Dichlorodimethylsilane Property

Melting point:

-76 °C

Boiling point:

70 °C(lit.)

Density 

1.333 g/mL at 20 °C

vapor pressure 

<200 hPa (20 °C)

refractive index 

n20/D 1.500

Flash point:

3 °F

storage temp. 

Store below +30°C.

solubility 

sol chlorinated solvents and ethereal solvents; reacts with protic solvents.

form 

liquid

Specific Gravity

1.0637

color 

colorless

explosive limit

1.75-48.5%(V)

Water Solubility 

reacts

Sensitive 

Moisture Sensitive

Hydrolytic Sensitivity

8: reacts rapidly with moisture, water, protic solvents

BRN 

605287

Stability:

Stable. Reacts violently with water and alcohols. Highly flammable. Incompatible with strong oxidizing agents, water, alcohols, caustics, ammonia.

CAS DataBase Reference

75-78-5(CAS DataBase Reference)

NIST Chemistry Reference

Silane, dichlorodimethyl-(75-78-5)

EPA Substance Registry System

Dimethyldichlorosilane (75-78-5)

Safety

Hazard Codes 

Xn,Xi,F,N,C

Risk Statements 

20-59-36/37/38-11-67-65-63-48/20-38-20/21-50/53-37-35-20/22-14-34

Safety Statements 

60-61-62-36/37-59-45-36/37/39-26-16-7/9-2

RIDADR 

UN 2924 3/PG 2

WGK Germany 

3

RTECS 

VV3150000

F 

3-10-19-21

Autoignition Temperature

425 °C

TSCA 

Yes

HazardClass 

3

PackingGroup 

II

HS Code 

29310095

Hazardous Substances Data

75-78-5(Hazardous Substances Data)

Toxicity

LD50 orally in Rabbit: 6056 mg/kg

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Danger

Hazard statements

H225Highly Flammable liquid and vapour

H304May be fatal if swallowed and enters airways

H314Causes severe skin burns and eye damage

H336May cause drowsiness or dizziness

H373May cause damage to organs through prolonged or repeated exposure

H412Harmful to aquatic life with long lasting effects

Precautionary statements

P210Keep away from heat/sparks/open flames/hot surfaces. — No smoking.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P301+P330+P331IF SWALLOWED: Rinse mouth. Do NOT induce vomiting.

P303+P361+P353IF ON SKIN (or hair): Remove/Take off Immediately all contaminated clothing. Rinse SKIN with water/shower.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

Dichlorodimethylsilane Chemical Properties,Usage,Production

Description

Dichlorodimethylsilane is a tetrahedral, organosilicon compound with the molecular formula Si(CH3)2Cl2. The compound is a colorless liquid at room temperature, has a pungent odor and readily reacts with water to form both cyclic and linear Si-O chains. On an industrial scale, dichlorodimethylsilane is manufactured as the main precursor to polysilane and dimethylsilicone compounds.

History

James Crafts and Charles Friedel are American chemists who first reported organosilicon compounds in 1863 by synthesizing tetraethylsilane from silicon tetrachloride and diethylzinc. Nevertheless, major progress in organosilicon chemistry occurred when Fredrick Kipping and his students reacted tetrachloride with Grignard reagents to produce diorganodichlorosilanes (R2SiCl2), which they used for their experiments. The dpemand for silicones increased in the 1930s as many aircraft companies needed better insulators for sealing materials and electric motors for aircraft engines; therefore, there was need for efficient synthesis of dichlorodimethylsilane.

Preparation

Dichlorodimethylsilane is prepared by passing methyl chloride through a heated tube packed with copper (I) chloride and ground silicon using Cu2O as the catalyst. Methyl chloride is the passed through a reactor to produce dichlorodimethylsilane.
2 CH3Cl + Si → (CH3)2SiCl2
The other products in this reaction apart from dichlorodimethylsilane include CH3)3SiCl, CH3SiHCl2, and CH3SiCl3, which can be separated fromone another by fractional distillation.

Applications

Dichlorodimethylsilane is majorly used in the production of silicones. Moreover, it is utilized in the synthesis of polysilanes, which are the main precursors to silicon carbide. Dichlorodimethylsilane can be used to coat glass to prevent the adsorption of micro-particles.

Chemical Properties

Dimethyldichlorosilane is a colorless to brown liquid with sharp, irritating odor. It is soluble in benzene and ether, emits smoke in humid air, toxic, and flammable.

Uses

Dichlorodimethylsilane is used to prepare a resin bound siloxane with tertiary alcohols and it is also used as a reagent for synthesis of optically active ansa-mettallocene polymerization catalysts. It acts as a precursor to silicone and polysilane compounds. It is also used in the glass coating to protect it from micro particles. It is involved in the preparation of resin bound siloxane with reactivity towards tertiary alcohols.

Uses

Dichlorodimethylsilane can be used as additive for pinacol cyclization; protecting group for diols and carbonyl compounds;precursor for a wide variety of siliconbased reagents.
Dichlorodimethylsilane (1) allows clean pinacol cyclization of a keto aldehyde to occur without competition from an aldol reaction (eq 1).

Production Methods

Produced by the action of silicon on methyl chloride in presence of copper catalyst, or by Grignard reaction from methyl chloride and silicon tetrachloride.

General Description

Dimethyldichlorosilane appears as a colorless fuming liquid with a pungent odor. Flash point 16 °F. Vapor and liquid may cause burns. Denser than water. Vapors heavier than air.

Reactivity Profile

Chlorosilanes, such as Dichlorodimethylsilane, are compounds in which silicon is bonded to from one to four chlorine atoms with other bonds to hydrogen and/or alkyl groups. Chlorosilanes react with water, moist air, or steam to produce heat and toxic, corrosive fumes of hydrogen chloride. They may also produce flammable gaseous H2. They can serve as chlorination agents. Chlorosilanes react vigorously with both organic and inorganic acids and with bases to generate toxic or flammable gases.

Health Hazard

Inhalation irritates mucous membranes. Severe gastrointestinal damage may occur. Vapors cause severe eye and lung injury. Upon short contact, second and third degree burns may occur.

Fire Hazard

Vapor may explode if ignited in an enclosed area. Reacts vigorously with water to generate hydrogen chloride. Hydrogen chloride and phosgene gases may be formed upon heating or in fire. Runoff to sewer may create fire or explosion hazard.

Safety Profile

Poison by ingestion and intraperitoneal routes. Moderately toxic by inhalation. A skin and severe eye irritant. Violent reaction on contact with water. When heated to decomposition it emits toxic fumes of Cl-. See also CHLOROSILANES.

Potential Exposure

PrimaryIrritant. Used as an intermediate in the manufacture of silicone polymers.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water ormilk. Do not induce vomiting. Medical observation isrecommended for 2448 h after breathing overexposure, aspulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consideradministering a corticosteroid spray.

storage

(1) Color Code—Red: Flammability Hazard: Storein a flammable liquid storage area or approved cabinetaway from ignition sources and corrosive and reactivematerials. (2) Color Code—Blue: Health Hazard/Poison:Store in a secure poison location. Dimethyldichlorosilanemust be stored to avoid contact with oxidizers (such as perchlorates, peroxides, permanganates, chlorates, andnitrates), since violent reactions occur. Before entering confined space where this chemical may be present, check tomake sure that an explosive concentration does not exist.Store in tightly closed containers in a cool, well-ventilatedarea away from water, steam, or moisture, because toxicand corrosive hydrogen chloride gas can be produced. Donot store at temperatures above 50℃/122°F. Sources ofignition, such as smoking and open flames, are prohibitedwhere dimethyldichlorosilane is handled, used, or stored.Metal containers involving the transfer of 5 gallons or moreof dimethyldichlorosilane should be grounded and bonded.

Shipping

Dimethyldichlorosilane requires a shipping labelof “FLAMMABLE LIQUID, CORROSIVE.” It falls inHazard Class 3 and Packing Group II

Purification Methods

Other impurities are chlorinated silanes and methylsilanes. Fractionate it through a 3/8in diameter 7ft Stedman column (p 11) rated at 100 theoretical plates at almost total reflux. See purification of MeSiCl2. Solutions in heptane, 1,1,1-trichloroethane or 1-chloronaphthalene are used for the silanization of glassware and pipettes. [Sauer & Hadsell J Am Chem Soc 70 3590 1948, Beilstein 4 IV 4110.]

Incompatibilities

Forms explosive gas mixture with air.Water, steam, and moisture forms toxic and corrosivehydrogen chloride gas. Incompatible with acetone, amines,ammonia, alcohols, strong oxidizers, caustics. Attacks mostmetals. Do not store in temperatures above 122°F/50℃.