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Physical & Chemical properties

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Description of key information

Since Distilled  Tall Oil is a complex mixture, two aspects need to be considered in relation to physicochemical properties. In the context of raw material handling and safe use it is important to understand the properties of the product as a whole.

An overview of the physicochemical properties of the whole product is given in Section 1.3.2 while physicochemical properties of the constituent blocks are given in Section 1.3.3.

Additional information

Physicochemical properties of whole substance

Table 1.8 of the chemical safety report gives an overview of the physicochemical properties of the substance and the evaluation undertaken for each endpoint.

Physical appearance

DTO is an amber to dark brown liquid at standard temperature and pressure. The substance is a UVCB, variations in the physical appearance (colour and viscosity) of the substance may occur depending on the natural variation in composition of the substance.

Melting/freezing point

A freezing temperature of 253 K (-20.15°C) has been determined for DTO in a GLP study according to OECD 102. DTO was observed to become increasingly viscous during cooling.

Boiling point

A boiling point of 634 K (360.85°C) at 99.14 kPa has been determined for the substance in a GLP study in accordance to OECD 103. DTO is observed to partially boil with decomposition.

Relative density

Relative density of 0.942 g/cm3 at 20.0 ± 0.5ºC has been determined for DTO in a GLP study according to OECD 109. A value of 0.95 – 1.0 g/cm3 has been reported for the test substance in a pair reviewed source. The substance has a density slightly less than that of water at ambient temperature.

Vapour pressure

DTO is a UVCB substance with varied composition. The vapour pressures of constituents are described in 1.3.3. The vapour pressure of the substance as a whole has been estimated using the method reported by PFA 2010b. A negligible vapour pressure of 0.00385 Pa at 25°C has been determined for the registered substance.

Surface tension

An aqueous solution surface tension value of 63.5 mN/m at 22°C has been determined for DTO in a GLP study according to OECD 115. Distilled Tall Oil is considered not surface active.

Water solubility

Water solubility has been determined in a GLP study for the test substance using a method in accordance to OECD 105. DTO has a water solubility of 4.22 x 10-2g/L 20 °C, at pH 4 - 4.1. A water solubility of 9 mg/l is also reported for the test substance in its entirety as a complex substance using the same method as stated above.

The water solubility of samples of DTO with resin acid contents of 10 and 40% has been determined in accordance with OECD 105, respective values of 8.4 mg/L and 8.7 mg/L have been determined for the samples at 20°C. Distilled Tall Oil is considered slightly soluble. The water solubilities of constituents are described in 1.3.3.

Partition coefficient

The n-octanol/water partition coefficients of constituents of a sample of DTO have been determined in accordance with OECD 117. The partition coefficient at pH 2.0 was determined to be in the range log Kow = 4.9 – 7.7, in unbuffered conditions at pH 5 – 6, the log Kow range was 3.2 – 6.8. The Kow values of constituents are described in 1.3.3.

Viscosity

A viscosity value of 111 mm2/s at 20°C (static) and 44.1 mm2/s at 40°C (static) has been determined for DTO in a GLP study according to OECD 114.

Dissociation constants

No measured data for dissociation constant of Distilled Tall Oil were available. The pKa value (normal conditions) was predicted using SPARC.

While the acids constituents (Fatty and Resin acids) group is ionisable, neutrals constituents such as alcohols are extremely weak acids and only dissociate under strongly basic conditions. In the range of pH usually considered relevant to the human body and environment, i.e. pH 2-9, acid constituents will ionise while the neutrals will be non-ionised.

Flash point

A flash point of 405°F (207.22°C) is reported for DTO using an open cup (Cleveland) method according to Test Guideline D-803 ASTM (Drew and Propst 1981).

Flammability

The substance is classified as not flammable or highly flammable on the basis of a flash point of 405°F (207.22°C). Further detail is discussed in section 6.2.

Oxidising properties

DTO is not oxidising. Further detail is discussed in section 6.3 of the chemical safety report.

Explosive properties

DTO is not explosive. Further detail is discussed in section 6.1 of the chemical safety report.

Physicochemical properties of constituents

The relevant properties for each block (vapour pressure, water solubility, n-octanol/water partition coefficient (log Kow) and Henry’s Law constant (HLC)) have been determined using the methods described in PFA (2010b).

The resultant properties for each block are also shown in Table 1.9. Biodegradation and ecotoxicity properties are covered in Sections 4 and 7 respectively.

Table 1.9: Properties of blocks for DTO

Block

Constituents

Molecular weight

Vapour pressure at 25°C (Pa)

log Kow3

pKa

Water solubility at

25°C (mg/L)

HLC at 25°C (Pa.m3/mol)

Percentage block in substance

1

Low boiling fatty acids

228.38

3.46E-02

3.86

4.75

1.57E+01

5.04E-01

0.030

2

C16 saturated - C18.3 unsaturated fatty acids

280.86

5.71E-03

4.97

4.74

1.19E+00

2.51E+00

51

3

C18 saturated - C24 saturated and unsaturated fatty acids

313.20

3.43E-03

5.71

4.74

1.42E-01

7.50E+00

16

4

Abietic acid

301.87

2.70E-04

3.61

4.73

3.58E+00

2.13E-02

20

5

Palustric acid

302.46

4.73E-05

4.54

4.75

5.47E-01

9.08E-03

1.5

6

Pimaric acid

302.46

1.57E-05

3.65

4.64

3.15E+00

5.23E-04

5.7

7

Sesquiterpene

250.47

2.82E-01

7.87

-

1.30E-03

5.44E+04

0.010

8

Abietol

-

-

-

-

-

-

0.00

9

Tetracosanol and dehydrated sterol

357.72

7.31E-04

8.00

-

2.39E-04

1.09E+03

2.5

10

Aldehydes

286.46

1.62E-03

5.99

-

6.41E-01

6.24E+00

0.26

11

Dimethoxystilbene

240.30

4.29E-03

4.69

-

2.64E+00

3.90E-01

0.070

12

Sitosterols and analoque

414.72

5.03E-08

8.00

-

1.18E-03

1.76E-02

0.0022

13

Polymeric acids*

 

 

 

-

 

 

3.2

14

Polymeric neutrals*

 

 

 

-

 

 

0.27

3 This refers to the log Kow of the non-ionised form, which is the agreed convention; however, when necessary the data are used to estimate Kow at pH 7 by standard equations.

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