TRIETHYLBORANE

Triethylborane, a pyrophoric liquid, serves as a versatile agent in organic synthesis, aiding in stereochemical control and acting as a catalyst for olefin polymerization alongside Ziegler-Natta and silica-supported chromium catalysts.

Triethylborane chemical formula is (CH3CH2)3B or (C2H5)3B, abbreviated Et3B.

Triethylborane is a chemical compound that is used as a reagent in organic chemistry.

CAS Number: 97-94-9

EC Number: 202-620-9

Molecular Formula: C6H15B

Molecular Weight (g/mol): 98.00

Synonyms: Triethylborane, 97-94-9, TRIETHYLBORON, Borane, triethyl-, Triethylborine, Z3S980Z4P3, Boron triethyl, Boron ethyl, MFCD00009022, HSDB 897, EINECS 202-620-9, BRN 1731462, triethylboran, Borethyl, triethyl borane, triethyl-borane, UNII-Z3S980Z4P3, BEt3, Et3B, Triethylborane, >=95%, TRIETHYLBORANE [MI], 4-04-00-04359 (Beilstein Handbook Reference), DTXSID2052653, (C2H5)3B, AKOS009156530, FT-0655589, T1984, EN300-35961, A845771, Q421149, 202-620-9 [EINECS], 4-04-00-04359 (Beilstein Handbook Reference) [Beilstein], 97-94-9 [RN], Borane, triethyl- [ACD/Index Name], ED2100000, Et3B [Formula], MFCD00009022 [MDL number], Triethylboran [German] [ACD/IUPAC Name], Triethylborane [ACD/IUPAC Name], Triéthylborane [French] [ACD/IUPAC Name], Trietilborano [Spanish], trietilborine [Spanish], トリエチルボラン [Japanese], (C2H5)3B, Borethyl, Boron triethyl, EINECS 202-620-9, TL8006029, Triethylboranemissing, TRIETHYLBORINE, Triethylborron?Boron Triethyl?

Triethylborane is a boron alkyl used in organic synthesis as an agent for stereochemical control, and as an adjuvant and silica-supported chromium catalysts for olefin polymerization.

Triethylborane, also called triethylboron, is an organoborane (a compound with a B–C bond).

Triethylborane is a colorless pyrophoric liquid.

Triethylborane chemical formula is (CH3CH2)3B or (C2H5)3B, abbreviated Et3B.

Triethylborane is soluble in organic solvents tetrahydrofuran and hexane

Triethylborane is an organoborane pyrophoric liquid.

Triethylborane is prepared on the plant scale by the reaction of AlEt3 and KBF4.

Triethylborane 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 registered under the REACH Regulation and is manufactured in and / or imported to the European Economic Area, for intermediate use only.

Triethylborane is used in formulation or re-packing, at industrial sites and in manufacturing.

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.

Triethylborane chemical formula can be written as C6H15B, or (CH3CH2)3B, or (C2H5)3B, or Et3B.

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 Triethylborane 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.

Triethylborane 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.

Uses of Triethylborane:

Triethylborane is radical initiator for hydrostannylation of alkynes.

Triethylborane is 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.

Triethylborane is raw material for a wide variety of boron compounds.

Triethylborane is used in protection OH-groups in organic compounds.

Triethylborane is used in rapid gasometric determination of OH-groups in alcohols, phenols, diols, sugars and other compound.

Triethylborane is used in water content determination in crystalline, hydrates of inorganic, complex and organic salts.

Triethylborane is used in preparative dehydration of salt and sugar hydrates.

Applications of Triethylborane:

Reactant for radical reductions of alkyl bromides with N-heterocyclic carbene boranes and synthesis of tetramethylammonium trialkylphenylborate salts with oxidation potential.

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.

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 Merlin engines that power the SpaceX Falcon 9 rocket use a triethylaluminium-triethylborane mixture (TEA-TEB) as a first- and second-stage ignitor.

The Firefly Aerospace Alpha launch vehicle’s Reaver engines are also ignited by a triethylaluminium-triethylborane mixture.

Organic chemistry:

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 Triethylborane absence.

For example, the enolate from treating cyclohexanone with potassium hydride produces 2-allylcyclohexanone in 90% yield when triethylborane is present.

Without Triethylborane, the product 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 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.

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 in the reductive cleavage of ethers and epoxides.

Triethylborane is used in the deoxygenation of primary and secondary alcohols.

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.

Handling and Storage of Triethylborane:

Advice on safe handling:

Work under hood.

Do not inhale Triethylborane/mixture.

Avoid generation of vapours/aerosols.

Hygiene measures:

Immediately change contaminated clothing.

Apply preventive skin protection.

Wash hands and face after working with Triethylborane.

Storage conditions:

Tightly closed.

Keep away from heat and sources of ignition.

Keep locked up or in an area accessible only to qualified or authorized persons.

Handle and store under inert gas.

Air sensitive.

Storage class:

Storage class (TRGS 510): 4.2: Pyrophoric and self-heating hazardous materials

Stability and Reactivity of Triethylborane:

Chemical stability:

Sensitive to air.

Conditions to avoid:

Pyrophoric

Exposure to air.

Incompatible materials:

Strong oxidizing agents

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.

First Aid Measures of Triethylborane:

General advice:

First aiders need to protect themselves.

Show Triethylborane safety data sheet to the doctor in attendance.

After inhalation:

Fresh air.

Call in physician.

In case of skin contact:

Take off immediately all contaminated clothing.

Rinse skin with water/ shower.

Call a physician immediately.

After eye contact:

Rinse out with plenty of water.

Immediately call in ophthalmologist.

Remove contact lenses.

If swallowed:

Give water to drink (two glasses at most).

Seek medical advice immediately.

In exceptional cases only, if medical care is not available within one hour, induce vomiting (only in persons who are wide awake and fully conscious), administer activated charcoal (20 – 40 g in a 10% slurry) and consult a doctor as quickly as possible.

Do not attempt to neutralise.

Firefighting Measures of Triethylborane:

Suitable extinguishing media:

Foam Carbon dioxide (CO2) Dry powder

Unsuitable extinguishing media:

For Triethylborane/mixture no limitations of extinguishing agents are given.

Special hazards arising from Triethylborane or mixture:

Carbon oxides

Borane/boron oxides

Combustible.

Development of hazardous combustion gases or vapours possible in the event of fire.

Advice for firefighters:

Stay in danger area only with self-contained breathing apparatus.

Prevent skin contact by keeping a safe distance or by wearing suitable protective clothing.

Further information:

Prevent fire extinguishing water from contaminating surface water or the ground water system.

Accidental Release Measures of Triethylborane:

Advice for non-emergency personnel:

Do not breathe vapors, aerosols.

Avoid Triethylborane contact.

Ensure adequate ventilation.

Evacuate the danger area, observe emergency procedures, consult an expert.

Environmental precautions:

Do not let product enter drains.

Methods and materials for containment and cleaning up:

Cover drains.

Collect, bind, and pump off spills.

Observe possible material restrictions.

Take up carefully with liquid-absorbent material.

Dispose of properly.

Clean up affected area.

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

Key: LALRXNPLTWZJIJ-UHFFFAOYSA-N

InChI=1/C6H15B/c1-4-7(5-2)6-3/h4-6H2,1-3H3

Key: LALRXNPLTWZJIJ-UHFFFAOYAU

SMILES: B(CC)(CC)CC

Linear Formula: (C2H5)3B

MDL Number: MFCD00009022

EC No.: 202-620-9

Beilstein/Reaxys No.: N/A

Pubchem CID: 7357

IUPAC Name: triethylborane

SMILES: B(CC)(CC)CC

InchI Identifier: InChI=1S/C6H15B/c1-4-7(5-2)6-3/h4-6H2,1-3H3

InchI Key: LALRXNPLTWZJIJ-UHFFFAOYSA-N

CAS: 97-94-9

Molecular Formula: C6H15B

Molecular Weight (g/mol): 98.00

MDL Number: MFCD00009022

InChI Key: LALRXNPLTWZJIJ-UHFFFAOYSA-N

PubChem CID: 7357

IUPAC Name: triethylborane

SMILES: CCB(CC)CC

EC / List no.: 202-620-9

CAS no.: 97-94-9

Mol. formula: C6H15B

Synonym(s): Triethylboron

Linear Formula: (C2H5)3B

CAS Number: 97-94-9

Molecular Weight: 97.99

EC Number: 202-620-9

MDL number: MFCD00009022

PubChem Substance ID: 24855572

NACRES: NA.22

Properties of Triethylborane:

Chemical formula: (CH3CH2)3B

Molar mass: 98.00 g/mol

Appearance: Colorless 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

Compound Formula: C6H15B

Molecular Weight: 97.99

Appearance: Colorless liquid

Melting Point: −93 °C

Boiling Point: 95 °C

Density: 0.677 g/mL

Solubility in H2O: N/A

Refractive Index: n20/D 1.397

Exact Mass: 98.126681

Monoisotopic Mass: 98.126681

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 g/mol

Hydrogen Bond Donor Count: 0

Hydrogen Bond Acceptor Count: 0

Rotatable Bond Count: 3

Exact Mass: 98.1266806 g/mol

Monoisotopic Mass: 98.1266806 g/mol

Topological Polar Surface Area: 0Å²

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:

Density: 0.865

Flash Point: −17°C (1°F)

Linear Formula: (CH3CH2)3B

Quantity: 25 mL

UN Number: UN2924

Beilstein: 1731462

Sensitivity: Air Sensitive

Solubility Information: Reacts with water.

Formula Weight: 98

Concentration or Composition (by Analyte or Components): 1M soln. in THF

Chemical Name or Material: Triethylborane

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