Dichlorodimethylsilane

Description

Dimethyldichlorosilane is a colorless liquidwith sharp, irritating odor. Molecular weight= 129.07;Specific gravity = 1.07 at 25℃; Boiling point = 70.5℃;Melting point=86℃; Vapor pressure= 110 mmHg at20℃; Flash point = 27℃; Autoignition temperature=375℃. Explosive limits: LEL = 3.4%; UEL=9.5℃.Hazard Identification (based on NFPA-704 M Rating

Chemical properties

Colorless to brown liquid

Physical properties

mp ?76°C; bp 70–71°C; d 1.064 g cm?3.

The Uses of Dichlorodimethylsilane

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).

The Uses of Dichlorodimethylsilane

Dichlorodimethylsilicon is a organosilicon compound and is the precursor to dimethylsilicone and polysilane compounds.

The Uses of Dichlorodimethylsilane

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.

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

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℃.