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Silanes and silicones

Hexamethyl diorthosilicate

Also known as hexamethoxydisiloxane, hexamethoxy disiloxane, trimethyl trimethoxysilyl silicate

CAS 4371-91-9Formula C6H18O7Si2Molar mass 258.38 g/molEC 224-467-7
GHS signal word: Danger. Pictograms: Flammable, Harmful or irritant
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Hexamethyl diorthosilicate chemical structure, C6H18O7Si2, CAS 4371-91-9
2D chemical structure

Key facts

What buyers check first

All properties
CAS number
4371-91-9
Formula
C6H18O7Si2
Molar mass
258.38 g/mol
EC number
224-467-7
HS code
292090
Category
Silanes and silicones

What is Hexamethyl diorthosilicate?

Plain description, key identifiers and synonyms

Hexamethyl diorthosilicate is a chemical substance with the molecular formula C6H18O7Si2 and a molar mass of 258.38 g/mol. Its CAS registry number is 4371-91-9. The IUPAC name is trimethyl trimethoxysilyl silicate.

Identifiers

Registry numbers, names and line notations, tap to copy

IUPAC name
trimethyl trimethoxysilyl silicate
CAS number
4371-91-9 CAS number cross-checked
EC number
224-467-7
Molecular formula
C6H18O7Si2
MDL number
MFCD02912820
InChIKey
XOAJIYVOSJHEQB-UHFFFAOYSA-N
InChI
InChI=1S/C6H18O7Si2/c1-7-14(8-2,9-3)13-15(10-4,11-5)12-6/h1-6H3
SMILES (canonical and isomeric)
CO[Si](OC)(OC)O[Si](OC)(OC)OC

Synonyms

  • hexamethoxydisiloxane
  • hexamethoxy disiloxane
  • trimethyl trimethoxysilyl silicate
  • Disiloxane, hexamethoxy-
  • Trimethyl trimethoxysilyl orthosilicate #
  • Disilicic acid (H6-Si2-O7), hexamethyl ester
  • C6H18O7Si2
  • hexamethyl disilicate
  • trimethyl trimethoxysilyl s
  • Trimethyl trimethoxysilyl orthosilicate

Physical and chemical properties

Measured values and descriptors computed from the structure

Physical and chemical properties

Measured values, check the supplier specification for your grade

No measured properties are recorded for this substance yet. Ask suppliers for a technical data sheet.

Values vary by grade. Ask suppliers for the COA or TDS of the batch you buy.

Computed descriptors

Calculated from the structure, useful for screening and formulation

Molecular weight
258.38 g/molcalc.
Exact mass
258.0591 Dacalc.
LogP (octanol/water)
-0.25calc.
Topological polar surface area
64.61 Ųcalc.
Hydrogen bond donors
0calc.
Hydrogen bond acceptors
7calc.
Rotatable bonds
8calc.
Heavy atoms
15calc.
Rings
0calc.
Aromatic rings
0calc.
Fraction sp3 carbons
1calc.
Formal charge
0calc.
Stereocentres
0calc.
Lipinski rule of five
Passes (0 violations)calc.

Calculated for screening. Confirm critical figures with the supplier.

Safety and hazards

GHS classification summary, not a safety data sheet

GHS signal word
Danger
GHS02: Flammable
Flammable
GHS07: Harmful or irritant
Harmful or irritant

Hazard statements

  • H225Highly flammable liquid and vapour.
  • H226Flammable liquid and vapour.
  • H315Causes skin irritation.
  • H319Causes serious eye irritation.
  • H335May cause respiratory irritation.
Precautionary statements (25)
  • P210Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P233Keep container tightly closed.
  • P240Ground and bond container and receiving equipment.
  • P241Use explosion-proof electrical, ventilating and lighting equipment.
  • P242Use non-sparking tools.
  • P243Take action to prevent static discharges.
  • P261Avoid breathing dust, fume, gas, mist, vapours or spray.
  • P264Wash skin thoroughly after handling.
  • P264 + P265Wash skin thoroughly after handling. Do not touch eyes.
  • P271Use only outdoors or in a well-ventilated area.
  • P280Wear protective gloves, protective clothing, eye protection and face protection.
  • P302 + P352If on skin: Wash with plenty of water.
  • P303 + P361 + P353If on skin (or hair): Take off immediately all contaminated clothing. Rinse skin with water or shower.
  • P304 + P340If inhaled: Remove person to fresh air and keep comfortable for breathing.
  • P305 + P351 + P338If in eyes: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing.
  • P319Get medical help if you feel unwell.
  • P321Specific treatment (see supplemental first aid instructions on the label).
  • P332 + P317If skin irritation occurs: Get medical help.
  • P337 + P317If eye irritation persists: Get medical help.
  • P362 + P364Take off contaminated clothing. And wash it before reuse.
  • P370 + P378In case of fire: Use appropriate media to extinguish.
  • P403 + P233Store in a well-ventilated place. Keep container tightly closed.
  • P403 + P235Store in a well-ventilated place. Keep cool.
  • P405Store locked up.
  • P501Dispose of contents and container in accordance with local regulations.

GHS classification summary, not a safety data sheet (SDS). Classifications can differ by supplier, grade and concentration. Always check the supplier's SDS.

Full safety data and first aid

Hexamethyl diorthosilicate suppliers

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Hexamethyl diorthosilicate price

Indicative price range per kg from live supplier offers

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Uses and applications

What the substance is used for, by industry and function

Applications are not documented for this substance yet. Suppliers often describe uses on their product pages, linked in the suppliers list above.

Regulatory status

Inventories, regulations and trade controls that list this substance

No regulatory list memberships are recorded for this substance yet. Always check the rules of the importing and exporting country before trade.

HS code and trade data

Customs classification and reported world trade statistics

Global trade

World import and export statistics for the HS code Hexamethyl diorthosilicate is traded under.

HS 2920.90Indicative HS code

Esters, other than thiophosphoric esters (phosphorothioates) and phosphite esters and their salts…

World exports in 2024
$1.05B
+8.0% vs 2023, imports $1.23B
2019 to 2024
Top exporters
  1. China33.4%
  2. Germany18.8%
  3. United States12.4%
Top importers
  1. United States19.2%
  2. Singapore8.9%
  3. South Korea6.9%
Reported customs values in USD, not prices.Full trade data

The HS code shown for Hexamethyl diorthosilicate is indicative (it was assigned by structure rules). Confirm the classification with your customs broker before shipping.

Frequently asked questions

Quick answers about Hexamethyl diorthosilicate, based on the data on this page

What is Hexamethyl diorthosilicate?

Hexamethyl diorthosilicate is a chemical substance with the molecular formula C6H18O7Si2 and a molar mass of 258.38 g/mol. Its CAS registry number is 4371-91-9. The IUPAC name is trimethyl trimethoxysilyl silicate.

What is the CAS number of Hexamethyl diorthosilicate?

The CAS registry number of Hexamethyl diorthosilicate is 4371-91-9.

What is the molecular formula and weight of Hexamethyl diorthosilicate?

The molecular formula of Hexamethyl diorthosilicate is C6H18O7Si2 and its molar mass is 258.38 g/mol.

Is Hexamethyl diorthosilicate hazardous?

Hexamethyl diorthosilicate carries the GHS signal word "Danger". Main hazards: highly flammable liquid and vapour, flammable liquid and vapour, causes skin irritation. This summary is not an SDS, always read the supplier safety data sheet.

What is the HS code of Hexamethyl diorthosilicate?

Hexamethyl diorthosilicate is usually classified under HS code 292090 (Esters of other inorganic acids of non-metals (excluding esters of hydrogen halides) and…). This is indicative, confirm it with your customs broker before shipping.

Where can I buy Hexamethyl diorthosilicate?

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What is the price of Hexamethyl diorthosilicate?

Suppliers quote Hexamethyl diorthosilicate on request because prices depend on grade, purity, quantity and destination. A free request on CompoundList gets you several quotes to compare.

Guides for buyers

Practical guides that help when you source, ship or handle Hexamethyl diorthosilicate

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Data last updated 7 Oct 2026. Details may have changed, please confirm them with the supplier. Report an error on this page
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