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Physicochemical properties

3-(Triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-propanamine is a liquid at standard temperature and pressure. A glass transition occurs at approximately -120°C and the boiling point is 358°C. It has a predicted density of 1.01 g/cm3 at 20°C and a predicted vapour pressure of 1.8E-04 Pa at 25°C.


The substance is classified as a non-flammable liquid on the basis of the boiling point and a measured flash point of 95°C. It is not pyrophoric or flammable in contact with water. It has a measured self-ignition temperature of 255°C, and is not explosive and not oxidising on the basis of chemical structure. It is not surface active.


The hydrolysis half-life time of 3-(triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-propanamine is 66.2 hours at 25°C and pH 7. It is not predicted to be surface active. It has a predicted low water solubility (23 mg/l), a predicted log Kow of 3.1 and a predicted vapour pressure of 1.8E-04 Pa at 25°C.


3-(Triethoxysilyl)-N-[3-(triethoxysilyl)propyl]-1-propanamine produces a silanol hydrolysis product

3-(trihydroxysilyl)-N-[3-(hydroxysilyl)propyl]-1-propanamine and ethanol according to the following equation:


[(CH3CH2O)3Si(CH2)3]2NH + 6H2O   →  [(HO)3Si(CH2)3]2NH + 6CH3CH2OH


The silanol hydrolysis product is predicted to be very soluble in water at 20-25°C (1E+06 mg/l) and has a predicted log Kow of -4.0. It is less volatile than the parent substance with a vapour pressure of 2.2E-010 Pa at 25°C (predicted).


Ethanol is miscible with water, has low log Kow (-0.3) and high vapour pressure (7910 Pa at 25°C) (Daubert, T E and Danner R P, 1985).


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


RSi(OH)3                         RSi(OH)2OSi(OH)2R                    RSi(OH)2O[Si(R)(OH)O]nSi(OH)2R


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


A highly cross-linked gel may form. 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.  

  • The nature of the R group

  • The number of Si-OH groups; silanetriols condense more rapidly than silanediols.

Additional information