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Environmental fate & pathways

Hydrolysis

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Administrative data

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Reference
Endpoint:
hydrolysis
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 111 (Hydrolysis as a Function of pH)
GLP compliance:
not specified
Analytical monitoring:
yes
Buffers:
The buffer solutions of pH4 and 7 were prepared with sodiumhydrogenphophate and citric acid. The solution of pH9 was prepared with boric acid, potassiumchloride and sodiumhydroxide. The buffer solutions were bubbled with helium to exclude dissolved oxygen.
Details on test conditions:
The stock solution was first made in methanol. Dilutions of this methanolic solution were made with the different buffers so that the final amount of organic solvent was less than 1% and the final concentration was less than half the saturation concentration according to the guideline.
Number of replicates:
four replicates in the main tests.
Preliminary study:
estimated half-lives at all pH (4, 7, and 9) > 2.4 hours
Transformation products:
not measured
pH:
4
Temp.:
25 °C
Hydrolysis rate constant:
0.01 h-1
DT50:
57 h
Key result
pH:
7
Temp.:
25 °C
Hydrolysis rate constant:
0.01 h-1
DT50:
53 h
pH:
9
Temp.:
25 °C
Hydrolysis rate constant:
0.01 h-1
DT50:
48 h
Validity criteria fulfilled:
not specified
Conclusions:
The determined half-lifes of N-(1,3-benzothiazol-2-ylsulfanyl)-N-cyclohexylcyclohexanamine at pH 4, 7 and 9 were 57, 53 and 48 hours, respectively (Bayer AG, 1997).
Executive summary:

The detrmined half-lifes of N-(1,3-benzothiazol-2-ylsulfanyl)-N-cyclohexylcyclohexanamine at pH 4, 7 and 9 were 57, 53 and 48 hours, respectively (Bayer AG, 1997).

Description of key information

According to the OECD Guideline 111 the hydrolysis half-lives of DCBS at pH 4, 7 and 9 were determined to be 57, 53 and 48 hours at 25°C, respectively (Bayer AG, 1997). The decrease of the concentrations of DCBS in buffer systems was followed by HPLC, but the identification of hydrolysis products were not carried out. In OECD-SIDS Initial Assessment Report of DCBS from 2004 the hydrolysis of DCBS at 50, 60 and 70°C were reported with Dicyclohexylamine and 2-mercaptobenzthiazole identified as hydrolysis products by LC-MS.

Key value for chemical safety assessment

Half-life for hydrolysis:
53 h
at the temperature of:
25 °C

Additional information

Although the study of CERI (2001) was used as critical study for SIDS endpoint, it is not used here as key study due to lack of detailed information and extrapolation of hydrolysis half-lives from 50, 60 and 70°C to 25 °C.