane, and Triethylborane predecessor A-12 OXCART.
Triethylborane is suitable for this because of Triethylborane pyrophoric properties, especially the fact that Triethylborane burns with very high temperature.
Triethylborane was chosen as an ignition method for reliability reasons, because the JP-7 fuel has very low volatility and is difficult to ignite.
Classical ignition plugs posed too high risk of a malfunction.
Triethylborane is used in 50 cm3 doses to start up each engine and to light the afterburners.
Industrially, triethylborane is used as an initiator in radical reactions, where Triethylborane is effective even at low temperatures.
As an initiator, Triethylborane can replace some organotin compounds.
Triethylborane reacts with metal enolates, yielding enoxytriethylborates with use in selective alkylation and aldol reactions.
Triethylborane is also used in reduction bond cleavage with lithium tri-tert-butoxyaluminohydride, in preparation of various boron compounds, deoxygenation of primary and secondary alcohols, rapid determination of -OH groups in organic compounds, dehydration of salt and sugar hydrates, determination of water content in crystalline hydrate compounds, in a variant of Reformatskii reaction, and has a range of other uses in organoborane chemistry.
Triethylborane is used in vapor deposition techniques as a boron source.
Examples are the plasma deposition of boron-containing hard carbon films, silicon nitride-boron nitride films, and for doping of diamond film with boron.
Other boron precursors used for such applications are eg. trimethylborane, boron trifluoride, diborane, and decaborane.
Sodium tetraethyl borate (NaTEB), a triethylboron derivative, is used as a powerful ethylation agent.
Reagent for:
Enantioselective umpolung allylation of aldehydes
Preparation of tetramethylammonium trialkylphenylborate salts
Catalyst for:
Radical reductions of alkyl bromides and iodides bearing electron withdrawing groups with N-heterocyclic carbene boranes
Synthesis of 1-substituted pyrrolines by N-diallylation of amines and ring-closing metathesis
Decarboxylative C-C bond cleavage reactions
Alkene hydrogenations
Aminyl radical cyclizations onto silyl enol ethers
Modifier for single-site organochromium ethylene polymerization catalysts
Triethylborane is used with lithium tri-tert-butoxyaluminohydride (cat. no. L2904) in the reductive cleavage of ethers and epoxides.
Triethylborane is used in the deoxygenation of primary and secondary alcohols.
Turbojet engine:
Triethylborane was used to ignite the JP-7 fuel in the Pratt & Whitney J58 turbojet/ramjet engines powering the Lockheed SR-71 Blackbird and Triethylborane predecessor, the A-12 OXCART.
Triethylborane is suitable because Triethylborane ignites readily upon exposure to oxygen.
Triethylborane was chosen as an ignition method for reliability reasons, and in the case of the Blackbird, because JP-7 fuel has very low volatility and is difficult to ignite.
Conventional ignition plugs posed a high risk of malfunction.
Triethylborane was used to start each engine and to ignite the afterburners.
Rocket:
Mixed with 10–15% triethylaluminium, Triethylborane was used before lift-off to ignite the F-1 engines on the Saturn V rocket.
The SpaceX Falcon 9 rocket also uses a triethylaluminium-triethylborane mixture (TEA-TEB) as a first- and second-stage ignitor.
Organic chemistry of Triethylborane:
Industrially, triethylborane is used as an initiator in radical reactions, where Triethylborane is effective even at low temperatures.
As an initiator, Triethylborane can replace some organotin compounds.
Triethylborane reacts with metal enolates, yielding enoxytriethylborates that can be alkylated at the α-carbon atom of the ketone more selectively than in Triethylboranes absence.
For example, the enolate from treating cyclohexanone with potassium hydride produces 2-allylcyclohexanone in 90% yield when triethylborane is present.
Without Triethylborane, Triethylborane mixture contains 43% of the mono-allylated product, 31% di-allylated cyclohexanones, and 28% unreacted starting material.
The choice of base and temperature influences whether the more or less stable enolate is produced, allowing control over the position of substituents.
Starting from 2-methylcyclohexanone, reacting with potassium hydride and triethylborane in THF at room temperature leads to the more substituted (and more stable) enolate, whilst reaction at −78 °C with potassium hexamethyldisilazide, KN[Si(CH3)3]
2 and triethylborane generates the less substituted (and less stable) enolate.
After reaction with methyl iodide the former mixture gives 2,2-dimethylcyclohexanone in 90% yield while the latter produces 2,6-dimethylcyclohexanone in 93% yield.
Triethylborane is used in the Barton–McCombie deoxygenation reaction for deoxygenation of alcohols.
In combination with lithium tri-tert-butoxyaluminum hydride Triethylborane cleaves ethers.
For example, THF is converted, after hydrolysis, to 1-butanol.
Triethylborane also promotes certain variants of the Reformatskii reaction.
Triethylborane is the precursor to the reducing agents lithium triethylborohydride ("Superhydride") and sodium triethylborohydride.
MH + Et3B → MBHEt3 (M = Li, Na)
Triethylborane reacts with methanol to form diethyl(methoxy)borane, which is used as the chelating agent in the Narasaka–Prasad reduction for the stereoselective generation of syn-1,3-diols from β-hydroxyketones.
Preparation and structure of Triethylborane:
Triethylborane is prepared by the reaction of trimethyl borate with triethylaluminium:
Et3Al + (MeO)3B → Et3B + (MeO)3Al
The molecule is monomeric, unlike H3B and Et3Al, which tend to dimerize.
Triethylborane has a planar BC3 core.
Uses of Triethylborane:
Triethylborane is used as a fuel additive, fuel igniter, polymerization catalyst, and intermediate.
Triethylborane is used in organic syntheses (radical initiator and blocking agent).
Fuel additive; igniter or fuel for jet and rocket engines; olefin polymerization catalyst; intermediate
Triethylborane (TEB) is used by the USAF as a fuel additive to nonhypergolic propellants to increase fuel ignition speed and retard engine flameout.
Methods of Manufacturing of Triethylborane:
Reaction of triethylaluminum and boron halide, or diborane and ethylene
Purification Methods of Triethylborane:
Triethylborane distils at 56-57o/220mm.
Triethylborane can also be purified via Triethylborane ammonia addition complex which is distilled in a high vacuum, decomposed with dry HCl, and the Et3B is distilled out.
Triethylborane is commercially available as a 15% solution in hexane or as 1M solution in hexane.
Chemical Properties of Triethylborane:
Clear colourless to light amber solution.
Miscible with most organic solvents; immiscible with water.
Handling and Storage of Triethylborane:
Precautions for safe handling of Triethylborane:
Handling in a well ventilated place.
Wear suitable protective clothing.
Avoid contact with skin and eyes.
Avoid formation of dust and aerosols.
Use non-sparking tools.
Prevent fire caused by electrostatic discharge steam.
Conditions for safe storage, including any incompatibilities of Triethylborane:
Store the container tightly closed in a dry, cool and well-ventilated place.
Store apart from foodstuff containers or incompatible materials.
Safety of Triethylborane:
Triethylborane is strongly pyrophoric, with an autoignition temperature of −20 °C (−4 °F), burning with an apple-green flame characteristic for boron compounds.
Thus, Triethylborane is typically handled and stored using air-free techniques.
Triethylborane is also acutely toxic if swallowed, with an LD50 of 235 mg/kg in rat test subjects.
Poison by ingestion and intraperitoneal routes.
Mildly toxic by inhalation.
Animal experiments show that the vapor is a poison which causes pulmonary irritation and convulsions.
A very dangerous fire hazard by spontaneous chemical reaction with oxichzers.
Spontaneously flammable in air.
Explodes in oxygen atmospheres.
Hypergolic reaction with triethylaluminum.
Ignites on contact with chlorine, bromine, or other halogens.
Will react with water or steam to produce toxic and flammable vapors.
To fight fire, do NOT use halogenated extinguishing agents.
When heated to decomposition or upon contact with air Triethylborane emits toxic acrid smoke and irritating fumes.
Disposal Methods of Triethylborane:
The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination.
Recycle any unused portion of the material for Triethylborane approved use or return Triethylborane to the manufacturer or supplier.
Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.
Preventive Measures of Triethylborane:
The scientific literature for the use of contact lenses in industry is conflicting.
The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses.
However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye.
In those specific cases, contact lenses should not be worn.
In any event, the usual eye protection equipment should be worn even when contact lenses are in place.
All equipment should be fully enclosed and carefully designed to eliminate any likelihood of autoignition.
All equipment must be purged before opening.
All possible sources of ignition should be eliminated and processes in which boron hydrides are heated must be minutely controlled.
Automatic leak detectors with visual and acoustic warning signals should be fitted.
Where possible, processes should be automated or operated by remote control.
All containers should be thoroughly flushed before maintenance work is carried out on them and, in event of leakage, only persons with adequate personal protective equipment should be allowed in vicinity of containers.
Identifiers of Triethylborane:
CAS Number: 97-94-9
ChemSpider: 7079
ECHA InfoCard: 100.002.383
EC Number: 202-620-9
PubChem CID: 7357
UNII: Z3S980Z4P3
CompTox Dashboard (EPA): DTXSID2052653
InChI: InChI=1S/C6H15B/c1-4-7(5-2)6-3/h4-6H2,1-3H3 check
Key: LALRXNPLTWZJIJ-UHFFFAOYSA-N check
InChI=1/C6H15B/c1-4-7(5-2)6-3/h4-6H2,1-3H3
Key: LALRXNPLTWZJIJ-UHFFFAOYAU
SMILES: B(CC)(CC)CC
Properties of Triethylborane:
Chemical formula: C6H15B
Molar mass: 98.00 g/mol
Appearance: Colorless to pale yellow liquid
Density: 0.677 g/cm3
Melting point: −93 °C (−135 °F; 180 K)
Boiling point: 95 °C (203 °F; 368 K)
Solubility in water: Not applicable; highly reactive
Quality Level: 100
Assay: ≥95%
Reaction suitability: reagent type - reductant
Refractive index: n20/D 1.397 (lit.)
bp: 95 °C (lit.)
mp: −93 °C (lit.)
Density: 0.677 g/mL at 25 °C (lit.)
SMILES string: CCB(CC)CC
InChI: 1S/C6H15B/c1-4-7(5-2)6-3/h4-6H2,1-3H3
InChI key: LALRXNPLTWZJIJ-UHFFFAOYSA-N
Molecular Weight: 98.00
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 0
Rotatable Bond Count: 3
Exact Mass: 98.1266806
Monoisotopic Mass: 98.1266806
Topological Polar Surface Area: 0 Ų
Heavy Atom Count: 7
Complexity: 25.7
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 1
Compound Is Canonicalized: Yes
Specifications of Triethylborane:
Concentration or Composition (by Analyte or Components): 1M soln. in THF
Flash Point: −17°C (1°F)
Linear Formula: (CH3CH2)3B
UN Number: UN2924
Quantity: 25mL
Solubility Information: Reacts with water.
Sensitivity: Air Sensitive
Formula Weight: 98
Chemical Name or Material: Triethylborane
Class of Triethylborane:
Specialty Chemicals
Functions of Triethylborane:
Catalyst, Additive
Related compounds of Triethylborane:
Tetraethyllead
Diborane
Sodium tetraethylborate
Trimethylborane
Names of Triethylborane:
Preferred IUPAC name of Triethylborane:
Triethylborane
Other names of Triethylborane:
Triethylborine, triethylboron
Synonyms of Triethylborane:
Triethylborane
97-94-9
TRIETHYLBORON
Borane, triethyl-
Triethylborine
UNII-Z3S980Z4P3
Z3S980Z4P3
Boron triethyl
Boron ethyl
MFCD00009022
HSDB 897
EINECS 202-620-9
BRN 1731462
triethylboran
Borethyl
triethyl borane
triethyl-borane
BEt3
Et3B
Triethylborane, >=95%
4-04-00-04359
DTXSID2052653
(C2H5)3B
AKOS009156530
ZINC169743058
Triethylborane solution, 1.0 M in THF
Triethylborane solution, 1.0 M in hexanes
FT-0655589
T1984
Triethylborane solution, 2.0 M in diethyl ether
A845771
Q421149
