Trimethyl(octadecyloxy)silane

Partition coefficient

Link to relevant study record(s)

Reference

Endpoint:

partition coefficient

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 107 (Partition Coefficient (n-octanol / water), Shake Flask Method)

GLP compliance:

no

Type of method:

flask method

Partition coefficient type:

octanol-water

Key result

Type:

log Pow

Partition coefficient:

> 4.1

Temp.:

23 °C

pH:

>= 6.3 - <= 6.6

A stock solution of the test substance in water saturated n-octanol was prepared. To 25 ml,

50 ml and 100 ml of the stock solution 50 ml of n-octanol saturated water were added. The

two-phase system was shaken vigorously at room temperature (23 °C) for one hour.

Subsequently the phases were separated by centrifugation for 20 min at 14500 rpm and the

test substance concentration in each phase was determined.

Stock solution : 1098 mg/l

Results in detail:

determ. no. stock solution [ml] water [ml] test substance conc. in water phase[mg/l] test substance conc. in noctanol phase [mg/l] log Pow

A1                     25                            50                     < 0,05                                                               612                                                               > 4,1

A2                     25                            50                     < 0,05                                                               545                                                                > 4,0

B1                     50                            50                     < 0,05                                                               586                                                               > 4,1

B2                     50                            50                     < 0,05                                                               580                                                               > 4,1

C1                    100                          50                     < 0,05                                                                504                                                               > 4,0

C2                    100                            50                      < 0,05                                                               377                                                               > (3,9)*

mean                                                                                                                                                                                                                              > 4,1

*: outlier, not evaluated

Recovery rate of test substance:

determ. no.     test substance in stock solution [mg]   test substance in n-octanol phase [mg]    test substance in water phase [mg]       sum [mg]       recovery rate [%]

A1                     27,5                                                 15,3                                                        < 0,0025                                          15,3              56

A2                     27,5                                                 13,6                                                        < 0,0025                                          13,6              50

B1                     54,9                                                 29,3                                                        < 0,0025                                          29,3              53

B2                     54,9                                                 29,0                                                        < 0,0025                                          29,0              53

C1                   109,8                                                 50,4                                                        < 0,0025                                          50,4              46

C2                   109,8                                                 37,7                                                        < 0,0025                                          37,7              34

Remark:

During the shake flask test significant hydrolysis of the test substance occurred. Due to the

water content of the water-saturated n-octanol even in the n-octanol phase hydrolysis takes

place. The hydrolysis product n-octadecanol is present in the n-octanol phase. For estimation

of log Pow the remaining concentration of octadecyloxytrimethylsilane in the n-octanol phase

was evaluated.

Concentration of octadecanol (hydrolysis product) and octadecyloxytrimethylsilane in

n-octanol phases:

determ. no.       octadecanol¹⁾ mg/l       octadecyloxytrimethylsilane mg/l       sum mg/l              ratio octadecanol/octadecyloxytrimethylsilane               recovery rate²⁾ %

A1                     376                                   612                                             988                            38/62                                                                      90

A2                     391                                   545                                             936                            42/58                                                                      85

B1                      266                                   586                                             852                            32/68                                                                      78

B2                     317                                   580                                             897                            36/64                                                                      82

C1                     428                                   504                                           932                            46/54                                                                      85

C2                     513                                   377                                           890                            58/42                                                                      81

1) estimated with response factor of octadecyloxytrimethylsilane

2) sum of octadecanol and octadecyloxytrimethylsilane vs. applied amount of octadecyloxytrimethylsilane

Description of key information

log Pow: > 4.1

Key value for chemical safety assessment

Log Kow (Log Pow):

4.1

at the temperature of:

23 °C

Additional information

The partition coefficient (log Pow) of the test substance was determined according to the

OECD Guideline for the Testing of Chemicals 107.

log Pow: > 4.1