4-[(2,4-dimethylphenyl)azo]-2,4-dihydro-5-methyl-2-phenyl-3H-pyrazol-3-one

Endpoint summary

Description of key information

Biodegradation in water

Biodegradability of 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one (CAS no. 6407 -78 -9) is predicted using QSAR toolbox version 3.3 (2017) with logKow as the primary descriptor. Test substance undergoes 5.68% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical 4 -[(E)-2 -(2,4 -dimethylphenyl) diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5 -one was estimated to be not readily biodegradable in water.

Additional information

Biodegradation in water

Various predicted data for the target compound 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one (CAS No. 6407-78-9) and supporting weight of evidence studies for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In a prediction done by SSS (2017) using OECD QSAR toolbox version 3.3 with logKow as the primary descriptor, percentage biodegradability of test chemical 4 -[(E)-2 -(2,4 -dimethylphenyl)diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5-one(CAS No. 6407-78-9) was estimated.Test substance undergoes 5.68% degradation by BOD in 28 days. Thus, based on percentage degradation, the test chemical4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-onewas estimated to be not readily biodegradable in water.

 

In another prediction using the Estimation Programs Interface Suite (EPI suite, 2017), the biodegradation potential of the test compound 4 -[(E)-2 -(2,4 -dimethylphenyl)diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5 -one(CAS No. 6407-78-9) in the presence of mixed populations of environmental microorganisms was estimated.The biodegradability of the substance was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical 4 -[(E)-2 -(2,4 -dimethylphenyl) diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5-oneis expected to be not readily biodegradable.

 

For the target chemical (CAS no. 6407-78-9) from secondary source (Environment Canada (EC) Health Canada (HC), 2016), biodegradability of test substance 4 -[(E)-2 -(2,4 -dimethylphenyl)diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5-one (CAS no.6407-78-9) was estimated using the BIOWIN Sub-models 3-6 and CATALOGIC model under aerobic conditions. The percentage degradation of chemical 4 -[(E)-2 -(2,4 -dimethylphenyl)diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5 -one was evaluated to be 0.56 -12.2% estimated by using the CATALOGIC model and on the basis of the output result of the BIOWIN Sub-models 3 -6, it indicates that chemical 4 -[(E)-2 -(2,4 -dimethylphenyl)diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5 -one biodegrades slowly. Thus, based on this, test chemical 4 -[(E)-2 -(2,4 -dimethylphenyl)diazen-1 -yl]-3 -methyl-1 -phenyl-4,5 -dihydro-1H-pyrazol-5 -one is considered to be not readily biodegradable in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017) for the read across chemical 1-Phenyl-3-methyl-5-pyrazolone (CAS no. 89-25-8),biodegradation experiment was conducted for 28 days for evaluating the percentage biodegradability of read across substance 1-Phenyl-3-methyl-5-pyrazolone. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of read across substance 1 -Phenyl-3 -methyl-5 -pyrazolone was determined to 0, 2 and 28% by BOD, TOC removal and HPLC parameter in 28 days. Thus, based on percentage degradation, 1-Phenyl-3-methyl-5-pyrazolone is considered to be not readily biodegradable in nature.

 

Another biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of another read across substance 1,2-bis(2-methylphenyl)guanidine (CAS no. 97-39-2) (J-CHECK, 2017 and secondary source OECD SIDS, 2007). The study was performed according to OECD Guide-line 301 C "Ready Biodegradability: Modified MITI Test under aerobic conditions. Activated sludge, non-adapted was used as a test inoculums for the study. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. Aniline was used as a reference substance for the study. Reference substance aniline undergoes 77 and 79% degradation after 14 and 28 days, respectively. The percentage degradation of substance 1,2 -bis(2 -methylphenyl)guanidine was determined to 1 and 0% by BOD and HPLC parameter in 28 days. Thus, based on percentage degradation,1,2-bis(2-methylphenyl)guanidine is considered to be not readily biodegradable in nature.

 

On the basis of above results for target chemical 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one(from OECD QSAR toolbox version 3.3, EPI suite, 2017 and secondary source, 2016) and for its read across substance (from authoritative database J-CHECK and secondary source OECD SIDS), it can be concluded that the test substance 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-onecan be expected to be not readily biodegradable in nature.