Dimethyldichlorosilane (HC-CM2268): A cornerstone of fine chemicals and diversified applications

   Dimethyldichlorosilane (DMCS for short) is an important silicone intermediate with the chemical formula (CH₃)₂SiCl₂. With its lively chemical properties and adjustable reactivity, it has become a key raw material for the synthesis of a variety of organosilicon polymers, modifiers and surface treatment agents, which are widely used in the fields of construction, textile, electronics, medical treatment, cosmetics, and so on. In this paper, we will discuss in depth the properties, production process, application areas and its development trend of dimethyl dichlorosilane.

I. Physicochemical properties and reaction characteristics of dimethyl dichlorosilane

Dimethyldichlorosilane is a colorless or light yellow transparent liquid with a pungent odor. Its main physical and chemical properties include:

Molecular weight: 129.06 g/mol

Boiling point: 70°C

Melting point: -76°C

Density: 1.06 g/cm³ (20°C)

Refractive index: 1.4023 (20°C)

Flash Point: -1°C

Solubility: Easily soluble in benzene, ether and other organic solvents, rapidly decomposed in water.

Dimethyldichlorosilane contains two active chlorine atoms in its molecular structure, making it extremely reactive. Common types of reactions include:

Hydrolysis: Reacts with water to form Dimethyldisilanol and hydrogen chloride. Dimethyldisilanol is unstable and will further polymerize to form dimethylsiloxane or cyclic dimethylsiloxane. This is a key step in the synthesis of silicone oils and rubbers.

Alcoholysis: Reacts with alcohols to form dimethyldialkoxysilanes. This reaction can be used to prepare silicone polymers with specific properties.

Ammonolysis: Reacts with ammonia or amines to form dimethyldiaminosilane.

Reacts with Grignard Reagent: Reacts with Grignard Reagent to introduce new organic groups, thereby changing the chemical structure.

Reaction with Metal Alcohol Salts: Reacts with metal alcohol salts to form metal-alcohol-substituted silanes, which can be used as catalysts or intermediates.

It is due to its high reactivity that dimethyldichlorosilane is involved in the synthesis of various organosilicon products as an important organosilicon intermediate.

II. Synthesis process and technological progress

1. Industrial synthesis routes

Direct synthesis (Rochow method)

Raw materials: silicon powder (Si), chloromethane (CH₃Cl)

Reactive:

Process Parameters:

Temperature: 280-320°C

Pressure: atmospheric to slightly positive

Catalyst: copper powder or copper-zinc alloy (conversion >85%)

By-product management

The co-produced methyltrichlorosilane (CH₃SiCl₃) accounts for about 10-15%, which is purified by distillation separation.

2. Green process innovation

Electrochemical synthesis:

Electrolysis of silicon with chloromethane in a nonprotonic solvent reduces the reaction temperature to 200°C and energy consumption by 35%;

Fluidized bed optimization:

The utilization of silica powder is increased to 92% with a multi-stage fluidized bed reactor (patented Wacker Chemie technology).

III. Core application areas

1. Silicone industry building blocks

Silicone oil and silicone rubber:

Hydrolyzed and condensed to form polydimethylsiloxane (PDMS), which is used for high-temperature grease (temperature resistance -50~250°C) and medical catheters (biocompatibility certification);

Dow Corning Silicone Rubber Seals with over 20 years of aging life.

Silicone preparation:

Co-hydrolyzed with phenylchlorosilane to synthesize high-temperature-resistant (>400°C) insulating resins for aerospace conductor coatings.

2. Surface treatment and functional materials

Fiberglass treatments:

Derived from dimethyldimethoxysilane to enhance the interfacial bonding between glass fiber and epoxy resin (interlayer shear strength +40%);

China Jushi Group's glass fiber for wind turbine blades, fatigue life increased to 25 years.

Nanomaterial modification:

Modifies the surface of titanium dioxide (TiO₂) for use in sunscreens (30% increase in SPF, no whitening);

Modified carbon nanotubes to enhance electrical conductivity of rubber composites (volume resistivity down to 10³ Ω-cm).

3. Electronics and semiconductor industry

Photoresist additives:

Enhanced photoresist etch resistance for sub-7nm processes (TSMC EUV technology validation);

Chip encapsulation materials:

Preparation of low-stress silicone gels to reduce coefficient of thermal expansion (CTE) to 15 ppm/°C (Intel Packaging Solutions).

4. Environmental and energy technologies

VOCs adsorption materials:

Synthetic porous silica-based adsorbent with toluene adsorption capacity > 250 mg/g (BASF industrial exhaust gas treatment system, Germany);

Li-ion battery diaphragm coating:

Enhancement of heat resistance of diaphragm to 200°C and suppression of thermal runaway (Ningde Times high safety battery technology).

5. Pharmaceuticals and

Drug carrier synthesis:

Preparation of mesoporous silica drug-loaded particles for pH-controlled release (drug loading rate >20%, release accuracy ±5%);

Pesticide synergists:

Modified glyphosate particles with 40% higher foliar adherence (Syngenta field trial data).

IV. Development trend of dimethyldichlorosilane

With the continuous progress of science and technology and the continuous expansion of application fields, the development of dimethyl dichlorosilane presents the following trends:

Development of green production process: The traditional direct production process produces some harmful by-products, such as chlorinated alkanes, which cause pollution to the environment. Therefore, the development of green production processes, such as the use of new catalysts, optimization of reaction conditions, recycling of by-products, etc., is the future direction of development.

Research and development of high-performance silicone products: As the requirements of various industries on the performance of materials continue to improve, the performance of silicone products also put forward higher requirements. Therefore, there is a need to develop high-performance silicone products with special functions, such as high temperature resistance, corrosion resistance, conductive, flame retardant, etc., in order to meet the needs of different areas of application.

Expanding application fields: Silicone products are used in more and more fields with their excellent performance. For example, in the field of new energy, silicone can be used to manufacture encapsulation materials for solar panels; in the field of biomedicine, silicone can be used to manufacture slow-release systems for drugs and so on.

Refined and customized production: With the intensification of competition in the market, customers have higher and higher demands for individualized products. Therefore, it is necessary to realize the refined and customized production of dimethyl dichlorosilane to meet the specific needs of different customers.

Intelligent production: Introducing automation control system, artificial intelligence and other technologies to realize the intelligence of the production process, improve the production efficiency, reduce the production cost, and ensure the stability of product quality.

V. Summary

As an important cornerstone of the silicone industry, dimethyldichlorosilane plays a vital role in many fields. With the continuous progress of science and technology and the expansion of application fields, dimethyl dichlorosilane will play an even more important role in the future. Through continuous innovation and development, more silicone products with excellent performance can be developed to make greater contributions to the development of various industries. We expect dimethyldichlorosilane to show broader application prospects in the future.

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