Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The standard sublimation enthalpies of 2,4-dichlorophenoxy acetic acid, 2,4-dichlorophenoxy propionic acid, 2,4-dichlorophenoxy butyric acid and their methyl esters 2,4-dichlorophenoxy acetic methyl ester and 2,4-dichlorophenoxy butyric methyl ester were determined from direct DSC measurements along with Langmuir and torsion effusion methods. For 2,4-dichlorophenoxy acetic acid, 2,4-dichlorophenoxy propionic acid and 2,4-dichlorophenoxy butyric acid, the following DsubHdeg (298 K)={(122+-5), (127+-8) and (137+-10) kJ*mol-1} respectively were selected. For 2,4-dichlorophenoxy acetic acid methyl ester and 2,4-dichlorophenoxy butyric acid methyl ester the DsubHdeg (298 K) final values 89 kJ*mol-1 and 100 kJ*mol-1 respectively were selected with an estimated error of +-10 kJ*mol-1. From torsion data the standard sublimation entropies for 2,4-dichlorophenoxy acetic acid, 2,4-dichlorophenoxy propionic acid and 2,4-dichlorophenoxy butyric acid equal to DsubSdeg (298 K)=239, 263 and 294 J*K-1*mol-1 respectively were derived, with an error of +- 4 J*K-1*mol-1 equal for all compounds.