Tetraethoxysilane

Metals -> Metalloid Compounds (Silicon)

Flammable agents - 3rd degree

SHARP, ESTER-LIKE ODOR

Faint odor

Sharp alcohol-like odor

0.933 at 68 °F (USCG, 1999) - Less dense than water; will float

0.933 at 20 °C

Bulk density: 7.8 lbs/gal at 20 °C

Relative density (water = 1): 0.93

0.93

0.9320 @ 20°C

Colorless liquid

Water-white

Reacts with water (NIOSH, 2024)

Soluble in ether

Slightly soluble in benzene

Miscible with alcohol

Decomposes in water

Solubility in water: slowly hydrolyzes

99 °F (USCG, 1999)

99 °F

125 °F (52 °C) (Open cup)

99 °F (Closed cup)

37 °CC, closed-cup

37 °C c.c.

336 °F at 760 mmHg (USCG, 1999)

168.8 °C

168 °C

336 °F

168.8 °C @760 [mm Hg]

336 °F

-121.9 °F (USCG, 1999)

-82.5 °C

-77 °C

-117 °F

-82.5 °C

-117 °F

7.22 (Air = 1)

Relative vapor density (air = 1): 7.22

Warning

H226: Flammable liquid and vapor [Warning Flammable liquids]

P210, P233, P240, P241, P242, P243, P261, P264+P265, P271, P280, P303+P361+P353, P304+P340, P305+P351+P338, P317, P319, P337+P317, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for < 0.1% (1 of 1197) of reports.

Warning

H226 (> 99.9%): Flammable liquid and vapor [Warning Flammable liquids]

Chemical: Silicic acid (H4SiO4), tetraethyl ester

Regulation (EC) No 1935/2004 (amended)

Silicic acid (H4SiO4), tetraethyl ester is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Silicic acid (H4SiO4), tetraethyl 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: 15-05-2023 https://echa.europa.eu/registration-dossier/-/registered-dossier/14920

Silicic acid, tetraethyl ester: HSNO Approval: HSR001223 Approved with controls

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 129 [Flammable Liquids (Water-Miscible / Noxious)]:

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

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

Flammable. Above 37 °C explosive vapour/air mixtures may be formed.

Inhalation of vapor causes eye and nose irritation, unsteadiness, tremors, salivation, respiratory difficulty, and unconsciousness. Contact with liquid irritates eyes and may cause dryness, cracking, and inflammation of skin. Ingestion may produce nausea, vomiting, and cramps. (USCG, 1999)

· May cause toxic effects if inhaled or absorbed through skin.

· May cause toxic effects if inhaled or absorbed through skin.

Rats that survived concentrations of 400 ppm for 7 hours/day for 30 days show liver, kidney, and lung damage. [ACGIH] Causes eye irritation at 250 ppm and tearing at 1,200 ppm; [CSH, p. 402] A skin and respiratory tract irritant; Liquid defats the skin and vapor may depress consciousness; [ICSC] In high-dose animal experiments, it acts as a general anesthetic; [ChemIDplus] See Methyl silicate.

1292 129

1292 129

1292 129

Section 8(a) of TSCA requires manufacturers of this chemical substance to report preliminary assessment information concerned with production, exposure, and use to EPA as cited in the preamble in 51 FR 41329. Effective date 8/23/00; Reporting date: 10/23/00.

Excerpt from ERG Guide 129 [Flammable Liquids (Water-Miscible / Noxious)]:

Use water spray, foam, alcohol-resistant foam. In case of fire: keep drums, etc., cool by spraying with water.

Fresh air, rest.

Remove contaminated clothes. Rinse skin with plenty of water or shower.

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

Rinse mouth.

· 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.

· 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 Ethyl silicate:

General First Aid:

General First Aid:

(General first aid procedures)

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

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

10.0 [ppm]

Water, foam, dry chemical, carbon dioxide

This chemical is a flammable liquid. Poisonous gases including carbon monoxide and silicon oxide are produced in fire. Use dry chemical, carbon dioxide, or foam extinguishers. Vapors are heavier than air and will collect in low areas. Vapors may travel long distances to ignition sources and flashback. Vapors in confined areas may explode when exposed to fire. Containers may explode in fire. Storage containers and parts of containers 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. 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 ...

Ethyl silicate must be stored to avoid contact with strong oxidizers (such as chlorine, bromine, and fluorine) since violent reactions occur. Before entering confined space where this chemical may be present, check to make sure that an explosive concentration does not exist. Store in tightly closed containers in a cool, well-ventilated area away from water. Sources of ignition, such as smoking and open flames, are prohibited where ethyl silicate is handled, used, or stored. Metal containers involving the transfer of five gallons or more of ethyl silicate should be grounded and bonded. Drums must be equipped with self-closing valves, pressure vacuum bungs, and flame arresters. Use only non-sparking tools and equipment, especially when opening and closing containers of ethyl silicate.

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.

Remove all ignition sources. Ventilate area of spill or leak. For small quantities, absorb on paper towels. Evaporate in safe place (such as a fume hood). Allow sufficient time for evaporating vapors to completely clear hood ductwork. Burn paper in suitable location away from combustible materials ... Ethyl silicate should not be allowed to enter a confined space, such as a sewer, because of the possibility of an explosion. Sewers designed to preclude formation of explosive concn of ethyl silicate vapors are permitted.

Collect leaking liquid in sealable containers. Absorb remaining liquid in sand or inert absorbent and remove to safe place. Note: Reacts with water to form an adhesive mass.

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.

Incineration in admixture with a more flammable solvent. /SRP: Process eqipped with afterburner and effluent gas scrubber./

Personal protection: complete protective clothing including self-contained breathing apparatus. Ventilation. Remove all ignition sources. Collect leaking and spilled liquid in sealable containers as far as possible. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations. Note: Reacts with water to form an adhesive mass.

Three experiments were conducted to determine the effects of excess dietary calcium carbonate, phosphorus and urine acidifying and alkalizing salts on silica urolith formation in a model using rats fed dextrose-based diets containing 2% tetraethylorthosilicate (TES). Diets containing 2% TES lowered wt gains to 91-95% of gains made by rats fed non-TES diets. Urine silica concn of rats fed TES were generally in the range of 50-60 mg/dL. In expt 1, rats fed TES with no additional dietary calcium carbonate had a silica urolith incidence of 35%. With additions of 1 and 2% calcium carbonate to the basal-TES diet, respective urolith incidences were 45 and 60% (r = 0.99, P < 0.02). In expt 2, monobasic sodium phosphate (MP) providing 0.2% additional phosphorus resulted in a mean urine pH of 6.42 and no uroliths. Dibasic sodium phosphate (DP) without and with 0.5% sodium bicarbonate (SB) resulted in respective urine pH values of 6.78 and 7.14 and urolith incidences of 15 and 20% (MP less than DP and DP + SB, P < 0.05). However, the uroliths were small averaging less than 1 mg. In expt 3, substitution of autoclaved egg albumin for casein, the protein source in expt 1 and 2, resulted in urine pH of 7.45 and a silica urolith incidence of 46%. An equal-molar mixture of MP and DP providing an added 0.2% phosphorus resulted in a urine pH of 7.07 and reduced the urolith incidence to 4%, and 0.75% of dietary ammonium chloride either with or without the added 0.2% phosphorus gave urine acidification and complete protection from uroliths ...

Rats fed a dextrose-casein type of diet adequate for normal growth and containing 2% of tetraethylorthosilicate were used to study the effect of sodium chloride and sodium sulfate drinking waters & dietary additions of chloride, sulfate & phosphate on formation of silica urinary calculi. 50% of rats fed the basal-tetraethylorthosilicate diet (2%) developed silica urinary calculi. Addition of 0.2 eq/kg diet of chloride, sulfate or phosphate as sodium salts (phosphate was an equal molar mixture of mono- and dibasic sodium phosphates) resulted in a reduction in silica urinary calculi (P <0.05) by dietary chloride (15% incidence) and phosphate (5% incidence) but not by sulfate (35% incidence).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 1(SRC), determined from a structure estimation method(2), indicates that tetraethyl silicate is expected have very high mobility in soil(SRC). Volatilization of tetraethyl silicate from moist soil surfaces may be an important fate process(SRC) given an estimated Henry's Law constant of 2.0X10-5 atm-cu m/mole(SRC), using a fragment constant estimation method(3). Tetraethyl silicate is expected to volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1.88 mm Hg at 25 °C(4). Biodegradation data were not available(SRC, 2009). Without special precautions, tetraethoxysilane hydrolyzes to a gel in about 10 days(5).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 1(SRC), determined from a structure estimation method(2), indicates that tetraethyl silicate is not 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 2.0X10-5 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 2.9 and 25 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 3(SRC), from an estimated log Kow of 0.04(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). Without special precautions, tetraethoxysilane hydrolyzes to a gel in about 10 days(8).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), tetraethyl silicate, which has a vapor pressure of 1.88 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase tetraethyl 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 16 hours(SRC), calculated from its rate constant of 2.5X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Tetraethyl 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

Cough. Dizziness. Headache. Sore throat.

Dry skin. Redness.

Redness. Pain.

Confusion. Vomiting. Further see Inhalation.

irritation eyes, nose; In Animals: lacrimation (discharge of tears); dyspnea (breathing difficulty), pulmonary edema; tremor, narcosis; liver, kidney damage; anemia

The following medical procedures should be made available to each employee who is exposed to ethyl silicate at potentially hazardous levels: Employees should be screened for history of certain medical conditions which might place the employees at increased risk from ethyl silicate exposure. /These are/ chronic respiratory disease ... liver disease ... kidney disease ... blood disease ... skin disease. ... Any employee developing the above-listed conditions should be referred for further medical examination.

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

/HUMAN EXPOSURE STUDIES/ ... Human experiments found: 3000 ppm is extremely irritating to the eyes and nose; 1200 ppm stings eyes and nose and produces tears; 700 ppm mildly stings eyes and nose; 250 ppm makes the eyes and nose tingle slightly; 85 ppm can be detected only by odor. It appeared that 700 ppm would be intolerable to human beings for more than half an hour.

/SIGNS AND SYMPTOMS/ Skin or eye contact can cause severe irritation or burns. The vapor can irritate the nose, eyes, throat, and bronchial tubes, causing cough and difficulty breathing. Higher exposures can cause pulmonary edema, a medical emergency that can be delayed for several hours. This can cause death. Repeated skin contact can cause dryness and cracking.

/SIGNS AND SYMPTOMS/ Orally, the ethyl silicate is moderately toxic, but may be /CNS depressant/ in high concentrations.

/SIGNS AND SYMPTOMS/ Potential symptoms of overexposure are irritation of eyes and nose.

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

An estimated BCF of 3 was calculated for ethyl silicate(SRC), using an estimated log Kow of 0.04(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 tetraethyl silicate is estimated as 2.0X10-5 atm-cu m/mole(SRC) using a fragment constant estimation method(1). This Henry's Law constant indicates that tetraethyl 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 2.9 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 25 days(SRC). Henry's Law constant of tetraethyl silicate indicates that volatilization from moist soil surfaces may occur(SRC). Tetraethyl silicate may volatilize from dry soil surfaces(SRC) based upon a vapor pressure of 1.88 mm Hg(3).

Section 8(a) of TSCA requires manufacturers of this chemical substance to report preliminary assessment information concerned with production, exposure, and use to EPA as cited in the preamble in 51 FR 41329. Effective date 8/23/00; Reporting date: 10/23/00.

Acute stomach, kidney, and bladder toxicity was evaluated in F344 rats after gastric gavage of tetraethylorthosilicate at daily doses of 0, 0.111, 0.223, and 0.333 g. Five rats of each sex at each dose were sacrificed after 1, 2, and 4 days. In tetraethylorthosilicate treated groups, silicate accumulated in the stomach glands and the muscle layer of the forestomach and glandular stomach.

Used in mortar and surface coatings to improve resistance to weather and chemical corrosion; [ACGIH] Used in the semiconductor/electronics industry; [CSH, p. 402] Used in castings for alloys with high melting points, copper alloys, and dental prosthetic devices; Also used as a source of silicon dioxide by vapor deposition and to produce refractory bricks and heat-resistant paints; [HSDB]

Semiconductor Manufacturing [Category: Industry]

Tetraethyl silicate is used as a preservative for stone, brick, concrete, and plaster. It is used in water, weather- and acid-proofing processes, heat- and chemical-resistant paints, and protective coatings.

In weatherproofing and for hardening stone, arresting decay and disintegration; in mfr of weatherproof and acid-proof mortars and cements; in the "lost wax" process for casting of high-melting alloys.[The Merck Index, Fourteenth Edition (2006)

Weatherproof and acid-proof mortar and cements, refractory bricks, other molded objects, heat-resistant paints, chemical-resistant paints, protective coatings for industrial buildings and castings, lacquers, bonding agent intermediate.

Used in ceramic processing

2023: 10,000,000 - <50,000,000 lb

Silicic acid (H4SiO4), tetraethyl 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#1532]

Production volume for non-confidential chemicals reported under the 2006 Inventory Update Rule. Chemical: Silicic acid (H4SiO4), tetraethyl ester. Aggreated National Production Volume: 500,000 to < 1 million lbs.

/Ethyl silicate/... is marketed in 2 grades, a 29% and 40% silicon dioxide, and in a "condensed" form consisting of 85% ethyl silicate and 15% polyethoxysiloxanes.

Extrema - 99.9999% grade /available/

Pure ethyl silicate >98%. A partially hydrolyzed or polymeric version with a substantial portion having an average of 4-5 silicon atoms and 40 wt% silicon dioxide content is called ethyl silicate 40.

Dynasil A

Adhesive Manufacturing

Silicic acid (H4SiO4), tetraethyl ester: ACTIVE