Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Endpoint summary

Administrative data

Description of key information

Additional information

Physico-chemical properties

(3-chloropropyl)diethoxymethylsilane is a liquid at standard temperature and pressure, with an estimated melting point of <20°C, and a measured boiling point of 206°C. It has a measured relative density of 0.987 at 20°C, a measured viscosity of 1.4 mPasat 25°Cand a predicted vapour pressure of 6.8 Pa at 20°C.


The substance is not classified as flammable on the basis of a measured flash point of 74°C and the boiling point of 206°C. It has a measured auto-ignition temperature of 210°C, and is not explosive and not oxidising on the basis of chemical structure.

In contact with water, (3-chloropropyl)diethoxymethylsilane is predicted to react very rapidly (half-life 9.5 hours at 20 - 25°C and pH7) to produce (3-chloropropyl)methylsilanediol and ethanol according to the following equation:

(ClCH2CH2CH2)Si(CH3)(OCH2CH3)2 + 2 H2O →

(ClCH2CH2CH2)Si(CH3)(OH)2 + 2 CH3CH2OH

Therefore, requirements for testing of water-based physicochemical properties for the substance are waived on the basis of instability in water. The properties of the silanol hydrolysis product, (3-chloropropyl)methylsilanediol,are assessed instead. The hydrolysis product is predicted to be soluble in water (6000 mg/l), with low log Kow (0.8). It is not surface active. The first dissociation constant of a structurally analogous silanediol (dimethylsilandiol) has been reported to be around pKa= 11.9. The hydrolysis product is less volatile than the parent substance (predicted vapour pressure = 0.021 Pa at 25°C).

Ethanol is miscible with water, has low log Kow (-0.3) and high vapour pressure (7910 Pa at 25°C).

Silanediols may undergo condensation reactions to give siloxane dimers, oligomers and polymers, according to the scheme:

R2Si(OH)2   R2Si(OH)OSi(OH)R2     R2Si(OH)O[Si(R2)O]nSi(OH)R2


(where R is an alkyl or aryl side-chain)


The degree of condensation that will occur may vary with:

  • Concentration of the silanol; the greater the initial concentration, the greater the degree of condensation. Significant condensation is not expected at concentrations less than approximately 100 mg/l, but is dependent on specific conditions.
  • pH; the condensation reaction may be either acid or base catalysed.
  • Temperature.
  • Other species present.
  • Timescale
  • The nature of the R group