tetramethyl orthosilicate

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| Watchedfields = changed

| verifiedrevid = 470604767

| ImageFileL1 = Tetramethyl orthosilicate.svg

| ImageFileR1 = Tetramethyl orthosilicate 3D.png

| IUPACName = Tetramethyl orthosilicate

| OtherNames = tetramethyl orthosilicate; methyl silicate; silicic acid, tetramethyl ester; silicon methoxide; TMOS

|Section1={{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| ChemSpiderID = 12161

| InChI = 1/C4H12O4Si/c1-5-9(6-2,7-3)8-4/h1-4H3

| InChIKey = LFQCEHFDDXELDD-UHFFFAOYAT

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C4H12O4Si/c1-5-9(6-2,7-3)8-4/h1-4H3

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = LFQCEHFDDXELDD-UHFFFAOYSA-N

| CASNo_Ref = {{cascite|correct|CAS}}

| CASNo = 681-84-5

| UNII_Ref = {{fdacite|correct|FDA}}

| UNII = 19D35VPL66

| PubChem = 12682

| SMILES = CO[Si](OC)(OC)OC

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|Section2={{Chembox Properties

| Formula = SiC₄H₁₂O₄

| MolarMass = 152.25

| Appearance = colourless liquid

| Density = 1.032

| MeltingPtC = 4 to 5

| MeltingPt_notes =

| BoilingPtC = 121 to 122

| Solubility = organic solvents

| VaporPressure = 12 mmHg (25°C)

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|Section3={{Chembox Hazards

| MainHazards = toxic

| FlashPtF = 205

| FlashPt_ref =

| AutoignitionPt =

| IDLH = N.D.{{PGCH|0428}}

| PEL = none

| REL = TWA 1 ppm (6 mg/m³)

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|Section8={{Chembox Related

| OtherCations = Trimethyl borate
Trimethyl phosphite

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Tetramethyl orthosilicate (TMOS) is the chemical compound with the formula Si(OCH₃)₄. This molecule consists of four methoxy groups bonded to a silicon atom. The basic properties are similar to the more popular tetraethyl orthosilicate, which is usually preferred because the product of hydrolysis, ethanol, is less toxic than methanol.

Tetramethyl orthosilicate hydrolyzes to SiO₂:

:Si(OCH₃)₄ + 2 H₂O → SiO₂ + 4 CH₃OH

In organic synthesis, Si(OCH₃)₄ has been used to convert ketones and aldehydes to the corresponding ketals and acetals, respectively.Sakurai, H. "Silicon(IV) Methoxide" in Encyclopedia of Reagents for Organic Synthesis 2001 John Wiley & Sons. {{doi|10.1002/047084289X.rs012}}