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Environmental fate & pathways

Hydrolysis

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Description of key information

Using the Arrhenius relationship, the hydrolysis rate constants were 2.66 x 10-7/sec, 1.39 x 10-7/sec, and 3.39 x 10-6/sec at pH 4, 7, and 9, respectively, and the estimated half-lives was 30.1 days, 57.8 days, and 2.37 days, respectively. For direct hydrolysis testing, the hydrolysis rate constants were 2.65 x 10 -7/sec, 1.17 x 10 -7/sec, and 2.96 x 10-6/sec at pH 4, 7, and 9, respectively, and the estimated half-lives were 30.2 days, 68.8 days, and 2.71 days, respectively.

Key value for chemical safety assessment

Additional information

The hydrolysis as a function of pH of Dibutyl terephthalate (CAS 1962-75-0) has been determined using a procedure designed to be compatible with Method 111 of the OECD Guidelines for Testing of Chemicals, 13 April2004. Results have been reported for the estimated half-life calculated using the Arrhenius relationship and for the measured half-life using data from hydrolysis testing performed directly at 25 °C. Using the Arrhenius relationship, the rate constants were 2.66 x 10-7/sec, 1.39 x 10-7/sec, and 3.39 x 10-6/sec at pH 4, 7, and 9, respectively, and the estimated half-lives was 30.1 days, 57.8 days, and 2.37 days, respectively. For direct hydrolysis testing, the rate constants were 2.65 x 10-7/sec, 1.17 x 10-7/sec, and 2.96 x 10-6/sec at pH 4, 7, and 9, respectively, and the estimated half-lives were 30.2 days, 68.8 days, and 2.71 days, respectively.

Predicted values for hydrolysis also were determined using QSAR-SPARC (SPARC Performs Automated Reasoning in Chemistry), version 4.5- SPARC uses computational algorithms based on fundamental chemical structure theory. Execution involves the classification of molecular structures and the selection and execution of the appropriate “mechanistic” model. Predicted values for

Log Hydrolysis second order rate constants in water were -13.88, -6.66, and -1.69 L/Mol-sec for neutral pH, acidic pH, and basic pH, respectively.