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EC number: 229-043-5 | CAS number: 6407-78-9
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
![](https://echa.europa.eu/o/diss-blank-theme/images/factsheets/A-REACH/factsheet/print_toxicological-information.png)
Endpoint summary
Administrative data
Description of key information
Acute oral toxicity:
Acute oral toxicity dose (LD50) for 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 predicted based on OECD QSAR toolbox 2906 mg/kg bw and different studies available on structurally similar read across substances 4,4'-(1E,1'E)-(3,3'-dichlorobiphenyl-4,4'-diyl)bis(diazene-2,1-diyl)bis(3-methyl-1-phenyl-1H-pyrazol-5(4H)-one) (CAS no: 3520-72-7) >5000 mg/kg bw and 3-methyl-1-phenyl-5-pyrazolone (CAS no: 89-25-8) > 2000 mg/kg bw. All these studies concluded that the LD50 value is >2000 mg/kg bw. Thus, comparing this value with the criteria of CLP regulation, 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one cannot be classified for acute oral toxicity.
Acute Inhalation Toxicity:
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) has very low vapour pressure (4.23E-07 Pa at 25°C), so the potential for the generation of inhalable vapours is very low. Also the normal conditions of use of this substance will not result in aerosols, particles or droplets of an inhalable size, so exposure to humans via the inhalatory route will be highly unlikely and therefore this end point was considered for waiver.
Key value for chemical safety assessment
Acute toxicity: via oral route
Link to relevant study records
- Endpoint:
- acute toxicity: oral
- Type of information:
- (Q)SAR
- Adequacy of study:
- weight of evidence
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- results derived from a valid (Q)SAR model and falling into its applicability domain, with limited documentation / justification
- Justification for type of information:
- Data is predicted using OECD QSAR toolbox version 3.3 and the supporting QMRF report has been attached.
- Qualifier:
- according to guideline
- Guideline:
- other: estimated data
- Principles of method if other than guideline:
- Prediction is done using QSAR Toolbox version 3.3.
- GLP compliance:
- not specified
- Test type:
- other: not specified
- Limit test:
- no
- Specific details on test material used for the study:
- Name: 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one
SMILES:Cc1ccc(N=NC2C(C)=NN(c3ccccc3)C2=O)c(C)c1
InChI:1S/C18H18N4O/c1-12-9-10-16(13(2)11-12)19-20-17-14(3)21-22(18(17)23)15-7-5-4-6-8-15/h4-11,17H,1-3H3/b20-19+
Molecular Weight: 306.367 g/mole
Mol. formula: C18H18N4O - Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- not specified
- Route of administration:
- oral: gavage
- Vehicle:
- unchanged (no vehicle)
- Details on oral exposure:
- not specified
- Doses:
- 2906 mg/kg
- No. of animals per sex per dose:
- 10
- Control animals:
- not specified
- Details on study design:
- not specified
- Statistics:
- not specified
- Preliminary study:
- not specified
- Sex:
- male/female
- Dose descriptor:
- LD50
- Effect level:
- 2 906 mg/kg bw
- Based on:
- test mat.
- Remarks on result:
- other: 50% mortality was observed
- Mortality:
- not specified
- Clinical signs:
- other: not specified
- Gross pathology:
- not specified
- Other findings:
- not specified
- Interpretation of results:
- other: Not classified
- Conclusions:
- LD50 was estimated to be 2906 mg/kg bw, when 10 male and female Sprague-Dawley rats were treated with 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) via oral gavage route.
- Executive summary:
In a prediction done by SSS (2017) using the OECD QSAR toolbox with log kow as the primary descriptor, the acute oral toxicity was estimated for 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). The LD50 was estimated to be 2906 mg/kg bw, when 10 male and female Sprague-Dawley rats were treated with 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one via oral gavage route.
Reference
The
prediction was based on dataset comprised from the following
descriptors: LD50
Estimation method: Takes average value from the 8 nearest neighbours
Domain logical expression:Result: In Domain
(((((("a"
or "b" or "c" or "d" or "e" or "f" or "g" )
and ("h"
and (
not "i")
)
)
and ("j"
and (
not "k")
)
)
and ("l"
and (
not "m")
)
)
and "n" )
and ("o"
and "p" )
)
Domain
logical expression index: "a"
Referential
boundary: The
target chemical should be classified as SN1 AND SN1 >> Nitrenium Ion
formation AND SN1 >> Nitrenium Ion formation >> Aromatic azo AND SN1 >>
Nitrenium Ion formation >> Unsaturated heterocyclic azo by DNA binding
by OECD
Domain
logical expression index: "b"
Referential
boundary: The
target chemical should be classified as Schiff base formation AND Schiff
base formation >> Pyrazolones and Pyrazolidinones derivatives AND Schiff
base formation >> Pyrazolones and Pyrazolidinones derivatives >>
Pyrazolones and Pyrazolidinones by Protein binding by OASIS v1.3
Domain
logical expression index: "c"
Referential
boundary: The
target chemical should be classified as Acylation AND Acylation >>
Direct Acylation Involving a Leaving group AND Acylation >> Direct
Acylation Involving a Leaving group >> Acetates AND SN2 AND SN2 >> SN2
reaction at sp3 carbon atom AND SN2 >> SN2 reaction at sp3 carbon atom
>> Alkyl diazo by Protein binding by OECD
Domain
logical expression index: "d"
Referential
boundary: The
target chemical should be classified as Amides AND Hydrazines by Aquatic
toxicity classification by ECOSAR
Domain
logical expression index: "e"
Referential
boundary: The
target chemical should be classified as Amides OR Hydrazines by Aquatic
toxicity classification by ECOSAR ONLY
Domain
logical expression index: "f"
Referential
boundary: The
target chemical should be classified as Acylation AND Acylation >>
Direct Acylation Involving a Leaving group AND Acylation >> Direct
Acylation Involving a Leaving group >> Acetates AND SN2 AND SN2 >> SN2
reaction at sp3 carbon atom AND SN2 >> SN2 reaction at sp3 carbon atom
>> Alkyl diazo by Protein binding by OECD
Domain
logical expression index: "g"
Referential
boundary: The
target chemical should be classified as Amides AND Hydrazines by Aquatic
toxicity classification by ECOSAR
Domain
logical expression index: "h"
Referential
boundary: The
target chemical should be classified as No alert found by DNA binding by
OASIS v.1.3
Domain
logical expression index: "i"
Referential
boundary: The
target chemical should be classified as Non-covalent interaction OR
Non-covalent interaction >> DNA intercalation OR Non-covalent
interaction >> DNA intercalation >> DNA Intercalators with Carboxamide
Side Chain OR Non-specific OR Non-specific >> Incorporation into
DNA/RNA, due to structural analogy with nucleoside bases OR
Non-specific >> Incorporation into DNA/RNA, due to structural analogy
with nucleoside bases >> Specific Imine and Thione Derivatives OR
Radical OR Radical >> Radical mechanism via ROS formation (indirect) OR
Radical >> Radical mechanism via ROS formation (indirect) >> Hydrazine
Derivatives OR Radical >> Radical mechanism via ROS formation (indirect)
>> Nitroarenes with Other Active Groups OR Radical >> Radical mechanism
via ROS formation (indirect) >> Specific Imine and Thione Derivatives OR
SN1 OR SN1 >> Nucleophilic attack after diazonium or carbenium ion
formation OR SN1 >> Nucleophilic attack after diazonium or carbenium ion
formation >> Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic
attack after reduction and nitrenium ion formation OR SN1 >>
Nucleophilic attack after reduction and nitrenium ion formation >>
Nitroarenes with Other Active Groups OR SN1 >> Nucleophilic substitution
on diazonium ions OR SN1 >> Nucleophilic substitution on diazonium ions
>> Specific Imine and Thione Derivatives OR SN2 OR SN2 >> SN2 attack on
activated carbon Csp3 or Csp2 OR SN2 >> SN2 attack on activated carbon
Csp3 or Csp2 >> Nitroarenes with Other Active Groups by DNA binding by
OASIS v.1.3
Domain
logical expression index: "j"
Referential
boundary: The
target chemical should be classified as (!Undefined)Group All Lipid
Solubility < 0.01 g/kg AND (!Undefined)Group CN Lipid Solubility < 0.4
g/kg AND Group All Melting Point > 200 C AND Group CN Aqueous Solubility
< 0.0001 g/L AND Group CN Aqueous Solubility < 0.1 g/L AND Group CN log
Kow > 4.5 AND Group CN log Kow > 5.5 AND Group CN Melting Point > 180 C
AND Group CN Molecular Weight > 290 g/mol AND Group CN Vapour Pressure <
0.001 Pa by Skin irritation/corrosion Exclusion rules by BfR
Domain
logical expression index: "k"
Referential
boundary: The
target chemical should be classified as (!Undefined)Group All log Kow <
-3.1 OR (!Undefined)Group All log Kow > 9 OR (!Undefined)Group All
Melting Point > 200 C OR (!Undefined)Group CNHal Lipid Solubility < 4
g/kg OR (!Undefined)Group CNHal Lipid Solubility < 400 g/kg OR
(!Undefined)Group CNS Surface Tension > 62 mN/m OR Group All log Kow <
-3.1 OR Group All log Kow > 9 OR Group CN Molecular Weight > 540 g/mol
OR Group CNHal Aqueous Solubility < 0.001 g/L OR Group CNHal Aqueous
Solubility < 0.1 g/L OR Group CNHal log Kow > 3.8 OR Group CNHal
Molecular Weight > 370 g/mol OR Group CNHal Molecular Weight > 380 g/mol
OR Group CNS log Kow < 0.5 OR Group CNS Melting Point > 120 C OR Group
CNS Melting Point > 50 C by Skin irritation/corrosion Exclusion rules by
BfR
Domain
logical expression index: "l"
Referential
boundary: The
target chemical should be classified as Inclusion rules not met by Skin
irritation/corrosion Inclusion rules by BfR
Domain
logical expression index: "m"
Referential
boundary: The
target chemical should be classified as Hydrazines,hydrazonium salts OR
Ketones by Skin irritation/corrosion Inclusion rules by BfR
Domain
logical expression index: "n"
Referential
boundary: The
target chemical should be classified as Not bioavailable by Lipinski
Rule Oasis ONLY
Domain
logical expression index: "o"
Parametric
boundary:The
target chemical should have a value of log Kow which is >= 4.21
Domain
logical expression index: "p"
Parametric
boundary:The
target chemical should have a value of log Kow which is <= 7.37
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- LD50
- Value:
- 2 906 mg/kg bw
- Quality of whole database:
- Data is Klimisch 2 and from QSAR toolbox 3.3.
Acute toxicity: via inhalation route
Link to relevant study records
- Endpoint:
- acute toxicity: inhalation
- Data waiving:
- other justification
- Justification for data waiving:
- other:
Reference
Endpoint conclusion
- Quality of whole database:
- Waiver
Acute toxicity: via dermal route
Endpoint conclusion
- Endpoint conclusion:
- no study available
Additional information
Acute oral toxicity:
In different studies, 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) has been investigated for acute oral toxicity to a greater or lesser extent. Often are the studies based on in-vivo experiments in rodents, i.e. most commonly in rats for 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one along with the study available on structurally similar read across substances 4,4'-(1E,1'E)-(3,3'-dichlorobiphenyl-4,4'-diyl)bis(diazene-2,1-diyl)bis(3-methyl-1-phenyl-1H-pyrazol-5(4H)-one) (3520-72-7) and 3-methyl-1-phenyl-5-pyrazolone (CAS no: 89-25-8). The predicted data using the OECD QSAR toolbox has also been compared with the experimental studies. The studies are summarized as below –
In a prediction done by SSS (2017) using the OECD QSAR toolbox with log kow as the primary descriptor, the acute oral toxicity was estimated for 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). The LD50 was estimated to be 2906 mg/kg bw, when 10 male and female Sprague-Dawley rats were treated with 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one via oral gavage route.
The above study is further supported by U.S. National Library of Medicine (ChemIDplus, 2017), for the structurally similar read across substance 4,4'-(1E,1'E)-(3,3'-dichlorobiphenyl-4,4'-diyl)bis(diazene-2,1-diyl)bis(3-methyl-1-phenyl-1H-pyrazol-5(4H)-one) (3520-72-7).Acute oral toxicity study was conducted in rats at the concentration of 5000 mg/kg bw. No Mortality was observed at dose5000 mg/kg bw. Hence, LD50 value was considered to be>5000 mg/kg bw, when rats were treated with4,4'-(1E,1'E)-(3,3'-dichlorobiphenyl-4,4'-diyl)bis(diazene-2,1-diyl)bis(3-methyl-1-phenyl-1H-pyrazol-5(4H)-one) via oral route.
This study is also supported by Scientific Committee on Consumer Products (SCCP, Opinion on phenyl methyl pyrazolone COLIPA N° A39; SCCP/1033/06, 19 December 2006),for the structurally similar read across substance 3-methyl-1-phenyl-5-pyrazolone (CAS no: 89-25-8). In a acute oral toxicity study, Sprague-Dawley male and female rat were treated at the concentration of 2000 mg/kg bw using three vehicles i.e.0.5% methylcellulose; 0.5% carboxymethylcellulose; propylene glycol orally by gavage. In Group 1 (vehicle: 0.5% methylcellulose), one female on day 1 and one male on day 2 was died. Group 2 (vehicle: 0.5% carboxymethylcellulose), One male died 4 hours after treatment, and 2 females died 4 hours or 6 hours after treatment, respectively. In Group 3 (vehicle: propylene glycol), No mortality was observed in treated male and female rat at 2000 mg/kg bw. In Group 1 (vehicle: 0.5% methylcellulose), hypoactivity or sedation, piloerection, ptosis of the eyelids, reddish colouration of the extremites, dyspnoea and rhinorrhea were observed in all animals on day 1. Lateral recumbence was noted in one female and Tremors were also observed in one male. Recovery was mentioned to be complete in the other animals. Group 2 (vehicle: 0.5% carboxymethylcellulose), hypoactivity or sedation, piloerection, ptosis of the eyelids, reddish colouration of the extremities, dyspnoea and rhinorrhea were observed in all animals on day 1. Recovery was mentioned to be complete in the other animals. In Group 3 (vehicle: propylene glycol), hypoactivity or sedation, piloerection, ptosis of the eyelids, reddish colouration of the extremities, dyspnoea and rhinorrhea were observed in all animals on day 1. Recovery was complete in all animals 6 hours after dosing. No effect on body weight gain observed in treated male and female rats during the 14 days observation period. No apparent macroscopic abnormalities were observed in treated male and female rats. Therefore, LD50 was considered to be > 2000 mg/kg bw, when Sprague-Dawley male and female rat were treated with didodecyl 3,3'-sulfanediyldipropanoate orally by gavage.
Thus, based on the above studies on 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 it’s read across substances, it can be concluded that LD50 value is >2000 mg/kg bw. Thus, comparing this value with the criteria of CLP regulation, 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one cannot be classified for acute oral toxicity.
Acute Inhalation Toxicity:
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) has very low vapour pressure (4.23E-07 Pa at 25°C), so the potential for the generation of inhalable vapours is very low. Also the normal conditions of use of this substance will not result in aerosols, particles or droplets of an inhalable size, so exposure to humans via the inhalatory route will be highly unlikely and therefore this end point was considered for waiver.
Justification for classification or non-classification
Based on the above studies and prediction on 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 it’s read across substances, it can be concluded that LD50 value is >2000 mg/kg bw for acute oral toxicity. Thus, comparing this value with the criteria of CLP regulation, 4-[(E)-2-(2,4-dimethylphenyl)diazen-1-yl]-3-methyl-1-phenyl-4,5-dihydro-1H-pyrazol-5-one cannot be classified for acute oral toxicity.For Acute Inhalation toxicity wavier were added so, not possible to classify.
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