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Dimethyldichlorosilane

Dimethyldichlorosilane, also known as dichlorodimethylsilane, is an organosilicon compound with the molecular formula C₂H₆Cl₂Si and a molecular weight of 129.07 g/mol. It features a tetrahedral structure centered on a silicon atom bonded to two methyl (CH₃) groups and two chlorine atoms, making it a key difunctional silane. At room temperature, it exists as a colorless, fuming liquid with a pungent odor, characterized by a melting point of -86°C, a boiling point of 70–71°C, a density of 1.06–1.07 g/mL, and a flash point of approximately -9°C.^[1]^[2]^[3] Dimethyldichlorosilane is produced on an industrial scale through the Müller-Rochow process, a direct synthesis method involving the copper-catalyzed reaction of finely ground elemental silicon with methyl chloride gas at elevated temperatures of 250–350°C, yielding a mixture of chlorosilanes from which it is distilled.^[4] This process, developed in the mid-20th century, accounts for the majority of global production, classifying dimethyldichlorosilane as a high-production-volume chemical with annual outputs in the millions of tons to support the silicone industry.^[1]^[5] The compound serves primarily as a foundational precursor in the manufacture of silicones, undergoing controlled hydrolysis to form silanol intermediates that polymerize into polydimethylsiloxane (PDMS) and related materials, which are widely used in sealants, adhesives, lubricants, medical devices, and coatings due to their thermal stability, flexibility, and water repellency.^[5]^[6] It also functions as a silane coupling agent for surface modification of nanoparticles and in the synthesis of specialty polysilanes.^[7] Handling dimethyldichlorosilane requires stringent precautions, as it is highly flammable, corrosive to skin and eyes, and reacts exothermically with water or moist air to liberate toxic hydrogen chloride gas, potentially causing severe burns or respiratory damage.^[8]^[9] It is denser than water, with vapors heavier than air, posing risks of pooling and ignition in confined spaces.^[1]

Properties

Physical properties

Dimethyldichlorosilane, with the chemical formula (CH₃)₂SiCl₂, has a molecular weight of 129.06 g/mol.^[10] It appears as a colorless fuming liquid at room temperature, characterized by a pungent odor.^[8] Key thermodynamic properties include a boiling point of 70 °C and a melting point of −76 °C.^[10] The compound has a density of 1.07 g/cm³ at 25 °C and a refractive index of 1.404 at 20 °C.^[10]^[2]

Property	Value	Conditions/Source
Density	1.07 g/cm³	25 °C^[10]
Refractive index	1.404	n₂₀/D^[10]
Boiling point	70 °C	lit.^[10]
Melting point	−76 °C	lit.^[10]
Flash point	−9 °C	closed cup^[2]
Vapor pressure	14.5 kPa	20 °C^[2]
Relative vapor density	4.4	(air = 1)^[2]

Dimethyldichlorosilane is immiscible with water, though it reacts vigorously upon contact, and it is soluble in organic solvents such as benzene and ether.^[11] Its vapors are heavier than air, contributing to potential accumulation in low-lying areas.^[8]

Chemical properties

Dimethyldichlorosilane features a tetrahedral molecular geometry, with the central silicon atom bonded to two methyl groups and two chlorine atoms via covalent bonds, exhibiting bond angles close to the ideal tetrahedral value of 109.5°.<grok:render type="render_inline_citation"> 20 </grok:render> This structure contributes to its organosilicon character, distinguishing it from carbon-based analogs due to the larger size and lower electronegativity of silicon compared to carbon.<grok:render type="render_inline_citation"> 20 </grok:render> The compound displays high reactivity attributable to the Si-Cl bonds, which are highly polar with partial positive charge on silicon, rendering the molecule susceptible to nucleophilic attack by moisture, water, or other nucleophiles such as alcohols and amines.<grok:render type="render_inline_citation"> 20 </grok:render><grok:render type="render_inline_citation"> 23 </grok:render> This polarity facilitates the release of chloride ions, positioning dimethyldichlorosilane as an effective chlorinating agent and source of chloride in synthetic transformations.<grok:render type="render_inline_citation"> 20 </grok:render><grok:render type="render_inline_citation"> 29 </grok:render> Regarding stability, dimethyldichlorosilane is thermally stable up to approximately 200 °C in the absence of moisture but undergoes rapid hydrolysis upon exposure to air or water, generating hydrochloric acid and forming siloxane oligomers exothermically.<grok:render type="render_inline_citation"> 20 </grok:render><grok:render type="render_inline_citation"> 23 </grok:render><grok:render type="render_inline_citation"> 34 </grok:render> This moisture sensitivity necessitates storage and handling under anhydrous conditions to prevent decomposition.<grok:render type="render_inline_citation"> 29 </grok:render> Spectroscopic characterization reveals distinctive features consistent with its structure. In infrared (IR) spectroscopy, characteristic absorption bands appear for Si-C stretching vibrations around 800–700 cm⁻¹ and Si-Cl stretching around 500–400 cm⁻¹, aiding in identification and purity assessment.<grok:render type="render_inline_citation"> 50 </grok:render><grok:render type="render_inline_citation"> 75 </grok:render> Proton nuclear magnetic resonance (¹H NMR) spectroscopy shows the methyl protons as a singlet at approximately 0.3 ppm (relative to tetramethylsilane), reflecting the deshielding effect of the electronegative chlorines on the silicon atom, though the exact shift can vary slightly with solvent (e.g., ~0.8 ppm in CDCl₃).<grok:render type="render_inline_citation"> 22 </grok:render>

Synthesis

Industrial production

Dimethyldichlorosilane is primarily produced on an industrial scale through the Müller-Rochow process, also known as the direct process, which involves the direct reaction of elemental silicon with methyl chloride in the presence of a copper catalyst.^[5] This method accounts for approximately 90% of the organosilicon monomers used in the silicone industry.^[12] The reaction is typically conducted at temperatures around 300 °C and atmospheric pressure, enabling efficient gas-solid contact.^[12] China dominates global production, accounting for over 50% of capacity as of 2017, a trend that has continued.^[13] The core reaction is represented by the equation:

\text{Si} + 2 \text{CH}_3\text{Cl} \xrightarrow{\text{Cu catalyst}} (\text{CH}_3)_2\text{SiCl}_2

The process utilizes metallurgical-grade silicon powder (purity >98%) and gaseous methyl chloride fed into a fluidized bed reactor, where the catalyst facilitates the formation of silicon-carbon bonds.^[5] The copper catalyst is prepared by impregnating silicon with copper compounds (e.g., CuO), followed by reduction to metallic copper, often incorporating promoters such as zinc (typically 0.1–1 wt% Zn relative to Cu) to enhance selectivity and suppress side reactions.^[12] Fluidized bed reactors are preferred for their ability to maintain uniform temperature and mixing, operating continuously with silicon conversion rates of 90–98% and methyl chloride conversion of 30–90%.^[5] The process achieves high selectivity toward dimethyldichlorosilane, up to 95% with optimized Zn-promoted catalysts, yielding products with purity exceeding 99.9% after fractional distillation.^[12] Byproducts, such as methyltrichlorosilane (CH₃SiCl₃) and trimethylchlorosilane ((CH₃)₃SiCl), constitute 5–10% of the output and are recycled or separated to maximize efficiency.^[5] Globally, annual production reaches about 1.4 million metric tons, underscoring its economic importance to the silicone sector, with leading manufacturers including Dow and Wacker Chemie.^[5]^[14]

Laboratory synthesis

In laboratory settings, dimethyldichlorosilane is commonly prepared via the Grignard reaction of silicon tetrachloride with dimethylmagnesium in dry ether under an inert atmosphere. The reaction proceeds according to the equation:

\text{SiCl}_4 + (\text{CH}_3)_2\text{Mg} \rightarrow (\text{CH}_3)_2\text{SiCl}_2 + \text{MgCl}_2

This method involves adding a solution of dimethylmagnesium in ether to silicon tetrachloride dissolved in ether, followed by refluxing the mixture for approximately 1 hour. The reaction mixture is then cooled and hydrolyzed with dilute hydrochloric acid to quench excess Grignard reagent, with the organic layer separated, dried over calcium chloride, and subjected to distillation.^[15] Yields for this Grignard approach typically range from 70% to 90% under controlled anhydrous conditions, depending on reagent purity and stoichiometry. Purification is achieved by fractional distillation under an inert atmosphere at reduced pressure, targeting the boiling point of 70°C to isolate dimethyldichlorosilane from potential byproducts such as methyltrichlorosilane isomers formed due to incomplete selectivity. Strict exclusion of moisture and oxygen is essential throughout to prevent premature hydrolysis of the moisture-sensitive product.^[15] Alternative laboratory routes include the use of methylmagnesium chloride (employing two equivalents to achieve dimethylation) or redistribution reactions starting from mixtures of other methylchlorosilanes, such as methyltrichlorosilane and trimethylchlorosilane, often facilitated by Lewis acid catalysts like aluminum chloride in sealed vessels at elevated temperatures. These redistribution methods allow adjustment of the silicon-methyl-chlorine ratio but require careful monitoring to favor dimethyldichlorosilane formation, with yields varying based on starting material composition.^[16]

Reactions

Hydrolysis and siloxane formation

Dimethyldichlorosilane undergoes hydrolysis in the presence of water to form dimethylsilanediol as the primary intermediate, accompanied by the release of hydrogen chloride as a byproduct. The reaction proceeds according to the equation:

(\ce{CH3})_2\ce{SiCl2} + 2 \ce{H2O} \rightarrow (\ce{CH3})_2\ce{Si(OH)2} + 2 \ce{HCl}

This process is highly exothermic and generates fuming HCl gas, necessitating careful control to manage the vigorous reaction and corrosive byproducts. The intermediate, dimethylsilanediol ((\ce{CH3})_2\ce{Si(OH)2}), is relatively unstable under typical conditions and readily undergoes condensation. This instability drives the subsequent formation of siloxane linkages through the elimination of water.^[17] Polymerization occurs via polycondensation of the silanediol units, yielding polydimethylsiloxane (PDMS) as the main product:

n (\ce{CH3})_2\ce{Si(OH)2} \rightarrow [(\ce{CH3})_2\ce{SiO}]_n + n \ce{H2O}

The resulting PDMS consists of linear chains with hydroxyl end groups or cyclic oligomers, depending on reaction conditions. Hydrolysis is typically conducted in controlled aqueous or ethereal media, often with dropwise addition of water to an organic solution of the silane at room temperature, to regulate the degree of polymerization and chain length. Acidic or basic catalysis can further influence the outcome, with industrial processes employing continuous reactors for efficiency.^[17] The hydrolysis step is rapid, often completing within minutes under ambient conditions, while the condensation rate is more variable and strongly depends on pH and temperature; for instance, optimal industrial hydrolysis maintains temperatures around 35°C and limits reaction time to under 15 minutes to minimize side reactions. At neutral or slightly acidic pH, condensation proceeds steadily, but rates increase with basic conditions, allowing for tailored polymer molecular weights.^[18]^[19]

Other reactions

Dimethyldichlorosilane undergoes nucleophilic substitution reactions where the chlorine atoms are replaced by nucleophiles such as alkoxides or amines. For instance, reaction with alkoxide ions yields dimethyldialkoxysilanes according to the equation:

(\ce{CH3})_2\ce{SiCl2} + 2 \ce{RO^-} \rightarrow (\ce{CH3})_2\ce{Si(OR)2} + 2 \ce{Cl^-}

This transformation is typically carried out in the presence of a base to facilitate the substitution, producing compounds useful as intermediates in organosilicon chemistry.^[20] Similarly, treatment with amines leads to the formation of dimethylsilylamines, as demonstrated in the synthesis of α-amino acid amides where dimethyldichlorosilane reacts with amino acids in the presence of a base like triethylamine.^[21] In organic synthesis, dimethyldichlorosilane serves as a protecting group by reacting with alcohols or thiols to form reversible silyl ethers. This is particularly effective for vicinal diols, where it forms cyclic five- or six-membered dimethylsilylene acetals that shield the hydroxyl groups under basic conditions and can be deprotected with fluoride ions or acid. The bridging nature of the dimethylsilyl unit provides stability comparable to other silyl protecting groups while allowing selective manipulation of other functional groups.^[22] Redistribution reactions of dimethyldichlorosilane with other silanes, such as methyltrichlorosilane or trimethylchlorosilane, occur under Lewis acid catalysis like aluminum chloride, yielding mixtures of methylchlorosilanes. These catalyzed disproportionation processes adjust the product distribution from the direct process, improving yields of desired monomers through chloride and methyl group exchanges. For example, the reaction proceeds via coordination of the catalyst to chlorine, facilitating silicon-carbon bond rearrangements.^[16] Dimethyldichlorosilane acts as a precursor for addition reactions to unsaturated compounds, primarily through conversion to hydrosilanes via catalytic hydrogenolysis, which then undergo hydrosilylation with alkenes or alkynes. This indirect route employs metal catalysts like iridium complexes to replace chlorines with hydrides, enabling anti-Markovnikov addition across carbon-carbon multiple bonds.^[23] At high temperatures, dimethyldichlorosilane undergoes thermal decomposition primarily via sequential loss of methyl radicals, leading to dichlorosilylene (SiCl₂) as a key intermediate. This process, studied under flash pyrolysis conditions from 1000 K to 1500 K, also involves minor pathways such as elimination of methane or methyl chloride, producing species like chloromethylchlorosilane. The Si-C bond homolysis dominates, with SiCl₂ serving as a reactive species in further gas-phase chemistry.^[24]

Applications

Silicone polymers

Dimethyldichlorosilane serves as the primary precursor in the synthesis of polydimethylsiloxane (PDMS), the most common silicone polymer, through a two-step process involving hydrolysis followed by condensation. During hydrolysis, dimethyldichlorosilane reacts with water to form dimethylsilanediol as an intermediate, which then undergoes polycondensation to yield linear or cyclic siloxanes, depending on reaction conditions such as temperature, pH, and solvent use.^[17] This process enables the formation of PDMS chains with repeating -Si(CH₃)₂O- units, providing the foundational structure for various silicone materials.^[25] In industrial production, controlled hydrolysis of dimethyldichlorosilane occurs in large-scale reactors, where the chlorosilane is added to water or aqueous mixtures under agitation to manage the exothermic reaction and by-product hydrochloric acid formation. The resulting silanol intermediates condense to produce silicone fluids, resins, or rubbers, with molecular weight and viscosity tailored by adjusting hydrolysis rates, catalyst addition, or subsequent polymerization steps like ring-opening of cyclic oligomers. Over 90% of all silicone products are derived from dimethyldichlorosilane, underscoring its dominance in the global silicone industry.^[26]^[25] The methyl groups in dimethyldichlorosilane impart key properties to the resulting PDMS, including a low glass transition temperature (around -123°C) due to the flexible siloxane backbone, enabling elastomeric behavior at low temperatures.^[27] Additionally, the polymer exhibits high thermal stability, with decomposition temperatures exceeding 300°C,^[28] and inherent hydrophobicity (water contact angle approximately 108°), arising from the non-polar methyl substituents that shield the siloxane chain.^[29] These attributes make PDMS suitable for applications requiring flexibility, heat resistance, and water repellency, such as sealants and elastomers. As of 2025, emerging applications include its use in producing heat-resistant and high-strength carbonized fibers for advanced composites, as well as in green tire manufacturing to enhance durability and performance.^[30]^[31] Variations in silicone polymers are achieved through co-hydrolysis of dimethyldichlorosilane with other chlorosilanes, such as methyltrichlorosilane or phenyltrichlorosilane, to introduce branching, crosslinking, or functional groups in copolymers. This approach allows for customized properties, like enhanced mechanical strength or adhesion, while maintaining the core siloxane structure derived from the primary monomer.^[32]

Surface modification

Dimethyldichlorosilane (DMDCS) is widely employed in the silanization of glass surfaces, where it reacts with silanol groups (Si-OH) on silica to form covalent (CH₃)₂Si-O-Si bonds, creating a thin, non-polar layer that deactivates the surface and imparts hydrophobicity.^[33] This process typically involves vapor deposition or solution-based methods, such as exposing clean glassware to DMDCS vapor in a desiccator for 1-2 hours or dipping in a 5% solution in toluene or chloroform followed by rinsing and drying.^[33]^[34] The resulting modification reduces surface energy, minimizes unwanted interactions with polar molecules, and enhances compatibility with organic solvents, making it essential for applications requiring low protein adsorption or improved flow in labware.^[22] In gas chromatography (GC), DMDCS silanization is crucial for treating column supports and liners, particularly silica-based packed columns, to prevent analyte adsorption by capping active silanol sites and reducing tailing.^[35] The treatment is commonly applied by passing a 1-5% DMDCS solution in toluene through the column at room temperature, followed by rinsing with solvent and baking to remove residuals, which ensures inertness and reproducible separations for polar compounds.^[36]^[34] This deactivation extends column lifetime and improves peak symmetry, as demonstrated in USP-compliant supports where DMDCS masking of silanol groups is standard for pharmaceutical analyses.^[37] DMDCS serves as a protecting group for hydroxyl functionalities in organic synthesis, reacting with alcohols to form stable dimethylsilyl ethers that shield the -OH from unwanted reactions under basic or nucleophilic conditions.^[38] Particularly useful for diols or hydroxy acids, it acts as a bridging agent, enabling selective deprotection via fluoride ions or mild hydrolysis while maintaining stability across a range of pH and temperatures.^[22] This application is prominent in carbohydrate chemistry, such as C-glycoside synthesis, where the group templates regioselective modifications.^[38] Beyond glass and synthesis, DMDCS enables water-repellent coatings on textiles and metals through chemical vapor deposition (CVD), where its volatility allows uniform monolayer formation, yielding superhydrophobic surfaces with water contact angles exceeding 150°.^[39] For polyester fabrics, CVD of DMDCS followed by plasma treatment creates durable oil-water separation membranes, while on metals like titanium, it reduces bacterial adhesion by altering surface wettability.^[39]^[40] The key advantages of DMDCS in these modifications include its high volatility for easy vapor-phase application, the non-polar methyl groups that confer low surface energy, and the resulting permeable yet hydrophobic interphase that blocks ion transport without compromising breathability.^[22]

History

Discovery

The first organosilicon compounds were reported in 1863 by French chemist Charles Friedel and American chemist James Mason Crafts through the reaction of silicon tetrachloride (SiCl₄) with diethylzinc ((C₂H₅)₂Zn), yielding tetraethylsilane ((C₂H₅)₄Si) alongside other alkylsilanes, though yields were low and purification challenging due to the reactive nature of the materials. Friedel and Crafts' work laid foundational insights into silicon-carbon bond formation.^[5] In the early 20th century, British chemist Frederic Stanley Kipping advanced the study of organosilicon compounds, including the first preparation of dimethyldichlorosilane, primarily through Grignard reagent methods. Kipping reacted methylmagnesium halides with silicon tetrachloride to produce methylchlorosilanes, systematically investigating their properties and reactivity. His research emphasized the differences between silicon and carbon analogs, noting the compound's tendency to form cyclic and linear siloxanes upon exposure to moisture. Kipping's efforts, spanning over 50 publications from 1899 to 1936, shifted focus from isolated alkylsilanes to broader organosilicon chemistry, though he viewed silicones as curiosities rather than practical materials.^[5] By the 1930s, dimethyldichlorosilane gained recognition as a crucial intermediate for silicone polymer synthesis, bridging academic research and potential industrial applications. Kipping's 1937 Bakerian Lecture to the Royal Society summarized decades of work, detailing the hydrolysis of dichlorosilanes like (CH₃)₂SiCl₂ to form siloxane oligomers and highlighting their unusual stability compared to organic counterparts. This publication underscored the compound's role in generating hydrolytically stable networks, influencing subsequent developments in silicone materials despite Kipping's skepticism about commercial viability.

Commercial development

The direct process for synthesizing dimethyldichlorosilane, a cornerstone of silicone production, was independently invented in the 1940s by Eugene G. Rochow at General Electric in the United States and Richard Müller at IG Farben (predecessor to Wacker Chemie) in Germany.^[5]^[12] Rochow's breakthrough occurred on May 10, 1940, when he reacted methyl chloride with a copper-silicon mixture at elevated temperatures to yield methylchlorosilanes, including dimethyldichlorosilane as the primary product.^[5] Müller developed a parallel method around the same time, filing a German patent in 1942 that paralleled Rochow's approach.^[12] These inventions shifted production from labor-intensive Grignard-based methods to a more economical, scalable direct synthesis using elemental silicon and alkyl halides.^[5] Rochow filed a U.S. patent application on September 26, 1941, which was granted as U.S. Patent 2,380,995 on August 7, 1945, detailing the copper-catalyzed reaction of silicon and methyl chloride. This patent laid the groundwork for industrial viability, enabling the selective production of dimethyldichlorosilane with yields up to 90% under optimized conditions.^[5] The first commercial efforts followed swiftly: Dow Corning Corporation, a joint venture between Corning Glass Works and Dow Chemical, launched silicone production in 1943, initially focusing on greases for World War II aircraft applications.^[41] General Electric broke ground on a pilot plant in Waterford, New York, in late 1943, with full operations commencing by 1947 using stirred-bed reactors.^[5] Post-World War II demand for silicones in aerospace (e.g., high-temperature sealants and insulators) and emerging electronics fueled explosive growth, transforming dimethyldichlorosilane from a laboratory curiosity into an industrial staple.^[5]^[41] The 1950s marked significant scale-up, as companies like Union Carbide and international producers adopted fluidized-bed reactors, boosting global output from pilot-scale to thousands of tons annually and enabling widespread commercialization.^[5] By mid-decade, the process had been refined for higher selectivity, with dimethyldichlorosilane yields exceeding 85% in continuous operations.^[5] In the 21st century, refinements emphasized purity and sustainability, achieving dimethyldichlorosilane grades up to 99.9% through advanced distillation and catalyst innovations like zinc- and tin-promoted copper systems.^[5]^[12] These advancements addressed impurities from byproducts, supporting applications in high-precision sectors like semiconductors.^[12] The compound's role as the primary precursor to silicone polymers has underpinned the industry's expansion, with the global silicone market valued at approximately $19.55 billion in 2025 and projected to reach $35.58 billion by 2034.^[42]

Safety and environmental considerations

Hazards

Dimethyldichlorosilane poses significant health risks primarily due to its corrosive nature and reactivity with moisture, generating hydrogen chloride (HCl) fumes. Direct contact with skin or eyes causes severe burns and tissue damage, often leading to pain, redness, and potential permanent injury. Inhalation of vapors acts as a respiratory irritant, causing coughing, throat irritation, and pulmonary edema in severe cases, with the HCl byproduct exacerbating these effects. Chronic exposure through repeated inhalation may result in lung irritation, bronchitis, and long-term respiratory issues such as shortness of breath.^[43]^[44]^[1] Toxicity studies indicate moderate acute oral toxicity, with an LD50 of 595 mg/kg in rats, classifying it as harmful if swallowed. Inhalation toxicity is higher, with an LC50 of 2.77 mg/L for a 4-hour vapour exposure in rats, underscoring the dangers of vapor inhalation. No evidence supports classification as a carcinogen, though chronic respiratory effects remain a concern.^[1]^[43] The compound is highly flammable, with a flash point of -9 °C (16 °F), enabling ignition at low temperatures. Vapors form explosive mixtures with air in concentrations ranging from 1.4% to 9.5% by volume, and the autoignition temperature is 410 °C. Fires involving dimethyldichlorosilane can release toxic HCl and other corrosive gases, intensifying hazards.^[45]^[2] Environmentally, dimethyldichlorosilane is toxic to aquatic life upon release, primarily through hydrolysis that produces HCl, which acidifies water and harms organisms. The hydrolysis byproducts, including dimethylsilanediol and subsequent condensation to methylsiloxanes such as octamethylcyclotetrasiloxane (D4), are persistent in the environment and exhibit bioaccumulation potential in aquatic species.^[46]^[47] Under international regulations, dimethyldichlorosilane is classified as UN 1162, a Class 3 flammable liquid with a subsidiary Class 8 corrosive hazard, requiring strict transport and storage protocols. In the European Union, under REACH, dimethyldichlorosilane is harmonized classified as a flammable liquid (Category 2; H225), acutely toxic by inhalation (Category 3; H331), skin corrosive (Category 1A; H314), and specific target organ toxicant (single exposure, respiratory tract irritation; Category 3; H335).^[8]^[48]

Handling and storage

Dimethyldichlorosilane requires careful handling to prevent reactions with moisture and ignition sources. Personnel should wear appropriate personal protective equipment, including PVC or neoprene gloves, chemical-resistant goggles or a full face shield, and a respirator certified for organic vapors and acid gases, such as a NIOSH-approved Type BAX-P or self-contained breathing apparatus. Operations must be conducted in a well-ventilated fume hood or area with local exhaust ventilation to minimize exposure to vapors.^[46]^[45]^[49] For storage, dimethyldichlorosilane should be kept in a cool, dry location under an inert atmosphere such as nitrogen, in tightly sealed containers made of glass or Teflon-lined steel to avoid corrosion or reaction. Carbon steel containers are also suitable for larger quantities, but non-ferrous metals like aluminum and alkali metals must be avoided due to potential violent reactions. Containers should be stored away from water, moisture, heat sources, and incompatible materials including acids, alcohols, and oxidizers, with grounding and bonding to prevent static discharge.^[43]^[46]^[49] During handling, dry solvents should be used for dilutions or transfers, and all equipment must be grounded with non-sparking tools to mitigate fire risks. Spills should be addressed immediately by evacuating the area, eliminating ignition sources, and neutralizing the material with soda ash or lime before absorption using dry sand or inert material like PetroGuard; the neutralized residue is then collected in suitable containers for disposal. Direct contact with water must be avoided to prevent exothermic hydrolysis.^[8]^[46]^[49] Disposal of dimethyldichlorosilane involves controlled hydrolysis to form siloxanes, followed by neutralization of the resulting hydrochloric acid with an alkaline solution, in compliance with Resource Conservation and Recovery Act (RCRA) guidelines for ignitable wastes (code D003). Waste should be managed at licensed facilities through incineration or burial after proper treatment, and empty containers must be decontaminated, such as with sodium hydroxide solution, before disposal.^[1]^[46]^[49] In emergencies, eyewash stations and safety showers must be readily available and operational. For fires, water fog or spray may be used to cool exposed containers from a safe distance, but direct streams should be avoided as they can cause violent reactions; preferred extinguishing agents include dry chemical, carbon dioxide, or alcohol-resistant foam. Firefighters should wear self-contained breathing apparatus and full protective gear.^[8]^[43]^[49]

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How is Polydimethylsiloxane (PDMS) Manufactured? | Silico®
Oct 7, 2023 · 2.1 Hydrolysis Reaction · Water replaces Cl atoms with OH groups, forming silanols. · Byproducts include hydrogen chloride (HCl), which must be ...
[25]
Silicone: Focus on four major directions of the industry chain
Sep 10, 2024 · Dimethyldichlorosilane is the most widely used silicone monomer, accounting for more than 90% of the total monomer. Deep processing of silicone
[26]
Polydimethylsiloxane (PDMS): Production, Properties,
Oct 23, 2023 · Multiple steps are involved in PDMS production. The first step polymerizes dimethyldichlorosilane to produce hydrochloric acid and a linear, ...
[27]
Well-Architectured Poly(dimethylsiloxane)-Containing Copolymers ...
This review focuses on PDMS copolymers because they are the most common polyorganosiloxane copolymers. However, the well-developed chemistry of silicone enables ...
[28]
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### Procedures and Uses for Silanizing Glass with Dimethyldichlorosilane (DMDCS)
[29]
Procedure for glass silanization - Chromatography Forum
May 20, 2006 · You will need to keep it in a (roughly) 5% solution of dimethyldichlorosilane in toluene for about 30 minutes. Then you may rinse and dry ...
[30]
[PDF] Packed Column GC Application Guide
Silanization, particularly with dimethyldichlorosilane (DMCS) is very effective in reducing tailing. Combined with acid washing and DMCS treatment, the.
[31]
Chapter 4: Gas chromatography - ScienceDirect
70 m X 0.3 mm I.D., was silanized by forcing a plug of 5% dimethyldichlorosilane in toluene through the column at room temperature. The column was rinsed ...
[32]
United States Pharmacopeia (USP) GC Supports | Products
The siliceous earth may be silanized by treating with an agent such as dimethyldichlorosilane to mask surface silanol groups. Uniport HP Chromosorb W HP<|control11|><|separator|>
[33]
[PDF] Silicon-Based Blocking Agents - Gelest, Inc.
The triethylsilyl protecting group is primarily used for the protection of alcohols, although other groups including amines and carboxylic acids have been ...
[34]
Preparation of a superhydrophobic and superoleophilic polyester ...
Feb 1, 2019 · Preparation of a superhydrophobic and superoleophilic polyester textile by chemical vapor deposition of dichlorodimethylsilane for Water–Oil ...
[35]
The Influence of Surface Modification on Bacterial Adhesion to ...
Dec 26, 2014 · This study examines bacterial adhesion on titanium-substrates used for bone implants. Adhesion is the most critical phase of bacterial colonization on medical ...Introduction · Experimental Section · Bacterial Adhesion Testing
[36]
[PDF] The Fascinating World of Silicones - American Coatings Association
Typical modified coatings contain around 30% of the binder as silicone and these coatings exhibit improved weatherability, increased moisture vapor transport, ...
[37]
Silicone Market Size to Hit USD 35.58 Billion by 2034
The silicone market size is calculated at USD 19.55 billion in 2025 and is predicted to increase from USD 20.92 billion in 2026 to approximately USD 35.58 ...
[38]
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### Summary of Hazards Identification and Related Data for Dichlorodimethylsilane (Aldrich - 40140)
[39]
[PDF] dichlorosilane - NJ.gov
The flash point is the temperature at which a liquid or solid gives off vapor that can form a flammable mixture with air. HHAG is the Human Health ...<|separator|>
[40]
[PDF] DIMETHYLDICHLOROSILANE, 98% - Gelest, Inc.
Nov 25, 2014 · SDS ID: SID4120.0. 4/9. SECTION 9: Physical and chemical properties. 9.1. Information on basic physical and chemical properties. Physical state.
[41]
[PDF] Dichlorodimethylsilane - Santa Cruz Biotechnology
Spills in the aquatic environment result in an increase in water acidity (because of the hydrochloric acid formation) which may harm aquatic life. HYDROGEN ...
[42]
Review of recent findings on occurrence and fates of siloxanes in ...
This review summarized the research progress, especially in the last decade, on production/consumption data, toxicities, analysis methods, environmental ...
[43]
[PDF] GLOBAL SAFE HANDLING OF CHLOROSILANES
In general, disposal of chlorosilanes can be accomplished by controlled introduction into water (hydrolysis) or neutralisation with aqueous alkaline (basic) ...