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Hydrolysis

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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:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to
Guideline:
other: as mentioned below
Principles of method if other than guideline:
The study was performed to investigate the kinetics and pathways of the degradation of selected halogenated DBPs (Disinfection byproducts), i.e. chlral hydrate in the presence of carbonate green rust; GR(CO3 2-).
GLP compliance:
not specified
Specific details on test material used for the study:
- Name of test material: Tricholoro acetaldehyde hydrate (Chloral hydrate)
- Molecular formula: C2-H3-Cl3-O2
- Molecular weight: 165.4026g/mol
- Smiles notation: C(C(O)O)(Cl)(Cl)Cl
- InChl: RNFNDJAIBTYOQL-UHFFFAOYSA-N
- Substance type: Organic
- Physical state: Solid
Radiolabelling:
not specified
Analytical monitoring:
yes
Details on sampling:
Not specified
Buffers:
- pH: 7.5 initial pH
- Type and final molarity of buffer: 25 mM MOPS buffer and 50 mM carbonate buffer
- Composition of buffer: Not specified
Estimation method (if used):
no
Details on test conditions:
Not specified
pH:
7.5
Temp.:
23 °C
Initial conc. measured:
88.1 other: µM
Remarks:
88.1 ± 1.2 µM (in MOPS buffer) at 22 ± 3 °C
pH:
7.5
Temp.:
23 °C
Initial conc. measured:
84.8 other: µM
Remarks:
84.8 ± 1.3 µM (in carbonate buffer) at 22 ± 3 °C
Number of replicates:
2
Positive controls:
not specified
Negative controls:
not specified
Statistical methods:
The overall loss and individual hydrolysis and reductive dehalogenation pseudo-first-order rate constants of the DBPs were determined by fitting the experimental data using Scientist for Windows (v. 2.01, Micromath Research). One-electron reduction potentials for the dehalogenation half reactions (E1 H) were determined via free energies computed using computational chemistry software as described by Chun et al.
Transformation products:
yes
No.:
#1
Details on hydrolysis and appearance of transformation product(s):
- Formation and decline of each transformation product during test: not specified
- Pathways for transformation: Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO3 2-).
Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%).
- Other:
Key result
pH:
7.5
Temp.:
23 °C
Hydrolysis rate constant:
0.001 h-1
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: using MOPS buffer
Key result
pH:
7.5
Temp.:
23 °C
Hydrolysis rate constant:
0.002 h-1
Type:
(pseudo-)first order (= half-life)
Remarks on result:
other: using carbonate buffer
Other kinetic parameters:
Reductive dehalogenation rates were 2.2X103/hr MOPS buffer and 8.5X105/hr Carbonate buffer
Ratio of MOPS to carbonate buffer = 25.9
Details on results:
Chloroform (Trichloromethane) was unreactive over 300 h.
Results with reference substance:
Not specified
Validity criteria fulfilled:
not specified
Conclusions:
At an initial concentration of 88 and 84.8 uM hydrolysis rate constants for chloral hydrate was determined to be 1.0X10-3/hr and 1.8X10-3/hr using MOPS buffer and carbonate buffers respectively in the presence of carbonate green rust; GR(CO32-).
Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO32-).
Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%).
Executive summary:

The study was performed to investigate the kinetics and pathways of the degradation of selected halogenated DBPs (Disinfection byproducts), i.e. cholral hydrate in the presence of carbonate green rust; GR(CO32-). DBP degradation experiments were carried out in 123 mL serum bottles containing a 2.4 g/L GR(CO32-) suspension buffered at pH 7.5 with Ar-sparged 25 mM MOPS buffer or 50 mM carbonate buffer at 22±3 °C. All batch experiments were conducted in duplicate. The overall loss and individual hydrolysis and reductive dehalogenation pseudo-first-order rate constants of the DBPs were determined by fitting the experimental data using Scientist for Windows (v. 2.01, Micromath Research).

At an initial concentration of 88 and 84.8 uM hydrolysis rate constants for chloral hydrate was determined to be 1.0X10-3/hr and 1.8X10-3/hr using MOPS buffer and carbonate buffers respectively in the presence of GR(CO32-). Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO32-). Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%).

Thus, from above study it can be considered that the substance chloral hydrate is very slowly hydrolysable.

Description of key information

At an initial concentration of 88 and 84.8 uM hydrolysis rate constants for chloral hydrate was determined to be 1.0X10-3/hr and 1.8X10-3/hr using MOPS buffer and carbonate buffers respectively in the presence of carbonate green rust; GR(CO32-).

Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO32-).

Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%).

Key value for chemical safety assessment

Additional information

The study was performed to investigate the kinetics and pathways of the degradation of selected halogenated DBPs (Disinfection byproducts), i.e. cholral hydrate in the presence of carbonate green rust; GR(CO32-). DBP degradation experiments were carried out in 123 mL serum bottles containing a 2.4 g/L GR(CO32-) suspension buffered at pH 7.5 with Ar-sparged 25 mM MOPS buffer or 50 mM carbonate buffer at 22±3 °C. All batch experiments were conducted in duplicate. The overall loss and individual hydrolysis and reductive dehalogenation pseudo-first-order rate constants of the DBPs were determined by fitting the experimental data using Scientist for Windows (v. 2.01, Micromath Research).

At an initial concentration of 88 and 84.8 uM hydrolysis rate constants for chloral hydrate was determined to be 1.0X10-3/hr and 1.8X10-3/hr using MOPS buffer and carbonate buffers respectively in the presence of GR(CO32-). Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO32-). Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%).

Thus, from above study it can be considered that the substance chloral hydrate is very slowly hydrolysable.