methyldichlorosilane

This chemical does not meet GHS hazard criteria for < 0.1% (1 of 2259) of reports.

H225 (> 99.9%): Highly Flammable liquid and vapor [Danger Flammable liquids]

H261 (99.6%): In contact with water releases flammable gas [Danger Substances and mixtures which in contact with water, emit flammable gases]

H301 (99%): Toxic if swallowed [Danger Acute toxicity, oral]

H314 (> 99.9%): Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]

H331 (99%): Toxic if inhaled [Danger Acute toxicity, inhalation]

P210, P231+P232, P233, P240, P241, P242, P243, P260, P261, P264, P270, P271, P280, P301+P316, P301+P330+P331, P302+P361+P354, P303+P361+P353, P304+P340, P305+P354+P338, P316, P321, P330, P363, P370+P378, P402+P404, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 2259 reports by companies from 12 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Reported as not meeting GHS hazard criteria per 1 of 2259 reports by companies.

There are 11 notifications provided by 2258 of 2259 reports by companies with hazard statement code(s).

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H225: Highly Flammable liquid and vapor [Danger Flammable liquids]

H260: In contact with water releases flammable gases which may ignite spontaneously [Danger Substances and mixtures which in contact with water, emit flammable gases]

H314: Causes severe skin burns and eye damage [Danger Skin corrosion/irritation]

H318: Causes serious eye damage [Danger Serious eye damage/eye irritation]

H330: Fatal if inhaled [Danger Acute toxicity, inhalation]

H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

P210, P223, P231+P232, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P271, P280, P284, P301+P330+P331, P302+P335+P334, P302+P361+P354, P303+P361+P353, P304+P340, P305+P354+P338, P316, P317, P319, P320, P321, P363, P370+P378, P402+P404, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Fresh air, rest. Half-upright position. Artificial respiration may be needed. Refer for medical attention.

Remove contaminated clothes. Rinse skin with plenty of water or shower. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Do NOT induce vomiting. Give nothing to drink. Refer for medical attention .

Get medical attention following all exposures to this compound.

INHALATION: remove victim from exposure; if breathing has stopped, begin artificial respiration.

EYES: flush with water for 15 min.

SKIN: flush with water.

INGESTION: do NOT induce vomiting; give large amounts of water. (USCG, 1999)

General First Aid:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

Specific First Aid:

· In case of contact with substance, wipe from skin immediately; flush skin or eyes with running water for at least 20 minutes.

In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product. Please consult the shipping paper and/or the "ERAP" section.

Excerpt from ERG Guide 139 [Substances - Water-Reactive (Emitting Flammable and Toxic Gases)]:

DO NOT USE WATER OR FOAM. (FOAM MAY BE USED FOR CHLOROSILANES, SEE BELOW).

SMALL FIRE: Dry chemical, soda ash, lime or sand.

LARGE FIRE: DRY sand, dry chemical, soda ash or lime or withdraw from area and let fire burn. FOR CHLOROSILANES, DO NOT USE WATER; use alcohol-resistant foam; DO NOT USE dry chemicals, soda ash or lime on chlorosilane fires (large or small) as they may release large quantities of hydrogen gas that may explode. If it can be done safely, move undamaged containers away from the area around the fire.

FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Cool containers with flooding quantities of water until well after fire is out. Do not get water inside containers. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks in direct contact with flames. (ERG, 2024)

Use AFFF, powder, carbon dioxide. NO hydrous agents. NO water. In case of fire: keep drums, etc., cool by spraying with water. NO direct contact with water.

Use dry chemical, foam, or carbon dioxide. DO NOT use water. Use water spray to keep fire-exposed containers cool. Approach fire from upwind to avoid hazardous vapors & toxic decomposition products.

The vapor is heavier than air and may travel along the ground; distant ignition possible.

Difficult to extinguish; reignition may occur. Contact with water applied to adjacent fires will generate irritating hydrogen chloride.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· Ventilate closed spaces before entering, but only if properly trained and equipped.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· Do not touch or walk through spilled material.

· Stop leak if you can do it without risk.

· DO NOT GET WATER on spilled substance or inside containers.

· Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material.

· FOR CHLOROSILANES, use alcohol-resistant foam to reduce vapors.

Small Spill

· Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to minimize spreading or contact with rain.

· Dike for later disposal; do not apply water unless directed to do so.

Powder Spill

· Cover powder spill with plastic sheet or tarp to minimize spreading and keep powder dry.

· DO NOT CLEAN-UP OR DISPOSE OF, EXCEPT UNDER SUPERVISION OF A SPECIALIST.

HCl - when spill Methyldichlorosilane into water.

Excerpt from ERG Guide 139 [Substances - Water-Reactive (Emitting Flammable and Toxic Gases)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: See ERG Table 1 - Initial Isolation and Protective Action Distances on the UN/NA 1242 datasheet.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

Immediate precautionary measure

· Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

· For highlighted materials: see Table 1 - Initial Isolation and Protective Action Distances.

· For non-highlighted materials: increase the immediate precautionary measure distance, in the downwind direction, as necessary.

· If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions.

When spilled in water

Small spill:

- ISOLATE in all directions: 30 m (100 ft)

Large spill:

- ISOLATE in all directions: 60 m (200 ft)

- PROTECT people from downwind during DAY time: 0.1 km (0.1 mi)

- PROTECT people from downwind during NIGHT time: 0.1 km (0.1 mi)

- PROTECT people from downwind during DAY time: 0.5 km (0.4 mi)

- PROTECT people from downwind during NIGHT time: 1.7 km (1.1 mi)

Evacuate danger area! Consult an expert! Personal protection: complete protective clothing including self-contained breathing apparatus. Do NOT wash away into sewer. NEVER direct water jet on liquid. Collect leaking and spilled liquid in sealable dry non-plastic containers as far as possible. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations.

Evacuate danger area! Consult an expert! Collect leaking liquid in sealable dry containers; do not use plastic containers. Absorb remaining liquid in sand or inert absorbent and remove to safe place. Do NOT wash away into sewer. NEVER direct water jet on liquid. (Extra personal protection: complete protective clothing including self-contained breathing apparatus.)

Eliminate all ignition sources. Stop or control the leak, if this can be done without undue risk. Use water spray to cool & disperse vapors & protect personnel. Control runoff & isolate discharged material for proper disposal.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

Avoid contact with skin and eyes. Use effective fume removal device. /Silanes/

Excerpt from ERG Guide 139 [Substances - Water-Reactive (Emitting Flammable and Toxic Gases)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. Do not touch or walk through spilled material. Stop leak if you can do it without risk. DO NOT GET WATER on spilled substance or inside containers. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. FOR CHLOROSILANES, use alcohol-resistant foam to reduce vapors.

SMALL SPILL: Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to minimize spreading or contact with rain. Dike for later disposal; do not apply water unless directed to do so.

POWDER SPILL: Cover powder spill with plastic sheet or tarp to minimize spreading and keep powder dry. DO NOT CLEAN-UP OR DISPOSE OF, EXCEPT UNDER SUPERVISION OF A SPECIALIST. (ERG, 2024)

Fireproof. Separated from oxidants, incompatible materials and food and feedstuffs. See Chemical Dangers. Cool. Dry. Well closed. Keep under inert gas.

Fireproof /storage/. Separated from oxidants, food and feedstuffs, incompatible materials. ...Cool. Dry. Well closed. Keep under inert gas.

Store in a cool, dry, well-ventilated location. Separate from acids, alkalies, oxidizing materials, & water. Outside or detached storage is preferred.

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Wear chemical protective clothing that is specifically recommended by the manufacturer when there is NO RISK OF FIRE.

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

TIH (Toxic Inhalation Hazard) - Term used to describe gases and volatile liquids that are toxic when inhaled. Some are TIH materials themselves, e.g., chlorine, and some release TIH gases when spilled in water, e.g., chlorosilanes. [ERG 2016].

AEGL 1: Notable discomfort, irritation, or certain asymptomatic non-sensory effects. However, the effects are not disabling and are transient and reversible upon cessation of exposure (Unit: ppm)

AEGL 2: Irreversible or other serious, long-lasting adverse health effects or an impaired ability to escape (Unit: ppm)

AEGL 3: Life-threatening health effects or death (Unit: ppm)

AEGLs Status: Final

0.90 [ppm]

11 [ppm]

50 [ppm]

· DO NOT USE WATER OR FOAM. (FOAM MAY BE USED FOR CHLOROSILANES, SEE BELOW)

Small Fire

· Dry chemical, soda ash, lime or sand.

Large Fire

· DRY sand, dry chemical, soda ash or lime or withdraw from area and let fire burn.

· FOR CHLOROSILANES, DO NOT USE WATER; use alcohol-resistant foam; DO NOT USE dry chemicals, soda ash or lime on chlorosilane fires (large or small) as they may release large quantities of hydrogen gas that may explode.

· If it can be done safely, move undamaged containers away from the area around the fire.

Fire Involving Tanks, Rail Tank Cars or Highway Tanks

· Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.

· Cool containers with flooding quantities of water until well after fire is out.

· Do not get water inside containers.

· Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank.

· ALWAYS stay away from tanks in direct contact with flames.

No indication can be given about the rate at which a harmful concentration of this substance in the air is reached on evaporation at 20 °C.

The substance is corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. Inhalation of the vapour may cause lung oedema. Exposure could cause death. Medical observation is indicated.

Full protective clothing; acid-vapor-type respiratory protection; rubber gloves; chemical worker's goggles; other protective equipment as necessary to protect skin and eyes. (USCG, 1999)

Wear special protective clothing & positive pressure self-contained breathing apparatus.

NO open flames, NO sparks and NO smoking. NO contact with hot surfaces. Closed system, ventilation, explosion-proof electrical equipment and lighting. Do NOT use compressed air for filling, discharging, or handling.

STRICT HYGIENE!

Use closed system or ventilation.

Protective gloves. Protective clothing.

Wear face shield or eye protection in combination with breathing protection.

Do not eat, drink, or smoke during work.

Methyldichlorosilane appears as a colorless fuming liquid with a pungent odor. Flash point: -26 °F; Boiling point: 41 °C (106 °F). Vapors heavier than air. Vapor and liquid may cause burns. Denser than water and decomposed by water to form hydrochloric acid, a corrosive material.

Colorless liquid with pungent odor; [ICSC]

COLOURLESS LIQUID WITH PUNGENT ODOUR.

Colorless liquid

ACRID ODOR

106.7 °F at 760 mmHg (USCG, 1999)

41 °C @760 [mm Hg]

-135 °F (USCG, 1999)

-14 °F (USCG, 1999)

15 °F (-9 °C) (Closed cup)

-22 °C (closed cup)

-22 °C c.c.

Sol in benzene, ether, heptane

SOL IN WATER

Solubility in water: reaction

1.11 at 77 °F (USCG, 1999) - Denser than water; will sink

1.10 at 27 °C

Relative density (water = 1): 1.1

1.10 @ 27°C

3.97 (AIR= 1)

Relative vapor density (air = 1): 3.97

429.0 [mmHg]

429 mm Hg at 25 °C

Vapor pressure, kPa at 20 °C: 47.1

429 [mm Hg] @25 °C

log Kow = 1.7 at 25 °C

greater than 600 °F (USCG, 1999)

>600 °F (>316 °C)

Toxic hydrogen chloride and phosgene gases may be formed.

The silanes decomp at elevated temp to liberate hydrogen and deposit a high purity silicon, which leads to some of the principal uses of silanes. /Silanes/

When heated to decomposition it emits toxic fumes of /hydrogen chloride/.

The substance decomposes on contact with bases, forming flammable/explosive gas.

-4,700 BTU/LB

106 BTU/LB

INDEX OF REFRACTION: 1.3983 @ 20 °C/D

RELEASES HYDROGEN IN AN ALKALINE MIXTURE

Organosilanes containing one or more Si--H bonds have excellent reducing capabilities. /Organosilanes/

The polarity of the Si--H bond is opposite to that of the C--H bond. This difference in polarity imparts hydride character to the Si--H bonds of organosilanes. This difference in electronegativities is not as great as in ionic hydrides, and the Si--H bond is still largely (98%) covalent. /Organosilanes/

Organo-functional silanes are noted for their ability to bond organic polymer systems to inorganic substrates. /Silane cmpd/

For more Other Experimental Properties (Complete) data for METHYLDICHLOROSILANE (7 total), please visit the HSDB record page.

Highly flammable. May enflame spontaneously in air [NFPA 1991]. Undergoes vigorous reaction with water to generate hydrogen chloride, heat and other products. The heat may be sufficient to ignite nearby combustible material.

Methyldichlorosilane reacts vigorously with water to generate gaseous HCl. Based on a scenario where the chemical is spilled into an excess of water (at least 5 fold excess of water), half of the maximum theoretical yield of Hydrogen Chloride gas will be created in 0.12 minutes. Experimental details are in the following: "Development of the Table of Initial Isolation and Protective Distances for the 2008 Emergency Response Guidebook", ANL/DIS-09-2, D.F. Brown, H.M. Hartmann, W.A. Freeman, and W.D. Haney, Argonne National Laboratory, Argonne, Illinois, June 2009.

Chlorosilanes

Highly Flammable

Water-Reactive

Pyrophoric

Chlorosilanes, such as METHYLDICHLOROSILANE, 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. Impact of dichlorosilane causes mixtures to burst into flame. This is the case, when the dichlorosilane and most likely related substances are mixed with oxidants such as potassium permanganate, lead oxide, copper oxide, or silver oxide, even under inert gas atmosphere [Bretherick, 1995, pg. 193]. With METHYLDICHLOROSILANE, toxic hydrogen chloride and phosgene gases may be formed when burned.

The pure material is not ignited by impact, but it is in presence of potassium permanganate or lead(II), (IV) oxide, or by copper oxide or silver oxide, even under an inert gas. /Oxidants/

Evolves hydrogen and may ignite on contact with base ... Reacts with water to produce hydrogen chloride.

Reacts violently with oxidants. ...Reacts in the presence of potassium permanganate, lead(II) oxide, copper oxide or silver oxide, causing fire and explosion hazard. Attacks many metals in presence of water.

The substance can be absorbed into the body by inhalation of its vapour and by ingestion.

Burning sensation. Cough. Sore throat. Laboured breathing. Shortness of breath. Symptoms may be delayed.

Redness. Blisters. Pain. Skin burns.

Redness. Pain. Severe deep burns.

Burning sensation. Abdominal pain. Shock or collapse.

Dermatotoxin - Skin burns.

Toxic Pneumonitis - Inflammation of the lungs induced by inhalation of metal fumes or toxic gases and vapors.

LC50 (rat) = 300 ppm/4h

LC50 Rat inhalation 300 ppm/ 4 hr

LD50 Rat oral 2830 uL/kg

No specific antidote is available /for chlorosilanes/, but first aid treatment consists of copious irrigation with water, & subsequent treatment is as for chemical burns in general. /Chlorosilanes/

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Anticipate seizures and treat if necessary ... . Monitor for shock and treat if necessary ... . For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal (refer to ingestion protocol in Section Three ... . Cover skin burns with sterile dressings after decontamination ... . /Silane, Chlorosilane, and Related Compounds/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Early intubation at the first sign of upper airway obstruction may be necessary. Positive-pressure ventilation techniques with a bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Silane, Chlorosilane, and related compounds/

/SIGNS AND SYMPTOMS/ Causes severe eye & skin burns. May be harmful if absorbed through skin or inhaled. Irritating to skin, eyes, & respiratory system.

/LABORATORY ANIMALS: Acute Exposure/ Tests by application of a drop to rabbit eyes have been made on tetrachlorosilane, dichloridimethyl silane, dichlorodiethylsilane, methyltrichlorosilane, & ethyl trichlorosilane. All the chlorosilanes were found to cause severe damage of the cornea & lids. More severe damage was caused by the alkylchlorosilanes than by tetrachlorosilane (silicone tetrachloride). The principal danger is from splash contamination. /Chlorosilanes/

/LABORATORY ANIMALS: Acute Exposure/ Corrosive to skin /of animals/ due to liberation of hydrochloric acid.

/LABORATORY ANIMALS: Acute Exposure/ All these compounds, even in very low doses ... caused severe burns of cornea and eyelids. ... /After/ application to the skin of the rabbit the region attacked by chlorosilanes blanches and then blisters appear ... /Chlorosilanes/

Methyldichlorosilane's production and use in the synthesis of siloxanes may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 429 mm Hg at 25 °C indicates methyldichlorosilane will exist solely as a vapor phase in the atmosphere. Vapor-phase methyldichlorosilane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 107 days. Methyl silanes are transparent to UV radiation >290 nm and therefore methydichlorosilane is not expected to undergo direct photolytic degradation. If released to soil, methyldichlorosilane is expected to react with soil and therefore soil mobility and volatization are not important environmental fate processes. All silicon chlorides are immediately and completely hydrolyzed by water; therefore if released to water, methyldichlorosilane is expected to instantaneously hydrolyze to methyl dihydroxysilane upon contact with water. Biodegradation of methyldichlorosilane is irrelevant due to hydrolysis. Bioconcentration of methyldichlorosilane will not occur due to the rapid hydrolysis. Occupational exposure to methyldichlorosilane may occur through inhalation with this compound at workplaces where methyldichlorosilane is produced or used. (SRC)

Methyldichlorosilane's production and use in the synthesis of siloxanes(1) may result in its release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: All silicon chlorides are immediately and completely hydrolyzed by water(1); therefore, methyldichlorosilane is expected to instantaneously hydrolyze to methyl dihydroxysilane upon contact with moist soil. Absorption to moist soil surfaces is not expected to be an important environmental fate process(SRC) due to this rapid hydrolysis(1). Methyldichlorosilane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 429 mm Hg(2).

AQUATIC FATE: All silicon chlorides are immediately and completely hydrolyzed by water(1); therefore, methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(1). Due to the rapid hydrolysis, bioconcentration and biodegradation are not important environmental factors for methyldichlorosilane(SRC) .

AQUATIC FATE: In water, chlorosilanes are hydrolyzed rapidly, releasing hydrochloric acid. /Chlorosilane/

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methyldichlorosilane, which has a vapor pressure of 429 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase methyldichlorosilane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 107 days (SRC), calculated from its rate constant of 1.5X10-13 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Methyl silanes are transparent to UV radiation >290 nm(4) and therefore methyldichlorosilane is not expected to undergo direct photolytic degradation(SRC).

For more Environmental Fate (Complete) data for METHYLDICHLOROSILANE (6 total), please visit the HSDB record page.

The rate constant for the vapor-phase reaction of methyldichlorosilane with photochemically-produced hydroxyl radicals has been estimated as 1.5X10-13 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 107 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). All silicon chlorides are immediately and completely hydrolyzed by water therefore methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(2). Methyl silanes are transparent to UV radiation >290 nm(3) and therefore methyldichlorosilane is not expected to undergo direct photolytic degradation(SRC).

Chlorosilanes are not expected to persist long enough to bioconcentrate. /Chlorosilanes/

All silicon chlorides are immediately and completely hydrolyzed by water therefore methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(1). Soil adsorption and mobility are negligible when compared to the immediate hydrolysis(SRC).

The Henry's Law constant for methyldichlorosilane is estimated as 1.3X10-2 atm-cu m/mole(SRC) using a fragment constant estimation method(1). Methyldichlorosilane's Henry's Law constant indicates that volatilization from moist soil surfaces may occur however hydrolysis from water(2) is expected to occur at a more rapid rate than volatilization from moist surfaces(SRC). All silicon chlorides are immediately and completely hydrolyzed by water therefore methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(2). Methyldichlorosilane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 429 mm Hg(3).

The high volatility of /chlorosilanes/ suggests that they will move freely into the atmosphere. /Chlorosilanes/

Occupational exposure to methyldichlorosilane may occur through inhalation and dermal contact with this compound at workplaces where methyldichlorosilane is produced or used. (SRC)

Methyldichlorosilane's production and use in the synthesis of siloxanes may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 429 mm Hg at 25 °C indicates methyldichlorosilane will exist solely as a vapor phase in the atmosphere. Vapor-phase methyldichlorosilane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 107 days. Methyl silanes are transparent to UV radiation >290 nm and therefore methydichlorosilane is not expected to undergo direct photolytic degradation. If released to soil, methyldichlorosilane is expected to react with soil and therefore soil mobility and volatization are not important environmental fate processes. All silicon chlorides are immediately and completely hydrolyzed by water; therefore if released to water, methyldichlorosilane is expected to instantaneously hydrolyze to methyl dihydroxysilane upon contact with water. Biodegradation of methyldichlorosilane is irrelevant due to hydrolysis. Bioconcentration of methyldichlorosilane will not occur due to the rapid hydrolysis. Occupational exposure to methyldichlorosilane may occur through inhalation with this compound at workplaces where methyldichlorosilane is produced or used. (SRC)

Methyldichlorosilane's production and use in the synthesis of siloxanes(1) may result in its release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: All silicon chlorides are immediately and completely hydrolyzed by water(1); therefore, methyldichlorosilane is expected to instantaneously hydrolyze to methyl dihydroxysilane upon contact with moist soil. Absorption to moist soil surfaces is not expected to be an important environmental fate process(SRC) due to this rapid hydrolysis(1). Methyldichlorosilane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 429 mm Hg(2).

AQUATIC FATE: All silicon chlorides are immediately and completely hydrolyzed by water(1); therefore, methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(1). Due to the rapid hydrolysis, bioconcentration and biodegradation are not important environmental factors for methyldichlorosilane(SRC) .

AQUATIC FATE: In water, chlorosilanes are hydrolyzed rapidly, releasing hydrochloric acid. /Chlorosilane/

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), methyldichlorosilane, which has a vapor pressure of 429 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase methyldichlorosilane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 107 days (SRC), calculated from its rate constant of 1.5X10-13 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Methyl silanes are transparent to UV radiation >290 nm(4) and therefore methyldichlorosilane is not expected to undergo direct photolytic degradation(SRC).

For more Environmental Fate (Complete) data for METHYLDICHLOROSILANE (6 total), please visit the HSDB record page.

The rate constant for the vapor-phase reaction of methyldichlorosilane with photochemically-produced hydroxyl radicals has been estimated as 1.5X10-13 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 107 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). All silicon chlorides are immediately and completely hydrolyzed by water therefore methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(2). Methyl silanes are transparent to UV radiation >290 nm(3) and therefore methyldichlorosilane is not expected to undergo direct photolytic degradation(SRC).

Chlorosilanes are not expected to persist long enough to bioconcentrate. /Chlorosilanes/

All silicon chlorides are immediately and completely hydrolyzed by water therefore methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(1). Soil adsorption and mobility are negligible when compared to the immediate hydrolysis(SRC).

The Henry's Law constant for methyldichlorosilane is estimated as 1.3X10-2 atm-cu m/mole(SRC) using a fragment constant estimation method(1). Methyldichlorosilane's Henry's Law constant indicates that volatilization from moist soil surfaces may occur however hydrolysis from water(2) is expected to occur at a more rapid rate than volatilization from moist surfaces(SRC). All silicon chlorides are immediately and completely hydrolyzed by water therefore methyldichlorosilane is expected to immediately hydrolyze to methyl dihydroxysilane upon contact with water(2). Methyldichlorosilane is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 429 mm Hg(3).

The high volatility of /chlorosilanes/ suggests that they will move freely into the atmosphere. /Chlorosilanes/

Occupational exposure to methyldichlorosilane may occur through inhalation and dermal contact with this compound at workplaces where methyldichlorosilane is produced or used. (SRC)

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

If ... THERE IS NO FIRE, go directly to the Table of Initial Isolation and Protective Action Distances /(see table below)/ ... to obtain initial isolation and protective action distances. IF THERE IS A FIRE, or IF A FIRE IS INVOLVED, go directly to the appropriate guide /(see guide(s) below)/ and use the evacuation information shown under PUBLIC SAFETY.

Table: Table of Initial Isolation and Protective Action Distances for Methyldichlorosilane (when spilled in water) [Table#2916]

Table of Water-Reactive Materials Which Produce Toxic Gases. Methyldichlorosilane

Table: Materials Which Produce Large Amounts of Toxic-by-Inhalation (TIH) Gas(es) When Spilled in Water [Table#2917]

/GUIDE 139: SUBSTANCES - WATER-REACTIVE (Emitting Flammable and Toxic Gases)/ Fire or Explosion: Produce flammable and toxic gases on contact with water. May ignite on contact with water or moist air. Some react vigorously or explosively on contact with water. May be ignited by heat, sparks or flames. May re-ignite after fire is extinguished. Some are transported in highly flammable liquids. Containers may explode when heated. Runoff may create fire or explosion hazard.

/GUIDE 139: SUBSTANCES - WATER-REACTIVE (Emitting Flammable and Toxic Gases)/ Health: Highly toxic: contact with water produces toxic gas, may be fatal if inhaled. Inhalation or contact with vapors, substance or decomposition products may cause severe injury or death. May produce corrosive solutions on contact with water. Fire will produce irritating, corrosive and/or toxic gases. Runoff from fire control may cause pollution.

For more DOT Emergency Guidelines (Complete) data for METHYLDICHLOROSILANE (10 total), please visit the HSDB record page.

UN 1242; METHYL DICHLOROSILANE

IMO 3.2; METHYL DICHLOROSILANE

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

Dangerous When Wet Corrosive Flammable Liquid

Airtight. Unbreakable packaging. Put breakable packaging into closed unbreakable container. Do not transport with food and feedstuffs.

UN Hazard Class: 4.3; UN Subsidiary Risks: 3 and 8; UN Pack Group: I