N-cyclohexylbenzothiazole-2-sulfenamide

Phototransformation in water

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in water

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Study type:

direct photolysis

Principles of method if other than guideline:

Substance was exposed to sunlight at a concentration of about 1 ppm in sterile pure water solution with 1% acetonitrile as cosolvent. A dark control was performed to estimate the approximate stability of the chemical in water. The losses of the substance in the dark control may have been due to oxidation or hydrolysis.

GLP compliance:

not specified

Analytical method:

high-performance liquid chromatography

Light source:

sunlight

Details on light source:

midday in August
The experimental tubes were placed in a location free of excessive reflections from walls and windowns and without morning or afternoon shadows.

Dark controls:

yes

Remarks:

at 23°C

Key result

% Degr.:

50

Sampling time:

26 min

Transformation products:

yes

The UV spectrum of Santocure shows that it absorbs moderately in the solar spectral region. The screening experiment for the sunlight photolysis of SC in pure water gave a rate constant of 4.4 (±0.1)*10^-6 sec^-1 at midday in August, which corresponds to a half-life of 26 minutes. As the photolysis proceeded, one major product was formed however not identified. Santocure also undergoes transformation in water in the dark. For a 1.0 ppm SC solution at room temperature (23°C), the first-order rate constant to be 2.0 (±0.07) *10^-9 sec^-1, which corresponds to a half-life of 9.6 hours. The same major product from the sunlight photolysis was also found in the dark reaction mixture.

Conclusions:

The screening experiment for the sunlight direct photolysis of CBS in pure water gave a first-order rate constant of 4.4 (±0.1)*10-6sec-1at midday in August, which corresponds to a half-life of 26 minutes (Monsanto, 1980).

Executive summary:

In a study on the phototransformation, N-cyclohexylbenzothiazole-2-sulphenamide was examined in Milli-Q water using 1% acetonitril with direct exposure to sunlight at midday in August 1979. The degradation of the test substance was monitored with HPLC and samples were taken directly from the test vessel and injected onto the HPLC column.

 

From the observed degradation via HPLC a first-order rate constant for the photolysis of N-cyclohexylbenzothiazole-2-sulphenamide in pure water was derived as 4.4(±0.1)*10-6sec-1, which corresponds to a half-life of 26 minutes.

 

 

 

Description of key information

The screening experiment for the sunlight direct photolysis of CBS in pure water gave a first-order rate constant of 4.4 (±0.1)*10-6 sec-1 at midday in August, which corresponds to a half-life of 26 minutes (Monsanto, 1980).

Key value for chemical safety assessment

Half-life in water:

26 min

Additional information

The values mentioned above refer to the top millimetres of a water body in summer, because of factors like cloudiness, shadowing effects of vegetation, absorption and scattering of light by suspended solids etc. The actual environmental lifetime is certainly longer.