Choline hydroxide

Boiling point

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

boiling point

Type of information:

(Q)SAR

Adequacy of study:

key study

Study period:

2017

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:

In this Case a QSAR was applied, for which no test guideline is required.

Boiling pt.:

144 °C

Remarks on result:

other: This QSAR test result was not provided with details on atmospheric pressure.

Conclusions:

The boiling point of choline hydroxide was calculated to be 144 °C.

Executive summary:

The boiling point of choline hydroxide was calculated with OPERA Model calculation. The boiling point was calculated to be 144 °C.

Reference 2

Endpoint:

boiling point

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2008-05-01 to 2008-06-02

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Data were gained within the flash point determination (well-documented GLP-study according Standard Test Method ASTM D93-07) of the 45% solution of choline base. The determination meets scientific principles and the given data indicate that the study was well-performed.

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:

other: Standard Test Method ASTM D93-07

Deviations:

not applicable

GLP compliance:

yes

Type of method:

other: flash point determination - open cup and closed cup flash point temperature (using the Pensky- Martens apparatus) under the non-equilibrium method

Boiling pt.:

> 90 - 99 °C

Atm. press.:

101.7 kPa

Decomposition:

ambiguous

Remarks:

grey vapours are indicative for decomposition

Decomp. temp.:

> 90 - 99 °C

Remarks on result:

other: at 90 - 99 °C the sample started to boil and produce grey vapours, extinguishing the test flame

Table 1: Full test results of Flash Point determination

Temperature °C	Barometric Pressure (kPa)	Ignition? Yes (y) / No (n)	Halo/ Enlarged test flame? Yes (y) / No (n)
20 – 29	101.7	n	n
30 – 39	101.7	n	n
40 – 49	101.7	n	n
50 – 59	101.7	n	n
60 – 69	101.7	n	n
70 – 79	101.7	n	n
80 – 89	101.7	n	n
*90 – 99	101.7	n	n
Fresh sample
20 – 29	101.7	n	n
30 – 39	101.7	n	n
40 – 49	101.7	n	n
50 – 59	101.7	n	n
60 – 69	101.7	n	n
70 – 79	101.7	n	n
80 – 89	101.7	n	n
*90 – 99	101.7	n	n

* - Sample started to boil and produce grey vapours which extinguished the test flame, therefore the test was terminated.

Conclusions:

The test was not performed according to one of the related test guidelines for the boiling point determination, but the examinations were made within a Klimisch 1 GLP guideline study for the flash point determinations including visual inspection of the test item. Hence, the observation that the "Sample started to boil and produce grey vapours which extinguished the test flame" at 90-99 °C can considered to be reliable. Since the test item in this study is a 45 % solution of the salt choline hydroxide, which is also the marketed form, it can be reasonably expected that the boiling point of this solution is related to the one of water, i.e. 100 °C at atmospheric pressure. So, the result is in the expected range and can therefore considered to be reliable.

Executive summary:

The boiling point of the 45 % solution of choline base was determined within the flash point determination (well-documented GLP-study according Standard Test Method ASTM D93-07) including visual inspection of the test item. It was observed that the sample started to boil and produce grey vapours which extinguished the test flame at 90-99 °C.

Description of key information

Boiling point: 90 - 99 °C (45 % aqueous solution of Choline base, start of boiling and production of grey vapours)

Calculated Boiling point of choline hydroxide with OPERA Model calculation: 144 °C.

 

In summary: The boiling point of the pure compound cannot be determined experimentally because the substance is expected to decompose before boiling. The boiling point of the pure substance was calculated to be 144 °C. Furthermore, the boiling point of an aqueous solution of Choline base (45 %) was reported as 90-99 °C.

Key value for chemical safety assessment

Boiling point at 101 325 Pa:

144 °C

Additional information

The Key study (Simmons Ch, 2008) was performed on a 45 % aqueous solution of choline hydroxide, which is the predominantly available form. The test was not performed according to one of the related test guidelines for the boiling point determination, but the examinations were made within a Klimisch 1 GLP guideline study for the flash point determinations including visual inspection of the test item. Hence, the observation that the "Sample started to boil and produce grey vapours which extinguished the test flame" at 90 - 99 °C can considered to be reliable. Since the test item in this study is a 45 % solution of the salt choline hydroxide, which is also the marketed form, it can be reasonably expected that the boiling point of this solution is related to the one of water, i.e. 100 °C at atmospheric pressure. So, the result is in the expected range and can therefore considered to be reliable.

Furthermore, the observation of grey vapours, resulting from a freeflowing, yellow tinted liquid, indicates first signs of decomposition of the test item, which is in general consistent with the observations made on another salt of choline, Choline chloride, which was tested without water.

 

Further information on the boiling point of choline hydroxide (pure) was provided with a OPERA Model calculation. The boiling point was calculated to be 144 °C.

 

So, in summary, the boiling point of pure choline hydroxide cannot be determined. According to REACH Annex VII section 7.3 Column 2, it is stated that the boiling point does not need to be determined if the substance decomposes before boiling. So, no datagaps were determined, and no further testing on the pure choline hydroxide is required. Since the 45 % aqueous solution of choline hydroxide is the predominantly available form on the market, it is justified to take its boiling point into consideration for risk assessment. The results here are reliable with restrictions and within the scientifically expected range, i.e. close to the boiling point of water. But also here, the grey vapours indicate decomposition.

So, sufficiently reliable data regarding the boiling points / decomposition temperature of both relevant forms of choline hydroxide is available, no datagaps were identified and the tonnage driven data requirement under REACH are fully met.