4-hydroxy-2,2,6,6-tetramethylpiperidinoxyl

Stability: thermal, sunlight, metals

Link to relevant study record(s)

Reference

Endpoint:

thermal stability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2012-07-06 to 2012-08-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: The study is regarded as reliable without restrictions because it was conducted in compliance with GLP regulation and guideline.

Qualifier:

according to guideline

Guideline:

OECD Guideline 113 (Screening Test for Thermal Stability and Stability in Air)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test substance thermally stable:

yes

Operating temp.:

>= 30 - <= 68 °C

Remarks on result:

other: All test showed an endothermic event (melting) with an mean onset temperature of 68 °C and an exothermal event (decomposition) starting at 150 °C and lasting over a wide temperature range up to approximately 300 °C.

Sublimation:

no

Test substance stable to sunlight:

not determined

Test substance stable to metals / metal ions:

not determined

In the table below the recorded data of all measurements are summarized.

Event No.	Heat flow	Exothermic events	Test 1	Test 2	Test 3
1	endothermal	Onset [°C]	68.3	68.4	66.1
2	exothermal	Onset [°C]	150	150	150
		Peak Maximum [°C]	212	213.6	211
		Int. norm. [J/g]	810	409	715.5
		Loss in weight [mg]	0.0	15.7	0.0
		Loss in weight [%]	0	85	0

 

All test showed an endothermic event (melting) with an mean onset temperature of 68 °C and an exothermal event (decomposition) starting at 150 °C and lasting over a wide temperature range up to approximately 300 °C. Experiment 2 was performed with an open crucible at ambient atmosphere. At this test a significant loss of mass was found.

Conclusions:

The test item is classified to be thermally stable at room temperature.

Description of key information

In a thermal stability study, no exothermal event was observed below the decomposition temperature. Therefore the test item 4-Hydroxy TEMPO is classified to be thermally stable at room temperature. 

Additional information

The thermal stability of 4-Hydroxy TEMPO was determined according to the OECD TG 113. Samples of the test item were weighed into glass crucibles. All samples were exposed to a temperature/time-gradient while the thermal heat-flow was recorded. All tests showed an endothermic event (melting) with an mean onset temperature of 68 °C and an exothermal event (decomposition) starting at 150 °C and lasting over a wide temperature range up to approximately 300 °C. According to the OECD Guideline 113 an exothermic event is assumed to be a decomposition. None of the results showed an exothermal event starting below 150 °C. Therefore the test item 4-Hydroxy TEMPO is classified to be thermally stable at room temperature.

Justification for classification or non-classification

Based on the study results, the substance was considered to be thermally stable at room temperature. No classification with regard to thermal stability according to Directive 67/548/EEC (DSD) and Regulation (EC) No 1272/2008 (CLP) is required.