Cyclohexanol

Melting point / freezing point

Link to relevant study record(s)

Reference

Reference 1

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

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 102 (Melting point / Melting Range)

Deviations:

no

Principles of method if other than guideline:

The heat capacity of cyclohexanol was measured between 14 and 320 °K with a low-temperature adiabatic calorimeter with plantinum resistance thermometer. The purified sample was transferred into the cell of the calorimeter (capacity of 30 cm3) by vacuum distillation. The weight of the sample employed was 27.548 g.

GLP compliance:

no

Type of method:

thermal analysis

Melting / freezing pt.:

25.9 °C

Atm. press.:

1 atm

Decomposition:

no

Sublimation:

no

An endothermic peak was observed consistently at 299K on cooling, corresponding to the freezing point, with several further endo- and exothermic transitions observed. No super cooling of the liquid state was observed with higher rates.

The melting point was corrected for pressure using the Clausius-Clapeyron equation.

Equilibrium temperatures during melting: 25.01% at 298.729K, 92.08% at 298.946K.

Conclusions:

The melting point/freezing point of the substance was determined to be 25.9 °C at atmospheric pressure.

Executive summary:

The heat capacity of cyclohexanol was measured between 14 and 320 °K with a low-temperature adiabatic calorimeter with plantinum resistance thermometer. The purified sample was transferred into the cell of the calorimeter (capacity of 30 cm3) by vacuum distillation. The weight of the sample employed was 27.548 g.
An endothermic peak was observed consistently at 299K on cooling at different rates, corresponding to the freezing point. The transition from solid to liquid occurred in a very narrow temperature range, and the melting point of pure cyclohexanol was determined to be 299 K. The melting point was corrected for pressure using the Clausius-Clapeyron equation.

Reference 2

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

documentation insufficient for assessment

Reason / purpose for cross-reference:

reference to same study

Qualifier:

no guideline followed

Principles of method if other than guideline:

Method of melting point determination not given. High purity claimed, which was achieved by unspecified purification step. All determined physical parameters in good agreement with high purity sample.

GLP compliance:

no

Type of method:

other: no data

Melting / freezing pt.:

25.26 °C

Atm. press.:

ca. 1 atm

Conclusions:

The melting point of purified substance was determined to be 25.26 °C.

Executive summary:

The melting point of a purified sample of cyclohexanol was determined to be 25.26 °C. The method of melting point determination was not described. Nevertheless, the value is in good agreement with other published experimental values.

Reference 3

Endpoint:

melting point/freezing point

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Remarks:

Only information from the abstract (English) was available, augmented by numerical results directly from the study (Japanese).

Reason / purpose for cross-reference:

reference to same study

Guideline:

other: no data

Principles of method if other than guideline:

No data

GLP compliance:

no

Melting / freezing pt.:

25.5 - 25.6 °C

Atm. press.:

ca. 1 atm

Conclusions:

The melting point was given as 25.5 to 25.6 °C at atmospheric pressure.

Reference 4

Endpoint:

melting point/freezing point

Type of information:

other: statistical review

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Statistical approach to available data, however, no attempt was made weight individual reported melting points for quality.

Qualifier:

no guideline followed

Principles of method if other than guideline:

The mean melting point was calculated for multiple measurements reported in the literature.

GLP compliance:

no

Type of method:

other: statistical review

Melting / freezing pt.:

24.1 °C

Atm. press.:

ca. 1 atm

Decomposition:

no

Sublimation:

no

Remarks on result:

other: 95%C.I. 23.67-24.54°C

Conclusions:

The mean literature melting point for cyclohexanol is 24.10 °C (23.67 – 24.54 °C). In addition to experimental uncertainty in the temperature measurement, the above statistical value can be expected to encompass variation due to sample purity, and unrecognised polymorphism. Bias introduced by data recycling cannot be excluded, but has been attempted to be controlled for, although without inspection of every literature reference.

Description of key information

24.10 °C (23.67 – 24.54 °C), statistical review of values of the melting point published in the literature (n = 26)

25.5-25.6 °C, Nitta 1948
25.62 °C, Hennings 1962
25.90 °C ±0.03 °C, Adachi 1968

Key value for chemical safety assessment

Melting / freezing point at 101 325 Pa:

24.1 °C

Additional information

A survey of available literature data was carried out for the melting point. The potential data sources were restricted to two bibliographic databases, augmented by data from studies previously identified as having high-quality results for other physico-chemical endpoints. No attempt was made to weight individual studies by reliability, instead a statistical approach was taken. Data from obvious secondary sources, and multiple reports of a numerically equivalent melting point by the same authors, were discarded as potential sources of bias due to data recycling. The mean melting point and confidence interval was calculated.

Three references with known high purity (Nitta, Hennings, Adachi) were reported with melting point somewhat higher than the mean value. This could be a reflection of melting point depression due to impurities, or potentially a result of unrecognised polymorphs in the literature.

The mean value is taken forward for the purposes of risk assessment, as being most representative of the commercial substance. The available data is considered to be relevant, reliable, and adequate for risk assessment purposes. The endpoint is considered complete, in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.1.1.