1-fluoro-2-nitrobenzene

Stability: thermal, sunlight, metals

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

thermal stability

Remarks:

DSC and ARC experiments and SADT determination

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

This safety study evaluated the thermal stability of 2-fluoronitrobenzene using Differential Scanning Calorimetry (DSC) and Accelerating Rate Calorimetry (ARC) experiments. In addition, the Self-Accelerating Decomposition Temperature (SADT) in a specific packaging was determined using the ARC method and by simulation with the TSS Thermokinetic Software.

GLP compliance:

no

Test substance thermally stable:

no

Remarks:

See "Any other information on results incl. tables"

1) Thermal stability using Differential Scanning Calorimetry (DSC)

 

Main heating procedure:

In the attached background material, see the thermogram in Appendix 2. In a heating mode of 2 °C/min, a highly energetic decomposition exotherm of 2906 J/g was observed between 350 and 425 °C (onset: 383 °C, peak: 400 °C), with a relatively fast kinetics.

 

Additional investigations:

- Other DSC experiments performed at heating rates of 0.5, 1 and 3 °C/min (in the attached background material, see the thermograms in Appendices 3 to 5): The order of magnitude of the decomposition energy was the same:

* Heating rate of 0.5 °C/min: A highly energetic decomposition exotherm of 3117 J/g was observed between ca. 330 and ca. 390 °C (onset: 362 °C, peak: 371 °C).

* Heating rate of 1 °C/min: A highly energetic decomposition exotherm of 3082 J/g was observed between ca. 345 and ca. 405 °C (onset: 371 °C, peak: 386 °C).

* Heating rate of 3 °C/min: A highly energetic decomposition exotherm of 3016 J/g was observed between ca. 350 and ca. 445 °C (onset: 392 °C, peak: 409 °C).

 

- Other DSC experiment conducted in an affiliated laboratory at heating rates of 1, 2 and 4° C/min (in the attached background document, see the thermogram in Appendix 6): The results are very close to the ones already obtained:

* Heating rate of 1 °C/min: A highly energetic decomposition exotherm of 3125 J/g was observed (onset: 315 °C, peak: 376 °C).

* Heating rate of 2 °C/min: A highly energetic decomposition exotherm of 3178 J/g was observed (onset: 313 °C, peak: 392 °C).

* Heating rate of 4 °C/min: A highly energetic decomposition exotherm of 2946 J/g was observed (onset: 333 °C, peak: 405 °C).

- Isothermal exposures at 330 and 350 °C for 24h (in the attached background document, see the thermograms in Appendices 7 and 8, respectively):

* Isothermal exposure at 330 °C: A highly energetic decomposition exotherm of 3046 J/g was observed.

* Isothermal exposure at 350 °C: A highly energetic decomposition exotherm of 2887 J/g was observed.

The heat flow is increasing at constant temperature. The decomposition kinetics is autocatalytic.

Conclusions from DSC experiments:

The decomposition onset temperature of 2-FNB is high but below 500°C and the decomposition energy is very high as well, higher than 500 J/g. Moreover, there is a NO2 group in the molecule which is associated with explosive properties and the oxygen balance for the molecule is -130 which is higher than the threshold of -200 defined in Section 2.1.4.3. of Annex I of CLP Regulation (EC) No 1272/2008. As a consequence, the explosive properties had to be investigated further and UN Test Series 1 is needed to decide on provisional acceptance or not of the substance into the class of explosives

2) Thermal stability using Acceleration Rate Calorimetry (ARC)

 

The exotherm detection temperature was 310.9°C. The ARC calorimeter switched to an adiabatic mode, with a temperature rise rate around 0.022°C/min and a pressure rise rate around 0.02 bar/min. The runaway reaction continued with a maximum temperature rise rate of 15.0°C/min reached at 376.1°C and a maximum pressure rise rate of 3.2 bar/min. The experiment stopped because the temperature exceeded the limit of the equipment (500°C). The final temperature was 499.5°C and the final pressure was 35.3 barA. After cooling at room temperature, the residual pressure was 13.7 barA. Therefore, there was formation of incondensable gases.

 

The ARC experiment thermal inertia or phi-factor was:

Φ= 1 + (m_cellx c_p.cell) / (m_samplex c_p.sample); where m = mass (kg) and c_p= specific heat capacity (J/kg/K)

Φ= 1 + (17.843 x 0.502) / (0.892 x 2.17) = 5.6.

The experimental temperature rise was: ΔT_exp> 499.5 – 310.9 = 188.6 °C.

The adiabatic temperature rise was: ΔT_ad>Φx ΔT_exp= 5.6 x 188.6 = 1061 °C.

The heat of decomposition was: ΔH_r> C_px ΔT_ad= 2.17 * 1061 = 2303 J/g.

This last value is lower than the value determined by DSC because the ARC experiment was interrupted by the control system during the exotherm.

 

3) SADT determination

 

SADT determination using the ARC method

 

SADT was determined to be equal to 280 °C using the Wilberforce derivation described in the field “Any other information on materials and methods incl. tables”. To apply this equation and the other ones described in the same field, the following parameters were used:

 

Parameter	Source (if relevant)	Value
SADT	Obtained from the Wilberforce derivation: SADT = TNR– (R x TNR^2) / EA)	551.8 K = 280 °C
R	Universal gas constant	8.314 J.mol^-1.K^-1
TNR	Determined from a curve representing the TMR on x-axis against the temperature on y-axis	559.2 K = 286 °C
TMR	TMR = τ = (m x Cp) / (U x A)	38820 s = 649.9 min
m	Measured	200.7 kg
Cp	Measured	2170 J.kg^-1.K^-1
U	It was assumed that 150 L of 2-FNB will be transported in a 180-L stainless steel barrel: U and A were taken from the ONU book for 200 L of 1H1 package	5.50 W.m^-2.K^-1
A		2.04 m^2
EA	Determined from the self-heat rate curve representing the decomposition kinetics between 311 °C (exotherm detection temperature during the ARC experiment) and 390 °C using zero-order kinetics	352.4 kJ/mol

SADT determination using simulation by TSS Software:

SADT values of 259 °C and 258 °C were obtained by simulation with the isoconversional and formal kinetic models, respectively, in a 180-liter stainless steel barrel.

Conclusions from SADT determinations:

As a conclusion, SADT is very high. The lowest value of 258 °C is obtained with the formal kinetic model (in a 180-liter stainless steel barrel). Therefore, SADT is higher than 75°C and the sample is not subjected to the classification procedure as a self-reactive substance.

Conclusions:

DSC experiments: During the main heating procedure with a heating mode of 2 °C/min, a highly energetic decomposition exotherm of 2906 J/g was observed between 350 and 425 °C (onset: 383 °C, peak: 400 °C), with a relatively fast kinetics. Additional DSC investigations confirmed the high exothermic decomposition energy.
ARC experiment: The onset temperature was determined at 310.9 °C with moderate temperature rise rates and pressure rise rates. There was formation of incondensable gases. A similarly high exothermic decomposition energy was determined.
SADT determination: Among the SADT values determined using the ARC method or by simulation with kinetic models in a 180-liter stainless steel barrel, the lowest obtained value was 258 °C.

Executive summary:

This safety study evaluated the thermal stability of 2-fluoronitrobenzene (2-FNB) using Differential Scanning Calorimetry (DSC) and Accelerating Rate Calorimetry (ARC) experiments. In addition, the Self-Accelerating Decomposition Temperature (SADT) in a specific packaging was determined using the ARC method and by simulation with the TSS Thermokinetic Software.

 

The main heating procedure conducted during the DSC experiments revealed that, in a heating mode of 2 °C/min, a highly energetic decomposition exotherm of 2906 J/g was observed between 350 and 425 °C (onset: 383 °C, peak: 400 °C), with a relatively fast kinetics. Additional DSC investigations performed at different heating rates, conducted in an affiliated laboratory or under isothermal exposures confirmed the high exothermic decomposition energy.

 

During the ARC experiment carried out to determine more precisely the onset temperature of 2-FNB sample decomposition, exotherm was detected at 310.9 °C with moderate temperature rise rates and pressure rise rates. There was formation of incondensable gases. A similarly high exothermic decomposition energy was determined.

 

The decomposition onset temperature of 2-FNB is thus high but below 500°C and the decomposition energy is very high as well, higher than 500 J/g. Moreover, there is a NO₂ group in the molecule which is associated with explosive properties and the oxygen balance for the molecule is -130 which is higher than the threshold of -200 defined in Section 2.1.4.3. of Annex I of CLP Regulation (EC) No 1272/2008. As a consequence, the explosive properties had to be investigated further and UN Test Series 1 is needed to decide on provisional acceptance or not of the substance into the class of explosives

 

Among the SADT values determined using the ARC method or by simulation with the isoconversional and formal kinetic models in a 180-liter stainless steel barrel, the lowest obtained value was 258 °C. Therefore, SADT is higher than 75°C and the sample is not subjected to the classification procedure as a self-reactive substance.

Reference 2

Endpoint:

thermal stability

Remarks:

DSC analysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 08 Jun 2015 to 22 Jan 2018

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Remarks:

A Klimisch score of 2 was assigned in spite of GLP compliance because several investigations had to be done before being able to finalise the report (for further details, see in the Endpoint Summary on thermal stability the description of the different experiments performed at Défitraces).

Reason / purpose for cross-reference:

reference to other study

Qualifier:

no guideline followed

Principles of method if other than guideline:

The objective of the test is to determine the behaviour of the test item during a heating procedure under nitrogen and at the atmospheric pressure using the Differential Scanning Calorimetry (DSC) method. This thermodynamic information allows determining if the test item gives exothermic reactions upon heating and if a more complete test on explosive properties is relevant.

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate from 2017-03-23

Test substance thermally stable:

no

Remarks:

See "Any other information on results incl. tables"

Key result

Operating temp.:

>= 25 - <= 600 °C

Remarks on result:

other: One exothermic peak was observed at about 420 °C. The enthalpy difference was 2668 J/g; corresponding to the exothermic decomposition energy.

Four assays were made: Three assays were not taken into account due to a wrong position of the crucible (assay No. 1), due to a too high weighing of the test item (assay No. 2) and due to the fact that the results were not reliable (assay No. 4). Results of assay No. 3 were reliable and were used to conclude the following:

One exothermic peak was observed at about 420 °C. The enthalpy difference was 2668 J/g, corresponding to the exothermic decomposition energy.

 

The onset of exothermic decomposition is thus below 500 °C and the exothermic reaction energy is thus more than 500 J/g; so the explosive properties of the test item should be investigated further.

Conclusions:

One exothermic peak was observed at about 420 °C. The enthalpy difference was 2668 J/g; corresponding to the exothermic decomposition energy.

Executive summary:

A Differential Scanning Calorimetry (DSC) analysis was run to determine the behaviour of 2-fluoronitrobenzene during a heating procedure under nitrogen and at the atmospheric pressure. One exothermic peak was observed at about 420 °C. The enthalpy difference was 2668 J/g; corresponding to the exothermic decomposition energy. The onset decomposition temperature was thus below 500 °C and the exothermic decomposition energy was thus above 500 J/g; implying that the explosive properties of 2-fluoronitrobenzene should be investigated further.

Reference 3

Endpoint:

thermal stability

Remarks:

DSC analysis

Type of information:

experimental study

Adequacy of study:

key study

Study period:

from 11 Feb 2019 to 04 Mar 2019

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Remarks:

Not GLP compliant, but ISO/IEC 17025 accreditation

Reason / purpose for cross-reference:

reference to other study

Qualifier:

according to guideline

Guideline:

other: ASTM E537-02 & DIN 51005

Principles of method if other than guideline:

The objective of the test was to determine the behaviour of the test item during a heating procedure in a closed atmosphere under air using the Differential Scanning Calorimetry (DSC) method. This thermodynamic information allows determining if the test item gives exothermic reactions upon heating and if a more complete test on explosive properties is relevant.

GLP compliance:

no

Other quality assurance:

ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)

Remarks:

Accreditation from 2016-07-26

Test substance thermally stable:

no

Remarks:

See "Any other information on results incl. tables"

Key result

Operating temp.:

ca. 25 - ca. 450 °C

Remarks on result:

other: An exothermic event was recorded from 329 to 436 °C with a peak at 411 °C. The exothermic reaction energy was 2751 J/g.

An exothermic event was recorded from 329 to 436 °C with a peak at 411 °C. The exothermic reaction energy was 2751 J/g.

The onset decomposition temperature was thus below 500 °C and the decomposition energy was thus above 500 J/g; implying that the explosive properties of the test item should be investigated further.

Conclusions:

An exothermic event was recorded from 329 to 436 °C with a peak at 411 °C. The exothermic reaction energy was 2751 J/g.

Executive summary:

A Differential Scanning Calorimetry (DSC) analysis was run to determine the behaviour of 2-fluoronitrobenzene during a heating procedure in a closed atmosphere under air. An exothermic event was recorded from 329 to 436 °C with a peak at 411 °C. The exothermic reaction energy was 2751 J/g. The onset decomposition temperature was thus below 500 °C and the exothermic decomposition energy was thus above 500 J/g; implying that the explosive properties of 2-fluoronitrobenzene should be investigated further.

Description of key information

Thermal stability:

DSC and ARC experiments: Several DSC and ARC analyses on 2-fluoronitrobenzene demonstrated that the onset of exothermic decomposition is below 500°C with an exothermic decomposition energy higher than 500 J/g; implying that the explosive properties of this substance should be investigated further.

SADT determination: Several methods were used to determine SADT (ARC method, simulation with kinetic models) and all the obtained values were clearly higher than 75 °C; implying that 2-fluoronitrobenzene is not subjected to the classification procedure as a self-reactive substance.

Additional information

Thermal stability:

DSC and ARC experiments:

Several DSC and ARC experiments were performed on 2-fluoronitrobenzene (2-FNB) over time:

- The risk of 2-fluoronitrobenzene thermal explosion was already studied in 1991 in Avonmouth (summarized here from the report of S. Egan, n°352/91/1574/SE/PM). DSC and autoclave experiments were carried out on 2-FNB. DSC experiment demonstrated that 2-FNB started decomposing from 380°C at a heating rate of 5°C/min, with a high released exothermic energy of 1246 J/g. The exotherm was not finished at 450°C. Therefore, the decomposition energy was underestimated. In the autoclave experiment, a violent exotherm was observed with gas generation from 345°C up to 500°C (5°C/min). The pressure increased from 10 barA to more than 200 barA.

- In 2015, Defitraces performed a DSC experiment on 2-FNB as well. One exothermic peak was observed at about 420°C (heating rate: 5 °C/min) and the decomposition energy was 441.8 J/g. Therefore, the onset of exothermic decomposition was below 500 °C and the exothermic decomposition energy was less than 500 J/g. Based on these conclusions and according to Section 2.1.4.3. of Annex I of CLP Regulation (EC) No 1272/2008, the substance should not be classified as explosive and the test on explosive properties could be waived. However, the discrepancies between these results and the previous ones (especially regarding the exothermic decomposition energy) encouraged to produce another experiment before concluding on the need to go ahead or not.

- This additional DSC experiment was performed by the Research & Innovation Center of Lyon (RICL) in 2016. During the main heating procedure of this study, with a heating mode of 2 °C/min, a highly energetic decomposition exotherm of 2906 J/g was observed between 350 and 425 °C (onset: 383 °C, peak: 400 °C), with a relatively fast kinetics. Additional DSC investigations confirmed the high exothermic decomposition energy. An ARC experiment was also carried out to determine more precisely the onset temperature of 2-FNB sample decomposition which was determined at 310.9 °C with moderate temperature rise rates and pressure rise rates. There was formation of incondensable gases. A similarly high exothermic decomposition energy was determined.

- Based on these observations, a new DSC assay was performed at Defitraces in 2018 which was in line with the result of the RICL, i.e. an exothermic peak was observed at about 420 °C with an exothermic reaction energy of more than 500 J/g (2668 J/g). Consequently the test report of Defitraces was amended with this new result and this amended report was included into the IUCLID endpoint study record. The origin of the very low value of exothermic decomposition energy found in the same laboratory in 2015 is still not understood.

- The DSC and ARC analyses performed at Avonmouth in 1991, at RICL in 2016 and at Defitraces in 2018 all confirmed that the onset of exothermic decomposition was below 500 °C and that the exothermic decomposition energy was above 500 J/g. This implied that the explosive properties of 2-fluoronitrobenzene had to be investigated further and it was decided to run UN Test Series 1 at Tüv-Süd Process Safety to decide on provisional acceptance or not of the substance into the class of explosives (see IUCLID Section 4.14).

- As a preamble to the performance of the UN Test Series 1, an additional DSC experiment was carried out at Tüv-Süd Process Safety in 2019. The obtained results confirmed the already available data (i.e. onset of exothermic decomposition < 500 °C and exothermic decomposition energy > 500 J/g). Indeed, an exothermic event was recorded from 329 to 436 °C with a peak at 411 °C (heating rate: 4 °C/min) and the exothermic reaction energy was 2751 J/g.

SADT determination:

During the study performed in 2016 at RICL, the Self-Accelerating Decomposition Temperature (SADT) in a specific packaging (180 L stainless steel barrel) was also determined using the ARC method and by simulation with the isoconversional and formal kinetic models using the TSS Thermokinetic Software. Among the SADT values obtained by these different ways, the lowest obtained value was 258 °C. Therefore, SADT was well higher than 75 °C and the sample was concluded as being not subjected to the classification procedure as a self-reactive substance.

Justification for classification or non-classification

Thermal stability (DSC and ARC experiments) and explosive properties: The DSC and ARC analyses performed on 2-fluoronitrobenzene confirmed that the onset of exothermic decomposition was below 500 °C and that the exothermic decomposition energy was above 500 J/g. This implied that the explosive properties had to be investigated further and it was decided to run UN Test Series 1 at Tüv-Süd Process Safety to decide on provisional acceptance or not of the substance into the class of explosives (see IUCLID Section 4.14).

Thermal stability (SADT determination) and self-reactive properties: Several methods were used to determine SADT (ARC method, simulation with kinetic models) and all the obtained values were clearly higher than 75 °C; implying that 2-fluoronitrobenzene is not subjected to the classification procedure as a self-reactive substance.