Registration Dossier

Diss Factsheets

Environmental fate & pathways

Phototransformation in air

Currently viewing:

Administrative data

Link to relevant study record(s)

Description of key information

Key value for chemical safety assessment

Additional information

Methyl-N-[3-(trimethoxysilyl)propyl]carbamate (CAS 23432-62-4) and its hydrolysis product methyl-N-[3-(trihydroxysilyl)propyl]carbamate contain no chromophores that would absorb visible or UV radiation, so direct photolysis is not likely to be significant. Indirect photolysis resulting from gas-phase reaction with photochemically-produced hydroxyl radicals may occur.

The SRC AOPWIN program (v1.92) has been used to obtain values of the rate constant kOH for reaction of methyl-N-[3-(trimethoxysilyl)propyl]carbamate (CAS 23432-62-4) and its hydrolysis product methyl-N-[3-(trihydroxysilyl)propyl]carbamate with hydroxyl radicals. This prediction method has not been validated to assess applicability to silanes and silanols, therefore, there is uncertainty associated with the calculated values obtained.

The overall half-life in air under default conditions of hydroxyl radical concentration was calculated using the following expressions:

kdegair(d-1) = kOH(cm3/molecule. sec) x OH Concair(molecules/cm3) x 24 x 3600

DT50(d) = ln 2/ kdegair(d-1)


kdegair = total rate constant for degradation in air

kOH = rate constant for reaction with hydroxyl radicals

OH Concair = concentration of hydroxyl radicals in air = 5 x 105OH molecules/ cm3

DT50 = half-life

The results are given in table below:

Table 4.1.2 Results of photodegradation in air calculations




kOH(cm3/molecule. sec)



kdegair (d-1)




0.93 Days (24-hr day; 0.5E6 OH/cm3)

0.64 Days (24-hr day; 0.5E6 OH/cm3)