Acid chlorides, coco

Henry's Law constant

Description of key information

From the water surface the hydrolysis products (acyl halides) of acid chlorides, coco will not evaporate into the atmosphere. 

Additional information

Parent compounds:

The parent compounds hydrolyse rapdily in wet environments and form the corresponding acids and HCl.

Hydrolysis products (acyl halides):

The Henry's Law Constant (HLC) was calculated for the uncharged form with the bond estimation method (EPISUITE v4.10; BASF, 2012). Using the method described in the REACH Guidance Document R7a, Appendix R.7.1-2 (pH correction of partition coefficients for ionisable substances, p. 189), this HLC was corrected for the charged molecule at pH 4 - 9 (BASF, 2012). The table below summarises the data:

Hydrolysis product	CAS no.	Input parameter		Corrected HLC *
		HLC * (uncharged)	pKa**	pH 4	pH 5	pH 7	pH 9
Octanoic acid	124-07-2	0.304	4.75	2.58E-01	1.09E-01	1.70E-03	1.71E-05
Decanoic acid	334-48-5	0.535	4.75	4.54E-01	1.93E-01	2.99E-03	3.01E-05
Lauric acid / Dodecanoic acid	143-07-7	0.944	4.75	8.01E-01	3.40E-01	5.28E-03	5.31E-05
Myristic acid / Tetradecanoic acid	544-63-8	1.66	4.75	1.41E+00	5.97E-01	9.28E-03	9.33E-05
Palmitic acid / Hexadecanoic acid	57-10-3	2.93	4.75	2.49E+00	1.05E+00	1.64E-02	1.65E-04
Stearic acid / Octadecanoic acid	57-11-4	5.16	4.75	4.38E+00	1.86E+00	2.89E-02	2.90E-04

* HLC = Henry’s Law Constant in Pa*m³/mol (at 25 °C)

** pKa from SPARC estimation (see chapter 4.21)

As can be deduced from the corrected HLC data, at environmentally relevant pH of 5 - 9 the hydrolysis products will not evaporate into the atmosphere (HLC < 1 Pa*m³/mol). Only at low pH there is a small tendency of the longer-chained molecules to slowly evaporate, but based on measured data (VP/WSol - not shown here) this tendency can be neglected.

In conclusion, the HLC of the charged molecules is expected to be < 1 Pa*m³/mol (pH 5 -9, 25°C). Therefore, significant evaporation of the substance from water is unlikely.