Registration Dossier

Data platform availability banner - registered substances factsheets

Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Physical & Chemical properties

Melting point / freezing point

Currently viewing:

Administrative data

Link to relevant study record(s)

Referenceopen allclose all

Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
A combination of differential thermal analysis (DTA) with time-of-flight mass spectrometry and data storage on magnetic tape is used to study thermal decomposition of cyanuric acid.
GLP compliance:
not specified
Type of method:
thermal analysis
Melting / freezing pt.:
375 - 400 °C
Decomposition:
yes
Conclusions:
Based on the DTA (differential thermal analysis) data, CYA decomposes at 375-400°C. The decomposition is endothermic. Mass spectrometric analysis of the gaseous products identified isocyanic acid (HCNO, CAS 75-13-8) as the major product with some carbon monoxide (CO, CAS 630-08-0).
Endpoint:
melting point/freezing point
Type of information:
other: Handbook data
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
No method stated. Handbook data which provides result only
GLP compliance:
not specified
Melting / freezing pt.:
320 °C
Decomposition:
yes
Conclusions:
Cyanuric acid decomposes to cyanic acid at 320°C
Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
The thermal decomposition of urea has been studied under flow reactor conditions using a differential scanning calorimeter (DSC) and Fourier transformed infrared spectroscopy (FT-IR). Biuret and cyanuric acid were decomposed in a separate set of experiments.
GLP compliance:
not specified
Melting / freezing pt.:
375 - 440 °C
Decomposition:
yes
Conclusions:
CYA decomposes at 375-440°C by differential scanning calorimetry (DSC). Fourier transform infrared (FT-IR) spectroscopy of the gaseous products confirmed production of isocyanic acid (HCNO, CAS 75-13-8). The temperature range found might have been lower and narrower if the temperature scanning rate was slower than the 20°C/min used.
Endpoint:
melting point/freezing point
Type of information:
experimental study
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Principles of method if other than guideline:
A study was performed on the thermal decomposition of urea under open reaction vessel conditions by thermogravimetric analysis (TGA), HPLC, Fourier transform-infrared (FT-IR), and an ammonium ion-selective electrode (ISE). The thermal decomposition of urea produces cyanuric acid.
Type of method:
thermal analysis
Melting / freezing pt.:
320 - 375 °C
Decomposition:
yes
Decomp. temp.:
375 °C

.

Conclusions:
CYA decomposes to isocyanic acid (HCNO, CAS 75-13-8). Thermogravimetric analysis (TGA) showed minor decomposition at temperatures below 320°C. However, decomposition begins in earnest above 320°C and the decomposition rate increases with increasing temperature. Decomposition is complete by 375°C.
Endpoint:
melting point/freezing point
Type of information:
other: Handbook data
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
data from handbook or collection of data
Principles of method if other than guideline:
No method stated. Handbook data which provides results only
GLP compliance:
not specified
Melting / freezing pt.:
350 - 360 °C
Decomposition:
yes
Conclusions:
Cyanuric acid decomposes at 350-360°C to from gaseous isocyanic acid (HCNO, CAS 75-13-8) which can condense to re-form cyanuric acid when the gaseous HCNO is cooled.

Description of key information

Several sources of literature are available which give a melting point of cyanuric acid in the region of 320 - 440°C.

Key value for chemical safety assessment

Additional information