Choline hydroxide

Melting point / freezing point

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

melting point/freezing point

Type of information:

(Q)SAR

Adequacy of study:

key study

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 adequate and reliable documentation / justification

Qualifier:

no guideline required

Principles of method if other than guideline:

The melting point was calculated using the OPERA calculation Model.

Melting / freezing pt.:

60.3 °C

Conclusions:

The melting point of pure choline hydroxide was calculated to be 60.3 °C.

Executive summary:

The melting point of pure choline hydroxide was calculated with OPERA Model calculation. The melting point was calculated to be 60.3 °C.

Reference 2

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2013-03-06 to 2013-03-07

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented guideline study in accordance with OECD 102

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

GLP compliance:

yes

Type of method:

method to determine freezing temperature

Melting / freezing pt.:

< -20 °C

Atm. press.:

ca. 100 kPa

Remarks on result:

other: The test substance was not frozen, after overnight storage at -20 °C.

Conclusions:

The freezing point of a 45 % solution of choline hydroxide was determined in an OECD 102 guideline study and consideration of guidance given in ECHA Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance December 2016 Section R.7.1.2.1., classified as reliable without restrictions. On removal from the freezer, a visual assessment of the physical state of the test substance was performed and an observation that the test substance was not frozen was recorded. A full study does not need to be conducted below a lower limit of -20 °C. Hence the freezing point of the test item was determined to be < -20 °C in this study. The outcome of this study is considered reasonable and within the scientifically expected ranges.

Executive summary:

The freezing point of a 45 % aqueous solution of choline hydroxide was determined according to OECD Guideline 102 (Melting point / Melting Range). The freezing point of the test item was determined to be < -20 °C in this study.The study was classified as Klimisch 1 (reliable without restriction) and fully satisfies the requirements of OECD 102.

Description of key information

- Freezing point of a 45 % aqueous solution of choline hydroxide: < -20 °C at ca. 100.0 kPa (OECD Guideline 102 - Melting point / Melting Range)

- Melting point calculated for pure choline hydroxide (OPERA model): 60.3 °C

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

60.3 °C

Additional information

The freezing point of a 45 % solution of choline hydroxide was determined in an OECD 102 guideline study, classified as reliable without restrictions (Klimisch 1) and which meets fully the OECD 102 guideline requirements. Hence, the results in general are considered as reliable.

Although the salt choline hydroxide is a solid compound, it is very hygroscopic and cannot be kept water-free under normal environmental conditions. Furthermore, it is marketed as a 45 % aqueous solution and is therefore the predominantly available form. Hence, it is justified out of scientific reasons and exposure considerations to regard choline hydroxide as aqueous solution. In ECHA guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint Specific Guidance December 2016 Section R.7.1.2.1 is written that a full study does not need to be conducted below a lower limit of -20 °C. Therefore the determination of the freezing point of the test item in a preliminary test as < -20 °C is considered to be sufficient.

The study was classified as Klimisch 1, the tonnage-driven data requirements under REACH are fully met. So, in general, no datagaps were identified, no further testing is required and the freezing point of < -20 °C can be used for human risk assessment.

 

In addition, the melting point of pure choline hydroxide was calculated with OPERA Model calculation. The melting point was calculated to be 60.3 °C.