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Metals -> Metalloid Compounds (Silicon)

Flammable agents - 3rd degree

1.02 (NIOSH, 2024) - Denser than water; will sink

1.0232 g/cu cm at 20 °C

Relative density (water = 1): 1.02

1.02

1.0232 @ 20°C

1.02

Colorless liquid

Clear, colorless liquid [Note: A solid below 28 degrees F].

Soluble (NIOSH, 2024)

Very soluble in ethanol

SOL IN ORGANIC SOLVENTS

Not soluble in water

Solubility in water: none

Soluble

205 °F (NIOSH, 2024)

205 °F

20 °C closed cup

20 °C c.c.

205 °F

205 °F

250 °F at 760 mmHg (NIOSH, 2024)

121 °C

121 °C

250 °F

121 °C @760 [mm Hg]

250 °F

28 °F (NIOSH, 2024)

-1 °C

-2 °C

28 °F

-1 °C

28 °F

Relative vapor density (air = 1): 5.3

Relative vapor density (air = 1): 5.3

12 mmHg at 77 °F (NIOSH, 2024)

16.5 [mmHg]

16.5 mm Hg at 20 °C (2.2 kPa)

Vapor pressure, kPa at 20 °C: 2.2

12 mmHg at 77 °F

7.5 [mm Hg] @14.4 °C

This chemical does not meet GHS hazard criteria for 14.6% (61 of 417) of reports.

Danger

H226 (81.3%): Flammable liquid and vapor [Warning Flammable liquids]

P210, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P270, P271, P280, P284, P302+P352, P303+P361+P353, P304+P340, P305+P354+P338, P316, P317, P319, P320, P321, P332+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 417 reports by companies from 22 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Danger

Chemical: Silicic acid (H4SiO4), tetramethyl ester

Silicic acid (H4SiO4), tetramethyl ester is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Silicic acid (H4SiO4), tetramethyl ester are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Status: Active Update: 25-06-2021 https://echa.europa.eu/registration-dossier/-/registered-dossier/5972

Tetramethyl orthosilicate: Does not have an individual approval but may be used under an appropriate group standard

The New Jersey Worker and Community Right to Know Act requires public and private employers to provide information about hazardous substances at their workplaces. (N.J.S.A. 34:5A-1 et. seq.)

Excerpt from ERG Guide 155 [Substances - Toxic and/or Corrosive (Flammable / Water-Sensitive)]:

· HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames.

Flammable. Above 20 °C explosive vapour/air mixtures may be formed.

Excerpt from ERG Guide 155 [Substances - Toxic and/or Corrosive (Flammable / Water-Sensitive)]:

· TOXIC and/or CORROSIVE; inhalation, ingestion or contact (skin, eyes) with vapors, dusts or substance may cause severe injury, burns or death.

Severe damage to the cornea has been reported after occupational exposure. Experimental animals exposed repeatedly to 30 ppm develop respiratory disease with bronchiolar inflammation. [ACGIH] Its severe corneal toxicity is delayed by several hours, and workers have little or no immediate eye symptoms. [HSDB] Has potential to cause pulmonary edema after high inhalation exposure; May have effects on liver and kidneys; [ICSC] See Ethyl silicate.

2606 155

2606 155

Excerpt from ERG Guide 155 [Substances - Toxic and/or Corrosive (Flammable / Water-Sensitive)]:

Use water spray, powder, foam, carbon dioxide.

Fresh air, rest. Half-upright position. Refer for medical attention.

Remove contaminated clothes. Rinse and then wash skin with water and soap.

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. Rest. Refer for medical attention .

· 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.

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

Excerpt from NIOSH Pocket Guide for Methyl silicate:

General First Aid:

(General first aid procedures)

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

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].

This chemical is a combustible liquid. Poisonous gases including silicon oxide are produced in fire. Use dry chemical, carbon dioxide, alcohol or polymer foam extinguishers. Do not use water. Vapors are heavier than air and will collect in low areas. Vapors in confined areas may explode when exposed to fire. Containers may explode in fire. Storage containers and parts of contaners may rocket great distances, in many directions. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters. Notify local health and fire officials and pollution control agencies. Containers may explode in fire. From a secure, explosion-proof location, use water spray to cool exposed containers. If cooling streams are ineffective (venting sound increases in volume and pitch, tank discolors or shows any signs of deforming), withdraw immediately to a secure position ...

If material on fire or involved in fire: Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Solid streams of water may be ineffective. Cool all affected containers with flooding quantities of water. Use foam, dry chemical, or carbon dioxide. Keep run-off water out of sewers and water sources ... If fire becomes uncontrollable or container is exposed to direct flame, consider evacuation of one-third (1/3) mile. /Methyl orthosilicate/

Suitable extinguishing media: For small (incipient) fires, use media such as "alcohol" foam, dry chemical, or carbon dioxide. For large fires, apply water from as far as possible. Use very large quantities (flooding) of water applied as a mist or spray; solid streams of water may be ineffective. Cool all affected containers with flooding quantities of water. ... Use water spray to cool unopend containers.

Special protective equipment for fire-fighters: Wear self contained breathing apparatus for fire fighting if necessary.

Separate from acids, oxidizing materials, and water. Outside or detached storage is preferred.

... Store in tightly closed containers in a cool, well-ventilated area away from water and moisture. Sources of ignition such as smoking and open flames are prohibited where methyl silicate is used, handled, or stored in a manner that could create a potential fire or explosion hazard.

Separated from food and feedstuffs.

Store in cool place. Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage. Store under inert gas. Moisture sensitive. Hydrolyses readily.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Evacuate and restrict persons not wearing protective equipment from area of spill or leak until cleanup is complete. Remove all ignition sources. Ventilate area of spill or leak. Absorb liquids in vermiculite, dry sand, earth, peat, carbon, or a similar material and deposit in sealed containers. Keep this chemical out of a confined space, such as a sewer, because of the possibility of an explosion, unless the sewer is designed to prevent the buildup of explosive concentrations. It may be necessary to contain and dispose of this chemical as a hazardous waste. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters ...

Initial isolation and protective action distances: Small spills (from a small package or a small leak from a large package): first isolate in all directions 200 feet. Then protect persons downwind 0.1 mile (day), 0.3 mile (night). Large spills (from a large package or from many small packages): first isolate in all directions 500 feet. Then protect persons downwind 0.3 mile (day), 1.0 mile (night). Distances shown are likely to be affected during the first 30 minutes after materials are spilled and could increase with time. If more than one tank car, cargo tank, portable tank, or large cylinder is involved in the incident is leaking, the protective action distance may need to be increased ...

Land spill: Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. Absorb bulk liquid with fly ash, cement powder, or commercial sorbents.

For more Cleanup Methods (Complete) data for Tetramethyl silicate (8 total), please visit the HSDB record page.

Burn in a chemical incinerator equipped with an afterburner and scrubber but exert extra care in igniting as this material is highly flammable. This combustible material may be burned in a chemical incinerator equipped with an afterburner and scrubber. Observe all federal, state, and local environmental regulations. Contact a licensed professional waste disposal service to dispose of this material.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity 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 and plant life; and conformance with environmental and public health regulations.

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 650(SRC), determined from a structure estimation method(2), indicates that tetramethyl silicate is expected to have low mobility in soil(SRC). Volatilization of tetramethyl silicate from moist soil surfaces may be an important fate process(SRC) given an estimated Henry's Law constant of 6.4X10-6 atm-cu m/mole(SRC), using a fragment constant estimation method(3). Tetramethyl silicate is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 16.5 mm Hg at 20 °C(4). Biodegradation data were not available(SRC, 2009).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 650(SRC), determined from a structure estimation method(2), indicates that tetramethyl silicate is expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces may occur(3) based upon an estimated Henry's Law constant of 6.4X10-6 atm-cu m/mole(SRC), developed using a fragment constant estimation method(4). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 7.3 and 57 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 3(SRC), from an estimated log Kow of -1.93(6) and a regression-derived equation(7), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Biodegradation data were not available(SRC, 2009).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), tetramethyl silicate, which has a vapor pressure of 16.5 mm Hg at 20 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase tetramethyl silicate 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 4.8 days(SRC), calculated from its rate constant of 3.3X10-12 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Tetramethyl silicate does not contain chromophores that absorb at wavelengths >290 nm(4) and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

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

inhalation, ingestion, skin and/or eye contact

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

Redness. Pain.

Redness. Pain. Loss of vision.

Abdominal pain.

irritation eyes, corneal damage (following even short-term exposure to the vapor); lung, kidney injury; pulmonary edema

Using a structure estimation method based on molecular connectivity indices(1), the Koc of tetramethyl silicate can be estimated to be 650(SRC). According to a classification scheme(2), this estimated Koc value suggests that tetramethyl silicate is expected to have low mobility in soil.

/HUMAN EXPOSURE STUDIES/ Efforts to estimate the air concn ... relative to corneal damage in man revealed that in general, 200-300 ppm are required for 15 min to produce minimal lesions, 1000 ppm to produce injury requiring hospitalization.

/SIGNS AND SYMPTOMS/ A severe eye irritant. This material can cause extensive necrosis (experimentally), keratoconus, and opaque cornea. It also causes severe human eye injuries, as well as necrosis of corneal cells, which progresses long after exposure has ceased. It is destructive and its effects resist treatment. Permanent blindness is possible from exposure to it.

/SIGNS AND SYMPTOMS/ Methyl silicate can affect you when breathed in. Severely irritates and burns the eyes and skin. Exposure to the vapor can cause severe eye damage and cause permanent blindness. This can occur up to 12 hours after exposure has ceased, even if no irritation is noticed at the time. Inhalation irritates the respiratory tract. Higher exposures can cause pulmonary edema, a medical emergency, that can be delayed for several hours. This can cause death. Exposure to high levels can damage the lungs and kidneys.

/SIGNS AND SYMPTOMS/ The substance irritates severely the eyes, the skin and the respiratory tract. Inhalation of vapor may cause lung edema ... The symptoms of lung edema often do not become manifest until a few hours have passed, and they are aggravated by physical effort ... The substance may have effects on the kidneys and liver..

For more Human Toxicity Excerpts (Complete) data for Tetramethyl silicate (6 total), please visit the HSDB record page.

An estimated BCF of 3 was calculated for tetramethyl silicate(SRC), using an estimated log Kow of -1.93(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Henry's Law constant for tetramethyl silicate is estimated as 6.4X10-6 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that tetramethyl silicate may volatilize from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 7.3 days(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 57 days(SRC) Tetramethyl silicate's Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). Tetramethyl silicate is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 16.5 mm Hg(3).

/LABORATORY ANIMALS: Acute Exposure/ The toxicities of silicon tetraalkoxides, including tetramethoxysilane [Si(OCH3)4, TMOS], tetraethoxysilane [Si(OC2H5)4, TEOS], tetrapropoxysilane [Si(OC3H7)4, TPOS] and tetrabuthoxysilane [Si(OC4H9)4, TBOS], were investigated with ip injection of 1,000 mg/kg of each compound. TMOS, as well as TEOS, caused acute tubular necrosis. Blood biochemical examination revealed elevation of blood urea nitrogen and creatinine in mice treated with TEOS, TPOS and TBOS, though TMOS treated mice died and therefore could not be examined. The severity of nephrotoxicity differs among these silicon tetraalkoxides. The spleens of mice treated with TMOS exhibited cytolysis in the white and red pulp, suggesting direct injury to the spleen. The kidney seems to be a common target organ of silicon tetraalkoxides.

/LABORATORY ANIMALS: Acute Exposure/ In range-finding toxicity tests ... undiluted methyl silicate /rated/ as very severe eye irritant in rabbits leading to marked edema and necrosis of the lid.

/LABORATORY ANIMALS: Acute Exposure/ Exposure of rabbits at 1000 ppm in dry air caused "delayed" eye burn; saturated vapor (15,000 ppm at 25 °C) for 5 min caused eye burn, but exposure for 4 min, none. Saturated vapor at 100% relative humidity for 5 min resulted in slight amt of necrosis.

/LABORATORY ANIMALS: Acute Exposure/ Highest concn that still produced no damage to the guinea pig eye, the most sensitive target site, were 135 ppm for 15 min, 90 ppm for 1 hr, 20 ppm for 8 periods of 1 hr each, and 20 ppm for 5 days of 8 periods of 1 hr. Brief exposures to high concn were productive of greater injury than lower concn for longer periods.

For more Non-Human Toxicity Excerpts (Complete) data for Tetramethyl silicate (6 total), please visit the HSDB record page.

The rate constant for the vapor-phase reaction of tetramethyl silicate with photochemically-produced hydroxyl radicals has been estimated as 3.3X10-12 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 4.8 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). Tetramethyl silicate is expected to undergo hydrolysis in the environment after 2 days(2). Tetramethyl silicate does not contain chromophores that absorb at wavelengths >290 nm(3) and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

Used in corrosion resistant coatings and in catalysts; used to manufacture silicone; [ACGIH]

Methyl silicate has been used in the ceramic industry for closing pores, including those in concrete and cement, for coating metal surfaces and as a bonding agent in paints and lacquers.

In coating picture screens of television picture tubes

Used in the glass frosting process

Used in the sol-gel synthesis of chromium-doped silicates and in the formation of hexagonal mesoporous silica layers.

2023: 50,000 - <250,000 lb

Silicic acid (H4SiO4), tetramethyl ester is listed as a High Production Volume (HPV) chemical (65FR81686). Chemicals listed as HPV were produced in or imported into the U.S. in >1 million pounds in 1990 and/or 1994. The HPV list is based on the 1990 Inventory Update Rule. (IUR) (40 CFR part 710 subpart B; 51FR21438).

Production volumes for non-confidential chemicals reported under the Inventory Update Rule. [Table#5421]

All Other Basic Inorganic Chemical Manufacturing

Silicic acid (H4SiO4), tetramethyl ester: ACTIVE

Silica aerogels are usually prepared by base-catalyzed reaction of tetramethoxysilane (TMOS) or tetraethoxysilane(TEOS), mostly with ammonia as the catalyst. A modification of this procedure is to pre-hydrolyze Si(OR)4 with a small amount of water under acidic conditions.