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Monochloroborane-dimethylsulfide, BH2Cl.SMe2, is formed in essentially quantitative yield upon reflux of an equimolar mixture of borane–dimethyl sulphide, BH3.SMe2, and tetrachloromethane; it can be used directly for production of dialkylchloroboranes by the hydroboration of alkenes.
Monochloroborane-dimethylsulfide is a chemical adduct formed by the coordination of monochloroborane (BH₂Cl) with dimethyl sulfide (CH₃)₂S, in which the electron-deficient boron atom of monochloroborane forms a dative (coordinate covalent) bond with the lone pair of electrons on the sulfur atom of dimethyl sulfide, creating a stabilized complex that is easier to handle than free monochloroborane.
Monochloroborane-dimethylsulfide has the chemical formula typically represented as BH₂Cl·S(CH₃)₂, and it exists as a colorless to pale yellow liquid under standard conditions, with a pungent odor reminiscent of sulfur-containing compounds.
CAS Number: 63348-81-2
Molecular Formula: C2H9BClS
Molecular Weight: 111.41
Synonyms:63348-81-2, chloro-(dimethyl-lambda4-sulfanylidene)borane, SCHEMBL7533425, KFDWJBJKOSFDRY-UHFFFAOYSA-N, AS-87655, DB-054459, MONOCHLOROBORANE-METHYLSULFIDE;MONOCHLOROBORANE-METHYL SULFIDE COMPLEX;BORON MONOCHLORIDE-METHYL SULFIDE COMPLEX;CHLOROBORANE-METHYL SULFIDE COMPLEX;Boron, chlorodihydrothiobismethane-, (T-4)-;Boron monochloride methyl sulfide complex, monoChloroborane methyl sulfide complex;Chloroborane methyl;Chloro(dimethyl sulfide)dihydroboron
Monochloroborane-dimethylsulfide reduces the extreme reactivity of Monochloroborane-dimethylsulfide, which is otherwise highly pyrophoric and prone to violent reactions with moisture, air, and many organic compounds, making it suitable as a controlled reagent in laboratory and industrial synthetic chemistry.
Monochloroborane-dimethylsulfide serves as a source of the reactive BH₂Cl fragment in a more stable form, allowing it to participate in hydroboration reactions, selective reduction reactions, and the formation of organoboron intermediates used in the synthesis of alcohols, amines, and other functionalized organic molecules.
Because the boron center is electron-deficient, the compound retains significant Lewis acidity, which is exploited in organic synthesis and catalytic processes.
Monochloroborane-dimethylsulfide is also moisture-sensitive, slowly releasing hydrogen chloride and borane when exposed to water, which means that strict anhydrous conditions and inert atmosphere handling (e.g., under nitrogen or argon) are required to maintain stability and prevent hazardous reactions.
Monochloroborane-dimethylsulfide is a stabilized, convenient form of highly reactive monochloroborane, formed through the coordination of dimethyl sulfide to boron, that allows chemists to perform controlled organoboron chemistry, selective reductions, and hydroboration reactions, while significantly reducing the risks associated with handling the free, highly reactive borane species.
Monochloroborane-dimethylsulfide is a Lewis acid–base adduct in which the electron-deficient boron atom of monochloroborane (BH₂Cl) forms a dative covalent bond with the lone pair of electrons on the sulfur atom of dimethyl sulfide (CH₃)₂S, producing a stabilized complex that is significantly less reactive and more manageable than free monochloroborane, while retaining the ability to act as a source of the highly reactive BH₂Cl fragment in synthetic transformations.
This adduct typically exists as a colorless to pale yellow liquid with a sharp, sulfur-like odor, and it is highly moisture-sensitive, reacting slowly with water to release borane and hydrogen chloride, which necessitates handling under strictly anhydrous conditions in inert atmospheres such as nitrogen or argon to prevent accidental hydrolysis or release of corrosive gases.
In addition to its role in hydroboration and reductions, Monochloroborane–dimethylsulfide is employed in specialty organoboron chemistry as a reagent for generating boron-containing intermediates, catalytically functionalized materials, and boron-mediated transformations, where its Lewis acidic boron center can coordinate to electron-rich sites on organic molecules, facilitating regioselective or stereoselective transformations.
Its controlled reactivity makes it suitable for multistep synthetic sequences, where the stability provided by the dimethyl sulfide ligand allows chemists to manipulate highly reactive boron species safely, perform sensitive reactions with minimal risk, and achieve high yields and selectivity.
Density: 1.059 g/mL at 25 °C (lit.)
Flash point: 76 °F
solubility: soluble in Benzene, Chloroform
form: Oil
color: Clear Colourless
Stability: Hygroscopic, Moisture Sensitive
UNSPSC Code: 12352101
NACRES: NA.22
Monochloroborane-dimethylsulfide is valued for its controlled reactivity in organic synthesis, where the boron center retains its strong Lewis acidity, enabling hydroboration of alkenes and alkynes, selective reduction of functional groups, and the generation of organoboron intermediates that are subsequently transformed into alcohols, amines, or other functionalized organic molecules.
Its stability relative to free BH₂Cl makes it suitable for laboratory-scale and industrial applications, as it can be weighed, measured, and handled safely under controlled conditions, allowing chemists to exploit the unique reactivity of boron–hydride species without the extreme hazards of pyrophoricity or violent moisture reactions.
Furthermore, the compound’s structure, combining a reactive boron moiety with a neutral sulfur donor ligand, enables it to act as a versatile reagent in catalytic or stoichiometric organoboron chemistry, providing a convenient and reliable source of boron for synthetic transformations.
Its use is particularly important in complex organic synthesis, pharmaceutical intermediate production, and specialized chemical research, where the generation of organoboron species under controlled conditions is critical for selectivity, yield, and safety.
In essence, Monochloroborane–dimethylsulfide represents a strategically stabilized form of monochloroborane, which allows chemists to access the powerful reactivity of BH₂Cl for hydroboration, reduction, and organoboron synthesis, while significantly reducing the handling hazards, pyrophoricity, and moisture sensitivity associated with free borane species, making it an indispensable reagent in both laboratory and industrial organoboron chemistry.
Monochloroborane-dimethylsulfide is a stabilized organoboron reagent formed by the coordination of highly reactive monochloroborane (BH₂Cl) with the lone electron pair of dimethyl sulfide (CH₃)₂S, resulting in a dative covalent bond that significantly moderates the extreme reactivity of BH₂Cl, making it safer and more manageable to store, transport, and handle in laboratory and industrial settings, while still retaining the essential boron-centered reactivity that allows it to participate in a wide range of organic transformations.
The adduct exists as a colorless to pale yellow liquid with a characteristic sulfurous odor, and it is extremely sensitive to moisture, as contact with water leads to hydrolysis, releasing borane species and hydrogen chloride, which can be corrosive and potentially hazardous, emphasizing the need for strict anhydrous handling and the use of inert gas atmospheres such as nitrogen or argon to maintain stability.
Chemically, Monochloroborane–dimethylsulfide serves as a versatile source of the BH₂Cl fragment, which can engage in hydroboration of unsaturated bonds, selective reduction of carbonyl and other functional groups, and the formation of organoboron intermediates that are subsequently converted into alcohols, amines, or other functionalized organic compounds, making it an essential reagent in complex organic synthesis, pharmaceutical intermediate production, and the preparation of fine chemicals.
The presence of the dimethyl sulfide ligand not only stabilizes the otherwise pyrophoric borane species but also allows for controlled release of reactive boron under desired conditions, enabling precise stoichiometric reactions and minimizing the risks of uncontrolled exothermic reactions or fires.
Uses Of Monochloroborane-dimethylsulfide:
Monochloroborane–dimethylsulfide is primarily utilized in organic synthesis and organoboron chemistry as a stabilized source of the highly reactive BH₂Cl fragment, which allows chemists to perform controlled hydroboration reactions on alkenes and alkynes, selectively adding boron across carbon–carbon multiple bonds to produce organoboron intermediates that can subsequently be converted into alcohols, amines, or other functionalized molecules, providing a safer and more manageable alternative to using free monochloroborane, which is highly pyrophoric and extremely sensitive to moisture.
In addition to hydroboration, the compound is applied in selective reductions of carbonyl compounds, including ketones and aldehydes, as well as other electrophilic functional groups, where the BH₂Cl moiety can act as a mild and controlled reducing agent, offering high regioselectivity and stereoselectivity, which is particularly valuable in the synthesis of pharmaceuticals, fine chemicals, and complex organic intermediates where precise control over reaction outcomes is critical.
Monochloroborane–dimethylsulfide is also used in the preparation of specialized boron-containing reagents and organoboron compounds for cross-coupling reactions, metal-catalyzed transformations, and the generation of boron-functionalized polymers or heterocycles, enabling chemists to construct complex molecular architectures that would be difficult or dangerous to achieve using more reactive or less stable borane sources.
Furthermore, it is employed in research and industrial laboratories for boron-mediated functionalizations, where the dimethyl sulfide ligand provides stability and controlled release of reactive BH₂Cl, allowing synthetic chemists to conduct reactions under safer, reproducible, and scalable conditions, while still exploiting the highly reactive nature of boron to create target molecules with precise chemical, stereochemical, and functional outcomes.
In essence, Monochloroborane–dimethylsulfide is a versatile, indispensable reagent in modern synthetic organic chemistry, bridging the gap between the high reactivity of free boranes and practical, controlled applications, and it is widely used in hydroboration, selective reductions, synthesis of organoboron intermediates, preparation of pharmaceutical and fine chemical precursors, and specialized boron-containing materials, making it a cornerstone reagent for complex molecule construction under safer and more controlled laboratory and industrial conditions.
Monochloroborane–dimethylsulfide serves as a highly valuable and versatile reagent in synthetic organic chemistry due to its ability to act as a stabilized yet reactive source of the BH₂Cl moiety, which enables chemists to carry out hydroboration reactions on a broad range of alkenes and alkynes with excellent regioselectivity and stereoselectivity, producing organoboron intermediates that can be subsequently converted into alcohols, amines, or other functionalized molecules through oxidation, substitution, or cross-coupling reactions, providing access to complex and highly functionalized organic compounds that are essential in pharmaceuticals, agrochemicals, and fine chemical synthesis.
In addition to hydroboration, Monochloroborane-dimethylsulfide is employed in the selective reduction of carbonyl-containing functional groups, including ketones, aldehydes, and acid derivatives, as well as other electrophilic substrates, where the BH₂Cl fragment acts as a mild, controllable reducing agent, offering precise control over reaction rates, chemoselectivity, and stereochemical outcomes, which is critical in the synthesis of complex natural products, chiral intermediates, and active pharmaceutical ingredients where even minor deviations in reaction conditions could lead to unwanted byproducts or loss of stereochemical integrity.
Monochloroborane–dimethylsulfide is also widely used in the preparation of organoboron intermediates for subsequent cross-coupling reactions, such as Suzuki–Miyaura couplings, and in the synthesis of boron-functionalized polymers, heterocycles, and advanced materials, where the compound’s stability allows chemists to handle, store, and measure the reagent safely while still harnessing the highly reactive BH₂Cl fragment to construct complex molecular architectures that would otherwise be difficult or hazardous to generate using free borane or monochloroborane.
Furthermore, in research and industrial laboratories, the reagent is employed for boron-mediated functionalizations where the dimethyl sulfide ligand stabilizes the borane center, permitting controlled release of BH₂Cl under carefully monitored conditions, which enables precise tuning of reaction kinetics, stoichiometry, and selectivity, thereby facilitating multistep syntheses, scale-up processes, and the production of highly specialized intermediates for pharmaceuticals, fine chemicals, or materials science applications where both safety and efficiency are paramount.
Safety Profile Of Monochloroborane-dimethylsulfide:
Monochloroborane-dimethylsulfide can cause severe skin and eye irritation upon direct contact, leading to redness, itching, pain, or chemical burns, because the BH₂Cl moiety is highly reactive and can hydrolyze in the presence of moisture on skin or in the eyes to release corrosive hydrogen chloride and reactive borane species, making protective gloves, long-sleeved garments, and safety goggles essential when handling the chemical in any laboratory or industrial environment.
Inhalation of vapors, aerosols, or fumes from Monochloroborane–dimethylsulfide can irritate the mucous membranes of the nose, throat, and lungs, producing coughing, sore throat, nasal discomfort, shortness of breath, or more severe respiratory distress under prolonged or high-level exposure, particularly because hydrolysis can generate acidic vapors and highly reactive boron hydrides, emphasizing the importance of working under fume hoods, in well-ventilated areas, or with appropriate respiratory protection.
The compound is highly moisture-sensitive and chemically reactive, undergoing hydrolysis upon contact with water, alcohols, or other nucleophiles to produce borane, hydrogen chloride, and other reactive intermediates, which can cause chemical burns, fires, or uncontrolled reactions, making it critical to store and handle the reagent under strictly anhydrous conditions with inert gas (nitrogen or argon) and avoid contact with incompatible chemicals such as strong oxidizers, acids, or bases.
